大型水体会对局部地区(局地)气候条件造成影响,三峡工程是当今世界规模最大的水利水电枢纽工程,为了分析三峡蓄水对当地气候变化的影响,以三峡库区10个站点为研究对象,利用气候倾向率、CVM检验等方法,系统分析了三峡库区66 a来气候变化特征以及蓄水对局地气候变化的影响。结果表明,三峡蓄水后局地温度下降,影响大坝附近299.83 km²的地区,影响距离最远距大坝12.65 km,大坝最近的秭归站温度在1997年发生突变,蓄水后20 a秭归站年平均温度较蓄水前20 a下降1.15 ℃;蓄水造成局地降水量增加,影响大坝附近2 914.88 km²的地区,影响距离最远距大坝109.15 km,大坝最近的秭归站降水在1997年突变,蓄水后20 a秭归站平均降水量较蓄水前上升245.90 mm;蓄水造成局地相对湿度增加,秭归、兴山站相对湿度分别在1997年、2003年突变,蓄水后20 a秭归站相对湿度较蓄水前20 a上升5.29%;蓄水造成局地日照时数下降,影响大坝附近2 045.66 km²的地区,影响距离距大坝最远41.06 km,距大坝最近的秭归站日照时数在2002年突变,蓄水后20 a秭归站日照时数较蓄水前20 a下降33.87 h。蓄水对气象要素影响的范围较小,对各要素共同造成影响的范围仅75.27 km²,各要素全部在蓄水期间发生突变的仅秭归一站。

Due to special underlying surface properties, large water bodies have impacts on local water thermal cycle and climate. The Three Gorges Project is the world's largest water conservancy project. In the present research, we analyzed systematically the characteristics of climate change in the Three Gorges Reservoir over the past 66 years and the impacts of water storage on local climate by means of climate tendency rate and CVM test. Results demonstrated that the local temperature of the Three Gorges Project has declined after impoundment, affecting an area of 299.83 km² near the dam, reaching 12.65 km away from the dam. The temperature of Zigui station, which is the closest to the dam, changed abruptly in 1997. The average annual temperature of Zigui two decades after the impoundment was 1.15 ℃ lower than that before the impoundment. Local precipitation has increased, affecting an area of 2 914.88 km², reaching 109.15 km away from the dam. The precipitation of Zigui station also changed abruptly in 1997, and the average precipitation of Zigui two decades after the impoundment increased by 245.90 mm compared with that before the impoundment. Water storage also led to the rise of local relative humidity. Zigui and Xingshan witnessed abrupt changes in relative humidity in 1997 and 2003, respectively, of which the former rose by 5.29% two deades after the impoundment. The number of sunshine hours reduced, affecting the nearby area of 2 045.66 km², extending 41.06 km away from the dam. The sunshine hours of Zigui changed abruptly in 2002, reducing by 33.87 hours compared with that two decades before the impoundment. In conclusion, water storage in the Three Gorges Reservoir has had a small scope of influence on meteorological elements, affecting an area of only 75.27 km² on all the elements; only Zigui station experienced abrupt changes in all the elements during water storage.

分析长寿区生态质量时空演变过程和影响因素对三峡库区生态建设及恢复具有重要意义。选取长寿区为研究区,以2002—2021年多景Landsat-5 TM 影像和 Landsat-8 OLI 影像构建遥感生态指数(RSEI),从时间和空间两个维度研究生态质量演变过程,并通过随机森林模型分析生态质量和影响因子之间的关系。结果表明:①长寿区RSEI均值由2002年的0.642 7降低到2006年的0.566 5,2010年以后RSEI均值稳步增加,生态质量呈“先恶化后好转,整体向好发展”的趋势;②生态质量较好的区域集中在高程较高的区域,较差的区域集中在长江两岸的工业园区、化工园区、城镇居民居住区;③2002—2021年长寿区生态质量改善面积为628.838 km²,占比44.16%;退化面积为183.269 km²,占比12.87%,改善效果明显;④随机森林模型分析发现高程和人口密度是影响RSEI空间变化的主要因子,人类活动和地形因素对区域生态质量变化起主导作用。利用RSEI和随机森林模型可以对长寿区及三峡库区内其他相似区域进行生态质量评价。

