The difference is examined in atmospheric circulation and Sea Surface Temperatures (SSTs) in the trop-ics and subtropics between weak and strong convection over the tropical western Pacific warm pool (signified as WPW...The difference is examined in atmospheric circulation and Sea Surface Temperatures (SSTs) in the trop-ics and subtropics between weak and strong convection over the tropical western Pacific warm pool (signified as WPWP). The WPWP is chosen as the region (110–160°E, 10–20°N), where the Outgoing Longwave Radiation (OLR) shows a great year-to-year variance. A composite study was carried out to examine the differences in atmospheric circulation and SSTs between weak and strong convection over WPWP. First, NCEP/NCAR re-analysis data and satellite-observed OLR data are used to examine the differences. ERA data, in which the OLR data are calculated, are then used for re-examination. The composite results show that the differences are remarkably similar in these two sets of data. The difference in circulations between weak and strong convection over WPWP is significantly associated with westward extension of the North Pacific subtropical anticyclone and stronger westerlies at the northwestern edge of the subtropical anticyclone. It also corresponds with the significant easterly anomaly and the descent anomaly in situ, i.e., over the WPWP. The most prominent characteristics of the difference of SSTs between weak and strong convection over the WPWP are the significant positive SST anomalies in the Indian Ocean, the Bay of Bengal and the South China Sea. In WPWP, however, there are only weak negative SST anomalies. Thus, the anomaly of OLR over WPWP is weakly associated with the SST anomalies in situ, while closely associated with the SST anomalies west of WPWP. Key words Convection over the western Pacific warm pool - Northwest Pacific subtropical high - Sea surface temperatures This study was supported by the “ National Key Programme for Developing Basic Sciences” G1998040900 Part 1.展开更多
The present study analyzes the differences in spatial and temporal variations of surface temperatures between early and late onset years of the South China Sea summer monsoon （SCSSM）. It is found that when the land ...The present study analyzes the differences in spatial and temporal variations of surface temperatures between early and late onset years of the South China Sea summer monsoon （SCSSM）. It is found that when the land surface temperature north of 40°N is lower （higher） and the sea surface temperature over the South China Sea-western North Pacific （SCS-WNP） is higher （lower） in winter, the onset of the SCSSM begins earlier （later）. When the land surface temperature north of 40°N is higher （lower） and the sea surface temperature over the SCS-WNP is lower （higher） in spring, the onset of the SCSSM occurs earlier （later）. The reason why the anomalies of the land surface temperatures north of 40°N can influence the atmospheric circulation is investigated by analysis of the wind and temperature fields. In order to verify the mechanisms of influence over the land and sea surface temperature distribution patterns and test the ability of the p-σ regional climate model （p-σ RCM9） to simulate the SCSSM onset, three types of years with early, normal, and late SCSSM onset are selected and the SCSSM regimes are numerically simulated. According to the results obtained from five sensitive experiments, when the land surface temperature is higher in the eastern part, north of 40°N, and lower in the western part, north of 40°N, and it rises faster in the eastern coastal regions and the Indian Peninsula, while the sea surface temperatures over the SCS-WNP are lower, the early onset of the SCSSM can be expected.展开更多
Daily and weekly sea surface temperature data of Tropical Rainfall Measuring Mission (TRMM) Microwave Imager and Advanced Microwave Scanning Radiometer-Earth Observing System sensors are used as forcing of the underly...Daily and weekly sea surface temperature data of Tropical Rainfall Measuring Mission (TRMM) Microwave Imager and Advanced Microwave Scanning Radiometer-Earth Observing System sensors are used as forcing of the underlying sea surface in the mesoscale numerical model to simulate Typhoon Dujuan that moved across the South China Sea in 2003. The numerical results show that different SSTs near the typhoon center result in differences in the atmospheric wind field, indicating that the model has a fast and obvious response to SSTs. Different SST influences the intensity and track of Dujuan to some degree and has significant impacts on its precipitation and latent heat flux near the eye. The SST influence on Dujuan is mainly fulfilled by changing the latent heat flux between the ocean surface and the atmosphere above.展开更多
Ship-borne infrared radiometric measurements conducted during the Chinese National Arctic Research Expedition(CHINARE)in 2008,2010,2012,2014,2016 and 2017 were used for in situ validation studies of the Moderate Resol...Ship-borne infrared radiometric measurements conducted during the Chinese National Arctic Research Expedition(CHINARE)in 2008,2010,2012,2014,2016 and 2017 were used for in situ validation studies of the Moderate Resolution Imaging Spectroradiometer(MODIS)sea ice surface temperature(IST)product.Observations of sea ice were made using a KT19.85 radiometer mounted on the Chinese icebreaker Xuelong between July and September over six years.The MODIS-derived ISTs from the satellites,Terra and Aqua,both show close correspondence with ISTs derived from radiometer spot measurements averaged over areas of 4 km×4 km,spanning the temperature range of 262–280 K with a±1.7 K(Aqua)and±1.6 K(Terra)variation.The consistency of the results over each year indicates that MODIS provides a suitable platform for remotely deriving surface temperature data when the sky is clear.Investigation into factors that cause the MODIS IST bias(defined as the difference between MODIS and KT19.85 ISTs)shows that large positive bias is caused by increased coverage of leads and melt ponds,while large negative bias mostly arises from undetected clouds.Thin vapor fog forming over Arctic sea ice may explain the cold bias when cloud cover is below 20%.展开更多
In this study,the authors investigated changes in Last Glacial Maximum （LGM） sea surface temperature （SST） simulated by the Paleoclimate Modelling Intercomparison Project （PMIP） multimodels and reconstructed by ...In this study,the authors investigated changes in Last Glacial Maximum （LGM） sea surface temperature （SST） simulated by the Paleoclimate Modelling Intercomparison Project （PMIP） multimodels and reconstructed by the Multiproxy Approach for the Reconstruction of the Glacial Ocean Surface （MARGO） project,focusing on model-data comparison.The results showed that the PMIP models produced greater ocean cooling in the North Pacific and Tropical Ocean than the MARGO,particularly in the northwestem Pacific,where the modeldata mismatch was larger.All the models failed to capture the anomalous east-west SST gradient in the North Atlantic.In addition,large discrepancies among the models were observed in the mid-latitude ocean,particularly with models in the second phase of the PMIP.Although these models showed better agreement with the MARGO,the latest models in the third phase of the PMIP did not show substantial progresses in simulating LGM ocean surface conditions.That is,improvements in the modeling community are still needed to describe SST for a better understanding of climate during the LGM.展开更多
