Nutrient uptake status dominates phytoplankton biomass and community structure in the Southern Ocean during austral summer,yet how nutrient utilization variability responds to phytoplankton community succession is sti...Nutrient uptake status dominates phytoplankton biomass and community structure in the Southern Ocean during austral summer,yet how nutrient utilization variability responds to phytoplankton community succession is still unclear,partly due to lack of data spanning the entire summer.In this study,nitrate,phosphate,and silicate combined with temperature,salinity,and apparent oxygen utilization(AOU)were analyzed along 45°E in the Cosmonaut Sea during December 2019,January 2021,and February 2022.The variations in nutrient utilization in the euphotic layer were studied using biogeochemical tracers,and seasonal nutrient depletion was also estimated.The results showed that nutrient distribution varied significantly from December to February.Significant positive correlations were observed for nitrate and silicate concentrations with salinity and AOU,indicating that nutrient distributions were mainly influenced by water mass and phytoplankton production.Increasing∆[N*]and decreasing∆[Si*]in the upper 50 m were observed south of 63.5°S from December to February,which possibly contributed to a progressive shift in dominant phytoplankton population from Phaeocystis antarctica to diatoms.The seasonal nutrient depletion generally increased from December to February.Moreover,the consumption of silicate substantially increased compared to nitrate,indicating that the abundance of diatoms was increasing with time during the austral summer.Our observations suggest that nutrient utilization status is closely related to phytoplankton community structure in the euphotic layer of the Cosmonaut Sea.展开更多
The estimation of glacier flow velocity on a short-term scale is very important for further glacier dynamics research.In this study,10 Sentinel-1 ascending images and 10 Sentinel-1 descending images of Urumqi Glacier ...The estimation of glacier flow velocity on a short-term scale is very important for further glacier dynamics research.In this study,10 Sentinel-1 ascending images and 10 Sentinel-1 descending images of Urumqi Glacier No.1 in 2017 were used to calculate the glacier flow velocity in a high coherence period by DIn SAR technology and MAI technology,while the offset tracking technology was used to estimate the glacier flow velocity in a low coherence period.Then,the monthly three-dimensional flow velocity of the glacier was calculated by the Helmert variance component estimation method.Finally,the accuracy of the estimated glacier flow velocity on a monthly scale was evaluated.The results showed that:(1)the monthly scale motion velocity of Urumqi Glacier No.1 in May,June,July,and August 2017 was 0.273 m/month,0.657 m/month,0.582 m/month,and 0.392 m/month,respectively.(2)The accuracy of glacier surface velocity from May 2017 to August 2017 was 0.033 m/month,0.026 m/month,0.034 m/month and 0.037 m/month,respectively.(3)The accuracy of glacier surface flow velocity from May 2017 to August 2017 was 0.018 m/month,0.031 m/month,0.029 m/month and 0.030 m/month,respectively.Therefore,the research methodology based on the Sentinel-1 ascending and descending data and presented in this paper was applicable to the estimation of monthly-scale flow velocity of mountain glaciers.展开更多
To address the excessive complexity of monthly scheduling and the impact of uncertain net load on the chargeable energy of storage,a reduced time-period monthly scheduling model for thermal generators and energy stora...To address the excessive complexity of monthly scheduling and the impact of uncertain net load on the chargeable energy of storage,a reduced time-period monthly scheduling model for thermal generators and energy storage,incorporating daily minimum chargeable energy constraints,was developed.Firstly,considering the variations in the frequency of unit start-ups and shutdowns under different levels of net load fluctuation,a method was proposed to reduce decision time periods for unit start-up and shut-down operations.This approach,based on the characteristics of net load fluctuations,minimizes the decision variables of units,thereby simplifying the monthly schedulingmodel.Secondly,the relationship between energy storage charging and discharging power,net load,and the total maximum/minimum output of units was analyzed.Based on this,daily minimum chargeable energy constraints were established to ensure the energy storage system meets charging requirements under extreme net load scenarios.Finally,taking into account the operational costs of thermal generators and energy storage,load loss costs,and operational constraints,the reduced time-period monthly schedulingmodel was constructed.Case studies demonstrate that the proposedmethod effectively generates economical monthly operation plans for thermal generators and energy storage,significantly reduces model solution time,and satisfies the charging requirements of energy storage under extreme net load conditions.展开更多
With the OLR data, the landfall and activity of tropical cyclones (TC) in southern China over a 20-year period (1975～1994) are studied. The result shows that the variation of the monthly anomalous OLR is somewhat tel...With the OLR data, the landfall and activity of tropical cyclones (TC) in southern China over a 20-year period (1975～1994) are studied. The result shows that the variation of the monthly anomalous OLR is somewhat teleconnected with the TC activity in southern China. The former is used to predict short-term climate for the latter over months with frequent or no TC influence. To some extent, the relationship between the TC activity in southern China and the monthly mean OLR anomalies is dependent on the climatological location of the subtropical high in northwestern Pacific region.展开更多
Macronutrients （N, P, K, Ca, Mg, and S） in litter of three primarily spruce （Picea purpurea Masters） （SF）, fir （Abies faxoniana Rehder ＆ E. H. Wilson） （FF）, and birch （Betula platyphylla Sukaczev） （BF） ...Macronutrients （N, P, K, Ca, Mg, and S） in litter of three primarily spruce （Picea purpurea Masters） （SF）, fir （Abies faxoniana Rehder ＆ E. H. Wilson） （FF）, and birch （Betula platyphylla Sukaczev） （BF） subalpine forests in western China were measured to understand the monthly variations in litter nutrient concentrations and annual and monthly nutrient returns via litteffall. Nutrient concentration in litter showed the rank order of Ca 〉 N 〉 Mg 〉 K 〉 S 〉 P. Monthly variations in nutrient concentrations were greater in leaf litter （LL） than other litter components. The highest and lowest concentrations of N, P, K, and S in LL were found in the growing season and the nongrowing season, respectively, but Ca and Mg were the opposite. Nutrient returns via litterfall showed a marked monthly pattern with a major peak in October and one or two small peaks in February and/or May, varying with the element and stand type, but no marked monthly variations in nutrient returns via woody litter, reproductive litter, except in May for the BF, and moss litter. Not only litter production but also nutrient concentration controlled the annual nutrient return and the monthly nutrient return pattern. The monthly patterns of the nutrient concentration and return were of ecological importance for nutrient cycling and plant growth in the subalpine forest ecosystems.展开更多
