不同强度热带气旋对中国降水变化的影响

基于1960—2017年2 000多个气象台站逐日降水数据和中国气象局热带气旋(TC)最佳路径资料集,采用客观天气图分析法(OSAT)识别得到TC降水。研究表明,中国TC降水总体呈显著下降趋势,较12年前的研究结果下降趋势变缓;TC盛期(7~9月)降水占到TC总降水的78.5%,TC盛期降水和TC非盛期降水均呈显著下降趋势。TC降水气候趋势在空间分布上以减少为主要特征,并表现出明显的地域差异,自南向北呈"减少—增多—减少"的分布型,减少趋势中心位于广东和海南。按TC影响期最大强度分级(弱TC、中等强度TC和强TC)研究不同强度TC降水的变化,结果显示,强TC降水表现出显著减少趋势,主要决定着TC总降水的影响范围和趋势等主要特征。进一步分析发现,影响TC频数在1960—2017年呈显著减少趋势,并在1995年发生突变;对1995年前后2个时期的对比研究显示,与前一时期(1960—1994年)相比,后一时期(1995—2017年)影响TC活动频次在20°N以南的海域呈现出显著的减少趋势,减少大值中心位于南海北部,而且这一特征也主要由影响TC中的强TC所决定;强TC的这一变化趋势导致了华南地区尤其是广东和海南TC降水日数的减少,进而使得TC降水减少。     

Climatic Characteristics of Influencing China Binary Tropical Cyclones

Based on the definition of Binary Tropical Cyclones (BTCs), the definition of influencing china binary tropical cyclones (ICBTCs) was proposed. During the BTCs period, if at least one of the two tropical cyclones causes precipitation over the mainland or one of the two largest islands-Hainan and Taiwan of China, the BTC is called ICBTC. Then, based on daily precipitation data and the tropical cyclone best track data during 1960-2017, this study analyzed the climatic characteristics of ICBTCs using the Objective Synoptic Analysis Technique (OSAT) and the above definitions. First, a total of 255 pairs of ICBTCs, which accounted for 60.6% of the total number of BTCs over the Western North Pacific, occurred with an annual average of 4.4. Annual frequency of ICBTCs showed a significant decreasing trend during 1960-2017. The longest duration of ICBTCs was 10 days, while durations concentrated in 1 day, 2 days and 3 days, accounting for 18.8%, 29.4% and 24.3%, respectively. In terms of geographical distribution, the ICBTCs mainly occurred over the range of 112°~138°E, 12°~30°N, with frequent zones in the oceans around the northern Philippines. In addition, both annual mean frequency and precipitation of the ICBTCs decrease from the southeast coast areas to the northwest inland regions, with severely-affected areas being the Taiwan Island, the Southeast Coast and the South Coast, and the most-severely-affected area being the Taiwan Island. Further analyses reveal that the average position of the two TCs on the maximum daily precipitation day during the ICBTCs period show an east-west distribution pattern, with the western TCs and the eastern TCs locating in the southwest wind water vapor channel of the East Asian Summer Monsoon and the warm-wet air flow of the southeast-wind on the southwest side of the subtropical high. This situation is beneficial to the western TCs obtaining water vapor from the southwest wind water vapor channel, and to the eastern TCs conveying water vapor to the western TCs, and then as a result, to the heavy rainfall over the Taiwan Island, the Southeast and the South Coasts of China caused by the western TCs.     

On the driving forces of historical changes in the fatalities of tropical cyclone disasters in China from 1951 to 2014