The aim of our study was to examine the contribution of surface waves from WAVEWATCH-III(WW3)to the variation in sea surface temperature(SST)in the Arctic Ocean.The simulated significant wave height(SWH)were validated...The aim of our study was to examine the contribution of surface waves from WAVEWATCH-III(WW3)to the variation in sea surface temperature(SST)in the Arctic Ocean.The simulated significant wave height(SWH)were validated against the products from Haiyang-2B(HY-2B)in 2021,obtaining a root mean squared error(RMSE)of 0.45 with a correlation of 0.96 and scatter index of 0.18.The wave-induced effects,i.e.,wave breaking and mixing induced by nonbearing waves resulting in changes in radiation stress and Stokes drift,were calculated from WW3,ERA-5 wind,SST,and salinity data from the National Centers for Environmental Prediction and were taken as forcing fields in the Stony Brook Parallel Ocean Model.The results showed that an RMSE of 0.81℃ with wave-induced effects was less than the RMSE of 1.11℃ achieved without the wave term compared with the simulated SST with the measurements from Argos.Considering the four wave effects and sea ice freezing,the SST in the Arctic Ocean decreased by up to 1℃ in winter.Regression analysis revealed that the SWH was linear in SST(values without subtraction of waves)in summer and autumn,but this behavior was not observed in spring or winter due to the presence of sea ice.The interannual variation also presented a negative relationship between the difference in SST and SWH.展开更多
Satellite-derived sea surface temperatures（SSTs） from the tropical rainfall measuring mission（TRMM）microwave imager（TMI） and the advanced microwave scanning radiometer for the earth observing system（AMSR-E） we...Satellite-derived sea surface temperatures（SSTs） from the tropical rainfall measuring mission（TRMM）microwave imager（TMI） and the advanced microwave scanning radiometer for the earth observing system（AMSR-E） were compared with non-pumped near-surface temperatures（NSTs） obtained from Argo profiling floats over the global oceans. Factors that might cause temperature differences were examined, including wind speed, columnar water vapor, liquid cloud water, and geographic location. The results show that both TMI and AMSR-E SSTs are highly correlated with the Argo NSTs; however, at low wind speeds, they are on average warmer than the Argo NSTs. The TMI performs slightly better than the AMSR-E at low wind speeds, whereas the TMI SST retrievals might be poorly calibrated at high wind speeds. The temperature differences indicate a warm bias of the TMI/AMSR-E when columnar water vapor is low, which can indicate that neither TMI nor AMSR-E SSTs are well calibrated at high latitudes. The SST in the Kuroshio Extension region has higher variability than in the Kuroshio region. The variability of the temperature difference between the satellite-retrieved SSTs and the Argo NSTs is lower in the Kuroshio Extension during spring. At low wind speeds, neither TMI nor AMSR-E SSTs are well calibrated, although the TMI performs better than the AMSR-E.展开更多
The North Atlantic Oscillation （NAO） is one of the leading modes of climate variability in the Northern Hemisphere. It has been shown that it clearly relates to changes in meteorological variables, such as surface t...The North Atlantic Oscillation （NAO） is one of the leading modes of climate variability in the Northern Hemisphere. It has been shown that it clearly relates to changes in meteorological variables, such as surface temperature, at hemispherical scales. However, recent studies have revealed that the NAO spatial pattern also depends upon solar forcing. Therefore, its effects on meteorological variables must vary depending upon this factor. Moreover, it could be that the Sun affects climate through variability patterns, a hypothesis that is the focus of this study. We find that the relationship between the NAO/AO and hemispheric temperature varies depending upon solar activity. The results show a positive significant correlation only when solar activity is high. Also, the results support the idea that solar activity influences tropospheric climate fluctuations in the Northern Hemisphere via the fluctuations of the stratospheric polar vortex .展开更多
The Alborz Mountains are some of the highest in Iran,and they play an important role in controlling the climate of the country’s northern regions.The land surface temperature(LST)is an important variable that affects...The Alborz Mountains are some of the highest in Iran,and they play an important role in controlling the climate of the country’s northern regions.The land surface temperature(LST)is an important variable that affects the ecosystem of this area.This study investigated the spatiotemporal changes and trends of the nighttime LST in the western region of the Central Alborz Mountains at elevations of 1500-4000 m above sea level.MODIS data were extracted for the period of 2000-2021,and the Mann-Kendall nonparametric test was applied to evaluating the changes in the LST.The results indicated a significant increasing trend for the monthly average LST in May-August along the southern aspect.Both the northern and southern aspects showed decreasing trends for the monthly average LST in October,November,and March and an increasing trend in other months.At all elevations,the average decadal change in the monthly average LST was more severe along the southern aspect(0.60°C)than along the northern aspect(0.37°C).The LST difference between the northern and southern aspects decreased in the cold months but increased in the hot months.At the same elevation,the difference in the lapse rate between the northern and southern aspects was greater in the hot months than in the cold months.With increasing elevation,the lapse rate between the northern and southern aspects disappeared.Climate change was concluded to greatly decrease the difference in LST at different elevations for April-July.展开更多
The significance of land surface temperature(LST)and near-surface air temperature(TAIR)extends to various applications,including the exploration of urban heat islands.Understanding urban heat islands is crucial for co...The significance of land surface temperature(LST)and near-surface air temperature(TAIR)extends to various applications,including the exploration of urban heat islands.Understanding urban heat islands is crucial for comprehending the intricate interactions among urbanization,climate dynamics,and human well-being.However,many aspects of these topics remain understudied.In this study,we conducted a comprehensive analysis of LST and TAIR,covering day and night and spanning all four seasons of a full year.We used global datasets and applied non-spatial and spatial analysis techniques in the Amman-Zarqa urban region,a typical arid to semiarid environment.The study had three primary objectives:(1)Assess how different human settlement types influence the variations in LST and TAIR across space and time.(2)Examine the spatial and temporal attributes of the relationships between TAIR and LST.(3)Synthesize insights regarding the spatial and temporal characteristics of urban heat islands in arid to semiarid environments.The findings unveiled that urban centers consistently exhibit the lowest daytime LST and maximum and minimum TAIR,across all seasons when compared to other human settlement types.Nighttime LST displayed more variable patterns.Urban centers act as surface urban cool islands during the day and canopy layer urban cool islands both day and night throughout the seasons.The presence of surface urban heat or cool islands at night is barely noticeable.Daytime and nighttime LST play a significant role in explaining the variability in maximum and minimum TAIR across all seasons,with the relationships exhibiting variations ranging from positive to non-significant to negative,influenced by location and seasonal changes.During the daytime,LST consistently exceeds TAIR across all seasons,whereas this relationship displays greater variability at night.The findings of this study hold significant implications for sustainable urban planning and efforts to combat the effects of urban heat islands.展开更多
