Summer weather characteristics on the Grove Mountain of East Antarctica

The summer weather characteristics of the Grove Mountain, East Antarctica, are presented based on the data obtained by Chinese National Antarctic Expedition (CHINARE) in January 1999. The result shows that the pattern of daily variation of temperature and the prevailing wind direction in Grove is similar to that of Zhongshan Station. However, the daily range of temperature and strong wind frequency are much higher than those of Zhongshan Station.The change of wind direction is close to the weather system that impacted the Grove Mountain. The warm and wet air from northern parts often causes the precipitation. The clear weather appears when controlled by eastern winds in January.     

OBSERVATIONAL STUDY OF MERIDIONAL VARIATION OF UV-B RADIATION DURING VOYAGES TO THE ARCTIC AND ANTARCTIC REGIONS

Based on 1999-2000 observations made by the first Arctic and sixteenth Antactic scientificvoyages,a study is undertaken about the meridional surface UV-B (B band ultraviolet rays)variations in 75°N-70°S.It is mitigated as a function of latitudes and marked by lower radiationaveraged over the Northern Hemisphere (NH) than over the Southern Hemisphere (SH),with itsdaily course basically similar to that of total radiation.Around polar summer noon hours (localtime) and where ice albedo is maximum,the strongest UV-B irradiance on the surfaceperpendicular to sun's beams as found at equatorial latitudes is measured sometimes.In the areasnear Zhongshan Station the increase of surface UV-B radiation shows a close relation to thedecrease of ozone in the higher atmosphere but it has a less intimate relation with its concentrationat ground.     

北冰洋浮冰和开阔海面上的能量平衡特征

利用中国首次北极考察队于 1 999年 8月 1 9日～ 2 4日在北冰洋浮冰区获得的大气近地层垂直廓线和辐射等资料 ,依据相似理论方法 ,对比分析了北冰洋无冰海面和冰面上热平衡参数的变化特征。结果表明 ,海面与大气和冰面与大气之间相互作用的边界层物理过程差异十分明显。冰面吸收的净辐射仅为海面的 6%左右 ,主要消耗于感热输送和冰面融化过程 ,不足部分由水汽在冰面上凝结释放的潜热和冰中的热通量来补充。海面吸收的净辐射主要消耗于潜热输送过程 ,占净辐射的 50 % ,其余热量传向水体深层和用于感热输送 ,分别占净辐射的 2 6%和 2 4 %。由此可见 ,在北冰洋夏季 ,无冰海面有大量的水汽向大气输送 ,这对研究北冰洋地区大气边界层的季节变化过程是至关重要的     

含有地形和摩擦时的风场近似与扰动的稳定性

本文讨论了含有地形、摩擦作用时的平衡风场近似表达式及其扰动稳定牲条件,得到了一些有意义的结果。     

近52年宁夏冬季极端寒冷事件的演变特征

利用1961-2012年宁夏19个测站完整的逐日最低温度资料,分析了近52年宁夏极端寒冷事件时空变化特征。结果表明,宁夏极端寒冷事件空间上表现为较好地一致性,存在"东西多、中部少"的分布特点,贺兰山脉对此起到了重要作用;宁夏寒冷事件年频次总体在减少,强度也呈减弱趋势,年发生日数、日最多站次与年频次有着显著的正相关关系;寒冷事件频数的显著性周期为2~6年,具有间歇性和跳跃性特征;寒冷事件在1980年前后,发生气候突变后与许多要素场的气候突变时间相吻合;21世纪以来,寒冷事件有增多趋势。环流特征分析发现,极端寒冷的多寡与冬季大气环流异常状况密切相关,冷事件多(少)发年乌拉尔山及其以东高压脊偏强(弱),东亚高度场明显负(正)异常,低压加深(减弱)。     