A prerequisite of a successful statistical downscaling is that large-scale predictors simulated by the General Circulation Model (GCM) must be realistic. It is assumed here that features smaller than the GCM resolutio...A prerequisite of a successful statistical downscaling is that large-scale predictors simulated by the General Circulation Model (GCM) must be realistic. It is assumed here that features smaller than the GCM resolution are important in determining the realism of the large-scale predictors. It is tested whether a three-step method can improve conventional one-step statistical downscaling. The method uses predictors that are upscaled from a dynamical downscaling instead of predictors taken directly from a GCM simulation. The method is applied to downscaling of monthly precipitation in Sweden. The statistical model used is a multiple regression model that uses indices of large-scale atmospheric circulation and 850-hPa specific humidity as predictors. Data from two GCMs (HadCM2 and ECHAM4) and two RCM experiments of the Rossby Centre model (RCA1) driven by the GCMs are used. It is found that upscaled RCA1 predictors capture the seasonal cycle better than those from the GCMs, and hence increase the reliability of the downscaled precipitation. However, there are only slight improvements in the simulation of the seasonal cycle of downscaled precipitation. Due to the cost of the method and the limited improvements in the downscaling results, the three-step method is not justified to replace the one-step method for downscaling of Swedish precipitation.展开更多
Rapid and accurate access to large-scale,high-resolution crop-type distribution maps is important for agricultural management and sustainable agricultural development.Due to the limitations of remote sensing image qua...Rapid and accurate access to large-scale,high-resolution crop-type distribution maps is important for agricultural management and sustainable agricultural development.Due to the limitations of remote sensing image quality and data processing capabilities,large-scale crop classification is still challenging.This study aimed to map the distribution of crops in Heilongjiang Province using Google Earth Engine(GEE)and Sentinel-1 and Sentinel-2 images.We obtained Sentinel-1 and Sentinel-2 images from all the covered study areas in the critical period for crop growth in 2018(May to September),combined monthly composite images of reflectance bands,vegetation indices and polarization bands as input features,and then performed crop classification using a Random Forest(RF)classifier.The results show that the Sentinel-1 and Sentinel-2 monthly composite images combined with the RF classifier can accurately generate the crop distribution map of the study area,and the overall accuracy(OA)reached 89.75%.Through experiments,we also found that the classification performance using time-series images is significantly better than that using single-period images.Compared with the use of traditional bands only(i.e.,the visible and near-infrared bands),the addition of shortwave infrared bands can improve the accuracy of crop classification most significantly,followed by the addition of red-edge bands.Adding common vegetation indices and Sentinel-1 data to the crop classification improved the overall classification accuracy and the OA by 0.2 and 0.6%,respectively,compared to using only the Sentinel-2 reflectance bands.The analysis of timeliness revealed that when the July image is available,the increase in the accuracy of crop classification is the highest.When the Sentinel-1 and Sentinel-2 images for May,June,and July are available,an OA greater than 80%can be achieved.The results of this study are applicable to large-scale,high-resolution crop classification and provide key technologies for remote sensing-based crop classification in small-scale agricultural areas.展开更多
The epidemiologic characteristics of 631 infant pertussis cases 〈 12 months, which accounted for 57.42% of the total cases, were analyzed by descriptive epidemiology in Tianjin, between 2010 and 2015. The incidence o...The epidemiologic characteristics of 631 infant pertussis cases 〈 12 months, which accounted for 57.42% of the total cases, were analyzed by descriptive epidemiology in Tianjin, between 2010 and 2015. The incidence of infants was 104.66/100,000, which was 118 times higher than in other age groups （P 〈 0.001）. The primary type of pertussis simultaneously presented in households was adult-to-infant （70.51%）. The parents were identified as the source of infection in 80.18% of cases for infants. The positive rate of placental antibody transfer was 31.06% and 3.13% for 3-month-old infants. Infants presented the highest age-specific pertussis incidence. The most important reason was parents were the important sources of infection, and secondly the lower level of antibodies in neonates and the rapid waning of maternal antibody titer.展开更多
In this study, the dynamics of monthly variation in litterfall and the amount of nutrients, i.e., organic C, N, P and K, in an Aleurites montana plantation were analyzed, based on a field study and experiments over on...In this study, the dynamics of monthly variation in litterfall and the amount of nutrients, i.e., organic C, N, P and K, in an Aleurites montana plantation were analyzed, based on a field study and experiments over one year. The results show that the litterfall mass of A. montana collected generally presents an ascending trend with maximum defoliation occurring in the autumn and winter （October-December）, accounting for 75.67% of the total amount of annual litterfalk The sequence in the amount of nutrients in A. montana litter was as follows： organic C 〉 N 〉 K 〉 P; their monthly amounts show various dynamic curves. Similar to the dynamics of the mass of monthly litterfall, the monthly returns of C, N, P and K generally show an ascending trend with their peak values all occurring in December. The mass of A. montana litterfall and the dynamics of its monthly nutrient return provide, to a certain degree, a scientific reference for planting and fertilizing A. montana.展开更多
The Miyun Reservoir is the most important water source for Beijing Municipality, the capital of China with a population of more than 12 million. In recent decades, the inflow to the reservoir has shown a decreasing tr...The Miyun Reservoir is the most important water source for Beijing Municipality, the capital of China with a population of more than 12 million. In recent decades, the inflow to the reservoir has shown a decreasing trend, which has seriously threatened water use in Beijing. In order to analyze the influents of land use and cover change (LUCC) upon inflow to Miyun Reservoir, terrain and land use information from remote sensing were utilized with a revised evapotranspiration estimation formula; a water loss model under conditions of human impacts was introduced; and a distributed monthly water balance model was established and applied to the Chaobai River Basin controlled by the Miyun Reservoir. The model simulation suggested that not only the impact of land cover change on evapotranspiration, but also the extra water loss caused by human activities, such as the water and soil conservation development projects should be considered. Although these development projects were of great benefit to human and ecological protection, they could reallocate water resources in time and space, and in a sense thereby influence the stream flow.展开更多
