| Heilongjiang Province is a typical region of climate warming,and because of its significant influence of monsoon,precipitation has obvious seasonal distribution characteristics,and precipitation has an important impact on agriculture,forestry and people’s daily production and life,so it is especially important to systematically study the changing characteristics of precipitation composition and its influencing factors in Heilongjiang Province in four seasons.In this paper,we analyzed the spatial and temporal characteristics of precipitation composition in Heilongjiang Province from1961 to 2020 by using precipitation data from 57 meteorological stations in Heilongjiang Province,combined with other meteorological data such as atmospheric circulation index and relative humidity and wind speed to investigate the relationship between atmospheric circulation and precipitation in four seasons,and quantitatively analyzed the meteorological factors affecting the composition of precipitation in four seasons.meteorological factors affecting the composition of precipitation in each season,the following conclusions were obtained.(1)The average precipitation in spring,summer,autumn and winter in Heilongjiang Province from 1961 to 2020 was 79.25 mm,344.16 mm,94.84 mm and14.21 mm.The precipitation increased at a highly significant rate of 5.63 mm/10 a and1.76 mm/10 a in spring and winter,respectively,while there was no significant change in summer and autumn.More than 70% of the stations showed significant increase in precipitation in both spring and winter,and there was no significant change in precipitation in summer and autumn.The average number of precipitation in spring,summer,autumn and winter in Heilongjiang Province was 23.54,41.85,23.55 and16.33.Among them,only spring increased significantly at the rate of 0.48 times/10 a,while the number of precipitation in the rest of the seasons did not change significantly.The regions with significant increase in precipitation in all seasons were concentrated in the southern region.(2)The four-season precipitation characteristics of Heilongjiang from 1961 to2020 are:(1)Spring precipitation has three phases of rainfall,snowfall,and sleet,and their amounts are 58.94 mm,7.85 mm,and 12.46 mm,among which spring rainfall increases significantly at a rate of 5.38 mm/10 a,and there is no significant change in the amount of snowfall and sleet.Spring rainfall increased significantly at 74% of the sites,with no significant changes in snowfall and sleet.The average number of rainfall,snowfall and sleet in spring was 15.20,5.03 and 3.31,of which the number of rainfall increased significantly at the rate of 0.78 times/10 a,the number of snowfall decreased significantly at the rate of-0.36 times/10 a,and the number of sleet changed insignificantly.The number of rainfall in spring significantly increased at 74% of the sites,the number of snowfall significantly decreased at 42% of the sites,and the number of sleet significantly increased in a small part of the southeastern region accounted for a relatively small percentage.(2)Summer precipitation has only one phase of rainfall,with the same characteristics as(1).(3)Autumn precipitation has rain,snow and sleet three phase state,the amount of 75.69 mm,9.65 mm,9.50 mm,the number of 15.54,5.87,2.14,the change is not significant.Only the number of snowfall in autumn was significantly reduced in 26% of the stations.(4)Winter precipitation has three phases of rainfall,snowfall and sleet,the amounts of which are 0.06 mm,13.76 mm and 0.39 mm,of which snowfall and sleet increase significantly at the rates of 1.65mm/10 a and 0.10 mm/10 a,respectively,with no significant change in rainfall.Snowfall in winter increased significantly at 81% of the sites,and rainfall and sleet changed significantly at fewer sites.The average number of rainfall,snowfall and sleet in winter was 0.05,16.14 and 0.14,of which the number of rainfall and sleet increased significantly at the rate of 0.02 times/10 a and 0.03 times/10 a,respectively,and the number of snowfall did not change significantly.The number of snowfall in winter increased significantly at 14% of the station stations,and the number of rainfall and rain-snowfall changed significantly at fewer stations.(3)The characteristics of rainfall changes at each level in Heilongjiang Province in each season from 1961 to 2020 are:(1)The average amounts of light rain,moderate rain,heavy rain and torrential rain in spring are 31.65 mm,20.75 mm,6.04 mm and0.51 mm;all levels increase significantly with rates of 2.02 mm/10 a,2.33 mm/10 a,The average number of spring light,moderate,heavy,and torrential rainfall was 13.60,1.40,0.19,and 0.01,with a significant increase in each class at the rates of 0.61,0.15,0.03,and 0.002 times/10 a,respectively.The variation in rainfall amount and number in each class was consistent in spatial characteristics are consistent,with a significant increase in light and moderate rainfall at most stations,a significant increase in heavy rainfall in the east and south,and insignificant spatial variation in torrential rainfall.