2008年1月我国南方冻雨过程的热力异常及其形成原因

利用中国604个地面台站的气象观测资料和NCEP 2.5°×2.5°再分析各等压面温度和环流场资料,从地面和大气垂直热力结构配置及其气候异常的角度出发,诊断分析了2008年1月我国南方雨雪冰冻过程的形成。结果表明,冻雨受灾的核心区域约为108°～113°E和25°～28°N范围,在该区域内2008年1月平均地面气温〈0...     

2005年河南省秋季持续阴雨天气成因分析

利用NcEP/NcAR 2.5°×2.5°日平均再分析资料和1°×1°资料及常规气象观测资料,分析了河南省2005年9月14日-10月3日长达18天(18日、22日间歇)的连阴雨天气成因.结果表明:200 hPa出现并且维持的高空急流,异常强大的南亚高压,偏西偏北的副热带高压,以及边界层的偏东风,是造成此次连阴雨天气的...     

影响华南地区西南低涡以及致洪低涡活动的统计研究

利用1996~2005年4~9月的MICAPS和NCEP/NCAR 2.5×2.5°再分析资料和统计、平均合成、综合分析等方法,对影响华南地区西南低涡以及致洪低涡活动进行了系统性的研究。     

浙江省春季降水及其水汽输送特征

利用浙江省34站1960-2009年3-5月累积降水量及NCEP/NCAR 2.5°×2.5°的多个再分析气象资料,采用趋势分析、相关分析以及合成分析等方法,对浙江省春季降水量的时空分布、影响浙江省春季降水的整层大气的水汽水平输送特征、各层水汽垂直输送以及各边界的水汽输送等特征进行了分析.揭示了利于浙江省春季降水的水汽...     

2010年12月江门两次强冷空气过程对比分析

利用NECP2.5°×2.5°分析资料和常规天气资料.对2010年12月江门两次强冷空气过程的环流背景、影响天气系统及成因进行对比分析.结果表明:500hP形成的异常强冷温度平流,是造成大幅降温的主要原因,冷平流降温和辐射降温相结合造成部分地区的严重低温霜冻;850hPa冷暖空气的辐合和200hPa辐散是强冷空气造成降...     

2009-09—2010-03贵州特大干旱分析

该文利用1971—2000年necp全球逐月的2.5°×2.5°再分析资料作为平均场与2009-09—2010-03的necp全球逐月的2.5°×2.5°再分析资料进行比较。分析了2009-09—2010-03特大干旱的时空分布及其同期的大气环流异常特征。结果表明:与常年同期相比,贵州降水量均为有气象观测记录以来最少值;贵州省平均气温12.4℃,为历史同期第3高。此次贵州特大干旱与大气环流异常有很大的关系,中高纬度环流及西太平洋副热带高压、西风带环流(冷空气活动)、低层流场、水汽输送以及垂直运动等都持续异常,不利于该地区的降水产生,再加上西风环流以及中高纬度环流配置不利于冷空气南下,因而该时段贵州干旱少雨。     

2009年铜仁地区高温干旱特征及成因诊断分析

利用1961-2009年铜仁地区10个县站逐日降水量资料、最高气温和平均气温资料,以及NCEP 2.5°×2.5°再分析资料,诊断分析了2009年7月10日～9月9日高温干旱的环流形势和物理量场,结果表明：（1）西太平洋副热带高压较常年异常偏强、偏西和南亚高压中心偏西、东伸偏强,是这次铜仁地区高温干旱发生的主要原因。（...     

西北地区春、夏季降水的水汽输送特征

运用1960—1997年内NCEP/NCAR的格点为2.5°×2.5°多个再分析气象要素资料以及西北地区95个加密测站降水资料,通过相关分析、合成分析等诊断方法对影响西北地区春、夏季降水的整层大气的水汽水平输送特征、各层水汽垂直输送特征以及西北地区春、夏季各个边界区域水汽输送特征进行了系列研究,揭示了西北地区季节性降水的水汽源以及水汽源三维输送路径特征;同时阐述了西北地区季节性降水与同期空中水汽含量显著性相关的原因。并用西北地区干、湿年份相关气象要素场对本文的一些分析结果进行了验证。     

近30年来影响福州的热带气旋统计研究

利用1975~2005年近30a来的MICAPS和NCEP 2.5°×2.5°再分析资料以及近年来沿海自动站大风资料,对影响福州的热带气旋以及着重对过程雨量超过150mm、过程雨量小于50mm的热带气旋活动进行系统性研究,给出对福州有影响的热带气旋活动的年频数、月际分布、登陆地点分类,以及沿海大风和降水等,为福州今后的台风预报提供一些依据。     

