太平洋—印度洋海温与我国东部旱涝型年代际变化的关系

对我国东部各区域的夏季降水的正交小波分解表明,其大于28年的分量可以很好地表示华北和长江中下游地区在20世纪70年代前后旱涝相反的年代际变化特征。合成分析表明,北太平洋、热带印度洋海温和东亚高空急流与我国东部夏季旱涝型的年代际变化密切相关。东亚高空急流和西太平洋副热带高压在70年代前后的年代际差异对旱涝型发生年代际变化起到重要作用;北太平洋和热带印度洋海温的年代际变化近百年来是协同一致的,二者有可能共同对旱涝型的变化产生影响。进一步分析指出,北太平洋—热带印度洋海温的变化与急流和副高的南北位置在年际和年代际尺度上都密切相关。可见,北太平洋-热带印度洋海表温度异常(SSTA)对于我国东部旱型涝的年代际变化确实具有重要的预示作用。

利用沃尔什系数讨论我国旱涝型影响因子

以太阳黑子数、南方涛动指数和地球自转速度等因子，利用沃尔什函数理论和多元统计分析，探讨了我国东部＊（１００°Ｅ以东）旱涝型影响因子，分析了它们的影响方式。结果表明：我国旱涝型的主要影响因子是南方涛动和地球自转速度等，其影响方式均以后延相关。

我国旱涝空间型的马尔科夫概型分析

旱涝灾害在我国是影响最大、也最为频繁的气候灾害。本文利用马尔科夫概型分析的原理和方法,在验证了我国旱涝空间型序列具有马尔科夫性质的基础上,计算出各状态的转移概率,进而分析了旱涝空间型序列的静态和动态结构,并揭示出旱涝空间型各状态演化的优势倾向。

ENSO事件与河南旱涝年型的关系

利用河南省1951～1998年旱涝灾害影响资料，划分了旱涝灾害年型，并分析了ENSO事件与河南旱涝年型的关系：在厄尔尼诺当年、次年及反厄尔尼诺年，干旱年成灾面积大于67万公顷的大旱年占旱年总数的61％，涝年成灾面积大于67万公顷的大涝年占涝年总数的65％；厄尔尼诺年旱年频率大于涝年频率，反厄尔尼诺年旱、涝年频率相当；弱、最弱及最强的厄尔尼诺开始年涝灾影响为主，中等及偏强厄尔尼诺开始年以旱灾为主；厄尔尼诺开始年与次年旱涝影响趋势相一致的频率达92％。

环渤海地区500年来的旱涝变化及其区域分异

用研究区 １４７０～ １９８５年的旱涝等级资料，划分了该地区５００年来旱涝变化的 ７个阶段，讨论 了不同阶段间旱涝型的变化及其旱涝区域分异意义、结果表明，５００年来研究区有４类主要旱涝型， 各型旱涝在不同阶段的重要程度及场型特征均有较大差异，深刻反映了该地区５００年来旱涝区域分异 特征的变化。通过对５００年来旱涝变化与温度变化的对比发现，较温暖期，研究区的旱涝型及旱涝区 域分异格局较多变，旱涝变化的区域差异性较大；较寒冷期，旱涝型及区域分异格局较稳定，旱涝 变化的区域差异性较小；而在小冰期最寒冷阶段，旱涝型及旱涝区域分异格局的变动十分频繁，旱 涝变化的区域差异性亦最大。

江淮梅雨异常空间分布型对比分析

利用国家气候中心整编的中国160个测站的月降水资料,提取1951—2012年江淮流域26站6、7月份的梅雨量距平场资料进行EOF分析,将梅雨雨型分为北涝南旱型和南涝北旱型。利用NCAR/NCEP再分析资料对两种空间分布的典型年大气环流背景特征进行合成分析,结果表明:北涝南旱年,高纬度鄂霍次克海高压阻塞形势偏强,极涡偏弱,西太平洋副热带高压和南亚高压位置偏北,东亚副热带夏季风偏强,水汽辐合中心偏北;南涝北旱年情形基本相反,高纬度鄂霍次克海高压阻塞形势和极涡偏强,西太平洋副热带高压和200 hPa南亚高压位置偏南,东亚副热带夏季风偏弱,水汽辐合中心偏南。

