Evaluation of cloud vertical structure simulated by recent BCC_AGCM versions through comparison with CALIPSO-GOCCP data   总被引：2，自引：0，他引：2  

WANG Fang  XIN Xiaoge  WANG Zaizhi  CHENG Yanjie  ZHANG Jie  YANG Song 《大气科学进展》2014,31(3):721-733

ABSTRACT The abilities of BCC-AGCM2.1 and BCC_AGCM2.2 to simulate the annual-mean cloud vertical structure （CVS） were evaluated through comparison with GCM-Oriented CALIPSO Cloud Product （CALIPSO-GOCCP） data. BCC-AGCM2.2 has a dynamical core and physical processes that are consistent with BCC-AGCM2.1, but has a higher horizontal resolution. Results showed that both BCC-AGCM versions underestimated the global-mean total cloud cover （TCC）, middle cloud cover （MCC） and low cloud cover （LCC）, and that BCC_AGCM2.2 underestimated the global-mean high cloud cover （HCC）. The global-mean cloud cover shows a systematic decrease from BCCA-GCM2.1 to BCC_AGCM2.2, especially for HCC. Geographically, HCC is significantly overestimated in the tropics, particularly by BCC_AGCM2,1, while LCC is generally overestimated over extra-tropical lands, but significantly underestimated over most of the oceans, especially for subtropical marine stratocumulus clouds. The leading EOF modes of CVS were extracted. The BCC_AGCMs perform well in reproducing EOF1, but with a larger variance explained. The two models also capture the basic features of EOF3, except an obvious deficiency in eigen- vector peaks. EOF2 has the largest simulation biases in both position and strength of eigenvector peaks. Furthermore, we investigated the effects of CVS on relative shortwave and longwave cloud radiative forcing （RSCRF and RLCRF）. Both BCC_AGCM versions successfully reproduce the sign of regression coefficients, except for RLCRF in PC1. However, the RSCRF relative contributions from PC1 and PC2 are overestimated, while the relative contribution from PC3 is underes timated in both BCC_AGCM versions. The RLCRF relative contribution is underestimated for PC2 and overestimated for PC3.  相似文献   

Heat budget of the south-central equatorial Pacific in CMIP3 models     

LIU Xiangcui  and  LIU Hailong 《大气科学进展》2014,31(3):669-680

ABSTRACT Using data from 17 coupled models and nine sets of corresponding Atmospheric Model Intercomparison Project （AMIP） results, we investigated annual and seasonal variation biases in the upper 50 m of the south-central equatorial Pacific, with a focus on the double-ITCZ bias, and examined the causes for the amplitude biases by using heat budget analysis. The results showed that, in the research region, most of the models simulate SSTs that are higher than or similar to observed. The simulated seasonal phase is close to that observed, but the amplitudes of more than half of the model results are larger than or equal to observations. Heat budget analysis demonstrated that strong shortwave radiation in individual atmospheric models is the main factor that leads to high SST values and that weak southward cold advection is an important mechanism for maintaining a high SST. For seasonal circulation, large surface shortwave radiation amplitudes cause large SST amplitudes.  相似文献   

1960年以来东亚季风区云-降水微物理的直接观测研究   总被引：1，自引：0，他引：1  

王东海  尹金方  翟国庆 《气象学报》2014,72(4):639-657

云-降水的直接观测结果是云微物理参数化的重要依据。自1960年以来,处于东亚季风影响下的中国实施了大量对云-降水微物理参数的观测和研究,旨在加深对云-降水微物理过程的认识,从而改进数值模式中云微物理参数化方案和指导人工影响天气作业。云-降水微物理参数包括气溶胶、冰核、云滴、雨滴、冰晶、雪晶、冰雹等粒子浓度和谱分布,以及云滴、雨滴含水量等。中国已有云-降水微物理参数的成果可归纳为:(1)通常云-降水微物理粒子浓度变化较大,但总体变化有一定的范围;(2)采用Γ函数拟合云滴谱更接近实际谱,但不同拟合谱参数差异较大;(3)可用指数函数和Γ函数来拟合层状云降水雨滴谱,Γ函数拟合积云和层积混合云降水雨滴谱精度更高;(4)中国冰核浓度较高,冰核浓度随温度的降低近似成指数变化;(5)冰晶谱、雪晶谱、冰雹谱通常采用指数函数来描述;(6)通常使用荣格(Junge)和Γ函数来分段描述气溶胶粒子谱拟合误差更小。由于云-降水过程及其反馈作用描述不准确是数值模式预报结果不确定性的最大因素,中国正在不断地推进云降水的微物理观测研究,以期进一步加深对东亚季风区云-降水微物理特征的认识,从而为模式中微物理参数化方案的改进提供观测依据和科学指导。基于数值预报模式中云微物理过程参数化发展的需要,总结了中国1960年以来云-降水微物理直接观测的研究成果,可为东亚地区云-降水微物理研究及其模式参数化方案的改进提供观测依据。此外,针对云微物理参化发展的需求,结合过去已有的大量观测提出了几点建议,为今后云-降水物理综合性观测方案的设计提供参考。  相似文献   

