短期气候预测的评估问题

该文系统地介绍了国内外评估月、季尺度短期气候预测结果的方法 ,比较了相关系数(R)、预报技巧分 (S)和准确率 (P)的特点 ,并对当前国内外气候预测业务水平进行了分析 ,着重对大气环流、气温、降水及 ENSO的预测水平进行了评估 ,指出国内外月、季尺度的降水预报的水平目前在 55%～ 60 %左右 ,对 ENSO的发生、结束和强度的预报水平有限 .文中探讨了短期气候预测的可预报性问题 ,提出月、季尺度气候预测的可预报性的理论上限可能为 6～ 1 2月 ,准确率在 80 %～ 85%之间 .     

陕西粮食供需平衡的思考

证券营业部计算机房和计算机网络的雷电防护是一个庞大而又复杂缜密的工程，电力保护、信号保护、等电位连接和各种接地中任何一个环节疏漏都可能带来灾难性后果。据统计，近年来因受雷电电磁脉冲而损失的计算机网络设备大幅上升，造成难以估算的经济损失。如1996年6月6日，重庆市农业银行大厦的计算机网络设备，因遭雷击损失107万元，其下属的信托公司证券部通信网络中断数小时，引起股民恐慌。     

江苏沿海对虾亲虾入室期规律分析及其预报

根据多年的生产试验,分析总结了江苏沿海对虾适宜入室的气象指标的分布特征以及不同地区最早、最适、最迟入室指标出现时间之间的相关性,并以射阳县、南通市为代表建立起预报方程,为江苏沿海做好亲虾入室的气象服务工作提供了理论依据和新的途径。     

呼和浩特市秋季一次大到暴雨天气过程分析

利用天气预报业务中的多种预报产品资料,对2008年9月21日呼和浩特地区秋季一次降水过程进行了分析,结果表明:(1)太平洋副高西伸,地面西南倒槽是本次降水形成的主要影响系统。(2)700hPa西南低空急流的形成与地面倒槽东移北上共同为降水提供了暖湿能量,对降水的形成发展起了重要作用。(3)在降水过程中,大气的高层辐散、低层辐合以及较强的垂直上升运动使降水加强。     

Advances in understanding the “Perfect Monsoon-influenced Typhoon”: Summary from International Conference on Typhoon Morakot (2009)

Typhoon Morakot (2009) produced 2855 mm of rain and was the deadliest typhoon to impact Taiwan with 619 deaths and 76 missing persons, including a landslide that wiped out an entire village. While Morakot did not exceed the heaviest 24-h rain record, the combination of heavy rain and long duration that led to the record accumulation is attributed to the southwest summer monsoon influence on the typhoon. Thus, a special combination of factors was involved in the Morakot disaster: (i) Strong southwesterly monsoon winds; (ii) Convergence between the typhoon circulation and monsoon flow to form an east-west oriented convective band over the Taiwan Strait that was quasi-stationary and long-lasting; (iii) A typhoon in a specific location relative to the Central Mountain Range and moving slowly; and (iv) Steep topography that provided rapid lifting of the moist air stream. The contributions of each of these four factors in leading to the Morakot disaster are reviewed primarily based on new research presented at the International Conference on Typhoon Morakot (2009). Historical data sets, new Doppler radar observations, and numerical modeling have advanced the understanding of the special conditions of monsoon-influenced typhoons such as Morakot. This research is also leading to modifications of existing and development of new forecasting tools. Gaps in scientific understanding, limits to the predictability, and requirements for advanced forecast guidance tools are described that are challenges to improved warnings of these extreme precipitation and flooding events in monsoon-influenced typhoons.     

闽东干旱概况及夏季人工增雨作业天气形势分析

对闽东干旱的成因和干旱的环流形势进行了探讨,着重分析了夏旱期间人工增雨作业的天气形势以及不同形势、不同云型下的降水情况。结果表明:闽东干旱的形成与大型环流形势、地理因素、土壤植被等有关,平均而言,沿海干旱明显多于内陆山区;夏季发生干旱的机率最大而且强度级别高,西太平洋副热带高压是致旱的主要天气系统;在夏季,台风型(T)、弱流场型(R)是进行人工增雨作业的优势天气型,Cb、Cu、Sc云是开展人工增雨作业比较适合的作业云。这些结果为夏旱期间开展人工增雨作业提供了理论依据。     

