集成物理统计模型在南海夏季风预测中的应用

利用影响南海夏季风年际变化的主要气候现象厄尔尼诺-南方涛动（El Ni?o-Southern Oscillation,ENSO）和对流层准两年振荡（Tropospheric Biennial Oscillation,TBO）相关的气候因子,提出了以过程判别函数确定物理过程的持续性,建立年际尺度的集成物理统计预测模型,而非年际尺度变率由经验统计模型预测,二者相结合,发展了集成物理-经验统计预测模型。经验模型在拟合时段的回报结果很好,但在独立样本预测时效果明显降低,其中预测评分（PS）降低了23%,距平相关系数（ACC）降低了63%;相比之下,集成物理-经验统计预测模型在独立样本预测时比经验模型有更好的预测结果（PS评分提高了9.5%,ACC提高了75%）,且预测结果相对稳定。此外,集成物理-经验统计预测模型对南海夏季风降水的空间分布也有一定预测能力。     

大气季节内振荡在华南降水预报中的应用

大气季节内振荡(ISO)在天气气候演变中扮演着重要角色,是中期和延伸期预报可预报性来源之一,同时大气ISO的年际变化与区域季节降水量的年际变化密切联系,对短期气候预测有指示意义。对热带大气ISO的年际变化研究做了简要回顾;重点介绍了ISO对华南降水的影响及其业务应用情况,主要包括赤道MJO对华南降水的影响、基于准两周振荡的汛期暴雨过程预报、热带ISO与热带外系统多尺度相互作用对强降水的影响、ISO对季节降水的影响、基于ISO建立的降水延伸期定量预测模型;最后对进一步加强ISO应用研究提出了几点思考。     

AN ANALYSIS ON INTERDECADAL VARIATIONS OF TROPICAL CYCLONE PRECIPITATION IN GUANGDONG PROVINCE OF CHINA

The interdecadal variations of tropical cyclones(TCs) and their precipitation over Guangdong Province are investigated using the observational data of TCs and precipitation from 26 observational stations in the province from 1951 to 2005.The results show that the TCs precipitation shows an oscillation with a peak value of about 25 years,with both the numbers of the Guangdong-influencing TCs and TCs formed in the western North Pacific oscillating with a peak value of about 23 years.The correlations are highly positive between the interdecadal variation of TC precipitation over the province and these numbers.The interdecadal variation of TC precipitation in the province shows significant negative correlations with the interdecadal variation of annual mean SST in some parts of the western North Pacific and the interdecadal variation of annual mean 500 hPa geopotential heights in some parts of the middle and high latitudes over the North Pacific.In general,there are high mean SSTs on the equator from central to eastern Pacific,low mean SSTs in the middle and high latitudes over the North Pacific and a main strong East Asian trough over the North Pacific in the period of less TC precipitation as compared with the period of more TC precipitation over the province.     

三频载波相位伪距平滑算法分析与比较

针对现代化卫星导航系统的三频新特点,本文推导了利用多频载波相位平滑单频伪距及组合伪距的一般算法,提出通用的计算方程和解析表达式,比对了三频GNSS系统中的3种平滑算法,并进行实测数据验证和分析。理论分析表明三频二阶伪距平滑算法噪声方差性能最差,三频一阶伪距平滑算法噪声方差性能与双频伪距平滑算法相当。     

对流层准两年振荡最新研究进展

为了更好地了解对流层准两年振荡(Tropospheric Biennial Oscillation,TBO)的最新研究概况及目前存在的问题,基于国家自然科学基金项目关于TBO的专门研究和近年来国内外的TBO研究工作,对TBO研究的最新进展作了综述。最新研究指出,热带暖海区的海-气耦合过程可以维持TBO循环而无需热带东太平洋的参与,表明了TBO确实是独立于ENSO而存在的海-气耦合系统,但是对于TBO的本质问题还需要多方面的深入研究。     

