Analysis of the Trends of Thunderstorms in 1951–2007 in Jiangsu Province

Based on the 1951–2007 thunderstorms in Jiangsu, a study is conducted for their climate trends, periodicity, spatiotemporal patterns, and the distributions of the first and last days of the thunderstorms at different guarantee rates (GRs) using climate tendency rate, wavelet analysis, and GR for diagnosis. Results suggest that the inter-annual number of thunderstorm days (TSDs) exhibits a decreasing trend in this province. The trend is displayed mainly in the decreasing TSD number in summer and autumn except in spring, when the variation is not significant in the study period. In this province, the TSD number declines by ~2 days per 10 years. On an inter-annual basis, the pronounced positive departures of the number take place chiefly in the early 1960s, the late 1960s to the early-mid-1970s, the late 1980s, and the late 1990s compared with the negative anomalies dominant in the late 1970s to the mid-1980s, the mid-to-late-1990s, and the late 1990s to 2007. There are vast differences in the initial and ending days at diverse GRs in different areas of the province. At 50% GR, the earliest (last) days occur from mid-March to early April (early to late September) while at 80% GR, the initial (last) days are from late March to early May (early to late October). For the distribution of periods, the periods >8–10 years are relatively stable for the entire province. Based on 1951–2007 period analysis, the region north (south) of the Huaihe River experiences TSDs less (more) than normal days in recent years.     

1954-2010年商丘降水变化趋势及突变分析

利用线性回归、Mann-Kendall等方法,对商丘站1953年12月-2010年11月的年、季降水资料进行趋势分析、突变检验。结果显示：年、季降水量线性变化趋势均不显著,年降水量、冬夏季降水量在增加,春秋季降水量略有减少。年降水量在2003年,冬季降水量在1997年、春季降水量在1992年、夏季降水量在2003年、秋...     

近55年来宾市雷暴日数特征分析

采用1956～2010年广西来宾市国家基本气象站常规地面气象观测资料,对雷暴日数特征进行了统计分析。结果表明,来宾市年雷暴日数在46～106d,年平均雷暴日数为72．4d;来宾市一年中任何一天都有可能出现雷暴天气,其中6、7、8月雷暴日数最多,约占全年雷暴日数的57．4％。小波分析显示,来宾年雷暴活动具有较强的9年周期...     

近40a中国不同量级降水对年降水量变化的影响性分析

采用1968-2007年全国595个气象台站的日降水资料,将降水量分为0．1～9．9mm、10～24．9mm、25～49．9mm和≥50mm共4个不同量级降水,通过趋势系数等统计诊断方法,分析了年雨日与年降水量相关性、年雨日与日平均降水强度的变化趋势、不同量级降水的日数和强度的变化趋势以及它们分别对年降水量变化的影响。...     

基于DERF的SD方法预测月降水和极端降水日数

针对动力气候模式对区域或更小空间尺度内的日降水预测技巧偏低的问题,应用最优子集回归 (OSR) 方法对国家气候中心业务化的月动力气候模式 (DERF) 输出的高度场、风场和海平面气压场进行降尺度处理用于降水预测,旨在提高预测准确率。1982—2006年交叉检验结果表明:OSR方法能显著提高降水预测技巧,其中11~40 d改善效果最为显著。在此基础上,应用一步法和两步法两种统计降尺度方法预测极端降水日数,交叉检验结果表明:两种方法均优于随机预测,冬季两步法预测技巧略高于一步法,夏季一步法略优于两步法。综合认为OSR,OSR结合随机天气发生器 (WG) 两种统计降尺度方法对月尺度降水或极端降水日数的预测均具有较高的技巧,可作为短期气候预测的重要参考信息。     

东江流域枯水期最长连续无降水日数的变化特征

利用1956-2008年东江流域各降雨站点逐日降雨资料,建立枯水期最长连续无降水日数时间序列（LCDD）,采用经验模态分解（EMD）方法分析该序列的多尺度振荡变化及趋势变化,应用Mann-Kendall法识别突变点,采用R／S分析方法探讨变化趋势的持续性特征,并初步分析LCDD变化的可能原因。结果表明：近53年来,最长...     