The recorded meteorological data of monthly mean surface air temperature from 72 meteorological stations over the Qinghal-Tibet Plateau in the period of 1960-2003 have been analyzed by using Empirical Orthogonal Funct...The recorded meteorological data of monthly mean surface air temperature from 72 meteorological stations over the Qinghal-Tibet Plateau in the period of 1960-2003 have been analyzed by using Empirical Orthogonal Function （EOF） method, to understand the detailed features of its temporal and spatial variations. The results show that there was a high consistency of the monthly mean surface air temperature, with a secondarily different variation between the north and the south of the plateau. Warming trend has existed at all stations since the 1960s, while the warming rates were different in various zones. The source regions of big rivers had intense warming tendency. June, November and December were the top three fast-warming months since the 1960s; while April, July and September presented dramatic warming tendency during the last decade.展开更多
In this study,we investigated the community structure of crustaceans(decapod and stomatopod) inhabiting the sandy mud bottoms of Laizhou Bay(northeastern China) monthly from May 2011 to April 2012.Investigation was st...In this study,we investigated the community structure of crustaceans(decapod and stomatopod) inhabiting the sandy mud bottoms of Laizhou Bay(northeastern China) monthly from May 2011 to April 2012.Investigation was stopped from December 2011 to February 2012 because of the extreme weather and sea ice.A total of 205,057 specimens belonging to 31 species(shrimp,15;crab,15;and stomatopod,1) were collected in 148 hauls.From 2011 to 2012,Oratosquilla oratoria was the dominant biomass species(47.80%),followed by Charybdis japonica(15.49%),Alpheus japonicas(12.61%),Portunus trituberculatus(6.46%),and Crangon spp.(4.19%).Crangon spp.was the most dominant species by individual(32.55%).O.oratoria was the most-frequently encountered species(81.76%),followed by Palaemon gravieri(70.95%),C.japonica(65.54%),A.japonicas(62.16%),and P.trituberculatus(54.73%).The biomass density increased from August to September 2011 and decreased from March 2012 to April 2012.The dynamics of the ecological indices evolve in a similar manner,with high values of diversity and evenness and rich species from May to June 2011 and low values from September to October 2011.O.oratoria,C.japonica,and P.trituberculatus differed by biomass data between groups I(samples obtained from September to October 2011) and II(samples in other months).These species contributed more than 70% to the similarity of the crustacean community structure.Furthermore,the subsets of environmental variables that best matched the crustacean-assemblage structure were as follows:water depth(WD) in summer(June to August);sea surface temperature(SST),dissolved oxygen(DO),and WD in autumn(September to November);and DO,salinity,and WD in spring(March to May).The calculated correlation coefficients and significance level were higher in the period of July to August 2011 than in other months.Comparing 2011 to 2012 with 1982 to 1983,the species composition remained stable.However,the dominant species changed significantly.High value and large species,such as F.chinensis,P.trituberculatus,and T.curvirostris,have been replaced by low value and small species(i.e.,Crangon spp.,P.gravieri,and C.japonica).展开更多
This paper presents the application of autoregressive integrated moving average （ARIMA）, seasonal ARIMA （SARIMA）, and Jordan-Elman artificial neural networks （ANN） models in forecasting the monthly streamflow of...This paper presents the application of autoregressive integrated moving average （ARIMA）, seasonal ARIMA （SARIMA）, and Jordan-Elman artificial neural networks （ANN） models in forecasting the monthly streamflow of the Kizil River in Xinjiang, China. Two different types of monthly streamflow data （original and deseasonalized data） were used to develop time series and Jordan-Elman ANN models using previous flow conditions as predictors. The one-month-ahead forecasting performances of all models for the testing period （1998-2005） were compared using the average monthly flow data from the Kalabeili gaging station on the Kizil River. The Jordan-Elman ANN models, using previous flow conditions as inputs, resulted in no significant improvement over time series models in one-month-ahead forecasting. The results suggest that the simple time series models （ARIMA and SARIMA） can be used in one-month-ahead streamflow forecasting at the study site with a simple and explicit model structure and a model performance similar to the Jordan-Elman ANN models.展开更多
Alcoholic liver disease(ALD) is the second most common diagnosis among patients undergoing liver transplantation(LT).The recovery results of patients transplanted for ALD are often at least as good as those of patient...Alcoholic liver disease(ALD) is the second most common diagnosis among patients undergoing liver transplantation(LT).The recovery results of patients transplanted for ALD are often at least as good as those of patients transplanted for other diagnoses and better than those suffering from hepatitis C virus, cryptogenic cirrhosis, or hepatocellular carcinoma.Inthe case of medically non-responding patients with severe acute alcoholic hepatitis or acute-on chronic liver failure, the refusal of LT is often based on the lack of the required alcohol abstinence period of six months.The obligatory abidance of a period of abstinence as a transplant eligibility requirement for medically non-responding patients seems unfair and inhumane, since the majority of these patients will not survive the six-month abstinence period.Data from various studies have challenged the 6-mo rule, while excellent survival results of LT have been observed in selected patients with severe alcoholic hepatitis not responding to medical therapy.Patients with severe advanced ALD should have legal access to LT.The mere lack of pre-LT abstinence should not be an obstacle for being listed.展开更多
This study investigates the long-term changes of monthly sea surface wind speeds over the China seas from 1988 to 2015. The 10-meter wind speeds products from four major global reanalysis datasets with high resolution...This study investigates the long-term changes of monthly sea surface wind speeds over the China seas from 1988 to 2015. The 10-meter wind speeds products from four major global reanalysis datasets with high resolution are used: Cross-Calibrated Multi-Platform data set(CCMP), NCEP climate forecast system reanalysis data set(CFSR),ERA-interim reanalysis data set(ERA-int) and Japanese 55-year reanalysis data set(JRA55). The monthly sea surface wind speeds of four major reanalysis data sets have been investigated through comparisons with the longterm and homogeneous observation wind speeds data recorded at ten stations. The results reveal that(1) the wind speeds bias of CCMP, CFSR, ERA-int and JRA55 are 0.91 m/s, 1.22 m/s, 0.62 m/s and 0.22 m/s, respectively.The wind speeds RMSE of CCMP, CFSR, ERA-int and JRA55 are 1.38 m/s, 1.59 m/s, 1.01 m/s and 0.96 m/s,respectively;(2) JRA55 and ERA-int provides a realistic representation of monthly wind speeds, while CCMP and CFSR tend to overestimate observed wind speeds. And all the four data sets tend to underestimate observed wind speeds in Bohai Sea and Yellow Sea;(3) Comparing the annual wind speeds trends between observation and the four data sets at ten stations for 1988-1997, 1988–2007 and 1988–2015, the result show that ERA-int is superior to represent homogeneity monthly wind speeds over the China seaes.展开更多