Tropical cyclone (TC) disasters have frequently caused casualties in the coastal areas of China. According to the statistics of dead and missing people due to TCs from 1951 to 2014, the number of fatalities has been significantly decreasing over time. However, deadly TC events have still caused great losses of life in recent years, which are characterized as significant abrupt fluctuations superimposed along the downward trend of the long-term fatality time series. The numbers of fatalities caused by TC disasters are influenced by variables such as the intensity of TC hazards, the population exposed to TCs and the vulnerability of people to TC hazards. It is thus of great significance to analyze their temporal characteristics and understand the forces driving these changes. First, the time series of the TC wind, precipitation, spatial distribution of population, fatality and disaster risk reduction (DRR) measures of China from 1951 to 2014 are reconstructed. Second, the improved power dissipation index, total precipitation, integrated intensity and index of exposed population are calculated, and the population vulnerability indices, including mean and relative fatality rates, are derived. Third, the change trend of each index is detected using the Mann–Kendall test. Finally, the main driving factors of the long-term change trend and fluctuations of the TC fatalities are analyzed by a negative binomial regression model and standard deviation statistics. It is found that the decrease in vulnerability based on the improvement in structural and non-structural measures is the main driving force of the decreases in fatalities over the past six decades. Although the total population and exposure have increased dramatically in the coastal areas of China, their contributions to the increase in the fatality risk were counteracted by the decrease in vulnerability. Abrupt and catastrophic disasters were mostly caused by TCs with hazards of high intensity that surpassed the capacity of structural measures; the lack of forecasting or early warning, as well as improper emergency response actions, may also have triggered the great loss of lives. To reduce the fatalities of future TCs, especially those that may exceed the capacity of structural measures, the enhancement of non-structural measures and the adaptation of resilience strategies should be priorities for future people-centered disaster management.

     

Characteristics of tropical cyclones in China and their impacts analysis

This paper discusses the characteristics of tropical cyclones (TCs) based on available data from 1951 to 2008, including the frequency of TC generation in the Western North Pacific (WNP) and those which make landfall in China. The impacts of TCs on both human and economic losses for the period 1983–2008 are also discussed. Examination of the frequency indicates a decreasing trend in the generation of TCs in the WNP since the 1980s, but the number of TCs making landfall has remained constant or shown only a slight decreasing trend. The number of casualties caused by TCs in China appears to show a slight decreasing trend while the value of economic loss is increasing significantly. These results can be attributed to increased natural disaster prevention and mitigation efforts by the Chinese government in recent years, and also reflect the rapid economic development in China particularly in TC-prone areas.     

Tropical Cyclone Impacts on Coastal Regions: the Case of the Yucatán and the Baja California Peninsulas,Mexico

Tropical cyclones (TCs) are large-scale natural disturbances that generate strong winds and heavy rainfall, impacting coastal and inland environments. TCs also influence biogeochemical and hydrological cycles controlling aquatic primary productivity in tropical and subtropical coastal ecosystems. We assessed TC landfall activity and identified sites along the Mexican east and west coasts with high frequency in the period 1970–2010 and evaluated TCs with significant precipitation. Changes in chlorophyll-a (Chl-a) concentrations before and after storm impacts were estimated using remotely sensed ocean color. There were 1,065 named TCs with a wide diversity in tracks. Three states with the highest number of landfalls were identified: Baja California Sur and Sinaloa on the west coast and Quintana Roo on the east coast. While a relative increase in Chl-a values following TC landfalls in the Baja California and Yucatán Peninsula regions appeared to be strongly linked to TC strength, the intensity of precipitation, the spatial scales of the two peninsulas, and the relative movement of TCs appeared to have contributed to Chl-a variability. Satellite estimates of Chl-a in the nearshore coastal waters following TC passage were likely enhanced by coastal morphology and water discharge along with constituents such as suspended particulate, colored dissolved organic matter and nutrients from rivers, tributaries, and groundwater.     

1960—2017年河西地区降水时空变化特征

利用1960—2017年日降水量资料,采用线性倾向趋势分析、滑动分析和泰森多边形法等,对河西地区多年降水时空变化特征及不同量级降水日数及降水强度的变化趋势进行了研究.结果表明:河西地区年均降水量为99.0 mm,呈现明显的逐年上升趋势,平均倾向率为8.72 mm?(10a)-1,月降水量为单峰分布,5—10月夏秋汛期降...     

西北地区45a来降水异常的时空变化及其标度特征

利用西北地区(73°~113°E,30°~50°N)157个气象站的1960—2004年日降水观测资料,通过非参数趋势检测和旋转主成分分析方法对年降水异常的时空特征进行研究.根据降水特征的差异,西北地区可以划分为西北东北部、东南部、西北部、西南部、中北部及中南部等6大区域.结果表明:西北地区降水自东南向西北逐步递减,降水变化趋势则是东南为负、西北为正,变化幅度东南大于西北.根据每个分区的降水序列标度特征,采用消除波动趋势分析方法,对6个分区45 a来降水时间序列所纪录的大气动力过程影响的时空差异进行分析,定量区分区域气候系统和局地要素对不同区域降水贡献的差异及其年代际变化.     