With correlation analysis and factor analysis methods, the effects of preceding Pacific SSTs on subtropical high indexes of main raining seasons are discussed. The results of correlation analysis show that the effects...With correlation analysis and factor analysis methods, the effects of preceding Pacific SSTs on subtropical high indexes of main raining seasons are discussed. The results of correlation analysis show that the effects of SSTs on five subtropical high indexes differ in seasons and regions. The variation of SSTs mostly affects the area and intensity indexes of the subtropical high, followed by the western ridge index, and the effect on the ridge line index is more remarkable than on the north boundary index. The results of factor analysis reveals that the first common factor of SST of each season reflected mainly the inverse relation of SSTs variation between the central and eastern part of equatorial Pacific and the western Pacific, which correlates better with the subtropical high indexes in the main raining seasons than other common factors of SST. The analysis of interdecadal variation indicated that the variation of SSTs was conducive to the emergence of the La Ni?a event before the end of 1970s, such that in the summer the subtropical high is likely to be weaker and smaller and located eastward and northward. After the 1980s, the opposite characteristics prevailed.展开更多
This work examines the spatial and temporal patterns of seasonal sea surface temperatures (SSTs) across the Gulf of Mexico (GoM) for the period 1901-2010. The Extended Reconstructed Sea Surface Temperature, version 4 ...This work examines the spatial and temporal patterns of seasonal sea surface temperatures (SSTs) across the Gulf of Mexico (GoM) for the period 1901-2010. The Extended Reconstructed Sea Surface Temperature, version 4 (ERSST.v4), dataset was selected for this study over other reconstructions because of its 2° × 2° grid cell spatial resolution, its recent update to adjust for known biases in SST observations, and its ability to be compared to other in situ studies of GoM SSTs. The monthly ERSST.v4 data were averaged seasonally for each year and grid cell in the GoM. Seasonal SST trends were then calculated for each grid cell with varying start dates (e.g., 1901-2010, 1911- 2010) to account for nonlinear SST changes over the study period. Results indicate that the GoM SSTs closely resemble those of global annual temperature trends: SSTs warmed from 1901 to ~1940, followed by a period with little trend or a slight cooling until the mid-1970s, and then a warming afterwards through 2010. The spatial patterns and magnitudes of SST changes, however, varied by season and location within the GoM. The spatial patterns involved gradients with latitudinal and/or longitudinal components: a southwest-northeast (warmer-cooler) gradient in winter, an east-west (warmer-cooler) gradient in spring and fall, and a northwest-southeast (warmer-cooler) gradient in summer. The magnitude of SST changes tended to be largest in summer, followed by spring, fall, and winter. The long-term (1901-2010) SST trends were significant throughout the GoM in summer and fall, but only significant towards the southwestern GoM in winter and spring. These results have implications in discussion of climate change and its impacts on tropical activity in the GoM Basin.展开更多
Human activities have significantly impacted the land surface temperature(LST),endangering human health;however,the relationship between these two factors has not been adequately quantified.This study comprehensively ...Human activities have significantly impacted the land surface temperature(LST),endangering human health;however,the relationship between these two factors has not been adequately quantified.This study comprehensively constructs a Human Activity Intensity(HAI)index and employs the Maximal Information Coefficient,four-quadrant model,and XGBoostSHAP model to investigate the spatiotemporal relationship and influencing factors of HAI-LST in the Yellow River Basin(YRB)from 2000 to 2020.The results indicated that from 2000 to 2020,as HAI and LST increased,the static HAI-LST relationship in the YRB showed a positive correlation that continued to strengthen.This dynamic relationship exhibited conflicting development,with the proportion of coordinated to conflicting regions shifting from 1:4 to 1:2,indicating a reduction in conflict intensity.Notably,only the degree of conflict in the source area decreased significantly,whereas it intensified in the upper and lower reaches.The key factors influencing the HAI-LST relationship include fractional vegetation cover,slope,precipitation,and evapotranspiration,along with region-specific factors such as PM_(2.5),biodiversity,and elevation.Based on these findings,region-specific ecological management strategies have been proposed to mitigate conflict-prone areas and alleviate thermal stress,thereby providing important guidance for promoting harmonious development between humans and nature.展开更多
The near-surface lapse rate reflects the atmospheric stability above the surface.Lapse rates calculated from land surface temperature(γTs)and near-surface air temperature( γTa )have been widely used.However,γTs and...The near-surface lapse rate reflects the atmospheric stability above the surface.Lapse rates calculated from land surface temperature(γTs)and near-surface air temperature( γTa )have been widely used.However,γTs and γTa have different sensitivity to local surface energy balance and large-scale energy transport and therefore they may have diverse spatial and temporal variability,which has not been clearly illustrated in existing studies.In this study,we calculated and compared γTa and γTs at^2200 stations over China from 1961 to 2014.This study finds that γTa and γTs have a similar multiyear national average(0.53°C/100 m)and seasonal cycle.Nevertheless,γTs shows steeper multiyear average than γTa at high latitudes,and γTs in summer is steeper than γTa ,especially in Northwest China.The North China shows the shallowest γTa and γTs,then inhibiting the vertical diffusion of air pollutants and further reducing the lapse rates due to accumulation of pollutants.Moreover,the long-term trend signs for γTa and γTs are opposite in northern China.However,the trends in γTa and γTs are both negative in Southwest China and positive in Southeast China.Surface incident solar radiation,surface downward longwave radiation and precipitant frequency jointly can account for 80%and 75%of the long-term trends in γTa and γTs in China,respectively,which provides an explanation of trends of γTa and γTs from perspective of surface energy balance.展开更多
Land surface temperature(LST)is an important parameter in land surface processes.Improving the accuracy of LST retrieval over the entire Tibetan Plateau(TP)using satellite images with high spatial resolution is an imp...Land surface temperature(LST)is an important parameter in land surface processes.Improving the accuracy of LST retrieval over the entire Tibetan Plateau(TP)using satellite images with high spatial resolution is an important and essential issue for studies of climate change on the TP.In this study,a random forest regression(RFR)model based on different land cover types and an improved generalized single-channel(SC)algorithm based on linear regression(LR)were proposed.Plateau-scale LST products with a 30 m spatial resolution from 2006 to 2017 were derived by 109,978 Landsat 7 Enhanced Thematic Mapper Plus images and the application of the Google Earth Engine.Validation between LST results obtained from different algorithms and in situ measurements from Tibetan observation and research platform showed that the root mean square errors of the LST results retrieved by the RFR and LR models were 1.890 and 2.767 K,respectively,which were smaller than that of the MODIS product(3.625 K)and the original SC method(5.836 K).展开更多