孟加拉湾对流对广西秋季暴雨影响分析

利用综合观测数据1 °×1 °FNL和2.5 °×2.5 °NCEP再分析资料、以及卫星云顶黑体辐射温度资料（TBB）,对2015年11月广西出现的三次暴雨过程（8日、11—12日和20日）的850 hPa水汽通量散度及水汽输送特征进行了对比分析。8日和20日暴雨的低层水汽主要来自南海,11—12日连续暴雨的水汽来自南海和孟加拉湾。暴雨前后TBB的分析表明,在暴雨发生前2~3 d,孟加拉湾对流发展到最强,孟加拉湾对流对广西秋季暴雨具有前兆信号特征。暴雨前后TBB时空剖面表明,暴雨发生前孟加拉湾对流有向广西波动传播的特征。模式敏感性实验显示,当关闭孟加拉湾对流2~3 d后,广西48 h累计雨量减小。      

30-Year atmospheric temperature record derived by one-dimensional variational data assimilation of MSU/AMSU-A observations

In the past, satellite observations of the microwave radiation emitted from the atmosphere have been directly utilized for deriving the climate tends of vertical-layer-averaged atmospheric temperatures. This study presents the 30-year atmospheric temperature trend derived by one-dimensional variational (1D-Var) data assimilation of Microwave Sounding Unit/Advanced Microwave Sounding Unit-A (MSU/AMSU-A) observations. Firstly, the radiance measurements from MSU on board the early National Oceanic and Atmospheric Administration (NOAA)-6 to NOAA-14 and AMSU-A on board NOAA-15 to -19 have been inter-calibrated to form a fundamental climate data record. A 1D-Var method is then employed to establish the thematic climate data record of atmospheric temperature profiles that are appropriate for climate change study. Verification of the MSU/AMSU-A derived temperature profiles with collocated Global Positioning System radio occultation data confirms a reasonable good accuracy of the derived atmospheric temperature profiles in the troposphere and low stratosphere. Finally, the global climate trend of the atmospheric temperature in clear-sky conditions is deduced, showing not only a global warming in the troposphere and a cooling in the stratosphere, but also a stronger warming in the upper troposphere than in the low troposphere.     

Mapping near-surface air temperature,pressure, relative humidity and wind speed over Mainland China with high spatiotemporal resolution

As part of a joint effort to construct an atmospheric forcing dataset for mainland China with high spatiotemporal reso- lution, a new approach is proposed to construct gridded near-surface temperature, relative humidity, wind speed and surface pressure with a resolution of 1 km× 1 km. The approach comprises two steps： （1） fit a partial thin-plate smoothing spline with orography and reanalysis data as explanatory variables to ground-based observations for estimating a trend surface; （2） apply a simple kriging procedure to the residual for trend surface correction. The proposed approach is applied to observations collected at approximately 700 stations over mainland China. The generated forcing fields are compared with the corresponding components of the National Centers for Environmental Predic- tion （NCEP） Climate Forecast System Reanalysis dataset and the Princeton meteorological forcing dataset. The comparison shows that, both within the station network and within the resolutions of the two gridded datasets, the interpolation errors of the proposed approach are markedly smaller than the two gridded datasets.     

MSU/AMSU微波亮温用于海洋高空大气温度气候变化研究的适用性探讨

利用美国大气海洋局卫星应用和研究实验室 (The Center for Satellite Applications and Research,STAR) 提供的MSU/AMSU卫星微波亮温资料V3.0版本,结合三套再分析资料数据集,通过对海洋上空不同高度、不同区域及不同季节的适用性分析,来探讨MSU/AMSU资料在热带海洋区域高空大气的温度变化特征,并通过合成分析揭示亮温资料与海洋的响应关系,从而探讨MSU/AMSU资料在热带海洋区域上的适用性和科学性。结果表明:（1）MSU/AMSU亮温资料在30 °E~70 °W,15 °S~15 °N范围的热带海洋区域适用性较好;（2）热带海洋区域对流层上层和中层大气均呈增温趋势,变化速率分别为0.045 K/(10 a) 和0.107 K/(10 a),增温突变现象出现在1980年代末—1990年代初,平流层低层大气呈降温趋势,变化速率为-0.345 K/(10 a),降温突变现象出现在1990年代中期;（3）在热带海洋区域,高空大气温度的变化趋势具有较强的区域性特征,相对于中东太平洋而言,印度洋-西太平洋区域的增、降温趋势变化更显著。对流层的增温幅度随高度的升高而有所降低。平流层低层的降温趋势在季节内变化不大,而对流层则是秋、冬季的增温趋势要明显大于春、夏季,冬季的增温尤为明显;（4）MSU/AMSU亮温资料对热带海洋温度异常有很好的响应关系,能在弥补海洋区域观测资料稀缺的情况下,对海洋区域起着较好的监测作用。      