Effects of various combinations of boundary layer schemes and microphysics schemes on the track forecasts of tropical cyclones over the South China Sea

This study investigates the effects of various combinations of the planetary boundary layer (PBL) schemes and the microphysics schemes on the numerical forecasting of tropical cyclones (TCs). Using different combinations of three PBL schemes (YSU, MYJ and MYNN2) and four microphysics schemes (Ferrier, Goddard, WSM6 and Lin), a number of experiments are carried out for five landed TCs in the South China Sea during 2012. Results show that the combination of the YSU and Ferrier schemes performs the best for the TC track forecasting, although it does not perform the best for the forecast of precipitation. Further analysis reveals that the best performance of the track forecast by the combination of the YSU and Ferrier schemes mainly attributes to a more accurate steering flow as well as TC wind structure produced by this combination. These results provide a valuable reference to the operational numerical forecasting of TC tracks in the future.     

Multi-scale Characteristics and Comprehensive Evaluation of Precipitation Heterogeneity in Guangxi

Aiming at the uneven spatial and temporal distribution of precipitation and frequent occurrence of drought and waterlogging disasters in Guangxi, the multi-scale characteristics and comprehensive evaluation of precipitation heterogeneity can provide scientific support for regional response to drought and waterlogging disasters and intelligent management of water resources. Based on the daily precipitation data of 87 grid points from 1961 to 2017 in Guangxi, the Precipitation Concentration Degree (PCD) and Precipitation Concentration Period (PCP) index were used to build day, pentad, ten days, month, season precipitation heterogeneity of multiple time scale level evaluation system. By using R/S analysis and geographical spatial analysis methods, the space-time evolution characteristics and climate division in Guangxi were discussed. The study showed that the spatial and temporal variation characteristics of PCD and PCP at the diurnal, synoptic and monthly scales were relatively consistent, and the heterogeneity of precipitation in Guangxi could be better expressed than that at the monthly and seasonal scales. The diachronic change of PCD in precipitation in Guangxi shows an increasing trend in northeast China and a decreasing trend in southwest China, and the trend of its future period is the same as the diachronic evolution. The spatial distribution of PCD in Guangxi has significant spatial autocorrelation and stratification heterogeneity, which are mainly reflected in the mean value, coefficient of variation and frequency of PCD. The comprehensive heterogeneity of precipitation in Guangxi is highly dispersed in the northeast, highly concentrated in the south, and slightly concentrated or dispersed in the northwest and central regions. The time-scale within a month is the best scale to express the non-uniformity of precipitation in Guangxi. If the advantages of more stable climatic and ten-day scales and more fine daily scales are taken into account, the use of climatic scale for daily sliding calculation and analysis will be the best way.     

长江源区1956-2000年径流量变化分析

利用Mann-Kendall趋势检验法对长江源区直门达水文站的资料进行分析,揭示长江源区年径流量在1956-2000年间呈微弱的减少趋势。结合流域气象资料分析,该时段流域内升温明显,最大可能蒸发量呈增加趋势,降水也呈微弱减少趋势。径流变化与降水变化基本一致,降雨-径流关系没有发生明显变化,表明1980-2000年降水量减少是该时段径流量减少的直接原因,温度升高有利于融冰融雪和降水形式的变化,但由于融冰融雪占径流补给的比率相对较小,该时段温度升高导致融冰融雪的增加不足以抵消降水量的减少对径流的影响。径流量季节变化分析,揭示长江源区春季径流呈增加的趋势,这可能与融雪过程提前以及融雪量增加有关。     

