The climate of Chongming Island

Chongming Island, located at the mouth of the Yangtze River, is the third largest island in China. Chongming Island in Shanghai is located in the north subtropical zone, with mild and humid climate, four distinct seasons, hot and humid summer, prevailing southeast wind, dry and cold winter and prevailing northerly wind, which belongs to a typical monsoon climate (subtropical monsoon climate). Typhoon, rainstorm, plum rain and drought are common disastrous climates. Spring generally lasts 73.4 days, and the average temperature is 10℃ ~ 22℃. Under the alternating influence of cold and warm air, the temperature rises slowly and jumps, and there is a cold air process every 4 ~ 6 days, with great changes and continuous rain, and the temperature is generally around 9℃. The highest temperature can rise to 29℃ in mid-April in warm spring, and the lowest temperature can drop to 3℃ in cold spring, resulting in late frost.

Summer generally lasts 94.7 days from June 17 to September 19, and the average temperature is higher than 22℃. The rainy season begins in the middle and late June, with an average of 25.2 days. The rainy season is 197.4 mm throughout the year, and ends in early July, entering the midsummer. The weather is hot, and the average number of days with the highest temperature above 35℃ is 3.4 days. The weather is sunny, sunny, and evaporation is large, and summer drought often occurs.

Autumn generally lasts 63.4 days, and the average temperature is 10℃ ~ 22℃. The temperature drops gradually, and the average temperature in late September can drop below 19℃. In most years 165438+ 10, there is little precipitation, and autumn drought often occurs, but there are also nearly one-third of the years where rainfall is concentrated.

Winter generally starts from165438+1October 22nd and ends on April 4th of the following year, and lasts for 133.7 days. The average climate temperature is below 10℃, which is the longest and driest season in a year. 65438+1The ten-day average temperature from early October to early February is about 3℃. The temperature in winter changes greatly from year to year, and the ten-day average temperature difference between warm winter and cold winter can reach more than 8℃. The lowest temperature is generally -6℃ ~-7℃, the extreme lowest temperature is-10.5℃, and the average number of days when the lowest temperature is below -5℃ is 5.5 days. The whole winter is the period with the least precipitation in the whole year, and there are few days of snow, with an average of 6.7 days. It rains continuously in spring, mainly from March to May. From 1958 to 1984, there are 32 rainy days for more than 7 consecutive days, with an average of 1.2 times per year, and 13 times for more than 0/0 days, with an average of 0.54 times per year. Continuous rainy days in spring often affect the timely sowing of cotton, leading to the epidemic of early rice rotten seedlings, wheat scab and Sclerotinia sclerotiorum.

It rains in early summer, mainly in rainy season. From 1958 to 1984, the average plum blossom period is June 16, and the average plum blossom period is 25.2 days, with the shortest being 5 days and the longest being 57 days. The average amount of plum rain 197.4 mm, the minimum is 6 1 mm, and the maximum is 538.2 mm.

In Chongming County, plum blossoms began early (before June 10), with a long plum blossom period and heavy plum rains (rainy days for more than 30 days and rainfall of more than 250 mm). The flowering periods of 1974, 1978 and 1980 were in May 18, May 27th and June 10, respectively, and the losses of wheat and rape were serious. During the period of 1974, the rainy season lasted for 75 days, and the rainfall was as high as 538.2 mm. In this year, the empty chaff rate of early rice reached 30.2%, the highest in history. 1977 and 1980, the rainy period was 57 days and 40 days respectively, and the rainfall was 247.5 mm and 270.6 mm respectively, which reduced the yield of early rice. Seven years (1960, 1962, 1974, 1976, 1977, 1980,198/kloc.

The continuous rainfall in autumn is divided into two stages: September of 65438+ 10 and late June to 165438+ 10 in mid-October. The total rainfall in September is greater than 140mm, and the rainy days are greater than 13 days, which will aggravate cotton boll rot and reduce yield and quality. The probability of occurrence is 33%. From late October of 10 to mid-October of110, the total rainfall for 20 consecutive days was more than 60mm, which delayed the autumn sowing season and reduced the quality. The probability of occurrence is 33%. Autumn continuous rainfall in Chongming County 196 1, 1963, 1967, 1972, 198 1 year.

The low temperature in spring is the cold in spring. During the period of 1958- 1984, after April 20th, the average temperature for three consecutive days was below 12℃ for five years, and the injury probability was 20.8%. Spring cold leads to the rot and death of early rice seedlings, which affects the normal growth and development of summer sowing crops.

The low temperature in early summer mainly occurs in late June in the early rainy season, 1958 ~ 198 1 year. This kind of weather has been around for 4 years, and the probability is 16.7%.

The low temperature range in autumn is 1958 ~ 1984. The lowest temperature in September is below 15.4℃ for 22 years, and the start date of low temperature is 4 years before September 20th, and only 1 year before September 18.

Drought, including summer drought and autumn drought, summer drought is caused by long sunny days without rain. From 1958 to 1984, there was 1 1 year without continuous rainfall for more than 30 days.

Summer and autumn are the most frequently affected seasons by typhoons. When a typhoon strikes, it is often accompanied by heavy rain. From 1949 to 1984, there are ***5 1 typhoon affecting Chongming county, with an average of10.5 per year, and there are 2 1 typhoon with magnitude 8 or above, which mostly occur in late July to late September.

Rainstorms usually occur in summer and autumn, and the 24-hour precipitation is generally above 50 mm. There are 58 rainstorms in 1958 ~ 1984, with an average of 2. 1 time per year, with the most frequent in June and September. The number and total amount of rainstorms in the east are more than those in the west. There are six heavy rainstorms with daily precipitation exceeding 100 mm, including 1960 on August 4th, 1976 on July 2nd, and the precipitation reached 211mm the next day ... Rainstorms in summer often cause waterlogging.