Uncertainty of AMSU-A derived temperature trends in relationship with clouds and precipitation over ocean

Microwave Sounding Unit (MSU) and Advanced Microwave Sounding Unit-A (AMSU-A) observations from a series of National Oceanic and Atmospheric Administration satellites have been extensively utilized for estimating the atmospheric temperature trend. For a given atmospheric temperature condition, the emission and scattering of clouds and precipitation modulate MSU and AMSU-A brightness temperatures. In this study, the effects of the radiation from clouds and precipitation on AMSU-A derived atmospheric temperature trend are assessed using the information from AMSU-A window channels. It is shown that the global mean temperature in the low and middle troposphere has a larger warming rate (about 20–30 % higher) when the cloud-affected radiances are removed from AMSU-A data. It is also shown that the inclusion of cloud-affected radiances in the trend analysis can significantly offset the stratospheric cooling represented by AMSU-A channel 9 over the middle and high latitudes of Northern Hemisphere.     

High-Resolution Mesoscale Analysis Data from the South China Heavy Rainfall Experiment (SCHeREX): Data Generation and Quality Evaluation

In this study,the observational data acquired in the South China Heavy Rainfall Experiment (SCHeREX)from May to July 2008 and 2009 were integrated and assimilated with the US National Oceanic and Atmospheric Administration's (NOAA) Local Analysis and Prediction System (LAPS; information available online at http://laps.fsl.noaa.gov).A high-resolution mesoscale analysis dataset was then generated at a spatial resolution of 5 km and a temporal resolution of 3 h in four observational areas:South China,Central China,Jianghuai area,and Yangtze River Delta area.The quality of this dataset was evaluated as follows.First,the dataset was qualitatively compared with radar reflectivity and TBB image for specific heavy rainfall events so as to examine its capability in reproduction of mesoscale systems.The results show that the SCHeREX analysis dataset has a strong capability in capturing severe mesoscale convective systems.Second,the mean deviation and root mean square error of the SCHeREX mesoscale analysis fields were analyzed and compared with radiosonde data.The results reveal that the errors of geopotential height,temperature,relative humidity,and wind of the SCHeREX analysis were within the acceptable range of observation errors.In particular,the average error was 45 m for geopotential height between 700 and 925 hPa,1.0-1.1℃ for temperature,less than 20％ for relative humidity,1.5-2.0 m s-1 for wind speed,and 20°-25° for wind direction.The above results clearly indicate that the SCHeREX mesoscale analysis dataset is of high quality and sufficient reliability,and it is applicable to refined mesoscale weather studies.     

从NOAA卫星AVHRR资料反演中国区域地表反照率

由NOAA卫星AVHRR短波通道1、2反射率反演地表反照率需要3个反演模式,分别是窄-宽波段反射率转换模式、大气顶双向反射模式、大气订正模式.基于模式和国家卫星气象中心接收处理的NOAA-18 AVHRR1B数据,处理了2006年1月至2010年12月的中国区域地表反照率,由于云的影响,15天合成技术用来形成周期为15天的地表反照率数据文件.2006年、2010年2年的处理结果与MODIS同类产品对比,RMS为0.028～0.074、相关系数为0.76～0.93,误差较大出现在冬季,原因是两者15天合成方法不同;5年的日平均地表反照率与21个中国地面气象一级辐射站的观测测值作对比,结果是：RMS为0.053、相关系数为0.88.反演模式系统误差以及云和气溶胶影响是卫星反演地表反照率的主要误差来源.     