Spatial and Temporal Features and Trend of Different Level Heat Waves Over China

Heat wave has become a severe problem over China in recent year. Based on daily air temperature data from 719 meteorological stations in China in the period of 1961-2012, the heat wave events were classified into three levels by duration: weak HW, medium heat wave and strong heat wave. This paper describes the spatial and temporal characteristics among three levels of heat wave over China during the period 1961-2013. The results showed that the number of hot days displayed a weakening trend from the 1960s to the early 1990s, followed by a strengthening trend from the late 1990s up to now. Long-term linear trends in hot days had significant regional differences, for instance, the number of hot days in southwest and southern China growing sharply than other regions; three levels heat wave occurred in different regions that weak heat wave usually occurred in the northwest and middle part of China while strong heat wave mainly happened in the southern part of China. When it came to the first day of heat wave, weak heat wave occurred earliest in China, and it happened around July 3rd while medium heat wave and strong heat wave always started on July 13th and July 14th, respectively. In general, the earliest heat wave was always found in southwest China while the last ones usually occurred in southern part and southwest China. Increasing trend of three levels heat wave were found in the entire country, except for southwest China. The trend of the last day of heat waves showed significant difference between northern and southern part of China. The last day of weak and medium heat wave occurred later in the south China, while strong heat wave happened earlier in north China.     

Temporal and spatial variation of the main water balance components in the three rivers source region, China from 1960 to 2000

The three rivers source region (TRSR) is the most sensitive region of global climate change in China. The temporal and spatial variations of main water balance components (precipitation, snowmelt, actual evaporation, runoff, etc.) during the period from 1960 to 2000 in the TRSR were analyzed by hydrologic simulation and statistical detection. The results showed that: when compared with the components in 1960s, (1) the variation of precipitation from 1970s to 1990s was not significant in the whole TRSR though it increased slightly in the Yellow River Source Region (YeSR) and Yangtze River Source Region (YaSR), but decreased slightly in the Lancang River Source Region (LcSR); (2) the snowmelt increased in most regions of TRSR except the downstream of YeSR and YaSR, but the trend was statistically significant only in the YeSR; (3) the actual evaporation increased continually in the whole TRSR, but the trends were significant in the middle stream of the YeSR and YaSR, and the YeSR was the greatest; (4) Although the runoff depth decreased gradually in the TRSR, the trends were significant only in the middle stream of the YeSR and YaSR and the YeSR was the greatest. Inevitably, the discharge decreased in the TRSR but the trend was not statistically significant. Climate change (i.e., the slightly decreasing of precipitation and the increasing of air temperature) was the most important factor to affect the variations of water balance components. The most sensitive region to climate change was YeSR, followed by YaSR, and the least one was LcSR. This study was expected to provide the foundation and a reference to analyze the water resources evolution and test the climate change impacts in TRSR as well as the whole China.     

Spatial and temporal analysis of a fatal landslide inventory in China from 1950 to 2016

Landslides result in severe casualties every year in China. However, there are few historical fatal landslide catalogs available to quantitatively assess the impact as well as the temporal and spatial patterns of landslides. The Fatal Landslide Event Inventory of China (FLEIC), which spans from 1950 to 2016, was compiled based on multiple data sources. The inventory contains 1911 non-seismically triggered landslides, which resulted in a total of 28,139 deaths in China during 1950–2016. The occurrence frequency of fatal landslides presented significantly different trends for different grades of events. Very large fatal landslide events (fatalities >?=?30) were on the rise during 1950–1999 and declined from 2000 to 2016. The decreasing trend after 2000 can be attributed to the increase in landslide mitigation investments. The small and medium-sized fatal landslide events (fatalities <?10) showed a significant increasing trend between 1950 and 2016, especially during the period of 2000–2016. This significant increasing trend is partly due to the improvement of the availability of landslide data online and may also be related to other factors including an increase in extreme precipitation events, the effects of land urbanization, and so on. This suggested that the inherent incompleteness of the landslide time series should be considered when analyzing. The fatal landslides mainly occurred between April and September (82.15%), which is consistent with the monthly precipitation variation in China. Spatially, most of the fatal landslides occurred in 14 provinces: five southwestern provinces (Yunnan, Sichuan, Guangxi, Guizhou, and Chongqing), five southeastern provinces (Hunan, Guangdong, Fujian, Jiangxi, and Zhejiang), Shaanxi and Shanxi, Hubei and Gansu. These 14 provinces account for 86% of the total fatal landslides and their associated fatalities. The spatial association between the fatal landslide density and possible influencing factors was assessed based on a geographical detector method. The results showed that the interacting factors between the precipitation and topography, soil, lithology, vegetation and population density are more closely related to the spatial distribution of fatal landslides than each individual factor.     

