In this paper, the principle to determine the atmospheric columnar Mie optical depth from downward total solar radiative flux is theoretically studied, and the effect on Mie optical depth solution of the errors in sur...In this paper, the principle to determine the atmospheric columnar Mie optical depth from downward total solar radiative flux is theoretically studied, and the effect on Mie optical depth solution of the errors in surface albedo, sin-gle scattering albedo, asymmetrical factor of scattering phase function, instrumental constant and the approximate expression of diffusion flux is analy/ed, and then a method for determining surface albedo in shorter wavelength range is presented.展开更多
Earth＇s variable rotation is mainly produced by the variability of the AAM（atmospheric angular momentum）. In particular, the axial AAM component X_3, which undergoes especially strong variations,induces changes in ...Earth＇s variable rotation is mainly produced by the variability of the AAM（atmospheric angular momentum）. In particular, the axial AAM component X_3, which undergoes especially strong variations,induces changes in the Earth＇s rotation rate. In this study we analysed maps of regional input into the effective axial AAM from 1948 through 2011 from NCEP/NCAR reanalysis. Global zonal circulation patterns related to the LOD（length of day） were described. We applied MSSA（Multichannel Singular Spectrum Analysis） jointly to the mass and motion components of AAM, which allowed us to extract annual, semiannual, 4-mo nth, quasi-biennial, 5-year, and low-frequency oscillations. PCs（Principal components） strongly related to ENSO（El Nino southern oscillation） were released. They can be used to study ENSO-induced changes in pressure and wind fields and their coupling to LOD. The PCs describing the trends have captured slow atmospheric circulation changes possibly related to climate variability.展开更多
In this paper, the winter atmospheric circulation, the convection along the equator and their variations of 1982 and 1983 are investigated. It is suggested that there was a well organized three dimensional structure o...In this paper, the winter atmospheric circulation, the convection along the equator and their variations of 1982 and 1983 are investigated. It is suggested that there was a well organized three dimensional structure of anomalies of the atmospheric circulations during 1982 winter which may be related to the variations of the convection in the equatorial region.展开更多
Air pollution,a critical environmental issue,necessitates urgent action.It originates from both human activities,like industrial emissions and vehicle pollution,and natural events such as sandstorms,leading to increas...Air pollution,a critical environmental issue,necessitates urgent action.It originates from both human activities,like industrial emissions and vehicle pollution,and natural events such as sandstorms,leading to increased atmospheric pollutants such as sulfur dioxide(SO_(2)),nitrogen dioxide(NO_(2)),ammonia ion(NH_(4)^(+)),black carbon,ozone,and fine particulate matter(PM_(2.5)).Leveraging China's extensive air quality monitoring data,artificial intelligence(AI)was used in this study to enhance air quality prediction and management.The study aims to utilize the vast air monitoring data more effectively by developing advanced air quality assessment methods and AI models.An AI-based method presented in this study was applied to train extensive air quality data,enabling an intelligent air quality index(AQI)that swiftly and accurately reflects air quality status,to assess impacts on sensitive groups,and to predict future trends.This smart prediction and optimization(SPO)approach not only utilizes existing monitoring network data efficiently but also offers precise future air quality forecasts,providing valuable strategies for pollution prevention and air quality improvement.Data on various pollutants were collected from four regions in China between August 2021 and July 2022,using diverse modeling techniques and machine learning methodologies.The models achieved a high accuracy level of around 99%,indicating the significant portion of air quality that falls into the unhealthy category,especially impacting sensitive groups and reflecting the adverse atmospheric conditions in the studied regions.展开更多
Using correlation analyses, composite analyses, and singular value decomposition, the relationship between the atmospheric cold source over the eastern Tibetan Plateau and atmospheric/ocean circulation is discussed. I...Using correlation analyses, composite analyses, and singular value decomposition, the relationship between the atmospheric cold source over the eastern Tibetan Plateau and atmospheric/ocean circulation is discussed. In winter, the anomaly of the strong (weak) atmospheric cold source over the eastern plateau causes low-level anomalous north (south) winds to appear in eastern China and low-level anomaly zonal west (east) winds to prevail in the equatorial Pacific from spring to autumn. This contributes to the anomalous warm (cold) sea surface temperature the following autumn and winter. In addition, the anomalous variation of sea surface temperature over the equatorial middle and eastern Pacific in winter can influence the snow depth and intensity of the cold source over the plateau in the following winter due to variation of the summer west Pacific subtropical high.展开更多
