Wheat (Triticum aestivum L.) production is a major economic activity in most regional and rural areas in the Southern Plains, a semi-arid region of the United States. This region is vulnerable to drought and is projec...Wheat (Triticum aestivum L.) production is a major economic activity in most regional and rural areas in the Southern Plains, a semi-arid region of the United States. This region is vulnerable to drought and is projected to experience a drier climate in the future. Since the interannual variability in climate in this region is linked to an ocean-atmospheric phenomenon, called El Niño-Southern Oscillation (ENSO), droughts in this region may be associated with ENSO. Droughts that occur during the critical growth phases of wheat can be extremely costly. However, the losses due to an impending drought can be minimized through mitigation measures if it is predicted in advance. Predicting the yield loss from an imminent drought is crucial for stakeholders. One of the reliable ways for such prediction is using a plant physiology-based agricultural drought index, such as Agricultural Reference Index for Drought (ARID). This study developed ENSO phase-specific, ARID-based models for predicting the drought-induced yield loss for winter wheat in this region by accounting for its phenological phase-specific sensitivity to drought. The reasonable values of the drought sensitivity coefficients of the yield model for each ENSO phase (El Niño, La Niña, or Neutral) indicated that the yield models reflected reasonably well the phenomena of water stress decreasing the winter wheat yields in this region during different ENSO phases. The values of various goodness-of-fit measures used, including the Nash-Sutcliffe Index (0.54 to 0.67), the Willmott Index (0.82 to 0.89), and the percentage error (20 to 26), indicated that the yield models performed fairly well at predicting the ENSO phase-specific loss of wheat yields from drought. This yield model may be useful for predicting yield loss from drought and scheduling irrigation allocation based on the phenological phase-specific sensitivity to drought as impacted by ENSO.展开更多
Some recent studies presented two existing types of ENSO events, one is the Eastern-Pacific(EP) type and the other the Central-Pacific(CP) type. This study examined the monitoring ability of several current operationa...Some recent studies presented two existing types of ENSO events, one is the Eastern-Pacific(EP) type and the other the Central-Pacific(CP) type. This study examined the monitoring ability of several current operational ENSO indices. The results indicated that a single index could not distinguish the EP and CP in the historical ENSO events during 1950-2009. The Nio 3 index may only be suitable for monitoring the EP-type ENSO, while the Nio 4 index works only for the CP-type ENSO. In order to capture the occurrence of ENSO events and distinguish the type, we considered a new monitoring index group using Nio 3 and Nio 4 indices. Further analysis confirmed that this index group can monitor different types of historical ENSO events with different spatial distribution of sea surface temperature. It has a good performance in determining the characteristics of the ENSO events, including peak intensity, onset,decay, and mature phase.展开更多
