Study on the Variation Characteristics of Precipitation Concentration Degree in Guangxi under the Background of Global Climate Becoming Warm

Based on the daily precipitation data of 87 meteorological observation stations in Guangxi during 1961-2008,the variation characteristics of precipitation concentration degree(PCD) in Guangxi were counted and analyzed by using Monte Carlo test method.The results showed that the climate warming in most areas of Guangxi was very obvious,and the annual precipitation concentration degree increased gradually from the northeast to the southwest in Guangxi.The precipitation concentration period was from the middle of April to the end of August and delayed from the northeast to the southwest in Guangxi.In the background which the global climate became warm,the annual precipitation in most areas of Guangxi had the trend which the precipitation concentrated strengthening.It was said that the probability of flood disaster had the increase trend.The precipitation concentration period had the earlier trend,which was more obvious in the north than in the south of Guangxi.The rainstorm concentration degree in the northwest of Guangxi and few parts had the decrease trend and had the increase trend in other areas.It was said that the probabilities of flood and mud-rock flow disasters increased.The rainstorm concentration periods in most areas had the later trend.

Climatic trends of different intensity heavy precipitation events concentration in China

Based on 740 stations of daily precipitation datasets in China, the precipitationconcentration degree （PCD） and precipitation-concentration period （PCP） of different intensity durative precipitation events were calculated to analyze their statistical characteristics, mainly including spatial and temporal distributions, variations and climatic trends of the two parameters of the durative heavy precipitation events in China. It is proved that these two parameters of heavy rainfall can display the temporal inhomogeneity in the precipitation field. And it is also found that there is a good positive relationship between the precipitation-concentration degree and annual rainfall amount in the Eastern and Central China. This method can be anolied in flood assessment and climate change fields.

Analysis of Intra-annual Heterogeneous Characteristics of Precipitation in Shaoguan City

Based on the daily precipitation data between 1965 and 2009 from 8 rainfall stations in Shaoguan City,the indexes of precipitation concentration degree（ PCD） and precipitation concentration period（ PCP） were calculated. And then inverse distance weighted（ IDW） interpolation method was used to analyze the heterogeneous distribution characteristics of inter-annual precipitation by introducing the spatial distribution of annual mean values,variable coefficients,correlation coefficients with annual precipitation,change trends and composite analysis. The results showed that PCD was mainly decreasing from southeast to northwest in spatial distribution,long-term average annual values of PCP were distributed in the first ten days of June at most region. Annual precipitation increased as PCD increased in southern region,but the change trend was the opposite in northern region. Annual precipitation increased as PCP lagged in most region. PCD and PCP mainly appeared upward trend. Composite analysis of PCD in more-precipitation years was similar to less-precipitation years in spatial distribution,but the PCD in less-precipitation years was higher.Seen from the mean in the whole region,PCP in more-precipitation years lagged about 20 days behind those in less-precipitation years. The research can provide basis for the production of agriculture and industry as well as disaster prevention and reduction.

CHARACTERISTICS OF RAINFALL VARIATION OVER EAST CHINA FOR THE LAST 50 YEARS AND THEIR RELATIONSHIP WITH DROUGHTS AND FLOODS

With the precipitation data of 113 stations in East China during the last 50 years,the characteristics of the precipitation,including Precipitation Concentration Degree (PCD) and Precipitation Concentration Period (PCP) and their tendencies,are analyzed.The results show that the PCD in the northern part of the region is markedly higher than that in the southern part,but the PCP in the south is much earlier than that in the north by about one and a half months,which displays significant regional differences in precipitation.With the global warming,precipitation over East China shows an increasing tendency,but PCD displays a trend that is neither increasing nor decreasing.At the same time,the PCP is later than before,which can be mainly found in Jiangxi and southern Henan provinces.As a result,there are strong associations between the precipitation,PCD and PCP,which can be shown in the years with more precipitation,stronger PCD and later-than-usual PCP.In a word,the abnormal distribution of precipitation,PCP,and PCD over East China results in more extreme events of precipitation and more droughts and floods.

