Responses of late spring （21 April 20 May） rainfall to the upper tropospheric cooling over East Asia are investigated with a regional climate model based on Laboratoire de M6t6orologie Dynamique Zoom （LMDZ4-RCM）. ...Responses of late spring （21 April 20 May） rainfall to the upper tropospheric cooling over East Asia are investigated with a regional climate model based on Laboratoire de M6t6orologie Dynamique Zoom （LMDZ4-RCM）. A control experiment is performed with two runs driven by the mean ERA-40 data during 1958-1977 and 1981 2000, respectively. The model reproduces the major decadal-scale circulation changes in late spring over East Asia, including a cooling in the upper troposphere and an anomalous meridional cell. Accordingly, the precipitation decrease is also captured in the southeast of the upper-level cooling region. To quantify the role of the upper-level cooling in the drought mechanism, a sensitivity experiment is further conducted with the cooling imposed in the upper troposphere. It is demonstrated that the upper-level cooling can generate the anomalous meridional cell and consequently the drought to the southeast of the cooling center. Therefore, upper tropospheric cooling should have played a dominant role in the observed late spring drought over Southeast China in recent decades.展开更多
In the spring of 2021,southwestern China(SWC)experienced extreme drought,accompanied by the highest seasonal-mean temperature record since 1961.This drought event occurred in the decaying phase of a La Niña event...In the spring of 2021,southwestern China(SWC)experienced extreme drought,accompanied by the highest seasonal-mean temperature record since 1961.This drought event occurred in the decaying phase of a La Niña event with negative geopotential height anomalies over the Philippine Sea,which is distinct from the historical perspective.Historically,spring drought over SWC is often linked to El Niño and strong western North Pacific subtropical high.Here,we show that the extreme drought in the spring of 2021 may be mainly driven by the atmospheric internal variability and amplified by the warming trend.Specifically,the evaporation increase due to the high temperature accounts for about 30%of drought severity,with the contributions of its linear trend portion being nearly 20%and the interannual variability portion being about 10%.Since the sea surface temperature forcing from the tropical central and eastern Pacific played a minor role in the occurrence of drought,it is a challenge for a climate model to capture the 2021 SWC drought beyond one-month lead times.展开更多
Guangzhou spring rainfall mainly exhibits interannual variation of Quasi-biannual and interdecadal variation of 30 yrs, and is in the period of weak rainfall at interdecadal time scale. SST anomalies （SSTA） of Nino3...Guangzhou spring rainfall mainly exhibits interannual variation of Quasi-biannual and interdecadal variation of 30 yrs, and is in the period of weak rainfall at interdecadal time scale. SST anomalies （SSTA） of Nino3 are the strongest precursor of Guangzhou spring rainfall. They have significant positive correlation from previous November and persist stably to April. Nino3 SSTA in the previous winter affects Guangzhou spring rainfall through North Pacific subtropical high and low wind in spring. When Nino3 SSTA is positive in the previous winter, sprirg subtropical high is intense and westward, South China is located in the area of ascending airflow at the edge of the subtropical high, and water vapor transporting to South China is intensified by anticyclone circulation to the east of the Philippines. So Guangzhou spring rainfall is heavy. When Nino3 SSTA is negative, the subtropical high is weak and eastward, South China is far away from the subtropical high and is located in the area of descending airflow, and water vapor transportirg to South China is weak because low-level cyclonic circulation controls areas to the east of the Philippines and north wind prevails in South China. So Guangzhou spring rainfall is weak ard spring drought is resulted.展开更多
为探究干旱区春小麦光合生理过程对干旱、高温的响应机制,在典型干旱区甘肃武威荒漠生态与农业气象试验站开展田间试验,设置充足供水(CK,土壤含水量保持在80%的田间持水量)、营养生长期开始干旱胁迫(T_(1))和生殖生长期开始干旱胁迫(T_(...为探究干旱区春小麦光合生理过程对干旱、高温的响应机制,在典型干旱区甘肃武威荒漠生态与农业气象试验站开展田间试验,设置充足供水(CK,土壤含水量保持在80%的田间持水量)、营养生长期开始干旱胁迫(T_(1))和生殖生长期开始干旱胁迫(T_(2))3种处理,测定春小麦在25℃(适宜温度)与31℃(高温)叶温调控条件下叶片光合特征的光响应曲线,分析高温条件下干旱胁迫对春小麦叶片光合参数、气体交换指标及水分利用效率(Water Use Efficiency,WUE)的影响。结果表明:(1)干旱胁迫显著降低春小麦净光合速率(P_(n)),降幅为22.8%~57.1%,高温条件下其降低幅度大于适温条件,且在强光下表现出明显光抑制现象,高温条件下干旱处理进一步降低春小麦叶片达到光饱和的光强阈值。高温加长期干旱会降低春小麦叶片表观量子效率、最大净光合速率、暗呼吸速率及光饱和点,同时增大光补偿点。(2)干旱导致气孔导度、蒸腾速率下降,胞间CO_(2)浓度在T_(1)处理高光强下累积。T_(2)处理春小麦叶片以气孔限制为主,而T_(1)处理在高温出现光合器官损伤,引发非气孔限制。(3)WUE总体表现为T_(2)>CK>T_(1)。随光强增大,CK处理WUE升高,T_(2)处理在适温时升高,高温时下降,T_(1)处理均呈先增后降趋势。本研究为干旱区春小麦节水灌溉及抗逆栽培提供理论依据。展开更多