We investigated the sensitivity of the size of a tropical cyclone(TC) to warming or cooling sea surface temperatures(SST) in its outer region by simulating the SST beyond a radius of 200 km from the TC center.Sensitiv...We investigated the sensitivity of the size of a tropical cyclone(TC) to warming or cooling sea surface temperatures(SST) in its outer region by simulating the SST beyond a radius of 200 km from the TC center.Sensitivity experiments showed that an increased SST outside the core region of the TC had a negative effect on its size.Warming in the outer region contributed to the local enhancement of the latent heat flux from sea surface,which promoted the development of small-scale convection and warmed the lower and midtroposphere.This warming altered the local pressure gradient force in the upper and lower troposphere in such a way that it weakened the secondary circulation of the TC and led to suppression of the spiral rainbands outside the eyewall.Further analysis showed that the outward-propagating rainband structure favored an increase in the size of the TC.The diabatic heat released by the rainbands induced an inflow at lower levels,facilitating expansion of the TC.The greater the distance of the rainbands from the center of the TC,given the same amplitude of diabatic heating,the stronger the forced inflow,resulting in a faster increase in the size of the TC.展开更多
The thermal effect of urban impervious surfaces （UIS） is a complex problem. It is thus necessary to study the relationship between UIS and land surface temperatures （LST） using complexity science theory and method...The thermal effect of urban impervious surfaces （UIS） is a complex problem. It is thus necessary to study the relationship between UIS and land surface temperatures （LST） using complexity science theory and methods. This paper investigates the long-range cross- correlation between UIS and LST with detrended cross- correlation analysis and multifractal detrended cross- correlation analysis, utilizing data from downtown Shanghai, China. UIS estimates were obtained from linear spectral mixture analysis, and LST was retrieved through application of the mono-window algorithm, using Landsat Thematic Mapper and Enhanced Thematic Mapper Plus data for 1997-2010. These results highlight a positive long-range cross-correlation between UIS and LST across People＇s Square in Shanghai. LST has a long memory for a certain spatial range of UIS values, such that a large increment in UIS is likely to be followed by a large increment in LST. While the multifractal long-range cross- correlation between UIS and LST was observed over a longer time period in the W-E direction （2002-2010） than in the N-S （2007-2010）, these observed correlations show a weakening during the study period as urbanization increased.展开更多
We investigate the relative importance of spring sea surface temperatures(SSTs)in different Indian Ocean(IO)domains,especially the northern and southern IO,for the development and intensity of the Asian summer monsoon...We investigate the relative importance of spring sea surface temperatures(SSTs)in different Indian Ocean(IO)domains,especially the northern and southern IO,for the development and intensity of the Asian summer monsoon.By performing unsupervised neural network analysis,the self-organizing map,we extract distinct patterns of springtime IO SST.The results show that the uniform warming(cooling)of the southern IO plays a crucial role in the warming(cooling)of both the basin-wide IO and tropical IO.The southern IO thus well represents the associations of basinwide IO and tropical IO with the Asian summer monsoon,and is instrumental in the relationship between the IO and summer monsoon.A warming in the southern IO is closely related to the weakening of large-scale meridional monsoon circulation in May and summer(June–August),including suppression of the South Asian monsoon development in May and the East Asian monsoon in summer.On the other hand,a warming in the northern IO appears to be associated with an earlier South Asian monsoon onset and a stronger East Asian monsoon.In summer,the connection of the springtime IO SST with the South Asian monsoon weakens,but that with the East Asian monsoon strengthens.Finally,a robust negative correlation is found between the warming of various IO domains and the development and intensity of the Southeast Asian monsoon.展开更多
Land surface temperature(LST)is the key variable in land-atmosphere interaction,having an important impact on weather and climate forecasting.However,achieving consistent analysis of LST and the atmosphere in assimila...Land surface temperature(LST)is the key variable in land-atmosphere interaction,having an important impact on weather and climate forecasting.However,achieving consistent analysis of LST and the atmosphere in assimilation is quite challenging.This is because there is limited knowledge about the cross-component background error covariance(BEC)between LST and atmospheric state variables.This study aims to clarify whether there is a relationship between the error of LST and atmospheric variables,and whether this relationship varies spatially and temporally.To this end,the BEC coupled with atmospheric variables and LST was constructed(LST-BEC),and its characteristics were analyzed based on the 2023 mei-yu season.The general characteristics of LST-BEC show that the LST is mainly correlated with the atmospheric temperature and the correlation decreases gradually with a rise in atmospheric height,and the error standard deviation of the LST is noticeably larger than that of the low-level atmospheric temperature.The spatiotemporal characteristics of LST-BEC on the heavy-rain day and light-rain day show that the error correlation and error standard deviation of LST and low-level atmospheric temperature and humidity are closely related to the weather background,and also have obvious diurnal variations.These results provide valuable information for strongly coupled land-atmosphere assimilation.展开更多
Global deforestation has been recognized as an important factor influencing climate change over the past century.However, uncertainties remain regarding its biophysical impacts on temperature across China. Utilizing m...Global deforestation has been recognized as an important factor influencing climate change over the past century.However, uncertainties remain regarding its biophysical impacts on temperature across China. Utilizing monthly data from eight global climate models of the Land Use Model Intercomparison Project, a multimodel comparison was conducted to quantitatively analyze the biophysical impacts of global deforestation on near-surface air temperature in China, using a surface energy balance decomposition method. Results show a 38%(29% to 45%) reduction in forest cover in China(ensemble mean and range across eight models) relative to pre-industrial levels, and an annual cooling of 0.6 K(0.05 to1.4 K) accompanied by global deforestation. Notably, surface albedo causes a cooling effect of 0.6 K(0.2 to 2.0 K), while surface latent and sensible heat fluxes partially offset this cooling by 0.2 K(-0.2 to 0.5 K) and 0.2 K(-0.04 to 0.6 K),respectively. These effects are more pronounced in winter and spring in deforested regions. Furthermore, the separation of atmospheric feedbacks under clear-sky and cloudy conditions show that the cloud radiative effect only accounts for 0.1 K(-0.1 to 0.4 K), while the clear-sky surface downward radiation is a significant cooling factor, contributing up to-0.5 K(-1.2 to 0.004 K), particularly in summer. However, the consistency of these models in simulating the impact of surface latent heat flux and albedo on surface temperature in China in response to deforestation is somewhat poor, highlighting the need to improve these related processes.展开更多
基金This study was supported by the " National Key Programme for Developing Basic Sciences"G 1998040900 Part 1.