FEATURES AND COMPARISONS OF THE QUASI-BIENNIAL VARIATIONS IN THE ASIA-PACIFIC MONSOON SUBSYSTEMS

The National Centers for Environmental Prediction (NCEP) reanalysis data, Climate Diagnostics Center Merged Analysis of Precipitation (CMAP) results, and NOAA Extended Reconstructed Sea Surface Temperature (SST), have been utilized in this paper to study the quasi-biennial variations in Asia-Pacific monsoon subsystems and associated SST anomalies (SSTA) and wind anomalies. Four monsoon indices are computed from NCEP/ National Center for Atmospheric Research (NCAR) reanalysis to represent the South Asian monsoon (SAM), South China Sea summer monsoon (SCSSM), Western North Pacific monsoon (WNPM) and East Asian monsoon (EAM), respectively. The quasi-biennial periods are very significant in Asia-Pacific monsoons (as discovered by power spectrum analysis), and for SAM and EAM---with moderate effects by El Ni?o-Southern Oscillation (ENSO)---the quasi-biennial periods are the most important factor. For SCSSM and WNPM (once again due to the effects of ENSO), the quasi-biennial periods are of secondary durations. There are obvious interdecadal variations in the quasi-biennial modes of the Asia-Pacific monsoon, so in the negative phase the biennial modes will not be significant or outstanding. The wind anomalies and SSTA associated with the biennial modes are very different in the SAM, WNPM and EAM regions. Since the WNPM and SCSSM are very similar in the biennial modes, they can be combined into one subsystem, called SCS/WNPM.     

平流层臭氧季节变化的动力和光化学作用之比较

1992年到2005年的HALOE资料显示, 在臭氧光化损耗中, ClOx 和NOx 的贡献大小和作用位置有所差异。SOCRATES3模式模拟表明, 两半球夏季高纬极区的臭氧减少, 主要是NOx的化学贡献; 北极春季和南极冬季副极地臭氧的变化, 主要是动力输送引起。南、北极春季臭氧减少的化学机制也有所不同, 南极春季的臭氧耗损包括极区内ClOx 的异相化学作用和副极区NOx的化学作用; 北极春季的臭氧耗损主要以NOx 和ClOx 的气相化学作用为主, 其中NOx 的作用更大。动力和光化学在臭氧变化中的贡献表明, 整个中低平流层及低纬平流层高层的动力输送贡献可达到45%, 而高纬平流层中上层, 化学作用贡献在65%以上。     

墨西哥帽小波变换的影响域和计算方案新探讨

该文分析了Torrence等人研究的墨西哥帽 (Mexican Hat) 小波变换的影响域和高频失真问题并探讨了解决方案。平移点b处、小波尺度为a的墨西哥帽小波函数的有效定义域为[ b-2.12a, b+2.12a], 以墨西哥帽为母函数的小波变换的真正影响域是2.12a, 小波尺度a的最大值应为N/4.24(N为时间序列长度)。提出了充分利用小波函数速降性质和立方样条插值小波系数的新计算方案, 消除了该计算方案产生虚假的显著高频周期振荡问题。利用正弦函数型时间序列小波变换的解析式检验了文中提出的新计算方案的合理性。利用新计算方案对冬季Ni?o3.4指数进行分析, 冬季Ni?o3.4指数的平均整体小波功率谱表明, 存在约12年的年代际变化和准4年的年际变化, 不存在显著的准两年周期振荡。     

Spatial patterns of Tropospheric Biennial Oscillation and its numerical simulation

In order to investigate the spatial patterns of the Tropospheric Biennial Oscillation （TBO） on the global scale, the Climate Prediction Center （CPC） Merged Analysis of Precipitation （CMAP） monthly averaged precipitation and the Climate Diagnostics Center （CDC） monthly outgoing long-wave radiation （OLR） and SST are used in conjunction with TBO bandpass-filtering. The results indicate active biennial variability in the tropical eastern-central Pacific regions. It is evident that observations reflect the biennial component of the ENSO rather than the TBO itself. Since some studies have pointed out that the TBO is a broad-scale phenomenon differing from the ENSO, to investigate the pure TBO the ENSO signal must be excluded. The Scale Interaction Experiment-FRCGC （SINTEX-F） coupled general circulation model （CGCM） developed at Japan Frontier Research Center for Global Change （FRCGC） can capture both the ENSO and the biennial signals. Air-sea interactions in the tropical eastern-central Pacific are decoupled to eliminate the effects of ENSO in a experiment by SINTEX-F and the results show that biennial variability still exists even without ENSO. It seems to mean that the TBO and ENSO are independent from each other. Furthermore, the model results indicate that the two key regions are southwest Sumatra and the tropical western Pacific for the TBO cycle.     

DIFFERENCES OF SOUTH CHINA SEA SUMMER MONSOON DERIVED BY NCEP AND ECMWF REANALYSIS DATA

1 INTRODUCTIONDue to long-term time series and many elements,reanalysis data of National Centers for EnvironmentalPrediction (NCEP) and European Center for Medium-Range Weather Forecasts (ECMWF) are widely usedin present climate studies. Even so, there arediscrepancies between NCEP and ECMWF reanalysis.Some climate fields may be better reproduced byNCEP than by ECMWF. On the other hand,ECMWFmay describe some climate characteristics morerealistically than NCEP. Xu et al.…