Study On The Complexity Of Snow-Soil Composite System And Relationship Between Soil Water And Heat

Snow cover is an important component of the climate system, geographical distribution of the cryosphere in the most widely, and has great effect on soil water content and temperature change. Every winter, in the northern and southern hemisphere high latitude and high altitude area, a large area of land was covered with snow, especially in China’s northeast, northwest and southwest of china. According to statistics, the area of winter snow cover distribution Chinese amounted to9.0×106km2, and the snow distribution is not uniform, stable snow cover area of4.2×106km2, the snow cover area of northeast area up to1.4×10km2, snow covered the longest area of snow cover days over170days.Heilongjiang province is located in China’s northeast border, is our country’s important commodity grain production base. In recent years, with the further exacerbate climate warming trend, Heilongjiang province led the spring drought, spring flood phenomenon more and more serious. How to use the winter snow is scientific and reasonable, to improve the utilization efficiency of water resources is of great significance to alleviate the drought in spring flood. Therefore, based on the typical cold region-Harbin city as the research object, using multivariate statistical theory, condition coverage of snow system theory method of freezing thawing soil water heat change characteristics of complex adaptation, the main research contents and conclusions are as follows:(1) Respectively from the water temperature, freezing and thawing, using the field test data, analyze day-change, cycle-change and the characteristic under no or have snow condition of snow-soil complex system, the results showed that:①In the natural state of the test period, the ground temperature variation showed a decline in the overall volatility trend after the first rise. The two polynomial fitting, the correlation coefficient R reached0.9396, significant correlation, namely:the ground temperature throughout the test period has the fluctuation trend to decrease significantly after rising. Due to the fluctuation of temperature, leading to soil temperature showed a trend of fluctuation. In addition, the ground temperature is in the negative temperature and time for the entire experimental period of2/3, sensitivity and the ground temperature changes than the atmospheric temperature.②Because of surface soil contacting with the atmosphere more often, the soil temperature changed relatively intense; different date the maximum temperature appeared at12o’clock; soil depth the temperature variation of magnitude smaller, especially100cm, no change in different time different soil temperatures of almost every date; soil temperature testing period produced all two pass zero degrees Celsius fluctuations, but different depths through time difference, the greater depth, through the late time; snow cover effects on soil temperature plays a role only in depth within a certain range, when more than40cm, the snow cover effects on soil temperature has been very weak.③Whether the ground temperature drop period, or the ground temperature rise period,100cm depth of soil moisture content is almost the same. Just drop in different period in the ground temperature, but the difference is small, at around2%; ground temperature in the descent phase, surface soil moisture change quickly. In surface temperature rising stage, different date surface soil moisture had more difference.④The snow covered soil composite system of farmland freeze-thaw characteristics can be obviously divided into two stages, unidirectional freezing stage and Double melting stage. Test early, due to the relatively high temperature, a temporary freeze deep around the stage, and then into the frozen deep and stable development stage. At the same time, the exchange of energy between the deep soil and transfer and surface compared, a lot weaker.(2) Using the wavelet coefficients, the approximate entropy of information theory and symbolic dynamics theory, the complexity characteristics of different depth soil water and temperature of snow-soil complex system, the results showed that:①The complex sorting of different depth soil moisture series of snow-soil complex system is:10cm water content>15cm soil moisture>40cm soil moisture=100cm soil moisture>5cm soil moisture=20cm soil moisture>80cm moisture soil. The surface10cm of soil moisture is affected by various factors, the soil water content structure complexity is relatively strong;②The complex sorting of different depth soil temperature series of snow-soil complex system is:5cm soil temperature>10cm soil temperature>15cm soil temperature>20cm soil temperature>40cm soil temperature>80cm soil temperature in>100cm soil temperature. The complexity results consistent with the actual, soil temperature and atmospheric surface layer in close contact, affected more solar radiation, energy exchange and transfer is also more intense, leading to its strong complexity. While the deep soil as the only energy can be obtained through the surface soil, its complexity is relatively weak.(3) Using multivariate statistical analysis theory, study on the relationship between factors and soil moisture and temperature of snow-soil complex system and the coupling characteristics in different snow conditions as well as the relationship between the same depth of soil moisture and soil temperature of different depth, between soil moisture content and soil temperature. The results showed that:①Under the no snow coverage condition, the meteorological factors and soil water content in different depth comprehensive significant influence order was:temperature, relative humidity, ground temperature, vapor pressure, wind direction, wind speed, air pressure; meteorological factor alone on different depth soil moisture content of the comprehensive effect of significant sorting was:temperature, pressure, relative humidity, vapor pressure, wind speed, ground temperature, wind direction. Compared with the simple correlation coefficient ranking, ranking changes in air pressure, by the minimum change in the original to second. The coupling effect between the meteorological factors to explain the role of soil water content in different depth was weak.②Under the snow coverage condition, the meteorological factors and soil water content in different depth comprehensive significant influence order was:water vapor pressure, pressure, ground temperature, air temperature, relative humidity, wind speed, wind direction; meteorological factor alone on different depth soil moisture content of the comprehensive effect of significant sorting was:the temperature, wind speed, pressure, vapor pressure, ground temperature, relative humidity, wind direction, compared with the simple correlation coefficient ranking, ranking the maximum pressure change, from the original fifth to the first. Compared with the partial correlation coefficient of sorting and no snow conditions, wind speed is adjusted from fifth to second now, the rest of the meteorological factors ranking changes small. The meteorological factors were very weak coupling on different depth of the soil water.③Under the no snow coverage condition, the meteorological factors and soil temperature in different depth comprehensive significant influence order was:the temperature, the vapor pressure, ground temperature, air pressure, relative humidity, wind direction, wind speed. Meteorological factor alone on different depth soil temperature of the comprehensive effect of significant sorting was:the temperature, the ground temperature, air pressure, wind direction, wind speed, water vapor pressure, relative humidity, compared with the simple correlation coefficient ranking, the ranking changed little. In addition, the coupling of wind speed and surface temperature has a linear effect on15cm soil temperature; coupling temperature and ground temperature was linear effect on soil temperature of20cm and40cm, linear coupling effect of other meteorological factors on other depth of soil temperature were not significantly.④Under the snow coverage condition, the meteorological factors and soil temperature in different depth comprehensive significant influence order was:ground temperature, vapor pressure, air temperature, air pressure, relative humidity, wind direction, wind speed. Compared with no snow conditions, only the ground temperature, vapor pressure, temperature of the order of the three for a simple adjustment, the rest did not change. Meteorological factor alone on different depth soil temperature of the comprehensive effect of significant sorting was:the temperature, the ground temperature, relative humidity, air pressure, wind direction, wind speed, water vapor pressure. Compared with the simple correlation coefficient ranking, vapor pressure varies greatly, from the original second to the last one. In addition, coupling temperature and ground temperature has a linear effect on40cm soil temperature, linear coupling effect of other meteorological factors on other soil temperature was not obvious.⑤With the increase of depth, the linear correlation between soil moisture and soil temperature gradually decreased. The following80cm, linear relationship between soil water content and soil temperature was not significant. At the same time, with the increase of depth of soil temperature, soil water content decreased with the decreasing. With the increase of depth, between soil moisture content and soil temperature function gradually reduce. Except for the80cm soil moisture content, the other deep soil water content has a linear relationship with the different depth of soil temperature, and negatively, that is:with the increase of soil temperature, soil water content in different depth decreases.