1961—2016年东北地区冬季寒潮事件变化特征及其对区域气候变暖的响应

利用东北地区1961—2016年164个气象台站逐日平均气温和最低气温数据,根据国家标准《寒潮等级》（GB/T 21987—2017）的单站冷空气等级,计算近56年来各单站不同等级冷空气过程的频次、强度、持续日数,应用趋势系数、Mann-Kendall检验、小波分析、相似系数等统计方法,研究了东北地区三种类型寒潮（超强寒潮、强寒潮、寒潮）的气候变化特征。结果表明：三种类型寒潮日数空间分布存在明显的地区差异,高海拔地区相对偏多,低海拔和平原地区相对偏少。年尺度上,1961—2016年三种类型寒潮日数和站次呈减少趋势,减少速率呈现为超强寒潮＞强寒潮＞寒潮;年代尺度上,三者均在20世纪60年代到70年代末期相对偏多,1980年开始进入一个相对偏少的时段,21世纪00年代中期以后有小幅度增加;寒潮日数和站次均存在明显的3~5 a短周期性变化。1961—2016年东北地区冬季气温在空间变化上全区呈一致的增加趋势,66%的站点增温显著,检测到冬季气温的突变点为1981年。东北地区气候变暖后,三种类型寒潮日数和站次均有明显的减少。     

松花江流域年降水和四季降水变化特征分析

利用松花江流域35个气象站1960~2010年的降水资料,采用协克里格插值法、线性倾向估计方法以及M-K秩次相关法等,分析了流域年降水和四季降水的时空变化特征。结果表明:(1)流域年降水由东部向西部递减,51年来流域大部分地区年降水呈不显著减少趋势。(2)流域春季降水呈不显著增加趋势,夏季呈不显著减少趋势,秋季呈不显著减少趋势,冬季降水呈显著增加趋势。(3)流域四季降水在二松源头地区一带较大,流域西部地区降水较少,松花江中下游两侧地区居中。(4)春季,流域大部分地区降水增加,但不显著。夏季,大部分地区降水减少,但不显著。秋季,全流域降水呈不显著减少趋势。冬季,全流域呈增加趋势,且绝大部分地区显著增加。(5)嫩江流域、松花江流域年降水-径流关系发生显著变化的时间是1974年、1980年和1999年。     

Spatial variability of rainfall trends in Iran

The main objective of this paper is to analyze the spatial variability of rainfall trends using the spatial variability methods of rainfall trend patterns in Iran. The study represents a method on the effectiveness of spatial variability for predicting rainfall trend patterns variations. In rainfall trend analysis and spatial variability methods, seven techniques were used: Mann–Kendall test, Sen’s slope method, geostatistical tools as a global polynomial interpolation and the spatial autocorrelation (Global Moran’s I), high/low clustering (Getis-Ord General G), precipitation concentration index, generate spatial weights matrix tool, and activation functions of semiliner, sigmoid, bipolar sigmoid, and hyperbolic tangent in the artificial neural network technique .For the spatial variability of monthly rainfall trends, trend tests were used in 140 stations of spatial variability of rainfall trends in the 1975–2014 period. We analyzed the long and short scale spatial variability of rainfall series in Iran. Spatial variability distribution of rainfall series was depicted using geostatistical methods (ordinary kriging). Relative nugget effect (RNE) predicted from variograms which showed weak, moderate, and strong spatial variability for seasonal and annual rainfall series. Moreover, the rainfall trends at each station were examined using the trend tests at a significance level of 0.05. The results show that temporal and spatial trend patterns are different in Iran and the monthly rainfall had a downward (decreasing) trend in most stations, and the trend was statistically significant for most of the series (73.5% of the stations demonstrated a decreasing trend with 0.5 significance level). Rainfall downward trends are generally temporal-spatial patterns in Iran. The monthly variations of rainfall decreased significantly throughout eastern and central Iran, but they increased in the west and north of Iran during the studied interval. The variability patterns of monthly rainfall were statistically significant and spatially random. Activation functions in the artificial neural network models, in annual time scale, had spatially dispersed distribution with other clustering patterns. The results of this study confirm that variability of rainfall revealing diverse patterns over Iran should be controlled mainly by trend patterns in the west and north parts and by random and dispersed patterns in the central, southern, and eastern parts.     