The chaotic systems of average monthly air temperature of Qingdao (SATQ) and the day SST of equatorial local area (DSSELA) are firstly studied by means of the sequency spectral method. It is shown that SATQ contains o...The chaotic systems of average monthly air temperature of Qingdao (SATQ) and the day SST of equatorial local area (DSSELA) are firstly studied by means of the sequency spectral method. It is shown that SATQ contains one-a period of predominant oscillation, two-a periods lower frepqency oscillation and 90-d, 63-d, 50-d, 40-d and 29-d lower frequency periods oscillation in DSSELA. Further more, the discrepancies between sequency spectrum and frequency spectrum are compared in this paper.展开更多
Global temperature has increased at a rapid rate in recent decades,and the warming rate at night is observed higher than that during the daytime among different regions.Nighttime anomalous high temperatures may pose a...Global temperature has increased at a rapid rate in recent decades,and the warming rate at night is observed higher than that during the daytime among different regions.Nighttime anomalous high temperatures may pose an additional risk to human health and society.Nevertheless,less research has explored the spatiotemporal trend and the local atmospheric mechanism of nocturnal temperature anomaly around the world.Here,we investigate the spatiotemporal trend of nighttime temperature anomaly(NTA)from 1961 to 2023,and analyze the underlying physical mechanism related to different extents of positive temperature anomaly.We find that NTA showed a significantly increased trend worldwide,with an increasing rate of0.21°C/decade.At the continental scale,NTA has increased faster in North America,Asia,and Europe.The occurrence of positive NTA is generally associated with local increased cloud cover,precipitation,and humidity,which contribute to enhanced downward longwave radiation and greenhouse effect at night.On the inter-annual scale,NTA is positively related to the preceding winter Oceanic Ni?o Index,indicating the possible modulation of El Ni?o-Southern Oscillation on the global nocturnal temperature.Our results could help to understand the variation and influence mechanism of anomalous nighttime temperature in recent decades,and inform the forecast of and response to hot nights.展开更多
Based on rain gauge data during 2008-2021 from national meteorological observation stations,this study investigated the performance of the precipitation field from the 1-km-resolution version of the China Atmospheric ...Based on rain gauge data during 2008-2021 from national meteorological observation stations,this study investigated the performance of the precipitation field from the 1-km-resolution version of the China Atmospheric Realtime Analysis(CARAS)over Hubei from the perspective of climatology,multiple-time scale variations,as well as fusion accuracy and detection capability at multiple temporal scales.The results show that CARAS precipitation can reproduce the spatial distribution patterns of climatological seasonal precipitation and rainy days well over the whole of Hubei compared with observational(OBS)precipitation,albeit deviations exist between CARAS and OBS in terms of magnitude.Moreover,high correlation and consistency between CARAS and OBS can be found in multiple-time scale variations over Hubei,with correlation coefficients of interannual,seasonal,and diurnal variation generally exceeding 0.85,0.98,and 0.95,respectively.Furthermore,CARAS has a relatively higher fusion accuracy in summer and winter,and stronger/weaker detection capability in spring/winter at a daily scale.However,the detection capability of CARAS at an hourly scale is weaker than that at a daily scale.With different precipitation intensity levels considered,CARAS daily precipitation shows relatively higher fusion accuracy in estimating moderate and heavy rain,and better detection capability in capturing no rain events.The variations of accuracy metrics and detection metrics under different precipitation intensities at an hourly scale generally resemble those at a daily scale.However,CARAS precipitation at an hourly scale shows a relatively lower fusion accuracy and weaker detection capability compared with that at a daily scale.This paper provides an insight into the characteristics of systematic deviations in CARAS precipitation over Hubei,which will benefit relevant applications of CARAS in meteorological operations over Hubei and the improvement of CARAS in the future.展开更多