内蒙古高温酷暑天气的气候学特征和环流类型

利用1971—2008年内蒙古117个观测站日最高气温资料,结合同期的NCEP再分析资料,分析了内蒙古高温酷暑天气的气候学特征。结果表明:内蒙古高温酷暑天气地域差异大,高温中心在阿拉善盟沙漠地区的拐子湖,年平均35℃高温日数达32天,也是全国的高温区之一;内蒙古的高温天气年日数有增长趋势,高温酷暑的影响在增强;内蒙古高温酷暑集中出现在盛夏季节6—8月,7月发生最多,占一半以上;最高气温出现在每日的14—17时,气温日较差大,多为干热天气。通过对内蒙古较大范围的64次高温天气过程分析总结,将内蒙古高温酷暑天气分为蒙古暖脊型、贝加尔湖高压坝型、副高西进型、乌拉尔山高脊型4个类型。大陆暖高压脊的强烈发展和维持与内蒙古高温酷暑天气密切相关。     

Reconstruction of hydrometeorological time series and its uncertainties for the Kaidu River Basin using multiple data sources

This paper tried to reconstruct the time series (TS) of monthly average temperature (MAT), monthly accumulated precipitation (MAP), and monthly accumulated runoff (MAR) during 1901–1960 in the Kaidu River Basin using the Delta method and the three-layered feed forward neural network with backpropagation algorithm (TLBP-FFNN) model. Uncertainties in the reconstruction of hydrometeorological parameters were also discussed. Available monthly observed hydrometeorological data covering the period 1961–2000 from the Kaidu River Basin, the monthly observed meteorological data from three stations in Central Asia, monthly grid climatic data from the Climatic Research Unit (CRU), and Coupled Model Intercomparison Project Phase 3 (CMIP3) dataset covering the period 1901–2000 were used for the reconstruction. It was found that the Delta method performed very well for calibrated and verified MAT in the Kaidu River Basin based on the monthly observed meteorological data from Central Asia, the monthly grid climatic data from CRU, and the CMIP3 dataset from 1961 to 2000. Although calibration and verification of MAP did not perform as well as MAT, MAP at Bayinbuluke station, an alpine meteorological station, showed a satisfactory result based on the data from CRU and CMIP3, indicating that the Delta method can be applied to reconstruct MAT in the Kaidu River Basin on the basis of the selected three data sources and MAP in the mountain area based on CRU and CMIP3. MAR at Dashankou station, a hydrological gauge station on the verge of the Tianshan Mountains, from 1961 to 2000 was well calibrated and verified using the TLBP-FFNN model with structure (8,1,1) by taking MAT and MAP of four meteorological stations from observation; CRU and CMIP3 data, respectively, as inputs; and the model was expanded to reconstruct TS during 1901–1960. While the characteristics of annual periodicity were depicted well by the TS of MAT, MAP, and MAR reconstructed over the target stations during the period 1901–1960, different high frequency signals were captured also. The annual average temperature (AAT) show a significant increasing trend during the 20th century, but annual accumulated precipitation (AAP) and annual accumulated runoff (AAR) do not. Although some uncertainties exist in the hydrometeorological reconstruction, this work should provide a viable reference for studying long-term change of climate and water resources as well as risk assessment of flood and drought in the Kaidu River Basin, a region of fast economic development.     

Influences of climate change on California and Nevada regions revealed by a high-resolution dynamical downscaling study

In this study, the influence of climate change to California and Nevada regions was investigated through high-resolution (4-km grid spacing) dynamical downscaling using the WRF (Weather Research & Forecasting) model. The dynamical downscaling was performed to both the GFS (Global forecast model) reanalysis (called GFS-WRF runs) from 2000?C2006 and PCM (Parallel Climate Model) simulations (called PCM-WRF runs) from 1997?C2006 and 2047?C2056. The downscaling results were first validated by comparing current model outputs with the observational analysis PRISM (Parameter-elevation Regressions on Independent Slopes Model) dataset. In general, the dominant features from GFS-WRF runs and PCM-WRF runs were consistent with each other, as well as with PRISM results. The influences of climate change on the California and Nevada regions can be inferred from the model future runs. The averaged temperature showed a positive trend in the future, as in other studies. The temperature increases by around 1?C2°C under the assumption of business as usual over 50?years. This leads to an upward shifting of the freezing level (the contour line of 0°C temperature) and more rain instead of snow in winter (December, January, and February). More hot days (>32.2°C or 90°F) and extreme hot days (>37.8°C or 100°F) are predicted in the Sacramento Valley and the southern parts of California and Nevada during summer (June, July, and August). More precipitation is predicted in northern California but not in southern California. Rainfall frequency slightly increases in the coast regions, but not in the inland area. No obvious trend of the surface wind was indicated. The probability distribution functions (PDF) of daily temperature, wind and precipitation for California and Nevada showed no significant change in shape in either winter or summer. The spatial distributions of precipitation frequency from GFS-WRF and PCM-WRF were highly correlated (r?=?0.83). However, overall positive shifts were seen in the temperature field; increases of 2°C for California and 3°C for Nevada in summer and 2.5°C for California and 1.5°C for Nevada in winter. The PDFs predicted higher precipitation in winter and lower precipitation in the summer for both California and Nevada.