1961—2010年全球变暖背景下中国空气湿度长期变化特征

空气湿度是重要的气象要素，与气温和降水密切相关，其长期变化特征是气候系统变化的重要表征。2003年前后全国自动站与人工站的更替使得相对湿度资料存在不能满足均一性的要求，亟需加强空气湿度变化特征方面研究。利用1961—2010年中国824个气象站订正后均一性较好的逐日气温、降水量和相对湿度数据，剔除缺测多的站点，采用线性回归分析、Mann-Kendall趋势检验和偏相关分析方法，综合分析中国水汽压和相对湿度的长期变化特征及其与气温和降水量的相关特征。结果表明：①全国各地年均水汽压呈增大趋势的站点占全部站点的90.3%；除春夏两季的黄土高原至云贵高原一带和长江下游地区、秋季的华南地区有所减小外，各季节全国水汽压普遍呈增大趋势。②全国年均相对湿度呈减小趋势的站点占64.1%；除河北北部至辽宁北部、陕西南部至黄淮地区、江南北部、青藏高原和四川西部地区以及西北大部呈增大趋势外，其余地区普遍减小；季节差异明显，春、夏和秋季，中东部大部分地区相对湿度以减小趋势为主；冬季除东北地区和云南减小外，其余大部分地区相对湿度增大。③全国各地水汽压与气温、降水量普遍以正相关为主，与气温的相关性强于与降水量的相关性；相对湿度与气温普遍呈显著的负相关，与降水量普遍以正相关为主。     

1961-2010年全球变暖背景下中国空气湿度长期变化特征

空气湿度是重要的气象要素，与气温和降水密切相关，其长期变化特征是气候系统变化的重要表征。2003年前后全国自动站与人工站的更替使得相对湿度资料存在不能满足均一性的要求，亟需加强空气湿度变化特征方面研究。利用1961—2010年中国824个气象站订正后均一性较好的逐日气温、降水量和相对湿度数据，剔除缺测多的站点，采用线性回归分析、Mann-Kendall趋势检验和偏相关分析方法，综合分析中国水汽压和相对湿度的长期变化特征及其与气温和降水量的相关特征。结果表明:①全国各地年均水汽压呈增大趋势的站点占全部站点的90.3%；除春夏两季的黄土高原至云贵高原一带和长江下游地区、秋季的华南地区有所减小外，各季节全国水汽压普遍呈增大趋势。②全国年均相对湿度呈减小趋势的站点占64.1%；除河北北部至辽宁北部、陕西南部至黄淮地区、江南北部、青藏高原和四川西部地区以及西北大部呈增大趋势外，其余地区普遍减小；季节差异明显，春、夏和秋季，中东部大部分地区相对湿度以减小趋势为主；冬季除东北地区和云南减小外，其余大部分地区相对湿度增大。③全国各地水汽压与气温、降水量普遍以正相关为主，与气温的相关性强于与降水量的相关性；相对湿度与气温普遍呈显著的负相关，与降水量普遍以正相关为主。     

中国干旱-半干旱区当代气候变化

本文在作者近年有关研究工作的基础上，结合最新资料和有关成果，对我国干旱－半干旱区当代气候变化做了比较系统的分析。结果表明，中国干旱－半干旱区气候变化与全国和北半球气候变化相比有一定的特点。冬夏温度变化不同，干旱－半干旱区降水变化趋势不同。     

1960-2009年塔里木河流域降水时空演化特征及原因分析

利用1960-2009年新疆塔里木河流域（TRB）26个气象站的日降水资料以及美国NCEP/NCAR的逐月再分析资料（2.5°×2.5°）,对塔里木河流域降水的时空分布特征及其原因进行了分析.结果表明：塔里木河流域降水总体上呈现由东南向西北逐渐增加的分布形态,但不同季节之间以及降水量多年和少年之间存在差异,这与水汽输送...