The modulation of tropical cyclogenesis over the southern South China Sea （SSCS） by the El Nin o- Southern Oscillation （ENSO） is examined in October–December （OND）, when tropical cyclone （TC） activities are m...The modulation of tropical cyclogenesis over the southern South China Sea （SSCS） by the El Nin o- Southern Oscillation （ENSO） is examined in October–December （OND）, when tropical cyclone （TC） activities are most active in this region. The results reveal that there were more TCs formed over the SSCS during La Nin a years and less TCs during El Nin o years. How different environmental factors （including low-level vorticity, mid-level relative humidity, vertical wind shear, and potential intensity） contribute to this influence is investigated, using a genesis potential （GP） index developed by Emanuel and Nolan. Composite anomalies of the GP index are produced for El Nin o and La Nin a years separately, which could account for the changes of TC frequency over the SSCS in different ENSO phases. The degree of contribution by each factor is determined quantitatively by producing composites of modified indices in which only one of the contributing factors varies, with the others set to climatology. The results show that the mid-level relative humidity makes the largest contribution to the ENSO modulation of tropical cyclogenesis over the SSCS. Although warmer sea surface temperatures （SSTs） and larger amount of evaporation from the ocean surface were observed over the SSCS during El Nin o years, anomalous descending motions due to the anomalous Walker circulations inhibited the upward transports of water vapor and led to less moisture contents in the middle troposphere, which suppressed TC formations.展开更多
针对1950—2009年的东部型(EP)和中部型(CP)ENSO事件,比较了目前国际上常用的ENSO监测指数对它们的监测能力。结果表明:单一的指数无法同时区分EP和CP型ENSO事件,其中Ni o 3指数只能有效识别EP型ENSO事件,而Ni o 4指数则对CP型事件具有...针对1950—2009年的东部型(EP)和中部型(CP)ENSO事件,比较了目前国际上常用的ENSO监测指数对它们的监测能力。结果表明:单一的指数无法同时区分EP和CP型ENSO事件,其中Ni o 3指数只能有效识别EP型ENSO事件,而Ni o 4指数则对CP型事件具有较强的监测能力。据此提出同时以Ni o 3和Ni o 4指数构建指数组的形式来监测不同类型的ENSO事件,结果表明,该指标组能够较全面监测历史上发生的不同分布类型ENSO事件,且能准确判定事件的峰值强度、起止时间和成熟期等其他特征。展开更多
基于热带太平洋SST和850 hPa风资料,分析了西太平洋暖池东界和东太平洋暖池南界的年际和年代际变异,并探讨了赤道太平洋纬向风异常对西太平洋暖池纬向运移的驱动作用以及热带东北太平洋经向风异常对东太平洋暖池经向变动的影响。在此基...基于热带太平洋SST和850 hPa风资料,分析了西太平洋暖池东界和东太平洋暖池南界的年际和年代际变异,并探讨了赤道太平洋纬向风异常对西太平洋暖池纬向运移的驱动作用以及热带东北太平洋经向风异常对东太平洋暖池经向变动的影响。在此基础上,研究了西太平洋暖池和东太平洋暖池变异对ENSO循环的联合影响,并提出了一个联合影响指数。结果表明,当联合指数为1.6时,有可能出现一次新的El Ni o事件。这为ENSO的形成和演变机制研究提供了一个新的线索。展开更多
文摘Wheat (Triticum aestivum L.) production is a major economic activity in most regional and rural areas in the Southern Plains, a semi-arid region of the United States. This region is vulnerable to drought and is projected to experience a drier climate in the future. Since the interannual variability in climate in this region is linked to an ocean-atmospheric phenomenon, called El Niño-Southern Oscillation (ENSO), droughts in this region may be associated with ENSO. Droughts that occur during the critical growth phases of wheat can be extremely costly. However, the losses due to an impending drought can be minimized through mitigation measures if it is predicted in advance. Predicting the yield loss from an imminent drought is crucial for stakeholders. One of the reliable ways for such prediction is using a plant physiology-based agricultural drought index, such as Agricultural Reference Index for Drought (ARID). This study developed ENSO phase-specific, ARID-based models for predicting the drought-induced yield loss for winter wheat in this region by accounting for its phenological phase-specific sensitivity to drought. The reasonable values of the drought sensitivity coefficients of the yield model for each ENSO phase (El Niño, La Niña, or Neutral) indicated that the yield models reflected reasonably well the phenomena of water stress decreasing the winter wheat yields in this region during different ENSO phases. The values of various goodness-of-fit measures used, including the Nash-Sutcliffe Index (0.54 to 0.67), the Willmott Index (0.82 to 0.89), and the percentage error (20 to 26), indicated that the yield models performed fairly well at predicting the ENSO phase-specific loss of wheat yields from drought. This yield model may be useful for predicting yield loss from drought and scheduling irrigation allocation based on the phenological phase-specific sensitivity to drought as impacted by ENSO.