Studying the spatio-temporal evolution process and changing factors of ecological quality in Changshou District of Chongqing is of great significance for the ecological construction and restoration of the Three Gorges Reservoir area. In this study, we utilized Landsat-5 TM images and Landsat-8 OLI images from 2002 to 2021 and constructed the Remote Sensing Ecological Index (RSEI). With the RSEI, we investigated the evolution of ecological quality in Changshou District from both temporal and spatial perspectives. Additionally, we employed the random forest model regression to analyze the correlation between ecological quality and potential driving factors. Our findings revealed the following: 1) The average RSEI in Changshou District declined from 0.642 7 in 2002 to 0.566 5 in 2006. However, since 2010, the average RSEI has exhibited a steady increase, indicating an overall improvement in ecological quality after a previous deterioration. 2) The areas with better ecological quality mainly concentrates in higher elevation regions, whereas the industrial park, chemical industry park, and urban residential areas along the Yangtze River exhibited relatively poorer ecological conditions. 3) Over the period from 2002 to 2021, Changshou District experienced an improved area of 628.838 km², accounting for 44.16% of the total, and a degraded area of 183.269 km², which represented 12.87% of the total. The overall effect of ecological quality improvement was evident. 4) Through random forest regression analysis, we identified elevation and population density as the primary potential driving factors influencing RSEI changes. Moreover, human activities and terrain factors played a dominant role in regional ecological changes. As a result, RSEI and the random forest model can be effectively utilized for evaluating the ecological quality of both Changshou District and similar areas within the Three Gorges Reservoir region.

基于ERA-Interim再分析资料,以滇中引水工程主要受水区为研究对象,计算了受水区上空21 a水汽输送通量及水汽输送通量散度,并对其水汽输送、水汽辐合与水汽辐散等特征进行分析,研究其水汽输送时空变化特征。结果表明:研究区年平均水汽输送由西北至东南方向逐渐增加,并以纬向输送为主;水汽来源随季节移动,研究区夏季受西南风控制,水汽输送强度明显小于其他3个季节;5—7月份,研究区水汽输送强度逐渐衰减,7月份,研究区850 hPa气压层南部地区存在水汽辐合中心,450 hPa气压层西南部为水汽辐散带,在西南部易于形成降水。

According to the ERA-Interim data, the 21-year water vapor transport flux and divergence over the main water-receiving area of the water diversion project in central Yunnan Province were calculated. The spatial-temporal characteristics of water vapor transport, convergence and divergence in the studied area were also analyzed. Results demonstrate that the annual average water vapor transport in the studied area gradually increases from the northwest to the southeast, and is dominated by latitudinal transport. The source of water vapor moves with the seasons and is controlled by southwest wind in summer. The intensity of water vapor transport in the studied area in summer is significantly lower than that in the other three seasons. From May to July, the intensity of water vapor transport shows a gradual decline. In July, a water vapor convergence center emerges in the south of the studied area on the 850 hPa barosphere and a water vapor divergent zone in the southwest on the 450 hPa barosphere, beneficial for the formation of precipitation in the southwest.

应用近5 a自动气象站观测资料,分析了华北地区最大人工湖——密云水库的局地气候效应。结果表明：① 密云水库库区相比于附近平原地带具有气温偏低、湿度偏高、风速偏弱、降水量偏大等特点。水库对区域气候的影响范围约在10 km内,离水库越近的地方,受影响越大。② 密云水库的气候效应主要体现在夏半年,尤以气温和降水最为明显。③ 水库南、北两侧受到的局地环流的影响具有明显的差异,库区东西方向的年平均局地风速约为0.14 m/s,南北方向约为 0.10 m/s。下垫面属性的热力差异及特殊地形条件使得密云水库附近同时存在山谷风和湖陆风现象,其叠加效应是导致区域内不同位置间气象要素出现季节性及日变化差异的主要原因。

There exists lake-land breeze that wind blowing onshore from lake to land during the day and offshore in the evening around lake area, due to differences in air pressure mainly caused by different heat capacities between lake and land. Generally speaking, the closer to the lake, the more remarkable the lake climate effects. For studying the lake climate effects, it is not only important for understanding the characteristics of local climate and atmospheric circulation, but also helpful for analyzing and forecasting meso-and micro-scale weather processes. Miyun Reservoir (MYR), which located at 15 km north of Miyun District of Beijing city, is the largest artificial lake in North China. Up to now, there are seldom reports on the influence of MYR on local weather and climate. Based on hourly observation data obtained by 77 automatic weather stations surrounding MYR from 2011 to 2015, local climate effects of MYR were explored and discussed in the present work. The results showed that: 1) comparing with peripheral plains, climate effects of MYR were characterized by the facts that lower air temperature, higher humidity, slightly weaker wind speed and larger rainfall. As far as regional climate was concerned, the MYR had a modulate effect on the local climate and the spatial extent of the effect is about 10 km. The closer to the MYR, the more notable the MYR climate effects. 2) The MYR climate effects were mainly occurred in the summer, especially for temperature and rainfall. In detail, averaged air temperature was lower of 0.96℃ and averaged rainfall amount was higher of 13.3% in MYR than in the adjacent plains, where has the same elevation with MYR away from 10km. In addition, there were significant differences in diurnal variations of meteorological factors between the south and north regions of the MYR. 3) Excluding the impact of the large-scale background wind field, local wind presented the characteristics of monthly variation, i.e., mountain breeze was dominant from April to September, especially in summer; while in other months, valley breeze was more prevailing, especially in the wintertime. In general, annual averaged local wind speed was about 0.14 m/s in the east-west direction, which was slightly larger than that of 0.10 m/s in the north-south direction around the MYR. 4) In summer, there existed significant differences in wind vectors at the south and north regions of the MYR, due to the influence of local circulation. In most time of the whole day, component anomalies were usually in the same phase, while component anomalies presented out of phase at the south and north regions of the MYR. Lake-land breeze and mountain-valley breeze had the same/opposite directions at the north/south regions of the MYR, and thus these correspondingly formed the overlaying/counteractive effects. Due to lake-land differences in heat capacities and topography effects, lake-land breeze and mountain-valley breeze in the areas around MYR usually existed at the same time, which mainly caused the differences in seasonal and diurnal variations of meteorological elements at different locations around the MYR region.