文摘The difference is examined in atmospheric circulation and Sea Surface Temperatures (SSTs) in the trop-ics and subtropics between weak and strong convection over the tropical western Pacific warm pool (signified as WPWP). The WPWP is chosen as the region (110–160°E, 10–20°N), where the Outgoing Longwave Radiation (OLR) shows a great year-to-year variance. A composite study was carried out to examine the differences in atmospheric circulation and SSTs between weak and strong convection over WPWP. First, NCEP/NCAR re-analysis data and satellite-observed OLR data are used to examine the differences. ERA data, in which the OLR data are calculated, are then used for re-examination. The composite results show that the differences are remarkably similar in these two sets of data. The difference in circulations between weak and strong convection over WPWP is significantly associated with westward extension of the North Pacific subtropical anticyclone and stronger westerlies at the northwestern edge of the subtropical anticyclone. It also corresponds with the significant easterly anomaly and the descent anomaly in situ, i.e., over the WPWP. The most prominent characteristics of the difference of SSTs between weak and strong convection over the WPWP are the significant positive SST anomalies in the Indian Ocean, the Bay of Bengal and the South China Sea. In WPWP, however, there are only weak negative SST anomalies. Thus, the anomaly of OLR over WPWP is weakly associated with the SST anomalies in situ, while closely associated with the SST anomalies west of WPWP. Key words Convection over the western Pacific warm pool - Northwest Pacific subtropical high - Sea surface temperatures This study was supported by the “ National Key Programme for Developing Basic Sciences” G1998040900 Part 1.
基金supported by the National Natural Science Foundation of China under Grant No. 40675042
文摘The present study analyzes the differences in spatial and temporal variations of surface temperatures between early and late onset years of the South China Sea summer monsoon （SCSSM）. It is found that when the land surface temperature north of 40°N is lower （higher） and the sea surface temperature over the South China Sea-western North Pacific （SCS-WNP） is higher （lower） in winter, the onset of the SCSSM begins earlier （later）. When the land surface temperature north of 40°N is higher （lower） and the sea surface temperature over the SCS-WNP is lower （higher） in spring, the onset of the SCSSM occurs earlier （later）. The reason why the anomalies of the land surface temperatures north of 40°N can influence the atmospheric circulation is investigated by analysis of the wind and temperature fields. In order to verify the mechanisms of influence over the land and sea surface temperature distribution patterns and test the ability of the p-σ regional climate model （p-σ RCM9） to simulate the SCSSM onset, three types of years with early, normal, and late SCSSM onset are selected and the SCSSM regimes are numerically simulated. According to the results obtained from five sensitive experiments, when the land surface temperature is higher in the eastern part, north of 40°N, and lower in the western part, north of 40°N, and it rises faster in the eastern coastal regions and the Indian Peninsula, while the sea surface temperatures over the SCS-WNP are lower, the early onset of the SCSSM can be expected.
基金Natural Science Foundation of China (U0733002, 40876009)Natural Science Foundation of Guangdong Province (8351030101000002)+1 种基金Science and Technology Planning Project of Guangdong Province (2008B030303025)Tropical Marine Meteorology Science Research Project
文摘Daily and weekly sea surface temperature data of Tropical Rainfall Measuring Mission (TRMM) Microwave Imager and Advanced Microwave Scanning Radiometer-Earth Observing System sensors are used as forcing of the underlying sea surface in the mesoscale numerical model to simulate Typhoon Dujuan that moved across the South China Sea in 2003. The numerical results show that different SSTs near the typhoon center result in differences in the atmospheric wind field, indicating that the model has a fast and obvious response to SSTs. Different SST influences the intensity and track of Dujuan to some degree and has significant impacts on its precipitation and latent heat flux near the eye. The SST influence on Dujuan is mainly fulfilled by changing the latent heat flux between the ocean surface and the atmosphere above.
基金The National Natural Science Foundation of China under contract No.41606222the National Key Research and Development Project under contract No.2016YFC1400303.
文摘Ship-borne infrared radiometric measurements conducted during the Chinese National Arctic Research Expedition(CHINARE)in 2008,2010,2012,2014,2016 and 2017 were used for in situ validation studies of the Moderate Resolution Imaging Spectroradiometer(MODIS)sea ice surface temperature(IST)product.Observations of sea ice were made using a KT19.85 radiometer mounted on the Chinese icebreaker Xuelong between July and September over six years.The MODIS-derived ISTs from the satellites,Terra and Aqua,both show close correspondence with ISTs derived from radiometer spot measurements averaged over areas of 4 km×4 km,spanning the temperature range of 262–280 K with a±1.7 K(Aqua)and±1.6 K(Terra)variation.The consistency of the results over each year indicates that MODIS provides a suitable platform for remotely deriving surface temperature data when the sky is clear.Investigation into factors that cause the MODIS IST bias(defined as the difference between MODIS and KT19.85 ISTs)shows that large positive bias is caused by increased coverage of leads and melt ponds,while large negative bias mostly arises from undetected clouds.Thin vapor fog forming over Arctic sea ice may explain the cold bias when cloud cover is below 20%.
基金supported by the National Basic Research Program of China(2010CB951901)the Strategic Priority Research Program of the Chinese Academy of Sciences(XDA05120703)+2 种基金the National Natural Science Foundation of China(41205051)supported by CEA(Centre dEtudes Atomiques),CNRS(Centre National de la Recherche Scientifique),the EU(European Union)project MOTIF(EVK2-CT-2002-00153)the Programme National d'Etude de la Dynamique du Climat(PNEDC)
文摘In this study,the authors investigated changes in Last Glacial Maximum （LGM） sea surface temperature （SST） simulated by the Paleoclimate Modelling Intercomparison Project （PMIP） multimodels and reconstructed by the Multiproxy Approach for the Reconstruction of the Glacial Ocean Surface （MARGO） project,focusing on model-data comparison.The results showed that the PMIP models produced greater ocean cooling in the North Pacific and Tropical Ocean than the MARGO,particularly in the northwestem Pacific,where the modeldata mismatch was larger.All the models failed to capture the anomalous east-west SST gradient in the North Atlantic.In addition,large discrepancies among the models were observed in the mid-latitude ocean,particularly with models in the second phase of the PMIP.Although these models showed better agreement with the MARGO,the latest models in the third phase of the PMIP did not show substantial progresses in simulating LGM ocean surface conditions.That is,improvements in the modeling community are still needed to describe SST for a better understanding of climate during the LGM.
