田阳三化螟蛾盛发高峰初日气象预警模型

三化螟为水稻主要害虫之一,单食水稻,在田阳一年发生完全4个世代,开展各世代螟蛾盛发高峰期气象预警,对科学适时防螟灭虫,虫口夺粮意义重大。利用农业植保部门提供的三化螟蛾盛发高峰期虫情资料和气象部门气象观测同期资料,采用逐步回归方法,建立三化螟蛾盛发高峰初日气象预警模型。结果表明:各世代预警模型输出的盛发高峰初日与实况误差3天的拟合正确率为82.2%～92.9%。试报2015—2016年,第1世代预报与实况误差为3天,第2代至第4世代误差为1～2天。三化螟蛾盛发高峰初日气象预警模型的拟合正确率、试报结果误差范围比较理想,可投入日常业务应用。     

中国极端干旱——空雨频率的主模态时空特征

利用国家气象中心的站点日降水观测资料,定义一个季节内无降水日出现的频率——空雨频率作为极端干旱的表征指标,对中国487个站点1980—2014年秋、冬、春三个连续季节的空雨频率进行季节-经验正交函数分解(S-EOF),发现我国极端干旱随季节演变的时空分布主要表现为前四个主模态的特征,累积方差贡献为40.6%。第一模态为秋、冬、春三季连旱模态,空雨频率呈现显著的上升趋势,大部分地区为异常变旱,冬季华南沿海变旱最显著。第二模态为秋与冬春干旱的反位相变化模态,空雨频率出现明显的秋-冬-春季反位相的季节反差现象,且存在弱的年代际振荡。第三模态为冬-春极端干旱反位相模态,对冬春两季的代表性较好,秋冬两季空雨频率的空间分布场为以长江流域为中心的极端变旱,而春季空雨频率呈现反位相变化。空雨频率以1998年为突变点存在明显的年代际转折。第四模态为南北偶极型秋-冬-春反位相模态,呈现出长江流域以南与长江流域以北三个季节空雨频率均为相反的位相分布。不同的模态反映不同季节、不同区域的空雨频率的变化,充分表现出我国干旱分布的复杂性。     

About possible geophysical causes of the decade fluctuations in the length of day

Fluctuations in the length of day (Δlod) can be caused by temporal variations of the inertia tensor described by the excitation function and by disturbances of the torque balance between core and mantle. Recent models of the atmospheric excitation of the variations of the lod certainly failed with respect to longer periods (e.g., at about 70 years), but seem to be responsible for the annual period, the 22 years period and for a part of the nearly 30 years period. So, another geophysical phenomenon is needed which is responsible for the remaining part of unexplained lod variations. Previous studies of the geomagnetic core-mantle coupling were re-examined using lod values from which atmospherically excited parts were removed. The remaining part of the 30 years period could be explained by core-mantle coupling. Additionally, the torque blance was realized by assuming lower values of the electrical conductivity at the bottom of the mantle. It was concluded that the consideration of geophysical processes within atmosphere and hydrosphere will be important for future refinements of the core-mantle coupling models of the decade fluctuations in the lod.     

LICHENOMETRY ON ADELAIDE ISLAND, ANTARCTIC PENINSULA: SIZE-FREQUENCY STUDIES, GROWTH RATES AND SNOWPATCHES

This paper presents new lichenometric population data from the Antarctic Peninsula (67°S), and describes a new approach to lichen growth-rate calibration in locations where dated surfaces are extremely rare. We use historical aerial photography and field surveys to identify sites of former perennial snowpatches where lichen populations now exist. As an independent check on lichen mortality by snowkill, and the timing of snow patch disappearance, we use a positive-degree day (PDD) approach based on monthly climate data from Rothera Research Station. We find that maximum growth rates for lichens <40 mm in diameter on Adelaide Island are around 0.8 mm/yr. Furthermore, we propose that our combined methodology may be more widely applicable to the Polar Regions where the construction of lichenometric dating (age-size) curves remains a problem.     

Aspects Of Ring Lasers As Local Earth Rotation Sensors

Ring laser rotation sensors are best known from inertial navigation, wherethey have many advantages over mechanical gyroscopes. They have recentlybeen greatly improved, and show potential as fully independent length-of-daysensors. We discuss some important aspects of current limitations in theirperformance. In particular we demonstrate a novel scheme for thestabilisation of a large ring laser against frequency pulling effectsinduced by backscatter.     