We present a specific-window method to subtract the interference of water vapor on terahertz frequency-domain spectroscopy（THz-FDS） at ambient temperature and pressure. A continuous-wave spectrometer based on photom...We present a specific-window method to subtract the interference of water vapor on terahertz frequency-domain spectroscopy（THz-FDS） at ambient temperature and pressure. A continuous-wave spectrometer based on photomixing was utilized to obtain THz-FDS of methanol vapor in the range of 50–1200 GHz. The distinctly spaced absorption features in the neighborhood of atmospheric windows of transparency were selected to perform linear fitting versus the calculated absorption cross section and obtain the concentration of methanol. Furthermore, the gradually decreased methanol vapor was quantified to demonstrate the reliability of the method.展开更多
Most Galactic metal-poor stars exhibit enhanced α-abundances（e.g.[Mg/Fe] ～ ＋0.4） according to previous studies of stellar chemical compositions.However, a handful of metal-poor stars with large deficiencies in Mg...Most Galactic metal-poor stars exhibit enhanced α-abundances（e.g.[Mg/Fe] ～ ＋0.4） according to previous studies of stellar chemical compositions.However, a handful of metal-poor stars with large deficiencies in Mg（e.g. [Mg/Fe]～-0.2） show severe departures from this α-enhancement trend. The sub-solar[Mg/Fe] ratios of these anomalous stars indicate that they possess different chemical enrichment histories than the majority of Galactic metal-poor stars. In previous work,we presented a method to select Mg-poor metal-poor stars from low-resolution SDSS spectra based on a spectral matching technique. In this paper, a similar method is applied to low-resolution（R ～ 1800） LAMOST spectra. Stellar [Mg/Fe] abundances are determined by using stellar parameters delivered by the LAMOST Data Release2 catalog. From a sample of ～ 60 000 stars with atmospheric parameters in the range Teff = [5500, 6500] K and [Fe/H] = [-2.4, ＋0.5], we select 15 candidate Mg-poor metal-poor stars.展开更多
In the equatorial zone the dynamic equations of the atmospheric motion are written inthe β-plane.These equations are linearized according to the mean atmospheric conditions.Numerical method is used to obtain a charac...In the equatorial zone the dynamic equations of the atmospheric motion are written inthe β-plane.These equations are linearized according to the mean atmospheric conditions.Numerical method is used to obtain a characteristic wave solution. Results obtained showthat the easterly wind shear changes the phase speed of low frequency waves more strikinglythan that of high frequency waves. The structure of the characteristic disturbances is sim-ilar to that in middle latitudes only with some exceptions in the relationship of geopo-tential field with vorticity field.展开更多
In this paper, the features and possible causes of sea surface temperature(SST) biases over the Northwest Pacific are investigated based on a mixed-layer heat budget analysis in 21 coupled general circulation models(C...In this paper, the features and possible causes of sea surface temperature(SST) biases over the Northwest Pacific are investigated based on a mixed-layer heat budget analysis in 21 coupled general circulation models(CGCMs) from phase 5 of the Coupled Model Inter-comparison Project(CMIP5). Most CMIP5 models show cold SST biases throughout the year over the Northwest Pacific. The largest biases appear during summer, and the smallest biases occur during winter. These cold SST biases are seen at the basin scale and are mainly located in the inner region of the low and mid-latitudes. According to the mixed-layer heat budget analysis, overestimation of upward net sea surface heat fluxes associated with atmospheric processes are primarily responsible for the cold SST biases. Among the different components of surface heat fluxes, overestimated upward latent heat fluxes induced by the excessively strong surface winds contribute the most to the cold SST biases during the spring, autumn, and winter seasons. Conversely, during the summer, overestimated upward latent heat fluxes and underestimated downward solar radiations at the sea surface are equally important. Further analysis suggests that the overly strong surface winds over the Northwest Pacific during winter and spring are associated with excessive precipitation over the Maritime Continent region,whereas those occurring during summer and autumn are associated with the excessive northward extension of the intertropical convergence zone(ITCZ). The excessive precipitation over the Maritime Continent region and the biases in the simulated ITCZ induce anomalous northeasterlies, which are in favor of enhancing low-level winds over the North Pacific. The enhanced surface wind increases the sea surface evaporation, which contributes to the excessive upward latent heat fluxes. Thus, the SST over the Northwest Pacific cools.展开更多
文摘In this paper, the principle to determine the atmospheric columnar Mie optical depth from downward total solar radiative flux is theoretically studied, and the effect on Mie optical depth solution of the errors in surface albedo, sin-gle scattering albedo, asymmetrical factor of scattering phase function, instrumental constant and the approximate expression of diffusion flux is analy/ed, and then a method for determining surface albedo in shorter wavelength range is presented.