Quantifying Responses of Winter Wheat Physiological Processes to Soil Water Stress for Use in Growth Simulation Modeling

A deep understanding of crop-water eco-physiological relations is the basis for quantifying plant physiological responses to soil water stress. Pot experiments were conducted to investigate the winter wheat crop-water relations under both drought and waterlogging conditions in two sequential growing seasons from 2000 to 2002, and then the data were used to develop and validate models simulating the responses of winter wheat growth to drought and waterlogging stress. The experiment consisted of four treatments, waterlogging (keep 1 to 2 cm water layer depth above soil surface), control (70%-80% field capacity), light drought (40%-50% field capacity) and severe drought (30%-40% field capacity) with six replicates at five stages in the 2000-2001 growth season. Three soil water content treatments (waterlogging, control and drought) with two replicates were designed in the 2001-2002 growth season. Waterlogging and control treatments are the same as in the 2000-2001 growth season. For the drought treatment, no water was supplied and the soil moisture decreased from field capacity to wilting point. Leaf net photosynthetic rate, transpiration rate, predawn leaf water potential, soil water potential, soil water content and dry matter weight of individual organs were measured. Based on crop-water eco-physiological relations, drought and waterlogging stress factors for winter wheat growth simulation model were put forward. Drought stress factors integrated soil water availability, the sensitivity of different development stages and the difference between physiological processes (such as photosynthesis, transpiration and partitioning). The quantification of waterlogging stress factor considered different crop species, soil water status, waterlogging days and sensitivity at different growth stages. Data sets from the pot experiments revealed favorable performance reliability for the simulation sub-models with the drought and waterlogging stress factors.

Asymmetric relationships between El Nino/La Nina and floods/droughts in the following summer over Chongqing,China

This study presents a detailed analysis of the asymmetric relationships between the warm/cold phase of the El Ni?o–Southern Oscillation and the typical flood/drought years in summer over Chongqing.Furthermore,its underpinning mechanisms are also explored.The results show that:(1)El Ni?o and La Ni?a have an asymmetric influence on summer precipitation in the following year over Chongqing.Generally,the composite atmospheric circulation anomalies for El Ni?o years are consistent with the composite results for typical flood years in summer over Chongqing,which indicates a tight link between typical flood years in summer over Chongqing and El Ni?o events.However,the relationship between typical drought years in summer over Chongqing and La Ni?a events is not significant.(2)From winter to the following summer,the extent of positive SST anomalies in the equatorial eastern Pacific associated with typical flood years in summer over Chongqing shrinks,whereas in the tropical Indian Ocean,the extent slightly expands.This trend indicates that the impact of El Ni?o on typical flood years in summer over Chongqing is maintained through the‘relay effect’of SSTs in the tropical Indian Ocean,which is the result of a lagged response of positive SST anomalies in the tropical Indian Ocean to El Ni?o events in winter.

Analysis of rainfall variability over Tanzania in late austral summer

Based on site-observation data,NCEP–NCAR reanalysis data,and Climatic Research Unit gridded data,the rainfall variability over Tanzania during late austral summer(January–March,JFM)was analyzed for the period 1961–2011.Further,the associated atmospheric circulation and SST anomalies(SSTAs)were explored to understand the mechanisms of dry-and wet-year cases based on an interannual time scale.The correlation,Morlet wavelet power spectrum,and composite analysis methods were employed.The results showed that the JFM standardized rainfall anomaly time series exhibited significant time scales of variability at interannual(2–8 years)and quasidecadal(8–12 years).During dry years,anomalous anticyclonic northeasterly flow originating from western tropical Indian and southeast trades from the Indian Ocean to the southeast were associated with subsiding dry air,which resulted in suppression of rainfall as observed.In the typical wet-year cases,meanwhile,anomalous westerlies from the tropical and southeast Atlantic were strengthened over the Congo basin,delivering more precipitation to the region.Significant correlation was exhibited over the western tropical and southeast Indian Ocean,as well as the southeast and tropical Atlantic Ocean.These SSTA patterns favored atmospheric general circulation anomalies that were closely related to JFM rainfall over Tanzania.