近50年滇池流域汛期降水时空演变特征分析

以滇池流域1970—2020年汛期(5—10月)降水量资料为依据,利用地理信息技术,采用Mann-Kendall检验法、小波分析等方法,分析近50年来滇池流域汛期降水年际变化的趋势性、周期性以及集中度、集中期、降水中心和旱涝发生频率等演变特征。结果表明:(1)近50年来,滇池流域汛期降水总体呈减少趋势,中部地区降水呈增加趋势,盘龙江上游的松华坝水库以上区域及南部地区降水呈减少趋势;(2)汛期降水年际变化存在31 a的主周期,中部主城区降水集中度高于南部地区;(3)汛期降水的中心整体呈现向东部、南部方向偏移的态势,且移动趋势显著;(4)滇池流域旱涝频发,尤其盘龙江中段昆明主城区为旱涝多发区。该成果对滇池流域水旱灾害防御及水资源管理具有参考意义。

河南省年季降水集中度研究

河南省地处中原,跨海河、黄河、淮河、长江四大流域,研究其降水时间分布均匀特征对全省水资源动态管理和水旱灾害防御具有重要意义。以河南省为研究对象,基于522个雨量站点的1956-2021年长系列降水量数据,采用降水集中指数PCI、降水集中度Q等指标,辅以Kriging空间插值等方法,分析了全省降水时间均匀特征及变化特点。结果表明:河南省降水时间均匀特征具有地区差异性,北部降水时间分布较为集中,南部降水时间分布较为均匀,集中程度总体上呈现由北向南递减;降水时间均匀特征的多年变化趋势较小,除河南省东北部及省辖淮河流域西北部分区域外,其他区域略呈集中趋势;降水时间均匀特征与降水量、气象干旱程度有一定的正向关联但相关性极弱,因此研究旱涝事件时应将降水时间均匀特征作为一个独立因素加以考虑。

金华地区汛期降水集中度和集中期特征分析

为探究金华地区汛期降水的非均匀分布特征及其变化趋势,本文利用逐日降水资料结合ECMWF再分析资料,运用改进的集中期和集中度算法分析了1971~2020年金华地区汛期降水在时间上的分布特征及演变趋势。结果表明金华地区汛期降水集中期首日在6月13日,与常年入梅时间吻合;金华地区总体上降水时间分布较均匀但年际变化大;降水集中度和集中期均存在准18 a周期。天气形势场上,降水集中年份最明显的异常为西太平洋副热带高压偏强偏西,以及菲律宾地区异常反气旋。菲律宾地区异常反气旋使初夏季节我国东部沿海西南气流水汽输送旺盛,并且造成西北太平洋副热带高压加强西伸,较强的副热带高压与西风槽之间的位势梯度可以增大西南暖湿气流的输送,减慢西风槽脊的移动,以形成较为稳定的环流配置,造成持续降水的出现,而在强的副热带高压继续西伸北抬后,西风带系统南下受阻,大型暖高压的下沉气流则会导致持续高温干旱酷暑天气,从而导致降水的异常集中。海温场上,降水异常集中年份前冬中东太平洋海温异常偏高,随后赤道中东太平洋海温差值逐渐转为显著的负异常,这种特征表明降水异常集中年份可能出现在厄尔尼诺的衰减阶段。

秦淮河流域降水汛期分配不均匀性分析

为探究秦淮河流域汛期降水不均匀性,本文以秦淮河流域内16个气象站点1978—2019年汛期逐日降水资料,利用反距离权重插值、气候倾向率、SPSS相关分析等方法对秦淮河流域汛期降水集中度P_(CD)和集中期P_(CP)进行分析。结果表明,1978—2019年,秦淮河流域汛期P_(CD)为0.09~0.57,呈不显著增加趋势,总的分布特征是中游高上下游低;P_(CP)波动范围为18.5~21.5旬,呈不显著延迟趋势,地域差异较小;汛期降水量与P_(CD)在流域内表现出一致正相关,而与P_(CP)基本呈负相关。多水年和少水年P_(CD)和P_(CP)空间分布差异较大。研究结果可为秦淮河流域洪涝灾害防治提供依据。

The Relationship between Precipitation Heterogeneity and Meteorological Drought/Flood in China

In this study, we investigated the spatial and temporal characteristics of precipitation heterogeneity and meteorological drought/flood in China based on the precipitation-concentration degree （PCD） and the inte- grated meteorological drought index. We also studied the corresponding relationship between precipitation heterogeneity and meteorological drought/flood in China by using Spearman correlation analysis and canon- ical correlation analysis. The results show that： （1） The severity of meteorological drought/flood exhibited a spatial pattern of gradual change from Northwest to Southeast China. （2） With a higher PCD and a delayed precipitation-concentration period （PCP）, the drought severity was higher but the flood severity was lower. In contrast, with a lower PCD and an early PCP, the drought severity was lower and the flood severity was higher. （3） The correlation between meteorological drought/flood and PCD was significant. The higher the PCD, the longer the duration of drought and more frequently, the droughts occurred, and vice versa. It is concluded that PCD and PCP were significantly correlated with meteorological drought/flood in China.