首先利用中国区域地面气象要素数据集（CMFD）分析了1992-2015年纳木错地区月平均降水分布，发现湖泊效应导致的下风向降水在10-11月较为明显。其次根据中国科学院纳木错多圈层综合观测研究站自动气象站2 m的风速和气温的数据，分析了2005-2015年焚风累积发生次数的月分布特征，发现12月焚风发生几率最大，且10月是秋季中发生焚风现象次数最多的月份的结果。再者，运用WRF模型对纳木错地区10月份降水进行了模拟，发现在已有大气环流背景条件下，纳木错地区秋季降水受到湖泊存在的影响比上游地形影响显著。有、无湖模拟试验表明，纳木错地区湖泊的存在会使周边地区尤其是湖泊下风向降水增多，影响范围可达100 km。上风向较高地形会使整个区域降水小幅增加，上风向地形导致的焚风效应对纳木错地区降水的影响较弱。

This paper analyzed the distribution of monthly averaged precipitation from 1992 to 2015 around Nam Co area by using CMFD (China meteorological forcing data) and the frequency of foehn from 1995 to 2015 by using wind and air temperature data from Nam Co station(Nam Co Station for Multisphere Observation and Research, Chinese Academy of Sciences). The results showed that the spatial lake-effect precipitation is most significant in fall, and foehn is the most frequent in December. And in October, the frequency of foehn is the most in fall. Then we simulated precipitation over Nam Co area in October using WRF. We found that under the background of air circulation, lake can affect the precipitation over Nam Co area more significantly than upstream orography. Comparing no lake experiment with control experiment, we can conclude that the exist of Nam Co lake can make surrounding area, especially downstream area, more precipitation and the effect distance can be 100 km. Upstream orography can enhance precipitation but the effect is little, and foehn has little effect on the precipitation in areas downstream of the lake.

为进一步了解高寒牧区气候变化,依据1976—2017年青海湖东北部海晏站逐日降水资料,采用百分位法确定冬、夏半年极端降雨（雪）阈值并统计极端降水事件,运用线性趋势、R/S和小波分析法分析极端降水事件变化特征、未来演变趋势及周期。结果表明：青海湖东北部地区冬、夏半年极端降水日数和极端降水量呈不显著增加趋势;冬半年极端降水强度和日最大降水量不显著增加,而夏半年不显著减小;极端降水对年降水的贡献率均以不同的速率增加,其中夏半年的极端降水对年降水的影响较大;冬半年降水日数不显著减小,而降水量显著增加,表明冬半年发生短时强降水的几率增大,夏半年的降水日数和降水量增加不明显;未来,冬半年极端降水日数增加趋势将发生转变,极端降水量与之前的变化趋势无关将继续呈现震荡性,其他各要素将持续前期的变化趋势;冬（夏）半年极端降水日数和降水量分别存在明显的周期变化特征。高寒牧区的极端降水研究对于预防短时强降水带来的雪灾、洪涝事件的发生意义重大。

To further understand the climate change in alpine pastoral areas, based on the daily precipitation data of Haiyan Station in the northeast of Qinghai Lake from 1976 to 2017, we determined the extreme precipitation (snow) threshold in winter (summer) half year and counted extreme precipitation events by using the percentile method, analyzed the variation characteristics, future trends and cycles of extreme precipitation events by linear trend, R/S and wavelet analysis. The results showed that: the extreme precipitation days and extreme precipitation in the northeastern of Qinghai Lake did not increase significantly in winter and summer half year; the extreme precipitation intensity and daily maximum precipitation did not increase significantly in winter half year, but did not decrease significantly in summer half year; the contribution rate of extreme precipitation to annual precipitation increased at different rates, and the extreme precipitation in summer half year had a greater impact on annual precipitation; the number of precipitation days in winter half year did not decrease significantly, while the precipitation increased significantly, indicating that the probability of short-term heavy precipitation in winter half year increased, and the number of precipitation days and precipitation in summer half year were not obvious; in the future, the trend of increasing the number of extreme precipitation days in winter half year would change; the extreme precipitation would continue to show volatility irrespective of the previous trend, and other factors would continue to change in the early stage; the number of extreme precipitation days and precipitation in winter (summer) half year had obvious periodic variation characteristics. The study of extreme precipitation in alpine pastoral areas is of significance in preventing the occurrence of snowstorms and floods caused by short-term heavy precipitation.