(2)The average amounts of light,moderate,heavy and torrential rainfall in summer were 86.95 mm,123.69 mm,92.88 mm and 40.64 mm;the average numbers of light,moderate,heavy and torrential rainfall in summer were 30.63,7.84,2.76 and 0.60.The amount and number of light rainfall in summer decreased significantly at the rates of-1.33 mm/10 a and-0.70 times/10 a,respectively;the amount and number of torrential rainfall increased significantly at the rates of 2.84 mm/10 a and 0.04 times/10 a,respectively;the amount and number of medium and heavy rainfall did not change significantly.The spatial characteristics of the changes in the amount and number of rainfall at each level are consistent,with a significant decrease in light rainfall in the west and east,a significant increase in heavy rainfall in the west and east,and fewer stations with significant changes in moderate and torrential rainfall.(3)The average amounts of light rain,moderate rain,heavy rain and torrential rain in autumn were33.21 mm,28.06 mm,11.56 mm and 2.86 mm;the average numbers of light rain,moderate rain,heavy rain and torrential rain in autumn were 13.28,1.86,0.35 and 0.04.The amount and number of torrential rainfall in autumn increased significantly at the rate of 1.23 mm/10 a and 0.02 times/10 a,the number of light rainfall decreased significantly at the rate of-0.35 times/10 a,and the changes in the amount,number and frequency of light rainfall,medium rainfall and heavy rainfall were not significant.The spatial characteristics of the changes in the amount and number of rainfall at each level are similar,with a significant decrease in light rainfall in the south,fewer stations with significant changes in moderate rainfall,a significant increase in heavy rainfall in a small part of the central region,and a significant increase in heavy rainfall in the central western region.(4)The characteristics of snowfall changes by season by class in Heilongjiang Province from 1961 to 2020 are:(1)The average amounts of light,moderate,heavy,and blizzard snow in spring were 2.70 mm,2.10 mm,1.99 mm,and 1.07 mm;the average numbers of light,moderate,heavy,and blizzard snow in spring were 4.05,0.60,0.30,and 0.07.The amount and number of light snowfall decreased significantly at the rates of-0.17 mm/10 a and-0.38 times/10 a,respectively,while the changes in the amount and number of medium,heavy and blizzard were not significant.The spatial characteristics of the changes in snowfall amount and number of times are consistent across all classes,with minor snow decreasing significantly at most sites,and moderate,heavy,and blizzard snow changing significantly at fewer sites.(2)The average amount of light,medium,heavy and blizzard snowfall in autumn is 3.20 mm,2.35 mm,2.29 mm and 1.80 mm;the average number of light,medium,heavy and blizzard snowfall in autumn is 4.74,0.68,0.34 and 0.11.Among them,only the number of light snowfall decreased significantly at a rate of-0.26 times/10 a,while the rest of the indicators did not change significantly.The spatial characteristics of rainfall and number of changes in each class are similar,with light snow significantly decreasing at most stations,moderate snow significantly increasing in the central eastern region,and heavy snow and blizzard significantly changing at fewer stations.(3)The average amount of light snow,moderate snow,heavy snow and blizzard in winter is 8.11 mm,3.16 mm,1.77 mm and 0.72 mm;the average number of light snow,moderate snow,heavy snow and blizzard in winter is 14.87,0.94,0.27 and 0.06.Among them,except for the number of light snow,which did not change significantly,the other indicators increased significantly at the rates of 0.32 mm/10 a,0.58 mm/10 a,0.50 mm/10 a,0.25 mm/10a;0.17 times/10 a,0.07 times/10 a,0.02 times/10 a,respectively.In winter,the amount of light,medium and heavy snow increased significantly at most sites,and the amount of blizzard changed significantly at fewer sites;the number of light snow decreased significantly at most sites,the number of medium and heavy snow increased significantly at most sites,and the number of blizzard changed insignificantly.(5)The precipitation in Heilongjiang Province is related to the atmospheric circulation indices in all four seasons,mainly including the western Pacific subtropical high area index,the Asian polar vortex intensity index and the Asian zonal circulation index,etc.The influence of the atmospheric circulation indices on the precipitation in each season varies.The precipitation composition of four seasons is related to relative humidity,air temperature and wind speed,among which relative humidity is more closely related to precipitation composition of four seasons,followed by air temperature and wind speed.This paper clarifies the spatial and temporal distribution of precipitation composition and its variation characteristics in Heilongjiang Province,and analyzes the atmospheric circulation index affecting precipitation in different seasons,as well as the relationship between relative humidity,air temperature,wind speed and precipitation composition in four seasons,so as to provide reference for the study of precipitation variation and its influence mechanism in different seasons in monsoon climate zones. |
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