Partial Least Squares Regression （PLSR） is used to study monthly changes in the influence of the Arctic Oscillation （AO） on spring, summer and autumn air temperature over China with the January 500 hPa geopotentia...Partial Least Squares Regression （PLSR） is used to study monthly changes in the influence of the Arctic Oscillation （AO） on spring, summer and autumn air temperature over China with the January 500 hPa geopotential height data from 1951 to 2004 and monthly temperature data from January to November at 160 stations in China. Several AO indices have been defined with the 500-hPa geopotential data and the index defined as the first principal component of the normalized geopotential data is best to be used to study the influence of the AO on SAT （surface air temperature） in China. There are three modes through which the AO in winter influences SAT in China. The influence of the AO on SAT in China changes monthly and is stronger in spring and summer than in autumn. The main influenced regions are Northeast China and the Changjiang River drainage area.展开更多
An exploratory spatial data analysis method (ESDA) was designed Apr.28,2002 for kriging monthly rainfall. Samples were monthly rainfall observed at 61 weather stations in eastern China over the period 1961-1998. Comp...An exploratory spatial data analysis method (ESDA) was designed Apr.28,2002 for kriging monthly rainfall. Samples were monthly rainfall observed at 61 weather stations in eastern China over the period 1961-1998. Comparison of five semivariogram models (Spherical, Exponential, Linear, Gaussian and Rational Quadratic) indicated that kriging fulfills the objective of finding better ways to estimate interpolation weights and can provide error information for monthly rainfall interpolation. ESDA yielded the three most common forms of experimental semivariogram for monthly rainfall in the area. All five models were appropriate for monthly rainfall interpolation but under different circumstances. Spherical, Exponential and Linear models perform as smoothing interpolator of the data, whereas Gaussian and Rational Quadratic models serve as an exact interpolator. Spherical, Exponential and Linear models tend to underestimate the values. On the contrary, Gaussian and Rational Quadratic models tend to overestimate the values. Since the suitable model for a specific month usually is not unique and each model does not show any bias toward one or more specific months, an ESDA is recommended for a better interpolation result.展开更多
In this study,the reversal of monthly East Asian winter air temperature(EAWT) in 2020/21 and its predictability were investigated.The reversal of monthly EAWT in 2020/21 was characterized by colder temperatures in ear...In this study,the reversal of monthly East Asian winter air temperature(EAWT) in 2020/21 and its predictability were investigated.The reversal of monthly EAWT in 2020/21 was characterized by colder temperatures in early winter(December 2020 to mid-January 2021) and warmer temperatures in late winter(mid-January to February 2021).Results show that the reversal in the intensity of the Siberian high(SH) also occurred between early and late winter in 2020/21.In early winter,as the Barents-Laptev sea ice in the previous September(i.e., in2020) reached a minimum for the period 1981-2020,the SH was strengthaned via a reduction of the meridional gradient between the Arctic and East Asia.In late winter,as a sudden stratospheric warming occurred on 5 January 2021,the stratospheric polar vortex weakened,with the weakest center shifting to North America in January.Subsequently,the negative Arctic Oscillation-like structure shifted towards North America in the middle and lower troposphere,which weakened the SH in late winter.Furthermore,the predictability of the reversal in EAWT in 2020/21 was validated based on monthly and daily predictions from NCEP-CFSv2(National Centers for Environment Prediction-Climate Forecast System,version 2).The results showed that the model was unable to reproduce the monthly reversal of EAWT.However,it was able to forecast the reversal date(18 January 2021)of EAWT at lead times of 1-20 days on the daily scale.展开更多
Haze pollution in early winter(December and January) in the Yangtze River Delta(YRD) and in North China(NC)are both severe;however, their monthly variations are significantly different. In this study, the dominant lar...Haze pollution in early winter(December and January) in the Yangtze River Delta(YRD) and in North China(NC)are both severe;however, their monthly variations are significantly different. In this study, the dominant large-scale atmospheric circulations and local meteorological conditions were investigated and compared over the YRD and NC in each month. Results showed that the YRD(NC) is dominated by the so-called Scandinavia(East Atlantic/West Russia)pattern in December, and these circulations weaken in January. The East Asian December and January monsoons over the YRD and NC have negative correlations with the number of haze days. The local descending motion facilitates less removal of haze pollution over the YRD, while the local ascending motion facilitates less removal of haze pollution over NC in January, despite a weaker relationship in December. Additionally, the monthly variations of atmospheric circulations showed that adverse meteorological conditions restrict the vertical(horizontal) dispersion of haze pollution in December(January) over the YRD, while the associated local weather conditions are similar in these two months over NC.展开更多
Predicting wind power gen eration over the medium and long term is helpful for dispatchi ng departme nts,as it aids in constructing generation plans and electricity market transactions.This study presents a monthly wi...Predicting wind power gen eration over the medium and long term is helpful for dispatchi ng departme nts,as it aids in constructing generation plans and electricity market transactions.This study presents a monthly wind power gen eration forecast!ng method based on a climate model and long short-term memory(LSTM)n eural n etwork.A non linear mappi ng model is established between the meteorological elements and wind power monthly utilization hours.After considering the meteorological data(as predicted for the future)and new installed capacity planning,the monthly wind power gen eration forecast results are output.A case study shows the effectiveness of the prediction method.展开更多
基金The National Polar Special Program“Impact and Response of Antarctic Seas to Climate Change”under contract Nos IRASCC 01-01-02 and IRASCC 02-02the National Key Research and Development Program of China under contract No.2022YFE0136500+1 种基金the National Natural Science Foundation of China(NSFC)under contract Nos 41976228,42276255 and 42176227the Scientific Research Fund of the Second Institute of Oceanography under contract Nos JG2011,JG2211 and JG2013.