Ensemble retrieval of atmospheric temperature profiles from AIRS     

ZHANG Jie  Zhenglong  LI  Jun  LI  Jinglong  LI 《大气科学进展》2014,31(3):559-569

ABSTRACT Satellite-based observations provide great opportunities for improving weather forecasting. Physical retrieval of atmo spheric profiles from satellite observations is sensitive to the uncertainty of the first guess and other factors. In order to improve the accuracy of the physical retrieval, an ensemble methodology was developed with an emphasis on perturbing the first guess. In the methodology, a normal probability density function （PDF） is used to select the optimal profile from the ensemble retrievals. The ensemble retrieval algorithm contains four steps： （1） regression retrieval for original first guess; （2） perturbation of the original first guess to generate new first guesses （ensemble first guesses）; （3） using the ensemble first guesses and nonlinear iterative physical retrieval to generate ensemble physical results; and （4） the final optimal profile is selected from the ensemble physical results by using PDE Temperature eigenvectors （EVs） were used to generate the pertur- bation and generate the ensemble first guess. Compared with the regular temperature profile retrievals from the Atmospheric InfraRed Sounder （AIRS）, the ensemble retrievals RMSE of temperature profiles selected by the PDF was reduced between 150 and 320 hPa and below 400 hPa, with a maximum improvement of 0.3 K at 400 hPa. The bias was also reduced in many layers, with a maximum improvement of 0.69 K at 460 hPa. The combined optimal （CombOpt） profile and a mean optimal （MeanOpt） profile of all ensemble physical results were improved below 150 hPa. The MeanOpt profile was better than the CombOpt profile, and was regarded as the final optimal （FinOpt） profile. This study lays the foundation for improving temperature retrievals from hyper-spectral infrared radiance measurements.  相似文献   

Planetary-Scale Wave Structures of the Earth’s Atmosphere Revealed from the COSMIC Observations   总被引：1，自引：0，他引：1       下载免费PDF全文

S. K. A. V. Prasad Rao ANISETTY  P. S. BRAHMANANDAM  G. UMA  A. Narendra BABU  HUANG Ching-Yuang  G. Anil KUMAR  S. Tulasi RAM  WANG Hsiao-Lan  CHU Yen-Hsyang 《Acta Meteorologica Sinica》2014,28(2):281-295

GPS radio occultation（GPS RO） method,an active satellite-to-satellite remote sensing technique,is capable of producing accurate,all-weather,round the clock,global refractive index,density,pressure,and temperature profiles of the troposphere and stratosphere.This study presents planetary-scale equatorially trapped Kelvin waves in temperature profiles retrieved using COSMIC（Constellation Observing System for Meteorology,Ionosphere,and Climate） satellites during 2006-2009 and their interactions with background atmospheric conditions.It is found that the Kelvin waves are not only associated with wave periods of higher than 10 days（slow Kelvin waves） with higher zonal wave numbers（either 1 or 2）,but also possessing downward phase progression,giving evidence that the source regions of them are located at lower altitudes.A thorough verification of outgoing longwave radiation（OLR） reveals that deep convection activity has developed regularly over the Indonesian region,suggesting that the Kelvin waves are driven by the convective activity.The derived Kelvin waves show enhanced（diminished） tendencies during westward（eastward） phase of the quasi-biennial oscillation（QBO） in zonal winds,implying a mutual relation between both of them.The El Nino and Southern Oscillation（ENSO） below 18 km and the QBO features between 18 and 27km in temperature profiles are observed during May 2006-May 2010 with the help of an adaptive data analysis technique known as Hilbert Huang Transform（HHT）.Further,temperature anomalies computed using COSMIC retrieved temperatures are critically evaluated during different phases of ENSO,which has revealed interesting results and are discussed in light of available literature.  相似文献   

巴丹吉林沙漠与小尺度湖泊夏季地表特征对比分析   总被引：1，自引：0，他引：1  

李建刚  奥银焕  吕世华  李照国  买买提艾力·买买依提明 《高原气象》2014,(3)

利用2009年7 9月"巴丹吉林沙漠陆气相互作用及其对区域气候的影响研究"试验所得观测资料,系统分析了夏季典型晴天下巴丹吉林沙漠和沙湖不同下垫面的辐射和能量收支特征。结果表明:(1)沙漠点和沙湖点土壤温湿度都有明显的日变化,表现为准正弦曲线。地表向下日较差逐步变小,日峰值和谷值都有明显的滞后性。5~10 cm土壤温、湿度受地表温度影响较大,20 cm以下不再有明显的日变化。沙湖点土壤湿度较大,且出现逆湿现象。(2)沙漠点和沙湖点太阳总辐射的日变化趋于一致;沙漠点大气长波辐射、地表长波辐射、有效辐射均比沙湖点略低,地表反射辐射大于沙湖点。沙漠的地表长波有效辐射均小于沙湖点,两观测点净辐射差异较小。(3)两观测点的地表反照率呈"U"形分布;沙漠点的日平均反照率为0.32,沙湖点为0.23。(4)沙漠点以感热输送为主,波文比为3.4;沙湖点则以潜热输送为主,波文比为0.2。  相似文献   