Groundwater extraction is used to alleviate drought in many habitats. However, widespread drought decreases spring discharge and there is a need to integrate climate change research into resource management and action...Groundwater extraction is used to alleviate drought in many habitats. However, widespread drought decreases spring discharge and there is a need to integrate climate change research into resource management and action. Accurate estimates of groundwater discharge may be valuable in improving decision support systems of hydrogeological resource exploitation. The present study performs a forecast for groundwater discharge in Aquifer?s Cervialto Mountains(southern Italy). A time series starting in 1883 was the basis for longterm predictions. An Ensemble Discharge Prediction(EDis P) was applied, and the progress of the discharge ensemble forecast was inferred with the aid of an Exponential Smoothing(ES) model initialized at different annual times. EDisP-ES hindcast model experiments were tested, and discharge plume-patterns forecast was assessed with horizon placed in the year 2044. A 46-year cycle pattern was identified by comparing simulations and observations, which is essential for the forecasting purpose. ED is P-ES performed an ensemble mean path for the coming decades that indicates a discharge regime within ± 1 standard deviation around the mean value of 4.1 m^3 s^(-1). These fluctuations are comparable with those observed in the period 1961-1980 and further back, with changepoints detectable around the years 2025 and 2035. Temporary drought conditions are expected after the year 2030.展开更多
文摘Responses of late spring （21 April 20 May） rainfall to the upper tropospheric cooling over East Asia are investigated with a regional climate model based on Laboratoire de M6t6orologie Dynamique Zoom （LMDZ4-RCM）. A control experiment is performed with two runs driven by the mean ERA-40 data during 1958-1977 and 1981 2000, respectively. The model reproduces the major decadal-scale circulation changes in late spring over East Asia, including a cooling in the upper troposphere and an anomalous meridional cell. Accordingly, the precipitation decrease is also captured in the southeast of the upper-level cooling region. To quantify the role of the upper-level cooling in the drought mechanism, a sensitivity experiment is further conducted with the cooling imposed in the upper troposphere. It is demonstrated that the upper-level cooling can generate the anomalous meridional cell and consequently the drought to the southeast of the cooling center. Therefore, upper tropospheric cooling should have played a dominant role in the observed late spring drought over Southeast China in recent decades.
基金supported by the National Key R&D Program of China(Grant No.2017YFA0605004)Guangdong Major Project of Basic and Applied Basic Research(Grant No.2020B0301030004)+2 种基金National Natural Science Foundations of China(Grant No.42175056)the China Meteorological Administration Innovation and Development Project(CXFZ2022J031)the Joint Open Project of KLME&CIC-FEMD,NUIST(Grant No.KLME202102).
文摘In the spring of 2021,southwestern China(SWC)experienced extreme drought,accompanied by the highest seasonal-mean temperature record since 1961.This drought event occurred in the decaying phase of a La Niña event with negative geopotential height anomalies over the Philippine Sea,which is distinct from the historical perspective.Historically,spring drought over SWC is often linked to El Niño and strong western North Pacific subtropical high.Here,we show that the extreme drought in the spring of 2021 may be mainly driven by the atmospheric internal variability and amplified by the warming trend.Specifically,the evaporation increase due to the high temperature accounts for about 30%of drought severity,with the contributions of its linear trend portion being nearly 20%and the interannual variability portion being about 10%.Since the sea surface temperature forcing from the tropical central and eastern Pacific played a minor role in the occurrence of drought,it is a challenge for a climate model to capture the 2021 SWC drought beyond one-month lead times.