文摘Nutrient uptake status dominates phytoplankton biomass and community structure in the Southern Ocean during austral summer,yet how nutrient utilization variability responds to phytoplankton community succession is still unclear,partly due to lack of data spanning the entire summer.In this study,nitrate,phosphate,and silicate combined with temperature,salinity,and apparent oxygen utilization(AOU)were analyzed along 45°E in the Cosmonaut Sea during December 2019,January 2021,and February 2022.The variations in nutrient utilization in the euphotic layer were studied using biogeochemical tracers,and seasonal nutrient depletion was also estimated.The results showed that nutrient distribution varied significantly from December to February.Significant positive correlations were observed for nitrate and silicate concentrations with salinity and AOU,indicating that nutrient distributions were mainly influenced by water mass and phytoplankton production.Increasing∆[N*]and decreasing∆[Si*]in the upper 50 m were observed south of 63.5°S from December to February,which possibly contributed to a progressive shift in dominant phytoplankton population from Phaeocystis antarctica to diatoms.The seasonal nutrient depletion generally increased from December to February.Moreover,the consumption of silicate substantially increased compared to nitrate,indicating that the abundance of diatoms was increasing with time during the austral summer.Our observations suggest that nutrient utilization status is closely related to phytoplankton community structure in the euphotic layer of the Cosmonaut Sea.
基金funded by the Basic scientific research fund projects(Youth Project)of the Educational Department of Liaoning Province in 2023(Grants No.JYTQN2023451)Liaoning Institute of Science and Technology doctoral research initiation fund project in 2023(Grants No.2307B27)+2 种基金Basic Research Project of Higher Education Institutions of Liaoning Provincial Department of Education(Grants No.2024JYTYB-12)the Basic scientific research fund projects(Youth Project)of the Educational Department of Liaoning Province in 2023(Grants No.JYTQN2024-21)Liaoning Institute of Science and Technology doctoral research initiation fund project in 2023(Grants No.2307B26)。
文摘The estimation of glacier flow velocity on a short-term scale is very important for further glacier dynamics research.In this study,10 Sentinel-1 ascending images and 10 Sentinel-1 descending images of Urumqi Glacier No.1 in 2017 were used to calculate the glacier flow velocity in a high coherence period by DIn SAR technology and MAI technology,while the offset tracking technology was used to estimate the glacier flow velocity in a low coherence period.Then,the monthly three-dimensional flow velocity of the glacier was calculated by the Helmert variance component estimation method.Finally,the accuracy of the estimated glacier flow velocity on a monthly scale was evaluated.The results showed that:(1)the monthly scale motion velocity of Urumqi Glacier No.1 in May,June,July,and August 2017 was 0.273 m/month,0.657 m/month,0.582 m/month,and 0.392 m/month,respectively.(2)The accuracy of glacier surface velocity from May 2017 to August 2017 was 0.033 m/month,0.026 m/month,0.034 m/month and 0.037 m/month,respectively.(3)The accuracy of glacier surface flow velocity from May 2017 to August 2017 was 0.018 m/month,0.031 m/month,0.029 m/month and 0.030 m/month,respectively.Therefore,the research methodology based on the Sentinel-1 ascending and descending data and presented in this paper was applicable to the estimation of monthly-scale flow velocity of mountain glaciers.
基金This study was supported by State Grid Corporation headquarters technology project(4000-202399368A-2-2-ZB).
文摘To address the excessive complexity of monthly scheduling and the impact of uncertain net load on the chargeable energy of storage,a reduced time-period monthly scheduling model for thermal generators and energy storage,incorporating daily minimum chargeable energy constraints,was developed.Firstly,considering the variations in the frequency of unit start-ups and shutdowns under different levels of net load fluctuation,a method was proposed to reduce decision time periods for unit start-up and shut-down operations.This approach,based on the characteristics of net load fluctuations,minimizes the decision variables of units,thereby simplifying the monthly schedulingmodel.Secondly,the relationship between energy storage charging and discharging power,net load,and the total maximum/minimum output of units was analyzed.Based on this,daily minimum chargeable energy constraints were established to ensure the energy storage system meets charging requirements under extreme net load scenarios.Finally,taking into account the operational costs of thermal generators and energy storage,load loss costs,and operational constraints,the reduced time-period monthly schedulingmodel was constructed.Case studies demonstrate that the proposedmethod effectively generates economical monthly operation plans for thermal generators and energy storage,significantly reduces model solution time,and satisfies the charging requirements of energy storage under extreme net load conditions.
基金Foundation for the"Application of OLR data in tropical weather"as part of a short-termscientific research project under the Science and Education Department of the China Meteorological Administration'96。
文摘With the OLR data, the landfall and activity of tropical cyclones (TC) in southern China over a 20-year period (1975～1994) are studied. The result shows that the variation of the monthly anomalous OLR is somewhat teleconnected with the TC activity in southern China. The former is used to predict short-term climate for the latter over months with frequent or no TC influence. To some extent, the relationship between the TC activity in southern China and the monthly mean OLR anomalies is dependent on the climatological location of the subtropical high in northwestern Pacific region.
基金Project supported by the National Natural Science Foundation of China (Nos. 30471378, 90202010 and 30211130504)the Applied and Basic Research Program of Sichuan Province, and the Talent-Recruiting Program of Sichuan Agricultural University
文摘Macronutrients （N, P, K, Ca, Mg, and S） in litter of three primarily spruce （Picea purpurea Masters） （SF）, fir （Abies faxoniana Rehder ＆ E. H. Wilson） （FF）, and birch （Betula platyphylla Sukaczev） （BF） subalpine forests in western China were measured to understand the monthly variations in litter nutrient concentrations and annual and monthly nutrient returns via litteffall. Nutrient concentration in litter showed the rank order of Ca 〉 N 〉 Mg 〉 K 〉 S 〉 P. Monthly variations in nutrient concentrations were greater in leaf litter （LL） than other litter components. The highest and lowest concentrations of N, P, K, and S in LL were found in the growing season and the nongrowing season, respectively, but Ca and Mg were the opposite. Nutrient returns via litterfall showed a marked monthly pattern with a major peak in October and one or two small peaks in February and/or May, varying with the element and stand type, but no marked monthly variations in nutrient returns via woody litter, reproductive litter, except in May for the BF, and moss litter. Not only litter production but also nutrient concentration controlled the annual nutrient return and the monthly nutrient return pattern. The monthly patterns of the nutrient concentration and return were of ecological importance for nutrient cycling and plant growth in the subalpine forest ecosystems.
