Seasonal and Intraseasonal Variations of East Asian Summer Monsoon Precipitation Simulated by a Regional Air-Sea Coupled Model

The performance of a regional air-sea coupled model, comprising the Regional Integrated Environment Model System (RIEMS) and the Princeton Ocean Model (POM), in simulating the seasonal and intraseasonal variations of East Asian summer monsoon (EASM) rainfall was investigated. Through comparisons of the model results among the coupled model, the uncoupled RIEMS, and observations, the impact of air-sea coupling on simulating the EASM was also evaluated. Results showed that the regional air-sea coupled climate model performed better in simulating the spatial pattern of the precipitation climatology and produced more realistic variations of the EASM rainfall in terms of its amplitude and principal EOF modes. The coupled model also showed greater skill than the uncoupled RIEMS in reproducing the principal features of climatological intraseasonal oscillation (CISO) of EASM rainfall, including its dominant period, intensity, and northward propagation. Further analysis indicated that the improvements in the simulation of the EASM rainfall climatology and its seasonal variation in the coupled model were due to better simulation of the western North Pacific Subtropical High, while the improvements of CISO simulation were owing to the realistic phase relationship between the intraseasonal convection and the underlying SST resulting from the air-sea coupling.     

近30a我国5级以上风日数的时空变化特征

利用全国397个测站逐日最大风速资料,分析了1975-2005年我国5级以上风日数的气候平均特征和长期变化趋势。研究表明：5级以上风主要出现在我国北方地区,受地形和海陆分布影响,南方局部地区5级以上风日数也较多。就季节分布而言,春季最多,夏季次之,秋季最少。5级风日数的比例在我国南方地区大于北方,6级以上风日数比例则呈现北多南少的分布特征。近30 a我国5级以上风日数呈线性减少趋势,春季风日数的减少趋势较其他季节明显,其中5级风日数的变化趋势较其他级风日数更为显著。     

An evaluation of the effects of cloud parameterization in the R42L9 GCM

Cloud is one of the uncertainty factors influencing the performance of a general circulation model (GCM)．Recently,the State Key Laboratory of Atmospheric Sciences and Geophysical Fluid Dynamics,Institute of Atmospheric Physics(LASG／IAP)has developed a new version of a GCM(R42L9)．In this     

CLIMATOLOGICAL CALCULATION OF SURFACE LATENT HEAT OVER CHINA

In the context of measurements from all the thermal balance stations over China,two methodsof calculating surface latent heat for its climatic features are proposed through experiments with arange of schemes,one being the empirical type based on the relationship between ground latent heatand vapor pressure,and the other upon the Bowen ratio parameterization.Either of them has itsunique merits so that they can be considered in specific case to have higher accuracy.On this basis.investigation is done of the feature of geographic distribution and annual variability of the heatacross the country.     

An Introduction to the Coupled Model FGOALS1.1-s and Its Performance in East Asia

The spectral version 1.1 of the Flexible Global Ocean-atmosphere-land System (FGOALS1.1-s) model was developed in the State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophys- ical Fluid Dynamics at the Institute of Atmospheric Physics (LASG/IAP). This paper reports the major modifications to the physical parameterization package in its atmospheric component, including the radia- tion scheme, convection scheme, and cloud scheme. Furthermore, the simulation of the East Asian Summer Mon...     

粤东地区太阳能资源及其利用气候分析

利用1971～2000年广东省汕头站日射观测资料,计算了粤东地区太阳总辐射,从太阳总辐射、气温、天空状况等方面分析了粤东地区太阳能资源的时空分布及其特点.指出粤东地区具有太阳总辐射量大、气候环境温度高,天空状况良好等自然气候条件,太阳能资源丰富,热状况优越,太阳能利用具有极大的发展空间.     

The outlook for precipitation measurements from space*

Abstract

To provide useful precipitation measurements from space, two requirements must be met: adequate spatial and temporal sampling of the storm and sufficient accuracy in the estimate of precipitation intensity. Although presently no single instrument or method completely satisfies both requirements, the visible/IR, microwave radiometer and radar methods can be used in a readepiction, manner. Visible/IR instruments provide good temporal sampling and rain area depiction, but recourse must be made to microwave measurements for quantitative rainfall estimates. The inadequacy of microwave radiometric measurements over land suggests, in turn, the use of radar. Several recently developed attenuating‐wavelength radar methods are discussed in terms of their accuracy, dynamic range and system implementation. Traditionally, the requirements of high resolution and adequate dynamic range have led to fairly costly and complex radar systems. Some simplifications and cost reduction can be made, however, by using K‐band wavelengths, which have the advantages of greater sensitivity at low rain rates and higher resolution capabilities. Several recently proposed methods of this kind are reviewed in terms of accuracy and system implementation. Finally, an adaptive‐pointing multi‐sensor instrument is described that would exploit certain advantages of the IR, radiometric and radar methods.     

Comparison of the Double Summer Monsoon Troughs over East Asia

Based on NCEP/NCAR reanalysis data, an investigation has been carried on the comparison of the double summer monsoon troughs over East Asia, which refer to the subtropical summer monsoon trough (subtropical-trough) and the South China Sea summer monsoon trough (SCS trough), respectively. The results show that the SCS trough is stronger than the subtropical-trough either in convergence or convection. The subtropical-trough extends up to higher levels and inclines northward with altitude, while, the SCS trough extends up to a lower level, and its position is seldom changed. The SCS trough establishes early and abruptly with the low level positive relative vorticity appearing suddenly, and retreats slowly, but the subtropical-trough establishes step by step with the positive relative vorticity initially over the Yunnan-Guizhou Plateau and Guangxi areas spreading gradually northeastward, and withdraws rapidly. The onset of SCS trough is obviously indicated by the reverse of the easterly, but the establishment of the subtropical-trough is characteristic of the westerly enhancement. The subtropical-trough has clearly frontal property, yet the SCS trough has not.     

山东省太阳辐射的计算及其分布

通过对国内外太阳总辐射气候学计算方法的分析对比,确定Q=Q0(a bS)为山东省太阳辐射最佳计算公式。根据济南、福山、莒县1961~2000年历年各月的总辐射和日照百分率,采用最小二乘法拟合出公式中各月的经验系数,并计算了山东省各地的月太阳总辐射。结果表明:山东省太阳总辐射年变化都表现为5月最大,12月最小。年太阳总辐射在4488~5692 MJ.m-2之间,北部多,南部少,其中年总辐射最大值出现在鲁北的庆云,其值高达5692 MJ.m-2,最低值出现在鲁西南的曹县,其值为4488 MJ.m-2。