青藏高原东南部昌都地区近地层湍流输送的观测研究

利用我国1998年第2次青藏高原气象科学试验 (TIPEX) 昌都的湍流观测资料, 初步分析了三维风速、温度和湿度湍流谱、归一化方差与稳定度的关系、湍流通量和整体输送系数.结果表明, 白天标准化的湍流谱大多数满足2/3次方定律.风速方差与稳定度的关系在不稳定条件下基本服从1/3次方定律, 但水平风速方差比垂直速度方差与稳定度的关系离散.中性层结下的A、B值比平原地区大, 与起伏地形的值接近, C值与平原地区和起伏地区的差异不大.温度和湿度方差与不稳定层结的关系基本满足1/3次方定律, 而在稳定层结下的关系均无明显规律.湍流通量在干湿期转换中有突变现象, 干期的动量和热量通量均大于湿期, 热源强度以感热为主, 占80%.湿期热源强度明显增大, 其中以潜热为主, 占热源强度的60%.整体输送系数与稳定度的关系明显, 拟合得到的中性层结条件下的C_DN和C_HN分别为4.40×10-3和4.70×10-3, 其结果大于高原中、西部的同期观测值.     

南极海冰涛动与ENSO的关系

对近30年南极海冰密集度资料的EOF和SVD分析，发现南极地区在罗斯海外围和别林斯高晋海的海冰密集度场存在着“翘翘板”的变化特征，并与ENSO有密切联系。由此定义两个海冰关键区的差值为南极海冰涛动指数（ASOI），ASOI超前SOI和Nino3指数2个月时，其正、负相关系数达到最大，并通过α=0.001的信度检验。ASOI高、低指数阶段对应的南半球海平面气温、气压场和风场的合成分析表明，海冰关键区的异常变化可能引起温度、气压、风场的响应而影响南太平洋的洋流，进而对ENSO的发生、发展产生影响。     

北京大气边界层中风和温度廓线的观测研究

为了研究冬季北京城区大气边界层结构的特征,分别在城区和郊区4个观测点利用系留气艇在2001年1月5～13日和2月21～28日进行了大气廓线探测,并分析了温度和风廓线垂直变化的基本特征.初步结果显示城市热岛效应十分明显,热岛强度随高度增加而递减,近地层热岛强度在晴天最大可达到4℃左右.除了近地层郊区的风速大于城区外,城区和郊区风速的垂直分布特征有较大差异.在100～200m高度以下,城区和郊区风速和风向随高度分布都出现了明显的拐点,300 m以上高度风向和风速基本趋于一致,表明城区和郊区的风廓线均受到城市覆盖层的影响.随着北京市区的规模不断扩大,在今后探测中应考虑郊区测点的代表性.     

AIR-SEA COUPLING FEATURES FROM THE WARM PHASE TO THE COLD PHASE OF ENSO CYCLES IN THE SEVENTIES TO THE EIGHTIES

Using the sea surface temperature and wind anomalies(SSTA and SSWA for short)of thetropical Pacific from January 1970 to December 1989,main spatial patterns of tropical PacificSSTA and SSWA coupling features in the transform course from the warm phase to the cold phaseof El Nino-southern Oscillation(ENSO)cycles are discussed.The main conclusions are as follows:(1)air-sea coupling patterns at the mature stage of ElNino(La Nina)are main spatial ones of tropical Pacific SSWA and SSTA coupling:(2)at themature stage of El Nino,the interaction of the anticyclonic anomaly wind,generated by the forcingof distinct meridional SSTA gradient in the Northern Hemisphere tropical central Pacific.with theCalifornia cold current and SSTA is mainly responsible for weakening of El Nino;(3)the secondsea temperature increase along the South American coast in the decaying course of El Nino resultsfrom the eastward movement of the weakened positive SSTA in the tropical central-eastern Pacificforced by anomalous west wind stress:(4)La Nina results from the joint effect of Walkercirculation,Ekman drift and negative SSTA in the tropical central-eastern Pacific.