准噶尔盆地东缘火山岩综合地球物理勘探

通过野外露头、钻井获取大量沉积地层、沉积岩、火山岩地球物理参数,初步分析火山岩重力、磁力、电阻率分布规律.以1∶5万高精度重、磁力资料及电法MT资料为基础,开展基于小波多尺度分析的重磁异常垂向二次导数对石炭系火山岩异常体边界进行约束,结合残差法模型反演提取电性异常体及二维地震解释石炭系火山岩地震相分析,开展综合地球物理勘探.石炭系火山岩主要属性特征为重力高、磁力高、高电阻;局部为重力中高、磁力高、中低电阻,对应的地震反射波阻外形呈扇状,内幕同相轴为中振幅、中高频、弱连续的火山岩储集体.研究区共解释石炭系有利火山岩体10个,受控于EW向断裂,为火山岩油气勘探有利区带.     

Spatial and Temporal Distribution and Variations in the Near-surface Soil Freezing Days across China, 1956-2006

Using surface soil daily minimum temperature from 845 meteorological stations across China, the long-term (1971-2000) mean and spatial distribution of the near-surface soil freezing days were estimated with annual values of the number of near surface soil freezing days. The time series for the number of freezing days were constructed and compared with air temperatures in the same period.Resultsshowed that long term mean value in the number of the near surface soil freezing days increased with the increasing latitudes and altitudes over China. Near-surface soils were frozen for more than 200 days in the Qinghai Tibet Plateau, northern Xinjiang and northeast of China. The boundaries of permafrost zones coincide with the contour of (220±10) days of near-surface soil freezing. Using the mean number of 15 days of near-surface soil freezing as criterion, we found that the southern boundary of seasonally frozen ground is around the 25°N line, and the regions south of 22°N are essentially unfrozen regions. The time series of the number of freezing days showed a significant linear trend with change with a slope of -0.22days/year over a period from 1956 through 2006. After the 1990s, the linear slope was up to -1.02 days / year, indicating that the rate of decrease in the number of near-surface soil freezing days has accelerated. Changes in the number of near surface soil freezing were in a negative correlation with air temperature, i.e., the number of near-surface soil freezing days decreases with increase in air temperature.Backgroundcolor represents the contour values of the departure of near-surface soil freezing days from the 1971-2000 mean; Black dashed line is the boundary of permafrost regions, red dashed line is the boundary between frozen and unfrozen ground regions in China     

新疆OLR基本特征及强震前的异常现象

利用美国国家环境监测中心的NOAA卫星长波辐射(OLR)月际资料进行数据的月距平、涡度场计算等处理,总结分析了新疆地区长波辐射场的基本特征.对2003年以来新疆及其周边地区发生的中强震进行研究,发现在部分地震前震中及附近地区出现较明显的高值辐射异常,认为这种现象可能与强震前的地一气系统变化有关.应用OLR资料进行新疆地区的地震趋势预测研究可在一定程度上弥补前兆台网监测能力的不足.     

Spatial distributions and interannual variations of snow cover over China in the last 40 years

By using the observational snow data of more than 700 weather stations,the interannual temporal and spatial characteristics of seasonal snow cover in China were analyzed.The results show that northern Xinjiang,northeastern China-Inner Mongolia,and the southwestern and southern portions of Tibetan Plateau are three regions in China with high seasonal snow cover and also an interannual anomaly of snow cover.According to the trend of both the snow depth and snow cover days,there are three changing patterns for the seasonal snow cover:The first type is that both snow depth and snow cover days simultaneously increase or decrease;this includes northern Xinjiang,middle and eastern Inner Mongolia,and so on.The second is that snow depth increases but snow cover days decrease;this type mainly locates in the eastern parts of the northeastern plain of China and the upper reaches of the Yangtze River.The last type is that snow depth decreases but snow cover days increase at the same time such as that in middle parts of Tibetan Plateau.Snow cover in China appears to have been having a slow increasing trend during the last 40 years.On the decadal scale,snow depth and snow cover days slightly increased in the 1960s and then decreased in the 1970s;they again turn to increasing in the 1980s and persist into 1990s.