The climate of Suzhou

General situation of Suzhou climate

Suzhou is located in the north subtropical humid monsoon climate zone, which is warm, humid and rainy, with obvious monsoon, four distinct seasons, long winter and summer and short spring and autumn. The average frost-free period of a year is 233 days. Due to the differences in topography and latitude, various unique microclimates have formed in the territory. Solar radiation, sunshine and temperature are centered on Taihu Lake, and the areas along the Yangtze River are low-value areas. The distribution of precipitation also has the same law. This slight regional climate difference divides the city's crop varieties into Taihu Lake forest and fruit climate zone, southern one-year double cropping climate zone, central one-year double cropping climate zone and cotton-grain rotation climate zone along the river.

I. Radiation and sunlight

The annual total solar radiation in Suzhou is 465 1. 1 joule/m2, the maximum value 1967 is 5 188.3 joules/m2, and the minimum value 1970 is 4348.9 joules/m2. The maximum solar radiation is 1580.8 Joule/m2 in summer. Followed by the spring, which is 1256.0 joules/square meter; Autumn 1045.9 joules/m2; Only 768.2 Joules/m2 in winter.

From spring to summer, with the increase of solar altitude angle, monthly solar radiation and total solar radiation continue to increase. By July, the total amount was 560.6 Joules/m2, and then it kept declining. In February, the lowest monthly total was 253.3 Joules/m2.

Annual average sunshine hours 1965.0 hours, maximum annual 1967 2357.6 hours, minimum annual 1952 l630.4 hours.

The seasonal distribution of sunshine hours is: spring (3? May) 454.9 hours, summer (6? August) 624.8 hours, autumn (9-9-l 65438+ 10/October) 486.7 hours, winter (12? February) 398.6 hours. The sunshine hours were the least in February, only l 19. 1 hour, and then increased month by month. August is the most, reaching 240 hours. Then it gradually decreased. Due to the increase of sunshine days in June 5438+ 10, the sunshine hours increased slightly compared with September, and decreased again from June 65438+ 10.

The average sunshine percentage in the whole year is 44%, the highest in summer is 49%, followed by autumn 47%, winter 42% and spring 39%.

Second, the temperature

(3000 BC-AD 1900) According to various records, it can be roughly divided into Neolithic Warm Period, Spring and Autumn Warm Period, Three Kingdoms Cold Period, Sui and Tang Warm Period, Northern Song Cold Period, Southern Song Warm Period, Yuan and Ming Cold Period and Qing Cold Period. The warm changes in Suzhou are slightly different from those in the whole country. Even compared with Nanjing and Shanghai which belong to the same climate zone, winter is warmer than Nanjing, but colder than Shanghai. Summer is cooler than Nanjing, but hotter than Shanghai.

In the 20th century, the temperature change in Suzhou (190 1- 1985) was relatively low in the first 30 years, rose to above the multi-year average in the late 1930s, and was 0.2% higher than the average in the late 40s and early 1950s. 0.5℃。 In the late 1960s, the temperature dropped again. 1969 The winter temperature is low, but the lowest annual average temperature appears in 1980.

According to the data analysis of 195 1- 1985, the annual average temperature in Suzhou is 15.7℃, the highest is 1953+07.0℃, and the lowest is1980+04. The hottest July, with an average temperature of 28.2℃; The most Leng Yue is 65438+ 10 month, with an average temperature of 3.0℃. The average annual variation of temperature is 25.2 degrees Celsius.

Spring (3? May) Due to the enhancement of solar radiation, the temperature rises rapidly, with an average temperature of 14.2℃ and a monthly average temperature of 5℃. Especially in April, the temperature rose the fastest, with an average temperature increase of 6℃. However, due to the frequent exchange of cold and warm air in the middle and lower reaches of the Yangtze River, the temperature fluctuation is unstable, and the sudden cooling and sudden heating change greatly. In early April, there is often "cold spring" weather below 0℃. It entered the rainy season in June, and the temperature did not rise significantly. After plum blossom in July, it entered midsummer, controlled by subtropical high, with the highest temperature, with an average monthly temperature of 28.2℃ and an average maximum temperature of 32℃, which is the hottest month in a year. The daily maximum temperature in hot summer is > 30℃(6? August) accounted for 97%.

195 1- 1998, the highest daily temperature in Suzhou exceeded 38℃ for only 9 years. The extreme maximum temperature is 39.2℃, which appears in June 1992. The temperature is still high in early September, with an average of 4? The daily maximum temperature is above 30℃ for five days, and it is above 30℃ in early September of some years, but it is more than 35 days. O℃ is rare, once every seven years. However, from September 2 to September 7 of 1995, there were six days of high temperature weather. Due to the strengthening of cold air, the solar radiation is weakened, and the average temperature in autumn is 17.6℃. In the first ten days of September, the subtropical high still has a certain force, and sometimes there is high temperature weather, commonly known as "autumn tiger", but it generally does not last long. Since mid-September, the main body of the Pacific subtropical high has rapidly withdrawn southward, the cold air has become increasingly active, the temperature has dropped significantly, and the monthly average cooling rate is above 5℃.

Winter is controlled by the continental cold high pressure, with cold and little rain, and the days when the daily minimum temperature is below 0℃ account for 93% of the whole year. The average temperature in winter is 4.3℃, and the average minimum temperature is 1. 1℃. 65438 10 is the coldest period in a year, with an average daily temperature of 3.0℃. Average minimum temperature-0.1℃; Freezing weather with daily minimum temperature

The daily average temperature ranges from 7.5℃ to 8.2℃ in spring, followed by 7.7℃ in autumn, 7.5℃ in winter and 6.9℃ in summer. The maximum daily temperature difference is 8.5℃ in April. But in July and August, it is the smallest, which is 6.8℃.