基金supported by grants from the Chinese Ministry of Science and Technology(2001BA611B-01)the Chinese Academy of Sciences,and SWECLIM which is financed by MISTRA and SMHI.
文摘A prerequisite of a successful statistical downscaling is that large-scale predictors simulated by the General Circulation Model (GCM) must be realistic. It is assumed here that features smaller than the GCM resolution are important in determining the realism of the large-scale predictors. It is tested whether a three-step method can improve conventional one-step statistical downscaling. The method uses predictors that are upscaled from a dynamical downscaling instead of predictors taken directly from a GCM simulation. The method is applied to downscaling of monthly precipitation in Sweden. The statistical model used is a multiple regression model that uses indices of large-scale atmospheric circulation and 850-hPa specific humidity as predictors. Data from two GCMs (HadCM2 and ECHAM4) and two RCM experiments of the Rossby Centre model (RCA1) driven by the GCMs are used. It is found that upscaled RCA1 predictors capture the seasonal cycle better than those from the GCMs, and hence increase the reliability of the downscaled precipitation. However, there are only slight improvements in the simulation of the seasonal cycle of downscaled precipitation. Due to the cost of the method and the limited improvements in the downscaling results, the three-step method is not justified to replace the one-step method for downscaling of Swedish precipitation.
基金funded by the National Key R&D Program of China(2017YFD0201803)the Talent Recruitment Project of Northeast Institute of Geography and Agroecology,Chinese Academy of Sciences.
文摘Rapid and accurate access to large-scale,high-resolution crop-type distribution maps is important for agricultural management and sustainable agricultural development.Due to the limitations of remote sensing image quality and data processing capabilities,large-scale crop classification is still challenging.This study aimed to map the distribution of crops in Heilongjiang Province using Google Earth Engine(GEE)and Sentinel-1 and Sentinel-2 images.We obtained Sentinel-1 and Sentinel-2 images from all the covered study areas in the critical period for crop growth in 2018(May to September),combined monthly composite images of reflectance bands,vegetation indices and polarization bands as input features,and then performed crop classification using a Random Forest(RF)classifier.The results show that the Sentinel-1 and Sentinel-2 monthly composite images combined with the RF classifier can accurately generate the crop distribution map of the study area,and the overall accuracy(OA)reached 89.75%.Through experiments,we also found that the classification performance using time-series images is significantly better than that using single-period images.Compared with the use of traditional bands only(i.e.,the visible and near-infrared bands),the addition of shortwave infrared bands can improve the accuracy of crop classification most significantly,followed by the addition of red-edge bands.Adding common vegetation indices and Sentinel-1 data to the crop classification improved the overall classification accuracy and the OA by 0.2 and 0.6%,respectively,compared to using only the Sentinel-2 reflectance bands.The analysis of timeliness revealed that when the July image is available,the increase in the accuracy of crop classification is the highest.When the Sentinel-1 and Sentinel-2 images for May,June,and July are available,an OA greater than 80%can be achieved.The results of this study are applicable to large-scale,high-resolution crop classification and provide key technologies for remote sensing-based crop classification in small-scale agricultural areas.
基金supported by the Research Fund of Tianjin Health and Family Planning Commission 2015KY18Science and Technology Major Project of Chinese Preventive Medicine Association Q2017A1225
文摘The epidemiologic characteristics of 631 infant pertussis cases 〈 12 months, which accounted for 57.42% of the total cases, were analyzed by descriptive epidemiology in Tianjin, between 2010 and 2015. The incidence of infants was 104.66/100,000, which was 118 times higher than in other age groups （P 〈 0.001）. The primary type of pertussis simultaneously presented in households was adult-to-infant （70.51%）. The parents were identified as the source of infection in 80.18% of cases for infants. The positive rate of placental antibody transfer was 31.06% and 3.13% for 3-month-old infants. Infants presented the highest age-specific pertussis incidence. The most important reason was parents were the important sources of infection, and secondly the lower level of antibodies in neonates and the rapid waning of maternal antibody titer.
基金sponsored in part by the Fujian Scitech Bureau for research in the universities of Fujian Province(No.2008F5014)The Fujian Forest Ecological System Process and Management Key Laboratory and the Forest Ecology Research Center of the Fujian Agriculture and Forestry University(FAFU) provided major funding
文摘In this study, the dynamics of monthly variation in litterfall and the amount of nutrients, i.e., organic C, N, P and K, in an Aleurites montana plantation were analyzed, based on a field study and experiments over one year. The results show that the litterfall mass of A. montana collected generally presents an ascending trend with maximum defoliation occurring in the autumn and winter （October-December）, accounting for 75.67% of the total amount of annual litterfalk The sequence in the amount of nutrients in A. montana litter was as follows： organic C 〉 N 〉 K 〉 P; their monthly amounts show various dynamic curves. Similar to the dynamics of the mass of monthly litterfall, the monthly returns of C, N, P and K generally show an ascending trend with their peak values all occurring in December. The mass of A. montana litterfall and the dynamics of its monthly nutrient return provide, to a certain degree, a scientific reference for planting and fertilizing A. montana.
