Spherical integral transforms of second-order gravitational tensor components onto third-order gravitational tensor components

New spherical integral formulas between components of the second- and third-order gravitational tensors are formulated in this article. First, we review the nomenclature and basic properties of the second- and third-order gravitational tensors. Initial points of mathematical derivations, i.e., the second- and third-order differential operators defined in the spherical local North-oriented reference frame and the analytical solutions of the gradiometric boundary-value problem, are also summarized. Secondly, we apply the third-order differential operators to the analytical solutions of the gradiometric boundary-value problem which gives 30 new integral formulas transforming (1) vertical-vertical, (2) vertical-horizontal and (3) horizontal-horizontal second-order gravitational tensor components onto their third-order counterparts. Using spherical polar coordinates related sub-integral kernels can efficiently be decomposed into azimuthal and isotropic parts. Both spectral and closed forms of the isotropic kernels are provided and their limits are investigated. Thirdly, numerical experiments are performed to test the consistency of the new integral transforms and to investigate properties of the sub-integral kernels. The new mathematical apparatus is valid for any harmonic potential field and may be exploited, e.g., when gravitational/magnetic second- and third-order tensor components become available in the future. The new integral formulas also extend the well-known Meissl diagram and enrich the theoretical apparatus of geodesy.     

TM图象数字镶嵌的几何精度分析及镶嵌方法的探讨

本文对ＴＭ数字镶嵌图象的内部几何精度进行分析后指出，传统的利用选取控制点建立图象间坐标转换方程，并利用此方程对图象进行处理，实施图象镶嵌的方法，在保证镶嵌图象几何精度方面存在着不足，用此方法得到的ＴＭ镶嵌图象的内部几何误差约８个象元；在对传统的图象数字镶嵌方法进行分析的基础上，笔者总结大量工作的经验并参照前人的作法，在选定的地图投影下利用旋转方法对ＴＭ图象进行处理，进而完成镶嵌工作、这种方法舍去了控制点选取的繁复过程，使镶嵌工作变得简单，同时可保证ＴＭ镶嵌图象的几何畸变很小，经检测，镶嵌后的ＴＭ图象内部几何误差小于２个象元。     

Relationships between Interannual and Intraseasonal Variations of the Asian-Western Pacific Summer Monsoon Hindcasted by BCC_CSM1.1（m）

Using hindcasts of the Beijing Climate Center Climate System Model, the relationships between interannual variability （IAV） and intraseasonal variability （ISV） of the Asian-western Pacific summer monsoon are diagnosed. Predictions show reasonable skill with respect to some basic characteristics of the ISV and IAV of the western North Pacific summer monsoon （WNPSM） and the Indian summer monsoon （ISM）. However, the links between the seasonally averaged ISV （SAISV） and seasonal mean of ISM are overestimated by the model. This deficiency may be partially attributable to the overestimated frequency of long breaks and underestimated frequency of long active spells of ISV in normal ISM years, although the model is capable of capturing the impact of ISV on the seasonal mean by its shift in the probability of phases. Furthermore, the interannual relationships of seasonal mean, SAISV, and seasonally averaged long-wave variability （SALWV; i.e., the part with periods longer than the intraseasonal scale） of the WNPSM and ISM with SST and low-level circulation are examined. The observed seasonal mean, SAISV, and SALWV show similar correlation patterns with SST and atmospheric circulation, but with different details. However, the model presents these correlation distributions with unrealistically small differences among different scales, and it somewhat overestimates the teleconnection between monsoon and tropical central-eastern Pacific SST for the ISM, but underestimates it for the WNPSM, the latter of which is partially related to the too-rapid decrease in the impact of E1 Nifio-Southern Oscillation with forecast time in the model.     