The distribution of annual average temperature varies with latitude, with a difference of 0.9℃ between north and south. In addition, there are two differences: First, the temperature regulation of Taihu Lake in the area along the lake is most obvious in winter. The average minimum temperature at Dongshan Station in Taihu Lake in June 5438+ 10 is 0.8℃ higher than that in the urban area and 1℃ higher than that in the northern counties (cities). This microclimate under the influence of the vast water body has created favorable conditions for citrus and other fruit forests to overwinter safely along the lake. The second is the "urban heat island" effect in urban areas. Due to the nature of the surface, the industrial and commercial and population density in urban areas is different from that in suburban counties, thus forming an "urban heat island". The number of days with the highest summer temperature > 35℃ in urban areas is 3.5 days longer than that in Wujiangduo 1. 1 day in the south and Kunshan in the southeast.

Third, precipitation

According to various historical records, during the year 2000 from the Han Dynasty to the Qing Dynasty, there were more than a hundred and dozens of major floods in Suzhou, including the Sui and Tang Dynasties 1300 to 1949, when there was 107 major flood. From the Three Kingdoms to 1949, Taihu Lake flooded 20 times, once every 84 years on average. There were 9 droughts in Taihu Lake, with an average of 185. It can be seen that there are more rainy and humid years in Suzhou history than rainy and dry years. If we consider the changes of cold and warm together, the changes of cold and warm, dry and wet in Jiangsu always alternate, with different periods.

In recent years 100 (1875- 1998), Suzhou has four rainy periods and three rainy periods. The three rainy periods were 65438+70s in 2009, 20th century 10s, 40s and 1990s respectively, and the average annual precipitation was about1200-1250mm. The three dry periods are 19, mid-1920s to mid-1930s, mid-1960s to late-1970s, with an average annual precipitation of about 900? 980 mm.

According to the data analysis of 1924- 1995, the annual average precipitation is 1094 mm, and the annual precipitation days are 125 days. The maximum annual precipitation in 1957 was 1555 mm, and the minimum annual precipitation in 23 years of the Republic of China (1934) was only 575 mm, with an annual variation of 980 mm, and the most rainy days were 154 days in 1980, with the least.

In a year, the precipitation and precipitation days are the most in June, with the annual average monthly precipitation 160mm and precipitation days 12.5 days. The monthly precipitation in 65438+February is the least, which is 40mm. In June, the precipitation days in 5438+ 10 were the least, with an average of 7.8 days.

Spring is increasingly affected by warm air, and precipitation and precipitation days increase month by month. The annual total precipitation in spring is 278 mm, reaching 486 mm in 1967, and only 180 mm in197. The average precipitation days in spring are 36.3 days. The total annual precipitation in summer is 420 mm, which is the first of the four seasons. The most frequent year is 760mm in 30 years of the Republic of China, and the least year is L 16mm in 23 years of the Republic of China. The average precipitation in summer is 34.8 days, with a maximum of 55 days in 1989 and a minimum of 22 days in 23 years of the Republic of China. The annual precipitation in autumn is 220 mm, but there is a great disparity between years, with the maximum being 627 mm in 1962 and the minimum being only 45 mm in 2 1 year. The average precipitation days in autumn is 27 days, which is the season with the least precipitation days in the whole year. But many years also have 42 days. The total precipitation in winter is 144 mm, which is the season with the least precipitation in the whole year, but it is 302 mm in many years such as 1953 and only 42 mm in a few years such as 1985. The average number of rainy days in winter is 27. 1 day, 1968 has 48 days, and 1962 has only 10 days.

The longest continuous precipitation days are 18 days, which occurred from June 30th to July 7th, 1969, and the precipitation is 154mm.

rice. The longest continuous days without precipitation is 66 days, which occurred on1973l65438+1October 9th-197465438+1October 3rd. The average precipitation intensity is the largest in summer, which is 1 1.8 mm/day; The minimum in winter is 6.5mm/day. June is the month with the largest precipitation intensity in the whole year, with the intensity of 12.7mm/ day; The maximum intensity of daily precipitation is 343mm/ day, which occurs on September 6th 1962. The annual precipitation variability is 17%, and the maximum precipitation variability in winter reaches 34%. The lowest in spring is 24%. The monthly precipitation variability is the largest in 10 month, accounting for 68%; The lowest in June was 36%.

There is no obvious difference in annual precipitation caused by different landforms in Suzhou, which is about 100 mm, with Dongshan and Wuxian being the most and Zhangjiagang the least. However, in some local precipitation in summer, regional differences are more obvious.

The average first snow day is 65438+February 24th, and the earliest snow has been seen on1976l65438+1October17th. The last snowy day on average is March 8, and the latest 1980 will be in late April. The average snowfall is 6.7 days, 1976- 1977 has 20 days, 1926- 1927 and197/year has no snow days. The annual distribution of snowfall is 5438+/kloc-0 in June, 2.7 days in October and 0.2 days in February. 1984 65438+1October 17- 19 * * It snowed 62,3 mm for three consecutive days, which is the heaviest snow in a century. Telecommunication lines over L meters in the city were interrupted by broken poles and inverted poles, and many high-voltage power lines tripped and blacked out, and transmission lines were crushed by heavy snow. Due to the heavy and deep snow, houses in various places collapsed, causing casualties. 1984 65438+1October 18 snowfall is 47.5mm, which is the largest daily snowfall on record.

The average number of days of snow in a year is 5 days, the most is 22 days in 1976- 1977, but there are also 8 days without snow. The earliest day of the first snow is 1985 65438+February 10, and the latest day is1976 March19. The maximum snow depth is 26 cm, which appears on 1984 1.09.