Comparative Study On Agricultural Climate Resources Throughout The Year And During The Corn Growing Period On The East And West Sides Of The Helan Mountain

The Helan Mountains are an important natural geographic boundary in China,and the dividing line between the monsoon and non-monsoon regions.The dynamic and thermal effects of the Helan Mountains on the atmosphere can lead to differences in agro-climatic resources between the east and west sides.Comparing and analyzing the total agro-climatic resources and their changing trends between the east and west sides of Helan Mountains can provide scientific support for agricultural planting layout and high and stable agricultural production.In this study,based on daily meteorological observations from five meteorological stations on the east and west sides of Helan Mountain from 1964 to 2018,combined with aerosol optical thickness（AOD）data and PM_2.5 data,and using methods such as climate propensity rate,Mann-Kendall mutation test,sensitivity analysis,and multiple stepwise regression,we systematically compared the annual,four-season and The total amount of light,heat and water resources and their interannual variation trends during the growing period of maize in the east and west of the Helan Mountains were systematically compared based on several indicators,and the meteorological environmental factors affecting the interannual variation of solar radiation,potential evapotranspiration and climate production potential in the east and west were quantified,and finally the interannual variation characteristics of maize production potential in the east and west were compared.The main conclusions are summarized as follows:（1）Comparative characteristics of annual and maize growing period solar radiation resources in the eastern and western sides of Helan Mountains.The annual cumulative sunshine hours on the east side of Helan Mountain（2972 h）were significantly lower than those on the west side（3171 h）from 1964 to 2018,and the interannual variation on both sides showed a significant decreasing trend（p<0.001）,with a non-significant difference in the variation trend.Except for spring,the number of sunshine hours showed a significant decreasing trend in all other seasons.The interannual variation of sunshine percentage was similar to that of sunshine hours,but the rate of decline was significantly faster on the east side than on the west side（p<0.1）.The differences in annual mean solar radiation between the two sides were not significant,with climate tendency rates of-55.7 MJ m^-2 10a^-1 and-39.3 MJ m^-2 10a^-1,respectively.correlation analysis showed that total cloudiness was the main factor of interannual variation of solar radiation and its differences between the east and west sides,followed by AOD,with little contribution from PM_2.5.（2）The comparative characteristics of heat resources between the east and west sides of Helan Mountains throughout the year and during the maize growing period.The multi-year average temperature on the east side of Helan Mountain（9.1°C）was 0.3°C higher than that on the west side（8.8°C）,and the annual average temperature(0.5°C 10a^-1 and 0.4°C 10a^-1),maximum temperature(0.4°C 10a^-1 and 0.3°C 10a^-1),and minimum temperature（both 0.6°C 10a-1）on the east and west sides from 1964 to 2018 showed a highly significant（p<0.001）upward trend,while the daily temperature difference(-0.2℃10a^-1 and-0.3℃10a^-1)showed a significant downward trend,and the interannual rate of change was faster on the east side than on the west side.The annual≥10℃active cumulative temperature on the east side was 25.8℃lower than that on the west side.The initial day of the average daily temperature≥10℃on the east and west sides was earlier,the final day was later,and the duration was longer,and the annual average duration on the east side was 4 days longer than that on the west side.It can be seen that the heat resources of maize on the east side are better than those on the west side（significant difference）,and the difference of maize growing period is smaller compared to the whole year（non-significant difference）.（3）The comparative characteristics of moisture resources on the east and west sides of Helan Mountain during the whole year and the maize growing period.Precipitation on the east side of Helan Mountain was significantly higher than that on the west side,and the rising trend of precipitation on the east and west sides during 55 years was not significant,the rising rate on the east side(3.6 mm 10a^-1)was not significantly faster than that on the west side(3.0 mm 10a^-1),and the rate of change of maize growing period was 2.8 mm 10a^-1 on the east side and 3.1 mm 10a^-1 on the west side.The actual evapotranspiration of maize was significantly lower on the east side than on the west side（p<0.001）,with significant differences in the interannual rates of change（p<0.1）(east side:1.2 mm 10a^-1 and-3.9 mm 10a^-1 on the west side).Both east and west sides showed a decreasing trend in annual and maize growing period dryness,and although the average annual dryness was greater on the west side,the rate of decrease was faster on the east side.The most sensitive factor for potential evapotranspiration on both sides was sunshine hours,and the maximum temperature during the maize growing period.The highest contribution to the variation of annual potential evapotranspiration on the east and west sides was the average air temperature,the relative humidity on the east side during the corn growing season,and the average wind speed on the west side.（4）Comparative characteristics of the climatic production potential of maize on the east and west sides of Helan Mountain.The photosynthetic production potential was highly consistent with the solar radiation change characteristics during 55 years.The average annual light and temperature and climatic production potential on the east side were greater than those on the west side,and the rate of increase was faster on the east side,and the climatic production potential was influenced by the increase of warming and humidification in the northwest.The climatic production potential decreased significantly relative to the light-temperature production potential,indicating that maize yield was severely affected by insufficient moisture supply,and the production potential on the west side was more severely affected by moisture.The greatest contribution to the interannual variation in climatic production potential on the east and west sides is the increased precipitation,in addition to the reduced solar radiation on the east side.the multi-year average climatic resource utilization rate on the east side（60.1%）is much less than that on the west side（94.9%）between 2003 and 2018,with a climate change propensity rate of-0.06%10a-1 and-0.08%10a-1,and the actual yields on the east side have much The actual yield on the east side has much room for improvement,and the water shortage problem on the west side is very prominent.