近10年来北京夏季城市热岛的变化及环境效应的分析研究

根据1993～2003年北京地区气象台站7、8月的温度资料,分析研究了近10年来北京夏季城市热岛的变化及其环境效应.结果表明：北京夏季城市热岛的水平范围扩大到近郊区和远郊区的通州,分布特征也由“单中心”转变为“多中心”;平均热岛强度呈逐渐增强趋势,在夏季出现了强热岛;北京夏季出现热岛和强热岛的天数激增,7月最大热岛强度也呈逐年上升趋势;热岛的强度和水平分布都有明显的日变化;由于热岛效应使城区增温显著,北京夏季的高温日（Tmax≥35℃）也逐年增多. 本文还指出朝阳区气象观测站由于周围高大植被的影响,观测资料已不具备城区代表性.同时也证明绿化对降低城市热岛效应是极为有效的.本文的研究成果对北京城市发展和规划有一定的科学参考价值.     

1981～2010年北京地区极端降水变化特征

采用北京地区20个常规气象站1981~2010年逐日降水数据,对北京地区极端降水的空间分布特征进行了分析。得到以下主要结论:1981~2010年,北京地区极端降水百分位数(第90、95和99个百分位数)阈值表现出较一致的空间分布特征,以第95个百分位数阈值计算的极端降水日数与降水阈值和降水量的分布有较大差异,极端降水量对总降水量的贡献可达30%~37%,极端降水强度分布与极端降水阈值分布相似。近30年,北京地区多数站点的极端降水量、降水日数和降水强度呈下降趋势,极端降水量以上甸子、怀柔、平谷和观象台下降较为明显,可达到40 mm(10 a)–1以上,极端降水强度以顺义、海淀、观象台、大兴和上甸子等站下降较为显著,每10 a降水强度减小趋势可达4 mm d–1,极端降水日数变化分布与极端降水量变化分布类似,极端降水强度变化与降水量和降水日数变化的分布有明显不同。     

华南强震相关背景的一些环境因子初探

研究了华南强震与太阳黑子、月相、地球自转和宇宙线GLE事件的关系,发现华南强震在太阳黑子活动周期中分布很不均衡,主要分布在峰段和谷段,这两段占76％,其中谷段占40～50％;由月相分布表明．阴历月份的初四和初十前后,是强震易发生时段,较之其它时段高3倍;此外．文中还给出华南强震与地球自转日长变化,宇宙线CLE事件等相关分析的初步结果。     

南极中山站极夜、极昼期间地磁场的日变化规律及特征

利用1991年南极中山站的地磁资料，分析研究了极夜（5，6，7月）及极昼（11，12月）期间地磁场的变化规律及特征．结果表明，极昼期间的S出现的双峰现象要比极夜期间的明显的多，S是叠加在S之上的极盖区地磁场静日变化；极夜期间的Sq,Sq和SD的变化幅度小于极昼期间的变化幅度，大约是极昼期的1／3，SD大约是极昼的3／4.这主要是由于极夜期间太阳的直射点在北半球，在南半球太阳的波辐射少；极昼期间太阳直射点在南半球，太阳的波辐射增大，致使空间电离层等效电流强度发生变化产生的．     

A modified monthly degree‐day model for evaluating glacier runoff changes in China. Part I: model development

The retreat of mountain glaciers and ice caps has dominated the rise in global sea level and is likely to remain an import component of eustatic sea‐level rise in the 21st century. Mountain glaciers are critical in supplying freshwater to populations inhabiting the valleys downstream who heavily rely on glacier runoff, such as arid and semi‐arid regions of western China. Owing to recent climate warming and the consequent rapid retreat of many glaciers, it is essential to evaluate the long‐term change in glacier melt water production, especially when considering the glacier area change. This paper describes the structure, principles and parameters of a modified monthly degree‐day model considering glacier area variation. Water balances in different elevation bands are calculated with full consideration of the monthly precipitation gradient and air temperature lapse rate. The degree‐day factors for ice and snow are tuned by comparing simulated variables to observation data for the same period, such as mass balance, equilibrium line altitude and glacier runoff depth. The glacier area–volume scaling factor is calibrated with the observed glacier area change monitored by remote sensing data of seven sub‐basins of the Tarim interior basin. Based on meteorological data, the glacier area, mass balance and runoff are estimated. The model can be used to evaluate the long‐term changes of melt water in all glacierized basins of western China, especially for those with limited observation data. Copyright © 2011 John Wiley & Sons, Ltd.