基金supported by the National Natural Science Foundation of China(Nos.42076238 and 42376174)the Natural Science Foundation of Shanghai(No.23ZR1426900).
文摘The aim of our study was to examine the contribution of surface waves from WAVEWATCH-III(WW3)to the variation in sea surface temperature(SST)in the Arctic Ocean.The simulated significant wave height(SWH)were validated against the products from Haiyang-2B(HY-2B)in 2021,obtaining a root mean squared error(RMSE)of 0.45 with a correlation of 0.96 and scatter index of 0.18.The wave-induced effects,i.e.,wave breaking and mixing induced by nonbearing waves resulting in changes in radiation stress and Stokes drift,were calculated from WW3,ERA-5 wind,SST,and salinity data from the National Centers for Environmental Prediction and were taken as forcing fields in the Stony Brook Parallel Ocean Model.The results showed that an RMSE of 0.81℃ with wave-induced effects was less than the RMSE of 1.11℃ achieved without the wave term compared with the simulated SST with the measurements from Argos.Considering the four wave effects and sea ice freezing,the SST in the Arctic Ocean decreased by up to 1℃ in winter.Regression analysis revealed that the SWH was linear in SST(values without subtraction of waves)in summer and autumn,but this behavior was not observed in spring or winter due to the presence of sea ice.The interannual variation also presented a negative relationship between the difference in SST and SWH.
基金The National Basic Research Program(973 Program)of China under contract No.2013CB430301the National Natural Science Foundation of China under contract Nos 41440039,41206022 and 41406022the Public Science and Technology Research Funds Projects of Ocean under contract No.201305032
文摘Satellite-derived sea surface temperatures（SSTs） from the tropical rainfall measuring mission（TRMM）microwave imager（TMI） and the advanced microwave scanning radiometer for the earth observing system（AMSR-E） were compared with non-pumped near-surface temperatures（NSTs） obtained from Argo profiling floats over the global oceans. Factors that might cause temperature differences were examined, including wind speed, columnar water vapor, liquid cloud water, and geographic location. The results show that both TMI and AMSR-E SSTs are highly correlated with the Argo NSTs; however, at low wind speeds, they are on average warmer than the Argo NSTs. The TMI performs slightly better than the AMSR-E at low wind speeds, whereas the TMI SST retrievals might be poorly calibrated at high wind speeds. The temperature differences indicate a warm bias of the TMI/AMSR-E when columnar water vapor is low, which can indicate that neither TMI nor AMSR-E SSTs are well calibrated at high latitudes. The SST in the Kuroshio Extension region has higher variability than in the Kuroshio region. The variability of the temperature difference between the satellite-retrieved SSTs and the Argo NSTs is lower in the Kuroshio Extension during spring. At low wind speeds, neither TMI nor AMSR-E SSTs are well calibrated, although the TMI performs better than the AMSR-E.
文摘The North Atlantic Oscillation （NAO） is one of the leading modes of climate variability in the Northern Hemisphere. It has been shown that it clearly relates to changes in meteorological variables, such as surface temperature, at hemispherical scales. However, recent studies have revealed that the NAO spatial pattern also depends upon solar forcing. Therefore, its effects on meteorological variables must vary depending upon this factor. Moreover, it could be that the Sun affects climate through variability patterns, a hypothesis that is the focus of this study. We find that the relationship between the NAO/AO and hemispheric temperature varies depending upon solar activity. The results show a positive significant correlation only when solar activity is high. Also, the results support the idea that solar activity influences tropospheric climate fluctuations in the Northern Hemisphere via the fluctuations of the stratospheric polar vortex .
文摘The Alborz Mountains are some of the highest in Iran,and they play an important role in controlling the climate of the country’s northern regions.The land surface temperature(LST)is an important variable that affects the ecosystem of this area.This study investigated the spatiotemporal changes and trends of the nighttime LST in the western region of the Central Alborz Mountains at elevations of 1500-4000 m above sea level.MODIS data were extracted for the period of 2000-2021,and the Mann-Kendall nonparametric test was applied to evaluating the changes in the LST.The results indicated a significant increasing trend for the monthly average LST in May-August along the southern aspect.Both the northern and southern aspects showed decreasing trends for the monthly average LST in October,November,and March and an increasing trend in other months.At all elevations,the average decadal change in the monthly average LST was more severe along the southern aspect(0.60°C)than along the northern aspect(0.37°C).The LST difference between the northern and southern aspects decreased in the cold months but increased in the hot months.At the same elevation,the difference in the lapse rate between the northern and southern aspects was greater in the hot months than in the cold months.With increasing elevation,the lapse rate between the northern and southern aspects disappeared.Climate change was concluded to greatly decrease the difference in LST at different elevations for April-July.
基金funded by Natural Sciences and Engineering Research Council of Canada(NSERC)[RGPIN-2022-04342].
文摘The significance of land surface temperature(LST)and near-surface air temperature(TAIR)extends to various applications,including the exploration of urban heat islands.Understanding urban heat islands is crucial for comprehending the intricate interactions among urbanization,climate dynamics,and human well-being.However,many aspects of these topics remain understudied.In this study,we conducted a comprehensive analysis of LST and TAIR,covering day and night and spanning all four seasons of a full year.We used global datasets and applied non-spatial and spatial analysis techniques in the Amman-Zarqa urban region,a typical arid to semiarid environment.The study had three primary objectives:(1)Assess how different human settlement types influence the variations in LST and TAIR across space and time.(2)Examine the spatial and temporal attributes of the relationships between TAIR and LST.(3)Synthesize insights regarding the spatial and temporal characteristics of urban heat islands in arid to semiarid environments.The findings unveiled that urban centers consistently exhibit the lowest daytime LST and maximum and minimum TAIR,across all seasons when compared to other human settlement types.Nighttime LST displayed more variable patterns.Urban centers act as surface urban cool islands during the day and canopy layer urban cool islands both day and night throughout the seasons.The presence of surface urban heat or cool islands at night is barely noticeable.Daytime and nighttime LST play a significant role in explaining the variability in maximum and minimum TAIR across all seasons,with the relationships exhibiting variations ranging from positive to non-significant to negative,influenced by location and seasonal changes.During the daytime,LST consistently exceeds TAIR across all seasons,whereas this relationship displays greater variability at night.The findings of this study hold significant implications for sustainable urban planning and efforts to combat the effects of urban heat islands.