基金supported by the Knowledge Innovation Key Project of Chinese Academy of Sciences (Nos. CX10G-E01-08 andKZCX2-SW-317) and the National Natural Science Foundation of China (No. 50279049)
文摘The Miyun Reservoir is the most important water source for Beijing Municipality, the capital of China with a population of more than 12 million. In recent decades, the inflow to the reservoir has shown a decreasing trend, which has seriously threatened water use in Beijing. In order to analyze the influents of land use and cover change (LUCC) upon inflow to Miyun Reservoir, terrain and land use information from remote sensing were utilized with a revised evapotranspiration estimation formula; a water loss model under conditions of human impacts was introduced; and a distributed monthly water balance model was established and applied to the Chaobai River Basin controlled by the Miyun Reservoir. The model simulation suggested that not only the impact of land cover change on evapotranspiration, but also the extra water loss caused by human activities, such as the water and soil conservation development projects should be considered. Although these development projects were of great benefit to human and ecological protection, they could reallocate water resources in time and space, and in a sense thereby influence the stream flow.
基金Under the auspices of the National Natural Science Foundation of China (No. 40401054, No. 40121101), Hundred Talents Program of Chinese Academy of Sciences, President Foundation of Chinese Academy of Sciences, Knowledge Innovation Program of Chinese Academy of Sciences (No. KZCX3-SW-339), National Basic Research Program of China (No. 2005CB422004)
文摘The recorded meteorological data of monthly mean surface air temperature from 72 meteorological stations over the Qinghal-Tibet Plateau in the period of 1960-2003 have been analyzed by using Empirical Orthogonal Function （EOF） method, to understand the detailed features of its temporal and spatial variations. The results show that there was a high consistency of the monthly mean surface air temperature, with a secondarily different variation between the north and the south of the plateau. Warming trend has existed at all stations since the 1960s, while the warming rates were different in various zones. The source regions of big rivers had intense warming tendency. June, November and December were the top three fast-warming months since the 1960s; while April, July and September presented dramatic warming tendency during the last decade.
基金supported by the National Basic Research Program of China (973 Program) (No.2015CB453303)the Special Fund for Agro-scientific Research in the Public Interest (No.201303050)the Taishan Scholar Program of Shandong Province (200867)
文摘In this study,we investigated the community structure of crustaceans(decapod and stomatopod) inhabiting the sandy mud bottoms of Laizhou Bay(northeastern China) monthly from May 2011 to April 2012.Investigation was stopped from December 2011 to February 2012 because of the extreme weather and sea ice.A total of 205,057 specimens belonging to 31 species(shrimp,15;crab,15;and stomatopod,1) were collected in 148 hauls.From 2011 to 2012,Oratosquilla oratoria was the dominant biomass species(47.80%),followed by Charybdis japonica(15.49%),Alpheus japonicas(12.61%),Portunus trituberculatus(6.46%),and Crangon spp.(4.19%).Crangon spp.was the most dominant species by individual(32.55%).O.oratoria was the most-frequently encountered species(81.76%),followed by Palaemon gravieri(70.95%),C.japonica(65.54%),A.japonicas(62.16%),and P.trituberculatus(54.73%).The biomass density increased from August to September 2011 and decreased from March 2012 to April 2012.The dynamics of the ecological indices evolve in a similar manner,with high values of diversity and evenness and rich species from May to June 2011 and low values from September to October 2011.O.oratoria,C.japonica,and P.trituberculatus differed by biomass data between groups I(samples obtained from September to October 2011) and II(samples in other months).These species contributed more than 70% to the similarity of the crustacean community structure.Furthermore,the subsets of environmental variables that best matched the crustacean-assemblage structure were as follows:water depth(WD) in summer(June to August);sea surface temperature(SST),dissolved oxygen(DO),and WD in autumn(September to November);and DO,salinity,and WD in spring(March to May).The calculated correlation coefficients and significance level were higher in the period of July to August 2011 than in other months.Comparing 2011 to 2012 with 1982 to 1983,the species composition remained stable.However,the dominant species changed significantly.High value and large species,such as F.chinensis,P.trituberculatus,and T.curvirostris,have been replaced by low value and small species(i.e.,Crangon spp.,P.gravieri,and C.japonica).
文摘This paper presents the application of autoregressive integrated moving average （ARIMA）, seasonal ARIMA （SARIMA）, and Jordan-Elman artificial neural networks （ANN） models in forecasting the monthly streamflow of the Kizil River in Xinjiang, China. Two different types of monthly streamflow data （original and deseasonalized data） were used to develop time series and Jordan-Elman ANN models using previous flow conditions as predictors. The one-month-ahead forecasting performances of all models for the testing period （1998-2005） were compared using the average monthly flow data from the Kalabeili gaging station on the Kizil River. The Jordan-Elman ANN models, using previous flow conditions as inputs, resulted in no significant improvement over time series models in one-month-ahead forecasting. The results suggest that the simple time series models （ARIMA and SARIMA） can be used in one-month-ahead streamflow forecasting at the study site with a simple and explicit model structure and a model performance similar to the Jordan-Elman ANN models.
文摘Alcoholic liver disease(ALD) is the second most common diagnosis among patients undergoing liver transplantation(LT).The recovery results of patients transplanted for ALD are often at least as good as those of patients transplanted for other diagnoses and better than those suffering from hepatitis C virus, cryptogenic cirrhosis, or hepatocellular carcinoma.Inthe case of medically non-responding patients with severe acute alcoholic hepatitis or acute-on chronic liver failure, the refusal of LT is often based on the lack of the required alcohol abstinence period of six months.The obligatory abidance of a period of abstinence as a transplant eligibility requirement for medically non-responding patients seems unfair and inhumane, since the majority of these patients will not survive the six-month abstinence period.Data from various studies have challenged the 6-mo rule, while excellent survival results of LT have been observed in selected patients with severe alcoholic hepatitis not responding to medical therapy.Patients with severe advanced ALD should have legal access to LT.The mere lack of pre-LT abstinence should not be an obstacle for being listed.