基金supported by Russian Foundation for Basic Research grants No. 17-05-00989, No. 16-05-00753,NRU HSE and visiting grants positions at Paris observatory and Wuhan university for the first authorpartially supported by grants by NSF/IGFA Belmont Forum Project (Grant No. ICER-1342644)the Chinese Academy of Sciences/SAFEA International Partnership Program for Creative Research Teams(Grant No. KZZD-EW-TZ-05)
文摘Earth＇s variable rotation is mainly produced by the variability of the AAM（atmospheric angular momentum）. In particular, the axial AAM component X_3, which undergoes especially strong variations,induces changes in the Earth＇s rotation rate. In this study we analysed maps of regional input into the effective axial AAM from 1948 through 2011 from NCEP/NCAR reanalysis. Global zonal circulation patterns related to the LOD（length of day） were described. We applied MSSA（Multichannel Singular Spectrum Analysis） jointly to the mass and motion components of AAM, which allowed us to extract annual, semiannual, 4-mo nth, quasi-biennial, 5-year, and low-frequency oscillations. PCs（Principal components） strongly related to ENSO（El Nino southern oscillation） were released. They can be used to study ENSO-induced changes in pressure and wind fields and their coupling to LOD. The PCs describing the trends have captured slow atmospheric circulation changes possibly related to climate variability.
文摘In this paper, the winter atmospheric circulation, the convection along the equator and their variations of 1982 and 1983 are investigated. It is suggested that there was a well organized three dimensional structure of anomalies of the atmospheric circulations during 1982 winter which may be related to the variations of the convection in the equatorial region.
基金supported by the National Key R&D Program of China(No.2023YFC3707201)the National Natural Science Foundation of China(No.52320105003)+2 种基金the Informatization Plan of Chinese Academy of Sciences(No.CASWX2023PY-0103)CAS-ANSO Co-funding Research Project(No.CAS-ANSO-CF-2024)the Fundamental Research Funds for the Central Universities(No.E3ET1803)。
文摘Air pollution,a critical environmental issue,necessitates urgent action.It originates from both human activities,like industrial emissions and vehicle pollution,and natural events such as sandstorms,leading to increased atmospheric pollutants such as sulfur dioxide(SO_(2)),nitrogen dioxide(NO_(2)),ammonia ion(NH_(4)^(+)),black carbon,ozone,and fine particulate matter(PM_(2.5)).Leveraging China's extensive air quality monitoring data,artificial intelligence(AI)was used in this study to enhance air quality prediction and management.The study aims to utilize the vast air monitoring data more effectively by developing advanced air quality assessment methods and AI models.An AI-based method presented in this study was applied to train extensive air quality data,enabling an intelligent air quality index(AQI)that swiftly and accurately reflects air quality status,to assess impacts on sensitive groups,and to predict future trends.This smart prediction and optimization(SPO)approach not only utilizes existing monitoring network data efficiently but also offers precise future air quality forecasts,providing valuable strategies for pollution prevention and air quality improvement.Data on various pollutants were collected from four regions in China between August 2021 and July 2022,using diverse modeling techniques and machine learning methodologies.The models achieved a high accuracy level of around 99%,indicating the significant portion of air quality that falls into the unhealthy category,especially impacting sensitive groups and reflecting the adverse atmospheric conditions in the studied regions.
基金Natural Science Foundation of China (90711003, 40633018)
文摘Using correlation analyses, composite analyses, and singular value decomposition, the relationship between the atmospheric cold source over the eastern Tibetan Plateau and atmospheric/ocean circulation is discussed. In winter, the anomaly of the strong (weak) atmospheric cold source over the eastern plateau causes low-level anomalous north (south) winds to appear in eastern China and low-level anomaly zonal west (east) winds to prevail in the equatorial Pacific from spring to autumn. This contributes to the anomalous warm (cold) sea surface temperature the following autumn and winter. In addition, the anomalous variation of sea surface temperature over the equatorial middle and eastern Pacific in winter can influence the snow depth and intensity of the cold source over the plateau in the following winter due to variation of the summer west Pacific subtropical high.