一次降水相态转换过程中温度垂直结构特征分析   总被引：6，自引：0，他引：6  

徐辉  宗志平 《高原气象》2014,(5)

2012年11月3-5日华北地区出现了该年度的第一次大范围雨雪天气过程,各地区依次都出现了雨转雪的复杂天气,这给预报带来了较大的难度。一直以来,冬季降水相态类型的预报都是国内外气象预报的难题之一,而温度的垂直结构特征是影响最终降水类型的关键因素之一。利用常规地面观测资料、NCEP再分析资料及中尺度数值模式WRF对此次雨雪天气过程中的温度垂直结构演变特征以及相态转变对温度垂直结构的作用等几个方面进行了分析讨论。结果表明:(1)在发生雨转雪过程中,温度递减率会持续减小,并最终会在低层形成一个上下一致的均温层,同时还伴有浅薄逆温层的产生;(2)降水相态类型严重依赖于温度的垂直结构,温度垂直结构的细微改变将决定最终到达地面的降水类型,因此,相关层次的厚度差可以成为判别降水相态类型的重要指标;(3)在降水类型由雨转雪的过程中,由于相关层次的融化作用,伴随着相态的变化温度垂直结构会发生一定程度的改变。  相似文献   

民勤地区紫外辐射的观测与模拟研究     

闭建荣  黄建平  高中明  史晋森  马越界  张武 《高原气象》2014,(2)

利用2010年春季民勤加强观测实验的地面辐射资料,分析了民勤沙漠干旱区总紫外辐射的变化特征,并对该地区的紫外辐射进行了估算和模拟。结果表明,紫外辐射和太阳总辐射表现出一致的变化特征,层云对两者的反射能力比卷云强。2010年6月紫外辐射的瞬时最大值为55.92 W·m-2,平均日总量为1.07 MJ·m-2,紫外辐射与太阳辐射比例的平均值为4.7%,其变化范围在3%~9%之间。根据晴空指数(Kt)与最大紫外辐射(UV0)及太阳总辐射(G)建立了民勤地区紫外辐射(UV)的估算方程:UV=2.94+1.22×(Kt×UV0)和UV=0.047G,均能较好地估计该地区的地表紫外辐射。由于受输入参数精度的限制,辐射传输模式SBDART低估了晴空条件下的紫外辐射,低估的总平均值为1.12 W·m-2(约5.6%),变化范围在-2.8~0.2 W·m-2之间。  相似文献   

基于一维变分算法的地基微波辐射计遥感大气温湿廓线研究   总被引：3，自引：1，他引：2  

王云  王振会  李青  朱雅毓 《气象学报》2014,72(3):570-582

为研究地基微波辐射计遥感温、湿度廓线的一维变分算法的反演能力,用北京地区2010—2011年00和12时(世界时)的多通道地基微波辐射计亮温资料进行试验。首先,利用同时次的地面观测资料、红外亮温(由地基微波辐射计自带红外传感器测得)及探空观测数据,给出提取无云样本的方案,得到432个无云样本;再以辐射传输模式计算得到的模拟亮温为参考,对无云条件下的观测亮温进行质量控制;然后利用探空数据进行模拟试验,结果发现,一维变分算法对3 km以下的温度廓线有较大调整。使反演结果更加接近探空,而对湿度廓线在0—10 km都有不同程度的优化;最后利用一维变分算法对地基微波辐射计观测亮温进行大气温湿廓线反演,将结果与探空对比可以看出,温度廓线的均方根误差小于2.9 K,绝对湿度的均方根误差小于0.47 g/m~3;进一步与地基微波辐射计自带神经网络的反演结果比较表明,一维变分的反演结果更接近实际大气。  相似文献   

基于地基微波辐射计资料对咸宁两次冰雹天气的观测分析   总被引：3，自引：2，他引：1  

黄治勇  徐桂荣  王晓芳  唐永兰 《气象》2014,40(2):216-222

利用地基微波辐射计观测资料,对两次冰雹过程进行观测分析。结果表明:中低层暖湿气流输送、中层干冷空气侵入,在0~10 km形成"上干、下湿"2层垂直分布结构。低层的感热和潜热随上升气流向上输送,2~3 km层明显增温,0、-5和-20℃层略微上升。同时,低层水汽也随上升气流向上输送,降雹前大气液态水总含量(ILW,下同)和大气水汽总含量(IWV,下同)及过冷水含量快速增长。水汽经过冷层后,冰晶增多增大。当冰晶增大落入0℃以上区融化层时,冰晶融化导致液态水增加,一部分形成冰雹或地面降水,导致降雹之后ILW、IWV及0℃以下液态水含量减小。上述结论对冰雹的预警有一定指示意义。  相似文献