高度城市化地区的降水集中度研究——以长三角城市群为例

在全球变暖和人类活动的背景下,降水在年内分布上发生了比较大的变化,对人民生产生活产生了巨大的影响,这一影响在城市化较高的地区尤为明显。基于多源降水数据(降水产品数据和气象站点数据)和夜间灯光数据,选定中国的长三角城市群作为研究区域,将基尼系数(Gini Index,GI)作为降水集中度的指标,利用Theil-Sen Median斜率估计和Mann-Kendall显著性检验进行趋势分析,最后通过相关性分析探究城市化程度与降水集中度的关系。研究结果表明:(1)CHIRPS(Climate Hazards Group InfraRed Precipitation with Station Data)数据计算得到的GI与站点数据结果的均方根误差为0.036,远小于CMFD数据(0.067)和MSWEP数据(0.083)的结果,表明CHIRPS数据具有最佳的适用性;(2)长三角城市群的降水不均匀性从南向北逐渐增加,并在城市群中部和西部呈现出显著上升的趋势,研究区域内的降水年内分布将会朝着集中分布的方向发展,极端降水事件出现的可能性增加;(3)城市化对降水集中度主要起到促进作用,城市的快速发展使得降水不均匀性增强,并且在城市群内的南京市、无锡市和镇江市等地区更为显著,更有可能发生城市内涝等灾害。研究对于城市的防洪设计、城市道路排水管道的设计和城市防洪应急响应预案的编制具有参考意义。

A graded index for evaluating precipitation heterogeneity in China

Precipitation heterogeneity has a nontrivial influence on human life. Many studies have analyzed precipitation heterogeneity but none have proposed a systematic graded index for its evaluation, and therefore, its true characteristics have not been expressed. After comparisons of various methods, the precipitation concentration degree(PCD) method was selected to study precipitation heterogeneity. In addition to the PCD, normal distribution functions, cumulative frequencies, and percentiles were used to establish a graded index for evaluating precipitation heterogeneity. A comprehensive evaluation of precipitation heterogeneity was performed, and its spatiotemporal variation in China from 1960 to 2013 was analyzed. The results indicated that(1) seven categories of precipitation heterogeneity were identified(high centralization, moderate centralization, mild centralization, normal, mild dispersion, moderate dispersion, and high dispersion) and(2) during the study period, the precipitation in more parts of China tended to be normal or dispersed, which is beneficial to human activities.

中国强降水过程时空集中度气候趋势

基于日降水资料序列提出一种度量不同强度降水过程时空集中程度的指标,根据中国740个气象站逐日降水资料研究分析了我国强降水过程集中度和集中期及其相关统计特征,结果表明暴雨过程年内集中度与年降水量正相关区与中国降水空间分布有很好的一致性;在对大范围洪涝灾害研究方面,暴雨过程年内集中度和集中期在定量地表征降水量在时空场上的非均匀性时有更高分辨力;暴雨过程年内集中度比较清晰地反映出长江流域、江淮地区洪涝增加的趋势及黄河中下游、华北强降水减少的趋势。该方法可直接应用到评估水旱灾害及其气候影响等领域。

东北地区降水年内分配的不均匀性

利用东北地区93个台站1961-2005年的逐日降水资料,通过降水集中度和降水集中期,讨论了该地区降水的年内分配不均匀分布特征。结果表明,东北地区的降水集中度自东南向西北逐渐递减;集中期具有南北高中间低的变化特点。从长期趋势上看,降水集中度的减小趋势显著,在该地区的东北部和西北部各有一个趋势明显的区域(通过0.05的显著性检验),但集中期的减小趋势不显著,只有2个台站通过显著性检验。年降水量与降水集中度和降水集中期的相关系数表明:东北地区年降水量与降水集中度呈显著的正相关,即年降水量越多(少)的地区,年内降水越集中(均匀);年降水量与降水集中期的关系并不显著。

1951—2012年中国降水集中度和集中期的时空格局

以1978年为分界点,对1978年前后的以周为单位的降水集中度和集中期的时空格局和变化趋势进行研究.结果表明：1）中国的降水集中度首先具有明显南北分异规律,其次在中国北部具有明显东西差异;最后,中国整体降水集中度波动呈现减小趋势,且1978年之前波动较大,1978年之后趋于平稳.2）中国的降水集中期主要集中在一年中的第26—30周左右,并在1978年前后有1~3周不同幅度的滞后和提前,且南方以推迟为主,北方以提前为主;中国整体降水集中期波动呈现微弱减少趋势,且1978年前显著减少,但1978年后显著增加.

