Review of Anomalous Climate Events in China during 2003

    Author:By Wang Ling    2004-10-24

    During 2003, China witnessed many anomalous climate events, such as severe drought, rainstorm-caused floods, extreme hot summer, low temperature with continuing rainfall, typhoon (tropical cyclone), hail and sandstorm, etc., which had led to great damage to national socioeconomic and lives. Therefore, the meteorological disasters in 2003 were more frequent and can be summarized as follows:

    o Spring drought in Northeast China: The precipitation in most areas of Northeast China was deficient since the fall of 2002. The rainfall was 30-80% less than normal between Jan. and May in 2003, accompanying with the higher temperature. It caused severe drought in west part of Northeast China and east part of Mongolia. Some areas had suffered the severe drought continuously since 1999. The drought during 2003 was much worse than the past. Such severe drought strongly affected the local agriculture where thousands of reservoirs dried up and hundreds of rivers stopped running. Furthermore, it resulted in several forest and grassland fires in Daxing'anling.

    o Continuous drought in summer and fall in South China: Most of areas in South China had suffered from deficient rainfall and hot summer in 2003. The total precipitation from July to early August was only 50-200 mm, which was 30-80 % less than normal, particularly in southern part of Hunan province, southern and middle part of Jiangxi province, northern part of Fujian province and southwestern part of Zhejiang province, where the precipitation was even less than 50mm, 80% less than normal. This is the most severe summer drought since 1971 in these areas. Among these areas, the worst was in southern and eastern part of Zhejiang province, where the drought level broke up the historical record in 1967. During the fall of 2003, these areas continuously suffered from deficient rainfall and hot weather. The extreme weather made some reaches of the Ganjiang River stop and made some rivers reach their lowest water level in past five decades. The Changsha reach of the Xiangjiang River had once reached its lowest water level since 1910. The continuous drought severely affected the hydroelectric stations and led to power shortage in many cities.

    o Local mountain torrents, landslides, and mud-rock flow: During the middle of May, heavy rainstorms attacked areas in south of Yangtze River valley, South China and Guizhou province, which caused severe water flooding in Xiangjiang River. The water level is above alerting level in main branch. Such flooding was also observed in mid-upper reaches of Ganjiang River, and upper reaches of Fu River. These water floods resulted in the severe mountain torrents in Chenzhou in Hunan province, Meizhou, Heyuan, and Shaoguan in Guangdong province, and caused great damage to local lives and properties. In early of July, continuous heavy rainstorms attacked Lishui River in Hunan, which led to the mountain torrents and mud-rock flows. In more than 20 counties and cities, 0.24 million hectares crops were flooded and 0.47 million people were displaced. On 12 July, short-time heavy rainstorm-caused mud-rock flow attacked Ganzi in Sichuan province; On 13 July, the most severe landslide attacked Zigui in Hubei province.

    o Severe summer floods in Huaihe River valley: Six concentrated rainfall processes happened in Huaihe River valley during the main flooding season(from 21 June to 22 July, 2003). The general precipitation was 400-500 mm in these areas. Particularly, the precipitation in some areas in Jiangsu province, Anhui province, and southeast of Henan province was observed as more as 500-600 mm, which is 1-2 times more than normal. Comparing with the same periods of historic precipitation in Huaihe River valley, the average precipitation during the main flooding season of 2003 ranked the second position in the past five decades following 1954. Since the distribution of rainfall was concentrated in specific time and space, the water level of Huaihe River rose rapidly and comprehensively which remained above the warning line for nearly one month. The Wangjiaba dam had to firstly open the sluice since 1991 in order to release floodwater on 3 and 11 July, respectively. According to uncompleted statistics, the floods affected 58 millions people, 2 millions of them were displaced immediately, 5.2 million hectares crops were flooded, and 1.2 million hectares of that was out of yield.