基金The Definition of El Nio/La Nia Episodes,a National Standard ProjectSpecialized Project for Public Welfare Industries(GYHY201406018,GYHY200806009)+2 种基金Program 973(2012CB955901)National Science and Technology Support Program(2009BAC51B05)National Youth Foundation for Natural Science(41005038)
文摘Some recent studies presented two existing types of ENSO events, one is the Eastern-Pacific(EP) type and the other the Central-Pacific(CP) type. This study examined the monitoring ability of several current operational ENSO indices. The results indicated that a single index could not distinguish the EP and CP in the historical ENSO events during 1950-2009. The Nio 3 index may only be suitable for monitoring the EP-type ENSO, while the Nio 4 index works only for the CP-type ENSO. In order to capture the occurrence of ENSO events and distinguish the type, we considered a new monitoring index group using Nio 3 and Nio 4 indices. Further analysis confirmed that this index group can monitor different types of historical ENSO events with different spatial distribution of sea surface temperature. It has a good performance in determining the characteristics of the ENSO events, including peak intensity, onset,decay, and mature phase.
基金The National Basic Research Program of China under contract No. 2011CB403500the fund from the State Key Laboratory of Satellite Ocean Environmental Dynamics (Second Institute of Oceanography) under contract No. SOED1108+1 种基金the fund from the State Key Laboratory of Tropical Oceanography (South China Sea Institute of Oceanology) under contract No. LED1002the tropical marine meteorology fund from the Institute of Tropical and Marine Meteorology and the Fundamental Research Funds for the Central Universities under contract No. 111gpy13
文摘The modulation of tropical cyclogenesis over the southern South China Sea （SSCS） by the El Nin o- Southern Oscillation （ENSO） is examined in October–December （OND）, when tropical cyclone （TC） activities are most active in this region. The results reveal that there were more TCs formed over the SSCS during La Nin a years and less TCs during El Nin o years. How different environmental factors （including low-level vorticity, mid-level relative humidity, vertical wind shear, and potential intensity） contribute to this influence is investigated, using a genesis potential （GP） index developed by Emanuel and Nolan. Composite anomalies of the GP index are produced for El Nin o and La Nin a years separately, which could account for the changes of TC frequency over the SSCS in different ENSO phases. The degree of contribution by each factor is determined quantitatively by producing composites of modified indices in which only one of the contributing factors varies, with the others set to climatology. The results show that the mid-level relative humidity makes the largest contribution to the ENSO modulation of tropical cyclogenesis over the SSCS. Although warmer sea surface temperatures （SSTs） and larger amount of evaporation from the ocean surface were observed over the SSCS during El Nin o years, anomalous descending motions due to the anomalous Walker circulations inhibited the upward transports of water vapor and led to less moisture contents in the middle troposphere, which suppressed TC formations.
文摘针对1950—2009年的东部型(EP)和中部型(CP)ENSO事件,比较了目前国际上常用的ENSO监测指数对它们的监测能力。结果表明:单一的指数无法同时区分EP和CP型ENSO事件,其中Ni o 3指数只能有效识别EP型ENSO事件,而Ni o 4指数则对CP型事件具有较强的监测能力。据此提出同时以Ni o 3和Ni o 4指数构建指数组的形式来监测不同类型的ENSO事件,结果表明,该指标组能够较全面监测历史上发生的不同分布类型ENSO事件,且能准确判定事件的峰值强度、起止时间和成熟期等其他特征。
文摘基于热带太平洋SST和850 hPa风资料,分析了西太平洋暖池东界和东太平洋暖池南界的年际和年代际变异,并探讨了赤道太平洋纬向风异常对西太平洋暖池纬向运移的驱动作用以及热带东北太平洋经向风异常对东太平洋暖池经向变动的影响。在此基础上,研究了西太平洋暖池和东太平洋暖池变异对ENSO循环的联合影响,并提出了一个联合影响指数。结果表明,当联合指数为1.6时,有可能出现一次新的El Ni o事件。这为ENSO的形成和演变机制研究提供了一个新的线索。