基金Research on the Technologies of Predicting Drought Prospects in Guangdong, a plannedproject for Guangdong Province (2005B32601007)
文摘Guangzhou spring rainfall mainly exhibits interannual variation of Quasi-biannual and interdecadal variation of 30 yrs, and is in the period of weak rainfall at interdecadal time scale. SST anomalies （SSTA） of Nino3 are the strongest precursor of Guangzhou spring rainfall. They have significant positive correlation from previous November and persist stably to April. Nino3 SSTA in the previous winter affects Guangzhou spring rainfall through North Pacific subtropical high and low wind in spring. When Nino3 SSTA is positive in the previous winter, sprirg subtropical high is intense and westward, South China is located in the area of ascending airflow at the edge of the subtropical high, and water vapor transporting to South China is intensified by anticyclone circulation to the east of the Philippines. So Guangzhou spring rainfall is heavy. When Nino3 SSTA is negative, the subtropical high is weak and eastward, South China is far away from the subtropical high and is located in the area of descending airflow, and water vapor transportirg to South China is weak because low-level cyclonic circulation controls areas to the east of the Philippines and north wind prevails in South China. So Guangzhou spring rainfall is weak ard spring drought is resulted.
文摘为探究干旱区春小麦光合生理过程对干旱、高温的响应机制,在典型干旱区甘肃武威荒漠生态与农业气象试验站开展田间试验,设置充足供水(CK,土壤含水量保持在80%的田间持水量)、营养生长期开始干旱胁迫(T_(1))和生殖生长期开始干旱胁迫(T_(2))3种处理,测定春小麦在25℃(适宜温度)与31℃(高温)叶温调控条件下叶片光合特征的光响应曲线,分析高温条件下干旱胁迫对春小麦叶片光合参数、气体交换指标及水分利用效率(Water Use Efficiency,WUE)的影响。结果表明:(1)干旱胁迫显著降低春小麦净光合速率(P_(n)),降幅为22.8%~57.1%,高温条件下其降低幅度大于适温条件,且在强光下表现出明显光抑制现象,高温条件下干旱处理进一步降低春小麦叶片达到光饱和的光强阈值。高温加长期干旱会降低春小麦叶片表观量子效率、最大净光合速率、暗呼吸速率及光饱和点,同时增大光补偿点。(2)干旱导致气孔导度、蒸腾速率下降,胞间CO_(2)浓度在T_(1)处理高光强下累积。T_(2)处理春小麦叶片以气孔限制为主,而T_(1)处理在高温出现光合器官损伤,引发非气孔限制。(3)WUE总体表现为T_(2)>CK>T_(1)。随光强增大,CK处理WUE升高,T_(2)处理在适温时升高,高温时下降,T_(1)处理均呈先增后降趋势。本研究为干旱区春小麦节水灌溉及抗逆栽培提供理论依据。
文摘Groundwater extraction is used to alleviate drought in many habitats. However, widespread drought decreases spring discharge and there is a need to integrate climate change research into resource management and action. Accurate estimates of groundwater discharge may be valuable in improving decision support systems of hydrogeological resource exploitation. The present study performs a forecast for groundwater discharge in Aquifer?s Cervialto Mountains(southern Italy). A time series starting in 1883 was the basis for longterm predictions. An Ensemble Discharge Prediction(EDis P) was applied, and the progress of the discharge ensemble forecast was inferred with the aid of an Exponential Smoothing(ES) model initialized at different annual times. EDisP-ES hindcast model experiments were tested, and discharge plume-patterns forecast was assessed with horizon placed in the year 2044. A 46-year cycle pattern was identified by comparing simulations and observations, which is essential for the forecasting purpose. ED is P-ES performed an ensemble mean path for the coming decades that indicates a discharge regime within ± 1 standard deviation around the mean value of 4.1 m^3 s^(-1). These fluctuations are comparable with those observed in the period 1961-1980 and further back, with changepoints detectable around the years 2025 and 2035. Temporary drought conditions are expected after the year 2030.