基金National Natural Science Foundation of China under contract No. 49776285.
文摘The chaotic systems of average monthly air temperature of Qingdao (SATQ) and the day SST of equatorial local area (DSSELA) are firstly studied by means of the sequency spectral method. It is shown that SATQ contains one-a period of predominant oscillation, two-a periods lower frepqency oscillation and 90-d, 63-d, 50-d, 40-d and 29-d lower frequency periods oscillation in DSSELA. Further more, the discrepancies between sequency spectrum and frequency spectrum are compared in this paper.
基金supported by the National Natural Science Foundation of China(Grant No.42475191)the Fundamental Research Funds for the Central Universities-Cemac‘Geo X’Interdisciplinary Program(Grant No.2024300245)the Postgraduate Research&Practice Innovation Program of Jiangsu Province。
文摘Global temperature has increased at a rapid rate in recent decades,and the warming rate at night is observed higher than that during the daytime among different regions.Nighttime anomalous high temperatures may pose an additional risk to human health and society.Nevertheless,less research has explored the spatiotemporal trend and the local atmospheric mechanism of nocturnal temperature anomaly around the world.Here,we investigate the spatiotemporal trend of nighttime temperature anomaly(NTA)from 1961 to 2023,and analyze the underlying physical mechanism related to different extents of positive temperature anomaly.We find that NTA showed a significantly increased trend worldwide,with an increasing rate of0.21°C/decade.At the continental scale,NTA has increased faster in North America,Asia,and Europe.The occurrence of positive NTA is generally associated with local increased cloud cover,precipitation,and humidity,which contribute to enhanced downward longwave radiation and greenhouse effect at night.On the inter-annual scale,NTA is positively related to the preceding winter Oceanic Ni?o Index,indicating the possible modulation of El Ni?o-Southern Oscillation on the global nocturnal temperature.Our results could help to understand the variation and influence mechanism of anomalous nighttime temperature in recent decades,and inform the forecast of and response to hot nights.
基金Key Research Project of Hubei Provincial Tobacco Company(027Y2022-006)Hubei Provincial Natural Science Foundation and Meteorological Innovation and Development Joint Foundation of China(2023AFD104,2022CFD132)+4 种基金Open Project Fund of China Meteorological Administration Basin Heavy Rainfall Key Laboratory(2023BHR-Y03)Open Re-search Fund of China Meteorological Administration/Ministry of Rural Agriculture Tobacco Meteorological Service Center(KYZX2023-08)National Natural Science Foundation of China(42105039)Basic Research Fund of WHIHR(202314)Open Research Topics of Key Open Laboratory of Hydro-Meteorology,China Meteorological Administration(23SWQXM018)。
文摘Based on rain gauge data during 2008-2021 from national meteorological observation stations,this study investigated the performance of the precipitation field from the 1-km-resolution version of the China Atmospheric Realtime Analysis(CARAS)over Hubei from the perspective of climatology,multiple-time scale variations,as well as fusion accuracy and detection capability at multiple temporal scales.The results show that CARAS precipitation can reproduce the spatial distribution patterns of climatological seasonal precipitation and rainy days well over the whole of Hubei compared with observational(OBS)precipitation,albeit deviations exist between CARAS and OBS in terms of magnitude.Moreover,high correlation and consistency between CARAS and OBS can be found in multiple-time scale variations over Hubei,with correlation coefficients of interannual,seasonal,and diurnal variation generally exceeding 0.85,0.98,and 0.95,respectively.Furthermore,CARAS has a relatively higher fusion accuracy in summer and winter,and stronger/weaker detection capability in spring/winter at a daily scale.However,the detection capability of CARAS at an hourly scale is weaker than that at a daily scale.With different precipitation intensity levels considered,CARAS daily precipitation shows relatively higher fusion accuracy in estimating moderate and heavy rain,and better detection capability in capturing no rain events.The variations of accuracy metrics and detection metrics under different precipitation intensities at an hourly scale generally resemble those at a daily scale.However,CARAS precipitation at an hourly scale shows a relatively lower fusion accuracy and weaker detection capability compared with that at a daily scale.This paper provides an insight into the characteristics of systematic deviations in CARAS precipitation over Hubei,which will benefit relevant applications of CARAS in meteorological operations over Hubei and the improvement of CARAS in the future.
