The CERES‐Rice Model‐Based Estimates of Potential Monsoon Season Rainfed Rice Productivity in Bangladesh*

Agricultural practices in Bangladesh are largely dependent on the monsoonal rainfall. Historically, Bangladesh often experiences severe droughts and floods during the monsoon months, with significant crop losses during both extreme conditions. This article provides a quantitative assessment of potential monsoon‐season aman rice for four transplanting dates: 1 June, 1 July, 15 July, and 15 August. A crop‐growth simulation model, the CERES‐Rice, is applied to sixteen locations representing major rice‐growing regions of Bangladesh to determine baseline yield estimates for four transplanting dates. The applications were conducted for 1975 through 1987. Average potential yield in Bangladesh is 6,907, 5,039, 3,637, and 1,762 kg ha^?1 for the above transplanting dates, respectively. In other words, Bangladesh would obtain 27 percent, 48 percent, and 75 percent less yield for 1 July, 15 July, and 15 August transplanting, respectively, than for 1 June transplanting. Potential yield vulnerability is the least for 1 June transplanting (up to 5 percent) and the highest (up to 66 percent) for 15 July transplanting date. The model applications show that regional variations exist for potential yield and yield vulnerability for a particular transplanting date. In addition, response of yield and vulnerability for a region changes with transplanting dates.     

ENSO 循环各阶段东亚夏季风特征的诊断研究

利用NCEP／NCAR再分析资料和NCAR海温资料及中国测站地温资料，对ENSO循环不同阶段东亚夏季风强弱变化进行了分析．并从此期间的海陆热力差异和季风低压变化来探讨海温异常对东亚夏季风的影响，结果表明：东亚夏季风指数有明显的年际变化和年代际变化，且与赤道东太平洋SST有较好的负相关关系，其中又以与三个月前的海温变化关系最好．在Ninol 2区为冷、暖水之后的三个月中，冷水期对应的东亚夏季风指数大于暖水期对应的东亚夏季风指数，东亚夏季风比暖水期强。赤道东太平洋SST变化期间亚洲大陆的地面温度和地面气压也有明显变化，这是引起ENSO不同阶段东亚夏季风变化的主要原因。     

RESPONSE OF THE ATMOSPHERIC GENERAL CIRCULATION TO WINTER SNOW COVER ANOMALY

In this paper,the response of the atmospheric general circulation to winter anomalous snowcover was investigated through observations studies and model simulation.Results from the observations show that:(1)the anomalous winter snow cover in theextratropics of Eurasian Continent bears an intimate relation to the contemporary atmosphericgeneral circulation.The positive anomaly of winter snow cover is usually accompanied by positiveatmospheric EUP teleconnection pattern and stronger East Asian winter monsoon:or vice versa.(2)The linkage between them suggests that the abnormal winter snow cover has an importantimpact on winter atmospheric general circulation.The anomalous snow cover pattern can lead tothe anomaly of winter atmospheric EUP teleconnection pattern and thus influence East AsianWinter monsoon.With NCAR CCM2 including BATS land surface scheme,three groups of experiments wereperformed to examine the atmospheric response to the anomalous snow cover pattern and explorethe relevant mechanism.Simulated results agree well with the observations,which testify thesignificant response of the atmosphere to snow cover anomaly.It is found that the radiative coolinginduced by anomalous snow cover plays an important role in above processes,and the feedback oflong-wave radiation can not be neglected.     

贵州夏季旱涝短期气候预测模型研究

对贵州夏季严重旱涝的短期气候预测因子进行了分析研究，确定了用东亚大槽和北美东岸大槽的异常配置建立的夏季旱涝预测信号等5个预测因子，并依据这些预测指标建立了贵州旱涝短期气候预测模型。预测模型经1997－2000年实际检验取得了较好的预报效果。     

广西2002年夏季多雨成因分析

广西 2 0 0 2年夏季 (6 - 8月 )大部地区降水偏多 ,究其成因 ,与前期气候异常、气候背景条件、前期及同期环流特征及系统、西太平洋副高位置及强弱 ,海温、纬向风指数及振幅、位相等物理因子变化有关     

北半球冬季雪盖对南宁地区盛夏降水的影响

利用卫星观测的1973～2001年北半球雪盖资料,分析了北半球、欧亚、北美雪盖面积变化与南宁地区盛夏6～8月降水的关系,结果表明南宁地区盛夏降水与冬季雪盖面积相关显著。     

东亚夏季风强弱年物理量的逐候变化及其对松嫩流域降水的影响

用施能定义的东亚夏季风指数,分别找出典型夏季风强弱年1961和1980年,分析水平风速、假相当位温、高度等的逐候变化特征与盛夏季节松嫩流域逐候降水量的关系。分析表明:东亚夏季风强弱对松嫩流域盛夏降水量有显著影响。在强夏季风年,较大的南风、较高的假相当位温、较深的东亚大槽使降水持续偏多。同时还发现,无论夏季风强弱,假相当位温高值总是与多降水相联系。     

京津冀区域春夏季降水的气候变化

利用方差极大旋转经验正交函数展开、最大熵谱、小波分析方法 ,对京津冀区域近 5 0年春夏季降水的地域特征与气候变化进行研究。结果表明此区域的降水场分别存在以下主要降水异常分布型 :夏季包括燕山迎风坡型、太行山迎风坡型、冀中平原型、冀东平原型、沿海平原型、冀北山地型、冀南平原型 ;春季包括平原中南部型、燕山南麓型、滨海平原型、京西山麓型、太行山迎风坡型、冀东北高原型、冀西北高原型 (坝上 )。同时 ,通过最大熵谱、小波分析 ,进一步分析各降水型的主要变化特征及主要周期。     

Relationship between land cover and monsoon interannual variations in east Asia

Asian monsoon have multiple forms of variations such as seasonal variation, intra-seasonal variation, interannual variation, etc. The interannual variations have not only yearly variations but also variations among several years. In general, the yearly variations are described with winter temperature and summer precipitation, and the variations among several years are reflected by circulation of ENSO events. In this study, at first, we analyze the relationship between land cover and interannual monsoon variations represented by precipitation changes using Singular Value Decomposition method based on the time series precipitation data and 8km NOAA AVHRR NDVI data covering 1982 to 1993 in east Asia. Furthermore, after confirmation and reclassification of ENSO events which are recognized as the strong signal of several year monsoon variation, using the same time series NDVI data during 1982 to 1993 in east Asia, we make a Principle Component Analysis and analyzed the correlation of the 7th component eigenvectors and Southern Oscillation Index (SOI) that indicates the characteristic of ENSO events, and summed up the temporal-spatial distribution features of east Asian land cover’s inter-annual variations that are being driven by changes of ENSO events.     

东亚土地覆盖动态与季风气侯年际变化的关系

以东亚地区 １９８２～１９８９年时间序列降水资料及 ＡＶＨＲＲ ８ ｋｍ ＮＤＶＩ数据为基本数据源，应用地理信息系统技术，分别研究了东亚地区夏季（５－９月）降水及土地覆盖的年际变化，并揭示了研究时间段内各自的变化规律。进一步用奇异值分解（ＳＶＤ）模型方法分析了以降水变化为表征的东亚地区气候年际变化与土地覆盖年际变化之间的关系。