黑龙江省玉米低温冷害风险评估及预估

利用气候资料、地理信息数据及社会经济数据,根据自然灾害风险理论和低温冷害形成机制,采用GIS技术,分析了黑龙江省玉米低温冷害的危险性和易损性,实现了玉米低温冷害的风险评估与区划,并利用CMIP5中的MRI-CGCM3模式模拟结果对黑龙江省2015-2044年玉米低温冷害风险进行预估。结果表明：1961年以来共有24年是低温冷害年,其中12年是严重低温冷害年。松嫩平原大部、三江平原大部及黑河南部是玉米一般低温冷害的多发区,同时该区暴露性较高,如有重度灾害发生,则对全省粮食产量产生严重影响。未来30年,黑龙江省低温冷害发生的概率有所减少,松嫩平原东部和南部是一般低温冷害的高风险区,三江平原西部是严重低温冷害的高风险区。     

黄淮海地区植被覆盖变化驱动力与驱动机制研究

基于1982-2003年GIMMS NDVI遥感资料、气候资料和社会经济统计资料,利用主成分分析、逐步回归等方法,对黄淮海地区植被覆盖变化的驱动力和驱动机制进行了研究,从气候、社会经济两方面分析了区内6种植被类型区植被覆盖变化的驱动机制。结果发现,不同植被类型区,其驱动机制差别很大,但总体来说,区内各类植被类型区植被覆盖变化大都受到气候和人类活动的共同驱动,主要驱动力为气候因素,人类活动在局部区域能够产生较大作用,而大范围区域植被NDVI(归一化植被指数)的变化或改变,主要受气候变化的影响。在此基础上,分别建立了6种植被类型区年均NDVI变化驱动力模型。     

垂直风切变对热带气旋强度及结构的影响

利用一个非静力、原始方程热带气旋模式(TCM4),通过对f平面不同强度的垂直风切变下理想热带气旋的模拟后发现:29.15°C的海温下理想热带气旋最大可能强度(MPI)接近910hPa,近中心最大风力可达到76 m·s-1左右。在理想条件下,能抑制热带气旋强度甚至减弱的垂直风切变临界值在8～10m·s-1。由于切变造成涡度平流随高度变化,使得在顺切变前部以及左侧边界层附近产生辐合,伴随着空气的气旋式螺旋上升,外流层对应区域产生辐散,从而使得强对流和强降水发生在顺切变左侧。     

Origin of the pre-tropical storm Debby (2006) African easterly wave-mesoscale convective system

The origins of the pre-Debby (2006) mesoscale convective system (MCS) and African easterly wave (AEW) and their precursors were traced back to the southwest Arabian Peninsula, Asir Mountains (AS), and Ethiopian Highlands (EH) in the vicinity of the ITCZ using satellite imagery, GFS analysis data and ARW model. The sources of the convective cloud clusters and vorticity perturbations were attributed to the cyclonic convergence of northeasterly Shamal wind and the Somali jet, especially when the Mediterranean High shifted toward east and the Indian Ocean high strengthened and its associated Somali jet penetrated farther to the north. The cyclonic vorticity perturbations were strengthened by the vorticity stretching associated with convective cloud clusters in the genesis region—southwest Arabian Peninsula. A conceptual model was proposed to explain the genesis of convective cloud clusters and cyclonic vorticity perturbations preceding the pre-Debby (2006) AEW–MCS system.     

我国短期气候动力预测模式系统的研究及试验

气候和气候异常对我国的国民经济发展具有重大影响,为提高短期气候预测的准确率,研究动力气候模式短期气候预测新技术至关重要.通过近5年的努力,建立了一套出月动力延伸预报模式,海气耦合的全球气候模式(AGCM+OGCM+海冰+高分辨率印度洋-太平洋海盆模式),区域气候模式季和年际尺度的业务动力模式组成的系统.初步把我国的短期气候预测水平由经验统计方法提高到定量和客观分析的水平上.在此基础上,已建成了一个具有物理基础的统计方法与气候动力模式相结合的综合气候预报系统.     

一次大暴雨过程的物理量诊断分析

本文利用2005年7月16日至18日的高空资料,对7月18日发生在广元的大暴雨天气过程进行了热力学和动力学诊断分析,结果表明:(1)在暴雨出现前,大气有一个能量聚集、湿层增厚的过程;(2)湿Q矢量辐合中心对应暴雨区,越接近强降水出现时间,诊断效果越好。