基于微波探测资料的全球大气亮温长期变化趋势研究

本文使用1978—2013年美国大气海洋局NOAA研发的STAR V3.0版本的MSU/AMSUA逐月亮温格点数据,引入集合经验模式分解(EEMD)方法,研究了高空大气亮温的非线性变化趋势,尤其注重亮温气候趋势的时间演变特征,并与传统线性回归(CLR)方法做了对比研究。结果表明,在全球对流层增温、平流层降温的大背景下,基于EEMD的亮温非线性趋势演变特征表现为:近10 a对流层中、高层全球平均增暖趋势放缓,甚至出现轻微的降温趋势;北半球对流层增暖首先出现在北极,随后向低纬度方向延伸。北极对流层增暖向上影响高层大气,最高可以扩展到平流层低层。南半球对流层中低纬度地区受北半球大气影响也出现增温。另外,近10 a南极地区出现显著的独立增温现象。平流层变冷北半球最早从中纬度地区开始发生,变冷逐渐增强的同时向极地和低纬度两侧扩张。南极上空平流层大气早期也出现显著变冷,然而随着2000年以后南极大范围增暖,平流层变冷逐渐转移到中低纬地区。     

中国区域平均降水量序列构建方法比较研究

由于地面观测台站空间分布不均匀,运用不同区域平均技术方法研究中国降水特征和变化规律的结果存在显著差异,是区域降水变化研究不确定性的重要来源之一。本文以“中国地面与CMORPH（CPC Morphing Technique）融合逐日降水产品”作为参照值,基于中国地面2425 站观测资料,采用5种网格尺寸的经纬度网格面积加权平均方法、省面积加权平均方法、直接平均方法等计算中国区域平均降水量时间序列,比较所得序列统计属性与参照值的偏差,判别方法的优劣。分析表明,1998～2012年,2.5°网格和5.0°网格区域平均方案所得年降水量序列的变化速率和离散程度同参照值最为接近,分别是最优和次优的区域平均方案。省面积加权平均方法对多年平均年降水量的计算准确,但对年降水量变化趋势的估计效果稍差,距平百分率序列很不准确。网格过疏或过密都会使区域平均结果出现较大误差,直接平均方法的误差亦偏大,可靠性较低。     

用NOAA/AVHRR探测地表反射率和NDVI的订正及误差分析

NOAA/ AVHRR反射率和标准化差值植被指数 (NDVI) 资料在气象、水文等领域都有广泛的应用。但因为地表双向反射和大气对可见光和近红外辐射的影响, 即使在地表没有变化的情况下, 卫星探测到的反射率和NDVI也有很大的变化。在除云处理和NOAA-14/AVHRR衰减校准的基础上, 利用6S模式对NOAA-14/AVHRR可见光和近红外反射率及NDVI资料进行了大气订正, 并利用Roujean和Rahman模式在大气订正后进行了双向反射订正。大气订正使可见光反射率减小3.34(反射率单位), 近红外反射率增加3.43(反射率单位), NDVI增加了0.22, 分别占各自平均值的78.2%, 15.9%, 35.5%。双向反射订正对NDVI的绝对值影响不大, 但消除了反射率和NDVI的不规则变化, 订正后能够较好地反映森林植被的物候效应。对各订正参数进行了误差分析, 结果表明订正对太阳和卫星天顶角的误差最敏感。     

Interdecadal Variations of Precipitation and Temperature in China Around the Abrupt Change of Atmospheric Circulation in 1976

The interdecadal characteristics of rainfall and temperature in China before and after the abrupt change of the general circulation in 1976 are analyzed using the global 2.5°×2.5° monthly mean reanalysis data from the National Centers for Environmental Prediction of US and the precipitation and temperature data at the 743 stations of China from the National Climate Center of China. The results show that after 1976, springtime precipitation and temperature were anomalously enhanced and reduced respectively in South China, while the reverse was true in the western Yangtze River basin. In summer, precipitation was anomalously less in South China, more in the Yangtze River basin, less again in North China and more again in Northeast China, showing a distribution pattern alternating with negative and positive anomalies （＂ , ＋, -, ＋＂）. Meanwhile, temperature shows a distribution of warming in South China, cooling in the Yangtze and Huaihe River basins, and warming again in northern China. In autumn, precipitation tended to decrease and temperature tended to increase in in South China and warming was most parts of the country. In winter, the trend across all parts of China. precipitation increased moderately The interdecadal decline of mean temperature in spring and summer in China was mainly due to the daily maximum temperature variation, while the interdecadal increase was mainly the result of the minimum temperature change. The overall warming in autumn （winter） was mostly influenced by the minimum （maximum） temperature variation. These changes were closely related to the north-south shifts of the ascending and descending branches of the Hadley cell, the strengthening and north-south progression of the westerly jet stream, and the atmospheric stratification and water vapor transport conditions.