文摘With correlation analysis and factor analysis methods, the effects of preceding Pacific SSTs on subtropical high indexes of main raining seasons are discussed. The results of correlation analysis show that the effects of SSTs on five subtropical high indexes differ in seasons and regions. The variation of SSTs mostly affects the area and intensity indexes of the subtropical high, followed by the western ridge index, and the effect on the ridge line index is more remarkable than on the north boundary index. The results of factor analysis reveals that the first common factor of SST of each season reflected mainly the inverse relation of SSTs variation between the central and eastern part of equatorial Pacific and the western Pacific, which correlates better with the subtropical high indexes in the main raining seasons than other common factors of SST. The analysis of interdecadal variation indicated that the variation of SSTs was conducive to the emergence of the La Ni?a event before the end of 1970s, such that in the summer the subtropical high is likely to be weaker and smaller and located eastward and northward. After the 1980s, the opposite characteristics prevailed.
文摘This work examines the spatial and temporal patterns of seasonal sea surface temperatures (SSTs) across the Gulf of Mexico (GoM) for the period 1901-2010. The Extended Reconstructed Sea Surface Temperature, version 4 (ERSST.v4), dataset was selected for this study over other reconstructions because of its 2° × 2° grid cell spatial resolution, its recent update to adjust for known biases in SST observations, and its ability to be compared to other in situ studies of GoM SSTs. The monthly ERSST.v4 data were averaged seasonally for each year and grid cell in the GoM. Seasonal SST trends were then calculated for each grid cell with varying start dates (e.g., 1901-2010, 1911- 2010) to account for nonlinear SST changes over the study period. Results indicate that the GoM SSTs closely resemble those of global annual temperature trends: SSTs warmed from 1901 to ~1940, followed by a period with little trend or a slight cooling until the mid-1970s, and then a warming afterwards through 2010. The spatial patterns and magnitudes of SST changes, however, varied by season and location within the GoM. The spatial patterns involved gradients with latitudinal and/or longitudinal components: a southwest-northeast (warmer-cooler) gradient in winter, an east-west (warmer-cooler) gradient in spring and fall, and a northwest-southeast (warmer-cooler) gradient in summer. The magnitude of SST changes tended to be largest in summer, followed by spring, fall, and winter. The long-term (1901-2010) SST trends were significant throughout the GoM in summer and fall, but only significant towards the southwestern GoM in winter and spring. These results have implications in discussion of climate change and its impacts on tropical activity in the GoM Basin.
基金Shanxi Province Graduate Research Practice Innovation Project,No.2023KY465Project on the Reform of Graduate Education and Teaching in Shanxi Province,No.2021YJJG146+1 种基金Research Project of Shanxi Provincial Cultural Relics Bureau,No.22-8-14-1400-119National Key R&D Program of China,No.2021YFB3901300。
文摘Human activities have significantly impacted the land surface temperature(LST),endangering human health;however,the relationship between these two factors has not been adequately quantified.This study comprehensively constructs a Human Activity Intensity(HAI)index and employs the Maximal Information Coefficient,four-quadrant model,and XGBoostSHAP model to investigate the spatiotemporal relationship and influencing factors of HAI-LST in the Yellow River Basin(YRB)from 2000 to 2020.The results indicated that from 2000 to 2020,as HAI and LST increased,the static HAI-LST relationship in the YRB showed a positive correlation that continued to strengthen.This dynamic relationship exhibited conflicting development,with the proportion of coordinated to conflicting regions shifting from 1:4 to 1:2,indicating a reduction in conflict intensity.Notably,only the degree of conflict in the source area decreased significantly,whereas it intensified in the upper and lower reaches.The key factors influencing the HAI-LST relationship include fractional vegetation cover,slope,precipitation,and evapotranspiration,along with region-specific factors such as PM_(2.5),biodiversity,and elevation.Based on these findings,region-specific ecological management strategies have been proposed to mitigate conflict-prone areas and alleviate thermal stress,thereby providing important guidance for promoting harmonious development between humans and nature.
基金This work was supported by the National Key Research&Development Program of China(2017YFA0603601)the National Natural Science Foundation of China(41525018 and 41930970)。
文摘The near-surface lapse rate reflects the atmospheric stability above the surface.Lapse rates calculated from land surface temperature(γTs)and near-surface air temperature( γTa )have been widely used.However,γTs and γTa have different sensitivity to local surface energy balance and large-scale energy transport and therefore they may have diverse spatial and temporal variability,which has not been clearly illustrated in existing studies.In this study,we calculated and compared γTa and γTs at^2200 stations over China from 1961 to 2014.This study finds that γTa and γTs have a similar multiyear national average(0.53°C/100 m)and seasonal cycle.Nevertheless,γTs shows steeper multiyear average than γTa at high latitudes,and γTs in summer is steeper than γTa ,especially in Northwest China.The North China shows the shallowest γTa and γTs,then inhibiting the vertical diffusion of air pollutants and further reducing the lapse rates due to accumulation of pollutants.Moreover,the long-term trend signs for γTa and γTs are opposite in northern China.However,the trends in γTa and γTs are both negative in Southwest China and positive in Southeast China.Surface incident solar radiation,surface downward longwave radiation and precipitant frequency jointly can account for 80%and 75%of the long-term trends in γTa and γTs in China,respectively,which provides an explanation of trends of γTa and γTs from perspective of surface energy balance.
基金supported by the Second Tibetan Plateau Scientifc Expedition and Research(STEP)Program[grant number:2019QZKK0103]Strategic Priority Research Program of Chinese Academy of Sciences[grant number:XDA20060101]+2 种基金National Natural Science Foundation of China[grant number 41875031,41522501,41275028,91837208]The Chinese Academy of Sciences[grant number QYZDJSSW-DQC019]CLIMATE-TPE[grant number:32070]in the framework of the ESA-MOST Dragon 4 Programme.
文摘Land surface temperature(LST)is an important parameter in land surface processes.Improving the accuracy of LST retrieval over the entire Tibetan Plateau(TP)using satellite images with high spatial resolution is an important and essential issue for studies of climate change on the TP.In this study,a random forest regression(RFR)model based on different land cover types and an improved generalized single-channel(SC)algorithm based on linear regression(LR)were proposed.Plateau-scale LST products with a 30 m spatial resolution from 2006 to 2017 were derived by 109,978 Landsat 7 Enhanced Thematic Mapper Plus images and the application of the Google Earth Engine.Validation between LST results obtained from different algorithms and in situ measurements from Tibetan observation and research platform showed that the root mean square errors of the LST results retrieved by the RFR and LR models were 1.890 and 2.767 K,respectively,which were smaller than that of the MODIS product(3.625 K)and the original SC method(5.836 K).