宁夏近50a降水集中度和集中期特征分析

利用宁夏气象台站1961-2010年逐侯降水量序列资料,研究了表征降水量时间分配特征的降水集中度(PCD)和集中期(PCP)的空间分布与年际变化特征。结果表明:宁夏降水PCP与PCD空间分布特征明显,中北部PCP比南部山区偏早1候,PCD自北向南逐渐减小,北部1年中最大降水出现的时间变率较大,且出现极端降水的可能性比中南部大;1961-2010年全区PCD与PCP呈微弱的下降趋势,但近20 a PCD明显增大,PCP显著推迟;PCD与PCP显著正相关,PCP出现得越晚,PCD集中度越高;各地的PCD与年降水量、汛期降水量以及年日最大降水量都有非常好的正相关性,正相关中心区位于北部的惠农、陶乐、中卫,中部的盐池、麻黄山和南部山区的大部,上述地区降水越集中,年降水量、汛期降水量以及年日最大降水量越大,导致洪涝灾害发生的可能性将越大;宁夏汛期降水多雨年各地降水更集中,且大降水中北部大部易出现得早,南部出现得晚;中高纬的北极涛动和低纬的南海季风对宁夏降水集中度有着显著的影响,北极涛动偏弱的年份,南海季风爆发偏早的年份,宁夏各地年降水比较集中。

华北雨季降水集中度和集中期的时空变化特征

运用新定义的降水集中度和集中期,讨论了我国华北地区雨季降水在时间上和空间上的分布特征和变化规律。结果表明,华北东部地区的降水较西部更为集中;集中期较晚,华北地区雨季降水集中期空间分布有较好的整体一致性;从长期趋势上看,集中度、集中期和雨季降水量都呈显著的下降趋势,但三者在空间上则表现出较大的区域差异,发生突变的时间都集中在20世纪70年代末至80年代初。集中度和集中期周期振荡不一致,但二者和雨季降水量在一定时间内存在相同周期;华北地区的降水量与集中度和集中期存在一致的正相关性,采用合成分析方法,华北地区多水年和少水年降水集中度的空间分布有明显的不同。青藏高原北部到蒙古高原的低压可能是影响华北降水集中度的最重要因子。华北地区雨季集中期和雨季降水量与东亚夏季风具有较好的正相关关系,华北北部地区为集中期与东亚夏季风的显著相关区。

近46年辽宁省降水集中程度研究

利用辽宁省25个台站1960—2005年逐候的降水资料,运用降水集中度和集中期分别讨论了辽宁省降水时空分布特征和变化规律,同时对多水年和少水年的集中度进行了比较。结果表明降水集中度和集中期能够定量地表征降水量在时空场上的非均一性,降水集中度平均为0.655,最大为0.749,最小为0.509;集中期平均为40.953候,最大值为45.221候,最小值为37.697候。年降水集中度和汛期降水集中度均呈减小趋势,汛期降水集中度减小的趋势明显。降水集中度的EOF分析显示取前3个特征值对应的特征向量可解释70%以上的方差。第一特征向量表现为全省一致性,而第二特征向量表征为东南与西北地区的反相,第三特征向量表征为东部山区与西部和沿海地区的反相。多水年的降水集中度明显比少水年的偏大且多水年的降水集中度分布较少水年复杂。

1961—2010年东北地区汛期极端降水的非均匀性特征

利用东北地区91站1961—2010年逐日降水资料,讨论东北地区汛期极端降水量的非均匀性分布特征。结果表明,东北地区极端降水量呈现由南向北逐渐减少的分布特征;极端降水主要集中出现在7月,东北地区中部极端降水出现相对比较分散,东北东部、北部、西部和南部出现比较集中;东北地区汛期纬度偏低地区极端降水量偏多,极端降水发生较晚,且较为集中,纬度偏高地区则反之。汛期极端降水量与集中度存在显著的负相关关系,即汛期极端降水量越多,极端降水越集中,特别是嫩江、松花江流域。

中国西北降水年内非均匀性特征分析

基于中国西北五省(区)1960-2004年112个台站逐日降水资料,通过表征时间分配特征的参数—集中度和集中期,对西北降水年内非均匀性分布特征进行了分析。结果表明:中国西北地区降水集中度和集中期的空间分布存在很大的差异:年降水集中度东、西部表现出反向变化趋势,而年降水集中期南、北部表现出反向变化趋势;年降水集中度、集中期与夏季北极涛动和东亚夏季风在年代际尺度上存在很好的相关性。

长江流域汛期降水集中程度和洪涝关系研究

运用新定义的降水集中度和集中期分别讨论了我国长江流域不同地段汛期降水在时间和空间上的分布特征和变化规律 .结果表明在对长江流域旱涝灾害研究方面 ,降水集中度和集中期能够定量地表征降水量在时空场上的非均匀性 ,提取出最大降水重心对应的时段 ,因此可以比较理想地分析旱涝灾害发生的基本特征及其形成机制 .