基金supported by the China Postdoctoral Science Foundation(No.2017M610771)
文摘We present a specific-window method to subtract the interference of water vapor on terahertz frequency-domain spectroscopy（THz-FDS） at ambient temperature and pressure. A continuous-wave spectrometer based on photomixing was utilized to obtain THz-FDS of methanol vapor in the range of 50–1200 GHz. The distinctly spaced absorption features in the neighborhood of atmospheric windows of transparency were selected to perform linear fitting versus the calculated absorption cross section and obtain the concentration of methanol. Furthermore, the gradually decreased methanol vapor was quantified to demonstrate the reliability of the method.
基金supported by the National Natural Science Foundation of China (Grant Nos. 11390371, 11233004, 11303040 and U1431106)
文摘Most Galactic metal-poor stars exhibit enhanced α-abundances（e.g.[Mg/Fe] ～ ＋0.4） according to previous studies of stellar chemical compositions.However, a handful of metal-poor stars with large deficiencies in Mg（e.g. [Mg/Fe]～-0.2） show severe departures from this α-enhancement trend. The sub-solar[Mg/Fe] ratios of these anomalous stars indicate that they possess different chemical enrichment histories than the majority of Galactic metal-poor stars. In previous work,we presented a method to select Mg-poor metal-poor stars from low-resolution SDSS spectra based on a spectral matching technique. In this paper, a similar method is applied to low-resolution（R ～ 1800） LAMOST spectra. Stellar [Mg/Fe] abundances are determined by using stellar parameters delivered by the LAMOST Data Release2 catalog. From a sample of ～ 60 000 stars with atmospheric parameters in the range Teff = [5500, 6500] K and [Fe/H] = [-2.4, ＋0.5], we select 15 candidate Mg-poor metal-poor stars.
文摘In the equatorial zone the dynamic equations of the atmospheric motion are written inthe β-plane.These equations are linearized according to the mean atmospheric conditions.Numerical method is used to obtain a characteristic wave solution. Results obtained showthat the easterly wind shear changes the phase speed of low frequency waves more strikinglythan that of high frequency waves. The structure of the characteristic disturbances is sim-ilar to that in middle latitudes only with some exceptions in the relationship of geopo-tential field with vorticity field.
基金supported by the National Key Research and Development Program of China(Grant No.2017YFA0604004)the R&D Special Fund for Public Welfare Industry(Meteorology)(Grant No.GYHY201506012)
文摘In this paper, the features and possible causes of sea surface temperature(SST) biases over the Northwest Pacific are investigated based on a mixed-layer heat budget analysis in 21 coupled general circulation models(CGCMs) from phase 5 of the Coupled Model Inter-comparison Project(CMIP5). Most CMIP5 models show cold SST biases throughout the year over the Northwest Pacific. The largest biases appear during summer, and the smallest biases occur during winter. These cold SST biases are seen at the basin scale and are mainly located in the inner region of the low and mid-latitudes. According to the mixed-layer heat budget analysis, overestimation of upward net sea surface heat fluxes associated with atmospheric processes are primarily responsible for the cold SST biases. Among the different components of surface heat fluxes, overestimated upward latent heat fluxes induced by the excessively strong surface winds contribute the most to the cold SST biases during the spring, autumn, and winter seasons. Conversely, during the summer, overestimated upward latent heat fluxes and underestimated downward solar radiations at the sea surface are equally important. Further analysis suggests that the overly strong surface winds over the Northwest Pacific during winter and spring are associated with excessive precipitation over the Maritime Continent region,whereas those occurring during summer and autumn are associated with the excessive northward extension of the intertropical convergence zone(ITCZ). The excessive precipitation over the Maritime Continent region and the biases in the simulated ITCZ induce anomalous northeasterlies, which are in favor of enhancing low-level winds over the North Pacific. The enhanced surface wind increases the sea surface evaporation, which contributes to the excessive upward latent heat fluxes. Thus, the SST over the Northwest Pacific cools.