基金Supported by the National Natural Science Foundation of China (42088101, 41805039, and 42175003)Natural Science Foundation of Zhejiang Province (LQ22D050002)Open Funds of the Wenzhou Key Laboratory for Typhoon Monitoring&Forecasting (WT-2022-KF-YB01)。
文摘We investigated the sensitivity of the size of a tropical cyclone(TC) to warming or cooling sea surface temperatures(SST) in its outer region by simulating the SST beyond a radius of 200 km from the TC center.Sensitivity experiments showed that an increased SST outside the core region of the TC had a negative effect on its size.Warming in the outer region contributed to the local enhancement of the latent heat flux from sea surface,which promoted the development of small-scale convection and warmed the lower and midtroposphere.This warming altered the local pressure gradient force in the upper and lower troposphere in such a way that it weakened the secondary circulation of the TC and led to suppression of the spiral rainbands outside the eyewall.Further analysis showed that the outward-propagating rainband structure favored an increase in the size of the TC.The diabatic heat released by the rainbands induced an inflow at lower levels,facilitating expansion of the TC.The greater the distance of the rainbands from the center of the TC,given the same amplitude of diabatic heating,the stronger the forced inflow,resulting in a faster increase in the size of the TC.
基金This work was supported by the National Natural Science Foundation of China （Grant Nos. 41102224 and 41130525）.
文摘The thermal effect of urban impervious surfaces （UIS） is a complex problem. It is thus necessary to study the relationship between UIS and land surface temperatures （LST） using complexity science theory and methods. This paper investigates the long-range cross- correlation between UIS and LST with detrended cross- correlation analysis and multifractal detrended cross- correlation analysis, utilizing data from downtown Shanghai, China. UIS estimates were obtained from linear spectral mixture analysis, and LST was retrieved through application of the mono-window algorithm, using Landsat Thematic Mapper and Enhanced Thematic Mapper Plus data for 1997-2010. These results highlight a positive long-range cross-correlation between UIS and LST across People＇s Square in Shanghai. LST has a long memory for a certain spatial range of UIS values, such that a large increment in UIS is likely to be followed by a large increment in LST. While the multifractal long-range cross- correlation between UIS and LST was observed over a longer time period in the W-E direction （2002-2010） than in the N-S （2007-2010）, these observed correlations show a weakening during the study period as urbanization increased.
基金Supported by the National Natural Science Foundation of China(42088101)Guangdong Major Project of Basic and Applied Basic Research(2020B0301030004)+1 种基金Guangdong Province Key Laboratory for Climate Change and Natural Disaster Studies(2020B1212060025)Jiangsu Collaborative Innovation Center for Climate Change.
文摘We investigate the relative importance of spring sea surface temperatures(SSTs)in different Indian Ocean(IO)domains,especially the northern and southern IO,for the development and intensity of the Asian summer monsoon.By performing unsupervised neural network analysis,the self-organizing map,we extract distinct patterns of springtime IO SST.The results show that the uniform warming(cooling)of the southern IO plays a crucial role in the warming(cooling)of both the basin-wide IO and tropical IO.The southern IO thus well represents the associations of basinwide IO and tropical IO with the Asian summer monsoon,and is instrumental in the relationship between the IO and summer monsoon.A warming in the southern IO is closely related to the weakening of large-scale meridional monsoon circulation in May and summer(June–August),including suppression of the South Asian monsoon development in May and the East Asian monsoon in summer.On the other hand,a warming in the northern IO appears to be associated with an earlier South Asian monsoon onset and a stronger East Asian monsoon.In summer,the connection of the springtime IO SST with the South Asian monsoon weakens,but that with the East Asian monsoon strengthens.Finally,a robust negative correlation is found between the warming of various IO domains and the development and intensity of the Southeast Asian monsoon.
基金sponsored by the National Natural Science Foundation of China[grant number U2442218]。
文摘Land surface temperature(LST)is the key variable in land-atmosphere interaction,having an important impact on weather and climate forecasting.However,achieving consistent analysis of LST and the atmosphere in assimilation is quite challenging.This is because there is limited knowledge about the cross-component background error covariance(BEC)between LST and atmospheric state variables.This study aims to clarify whether there is a relationship between the error of LST and atmospheric variables,and whether this relationship varies spatially and temporally.To this end,the BEC coupled with atmospheric variables and LST was constructed(LST-BEC),and its characteristics were analyzed based on the 2023 mei-yu season.The general characteristics of LST-BEC show that the LST is mainly correlated with the atmospheric temperature and the correlation decreases gradually with a rise in atmospheric height,and the error standard deviation of the LST is noticeably larger than that of the low-level atmospheric temperature.The spatiotemporal characteristics of LST-BEC on the heavy-rain day and light-rain day show that the error correlation and error standard deviation of LST and low-level atmospheric temperature and humidity are closely related to the weather background,and also have obvious diurnal variations.These results provide valuable information for strongly coupled land-atmosphere assimilation.
基金supported by the National Natural Science Foundation of China (Grant No.42305041)the Natural Science Foundation of Hubei Province of China (Grant No.2020CFB331)supported by the National Key Scientific and Technological Infrastructure project “Earth System Numerical Simulation Facility” (Earth Lab)。
文摘Global deforestation has been recognized as an important factor influencing climate change over the past century.However, uncertainties remain regarding its biophysical impacts on temperature across China. Utilizing monthly data from eight global climate models of the Land Use Model Intercomparison Project, a multimodel comparison was conducted to quantitatively analyze the biophysical impacts of global deforestation on near-surface air temperature in China, using a surface energy balance decomposition method. Results show a 38%(29% to 45%) reduction in forest cover in China(ensemble mean and range across eight models) relative to pre-industrial levels, and an annual cooling of 0.6 K(0.05 to1.4 K) accompanied by global deforestation. Notably, surface albedo causes a cooling effect of 0.6 K(0.2 to 2.0 K), while surface latent and sensible heat fluxes partially offset this cooling by 0.2 K(-0.2 to 0.5 K) and 0.2 K(-0.04 to 0.6 K),respectively. These effects are more pronounced in winter and spring in deforested regions. Furthermore, the separation of atmospheric feedbacks under clear-sky and cloudy conditions show that the cloud radiative effect only accounts for 0.1 K(-0.1 to 0.4 K), while the clear-sky surface downward radiation is a significant cooling factor, contributing up to-0.5 K(-1.2 to 0.004 K), particularly in summer. However, the consistency of these models in simulating the impact of surface latent heat flux and albedo on surface temperature in China in response to deforestation is somewhat poor, highlighting the need to improve these related processes.