    o Fall floods in the mid and lower reaches of Yellow River From late August to early September, frequent heavy rainfall happened in some regions of Northwest China, North China, between the Yellow and Haihe River, Hubei province, and Sichuan province, where the precipitation wais 1-2 times more than normal. The heavy rainfall led to the severe floods in some regions of Shanxi province, Henan province, Shandong province, Hubei province and Sichuan province. The flood peak was frequently observed above the alerting threshold of the Weihe River, and the fall flood in Han River was quickly developed. During late September to mid of October, the heavy rainfalls once again attacked these regions, caused the water flooding in Weihe Rive and in mid and lower reaches of Yellow River. All these floods resulted in a historical infrequent fall flood in the Yellow River, some regions in Shaanxi, Shanxi, Henan and Shandong provinces even suffered the worst flood in history.

    o Long continued high temperature in southern part of China A large-scale and long continued hot weather attacked the regions in southern part of China during the summer of 2003, particularly in south of Yangtze River and South China, the hot weather persistently dominated these regions, where the maximum temperature was 38-40℃ in south part of Huanghuai, mid and lower reaches of Yangtze River, northern part of South China, east of Sichuan province, as well as Chongqing city. It was even up to 40-43℃ in middle and southwest of Zhejiang, north of Fujian, middle of Jiangxi province, meanwhile 43.2℃ was reported in Lishui, Zhejiang province. The maximum temperature was higher than the historical record in most parts of Zhejiang province, Fujian province, Jiangxi province, and some areas of Jiangsu, Anhui, Guangdong and Guangxi provinces. In the mid-lower valley of Yangtze River and southern parts, where the number of high temperature days (i.e. daily maximum temperature≥35℃) was 10-30 days, in the mid-east of South of Yangtze River and northern part of South China, the number was 30-50 days, and more than 50 days in some area. Generally, the number of high temperature days was 5-25 days above normal in most parts of these areas. The persistent hot weather enhanced the drought in South China, which greatly affected daily work and routine living of the local people.# o Low temperature with continuing rainfall in the region between the Yellow and Yangtze River From mid August to early September, corresponding to the key period for crops growth and yield making between the Yellow and Haihe River, an unbroken spell of rainfall and cold weather dominated southern part of North China, the region between the Yellow and Yangtze River and northeast part of Sichuan province, therefore, the crop yield and its quality were severely affected by the persisting rainfall and low temperature with less sunshine. The weather caused a widely filed flood and worm disease spreading, the crop yield in Henan, Anhui, Hubei, and Jiangsu provinces suffered much severe damage. During late September to mid October, such kind of weather once again visited these regions with much more rainfall, lower temperature and less sunshine, which severely suppressed the yield output and postponed the harvest season greatly.

    o The typhoon Dujuan swept across Guangdong Twenty-one typhoons formed in western North Pacific and South China Sea, and 6 of them made a landfall in China, the number of typhoon and typhoon caused damage was slightly less than normal. The plentiful precipitation associated with typhoon alleviate the severe drought and hot weather in South China, however, the No. 13 landfall typhoon, namely Dujuan, which swept across Guangdong province and greatly damaged 14 cities, such as Guangzhou, Shenzhen, Meizhou, Zhongshan and Zhuhai, where 16.29 million people were afflicted, 44 people died, and 0.26 million hectares crops were flooded.

    o Hails and tornado attack More than 1,300 counties (cities) in China were attacked by the hail or tornado during 2003. The frequency and damage were more than normal. In 12 April, hailstorm attacked 35 counties (cities) in Jiangxi, Zhejiang and Fujian provinces, where the maximum diameter of the hail is 60-70 mm and the maximum wind is about 8-11 in degree, such hailstorm damaged 50 thousands hectares crops, 60 thousands houses, and resulted in 8 people's death. During 19-21 June, 38 counties in Henan province were successively visited by hailstorm, rainstorm, and windstorm, in some area, where the hailing lasted 20-30 minutes, and the hail maximum diameter was 50 mm with about 10 in degree transit wind speed. Such storms gave rise to a reduction of crops and out of yield, damaged 0.13 million hectares crops and caused 5 people's death.# o Sandstorms 7 processes of dust weathers were observed in spring of 2003, and 2 of which developed into sandstorms. The strongest and widely-affected sandstorm formed in 8-11 April, which attacked most parts of Northwest, Shanxi, Liaoning and affected 30 millions people, 4.3 millions hectares cultivated land and 59 millions hectares grass. However, the frequency, affected areas, and caused damage by the sandstorm were less than the past several years, and no dust weather was observed in North China in March of 2003 in contrast to that of recent years.

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