基金The National Key R&D Program of China under contract No.2016YFC1401905the National Natural Science Foundation of China under contract No.41776004the Fundamental Research Funds for the Central Universities under contract No.2016B12514
文摘This study investigates the long-term changes of monthly sea surface wind speeds over the China seas from 1988 to 2015. The 10-meter wind speeds products from four major global reanalysis datasets with high resolution are used: Cross-Calibrated Multi-Platform data set(CCMP), NCEP climate forecast system reanalysis data set(CFSR),ERA-interim reanalysis data set(ERA-int) and Japanese 55-year reanalysis data set(JRA55). The monthly sea surface wind speeds of four major reanalysis data sets have been investigated through comparisons with the longterm and homogeneous observation wind speeds data recorded at ten stations. The results reveal that(1) the wind speeds bias of CCMP, CFSR, ERA-int and JRA55 are 0.91 m/s, 1.22 m/s, 0.62 m/s and 0.22 m/s, respectively.The wind speeds RMSE of CCMP, CFSR, ERA-int and JRA55 are 1.38 m/s, 1.59 m/s, 1.01 m/s and 0.96 m/s,respectively;(2) JRA55 and ERA-int provides a realistic representation of monthly wind speeds, while CCMP and CFSR tend to overestimate observed wind speeds. And all the four data sets tend to underestimate observed wind speeds in Bohai Sea and Yellow Sea;(3) Comparing the annual wind speeds trends between observation and the four data sets at ten stations for 1988-1997, 1988–2007 and 1988–2015, the result show that ERA-int is superior to represent homogeneity monthly wind speeds over the China seaes.
文摘Partial Least Squares Regression （PLSR） is used to study monthly changes in the influence of the Arctic Oscillation （AO） on spring, summer and autumn air temperature over China with the January 500 hPa geopotential height data from 1951 to 2004 and monthly temperature data from January to November at 160 stations in China. Several AO indices have been defined with the 500-hPa geopotential data and the index defined as the first principal component of the normalized geopotential data is best to be used to study the influence of the AO on SAT （surface air temperature） in China. There are three modes through which the AO in winter influences SAT in China. The influence of the AO on SAT in China changes monthly and is stronger in spring and summer than in autumn. The main influenced regions are Northeast China and the Changjiang River drainage area.
文摘An exploratory spatial data analysis method (ESDA) was designed Apr.28,2002 for kriging monthly rainfall. Samples were monthly rainfall observed at 61 weather stations in eastern China over the period 1961-1998. Comparison of five semivariogram models (Spherical, Exponential, Linear, Gaussian and Rational Quadratic) indicated that kriging fulfills the objective of finding better ways to estimate interpolation weights and can provide error information for monthly rainfall interpolation. ESDA yielded the three most common forms of experimental semivariogram for monthly rainfall in the area. All five models were appropriate for monthly rainfall interpolation but under different circumstances. Spherical, Exponential and Linear models perform as smoothing interpolator of the data, whereas Gaussian and Rational Quadratic models serve as an exact interpolator. Spherical, Exponential and Linear models tend to underestimate the values. On the contrary, Gaussian and Rational Quadratic models tend to overestimate the values. Since the suitable model for a specific month usually is not unique and each model does not show any bias toward one or more specific months, an ESDA is recommended for a better interpolation result.
基金jointly supported by the National Natural Science Foundation of China [grant numbers 42088101 and 41730964]the Innovation Group Project of the Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai) [grant number 311021001]。
文摘In this study,the reversal of monthly East Asian winter air temperature(EAWT) in 2020/21 and its predictability were investigated.The reversal of monthly EAWT in 2020/21 was characterized by colder temperatures in early winter(December 2020 to mid-January 2021) and warmer temperatures in late winter(mid-January to February 2021).Results show that the reversal in the intensity of the Siberian high(SH) also occurred between early and late winter in 2020/21.In early winter,as the Barents-Laptev sea ice in the previous September(i.e., in2020) reached a minimum for the period 1981-2020,the SH was strengthaned via a reduction of the meridional gradient between the Arctic and East Asia.In late winter,as a sudden stratospheric warming occurred on 5 January 2021,the stratospheric polar vortex weakened,with the weakest center shifting to North America in January.Subsequently,the negative Arctic Oscillation-like structure shifted towards North America in the middle and lower troposphere,which weakened the SH in late winter.Furthermore,the predictability of the reversal in EAWT in 2020/21 was validated based on monthly and daily predictions from NCEP-CFSv2(National Centers for Environment Prediction-Climate Forecast System,version 2).The results showed that the model was unable to reproduce the monthly reversal of EAWT.However,it was able to forecast the reversal date(18 January 2021)of EAWT at lead times of 1-20 days on the daily scale.
基金supported by the National Key Research and Development Plan (Grant No. 2016YFA0600703)the National Natural Science Foundation of China (Grant Nos. 91744311, 41991283 and 41705058)the funding of the Jiangsu Innovation & Entrepreneurship Team。
文摘Haze pollution in early winter(December and January) in the Yangtze River Delta(YRD) and in North China(NC)are both severe;however, their monthly variations are significantly different. In this study, the dominant large-scale atmospheric circulations and local meteorological conditions were investigated and compared over the YRD and NC in each month. Results showed that the YRD(NC) is dominated by the so-called Scandinavia(East Atlantic/West Russia)pattern in December, and these circulations weaken in January. The East Asian December and January monsoons over the YRD and NC have negative correlations with the number of haze days. The local descending motion facilitates less removal of haze pollution over the YRD, while the local ascending motion facilitates less removal of haze pollution over NC in January, despite a weaker relationship in December. Additionally, the monthly variations of atmospheric circulations showed that adverse meteorological conditions restrict the vertical(horizontal) dispersion of haze pollution in December(January) over the YRD, while the associated local weather conditions are similar in these two months over NC.
基金National Key R&D Program of China"Study on impact assessment of ecological climate and environment on the wind fann and photovoltaic plants"(2018YFB1502800)Science and Technology Project of State Grid Hebei Electric Power Company"Research and application of medium and long-term forecasting technology for regional wind and photovoltaic resources and generation capacity",(5204BB170007)Special Fund Project of Hebei Provincial Government(19214310D).
文摘Predicting wind power gen eration over the medium and long term is helpful for dispatchi ng departme nts,as it aids in constructing generation plans and electricity market transactions.This study presents a monthly wind power gen eration forecast!ng method based on a climate model and long short-term memory(LSTM)n eural n etwork.A non linear mappi ng model is established between the meteorological elements and wind power monthly utilization hours.After considering the meteorological data(as predicted for the future)and new installed capacity planning,the monthly wind power gen eration forecast results are output.A case study shows the effectiveness of the prediction method.
