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选取耕地面积居世界第二位的印度作为研究区域,利用中国自主研发的区域气候模式(RIEMS2.0)和土地利用变化资料,进行潜在植被和雨养农田的长时间积分模拟对比试验,分析了印度农田扩张对区域气候的影响及其机制。结果表明:农田扩张使得印度区域平均气温升高0.1℃,平均降水强度减少0.1 mm·d~(-1),总降水量减少12.8%;农田扩张的气候效应存在明显区域差异和季节差异,在副热带湿润区气温增加0.5~1.0℃,在干旱和半干旱区气温增加0.3~0.5℃,在热带地区气温则下降;农田扩张使得季风前期和冬季气温分别增加0.5℃和0.2℃;季风后期气温降低0.5℃,季风季节气温没有明显变化;在副热带湿润区、干旱和半干旱区降水明显减少,干旱季节特别是季风前期降水减少最为显著,达到0.3 mm·d~(-1);印度农田扩张使得年平均感热通量增加、潜热通量减少,其中植被的蒸散作用引起的潜热通量的变化,尤其是季风前期潜热通量明显减少,是区域气温升高、降水减少的重要原因;农田扩张使得印度大陆上空(850 h Pa高度)受较弱的辐散环流控制,辐散下沉气流是造成当地气温升高、降水减少的又一原因。
In this paper, India, the second largest cultivated area in the world, is chosen as the research area. By using the independently developed regional climate model (RIEMS2.0) and land use change data in China, long-term integral simulation tests of potential vegetation and rainfed farmland are carried out. Influence of Indian Farmland Expansion on Regional Climate and Its Mechanism. The results showed that the expansion of farmland caused the average temperature in India to increase by 0.1 ℃, the average rainfall intensity decreased by 0.1 mm · d -1, and the total precipitation decreased by 12.8%. There were obvious regional differences and seasonal differences in the climate effects of farmland expansion. Subtropical humid zone temperature increased 0.5 ~ 1.0 ℃, in the arid and semi-arid zone temperature increased 0.3 ~ 0.5 ℃, in the tropical zone temperature decreased; farmland expansion makes the monsoon and winter temperatures were increased by 0.5 ℃ and 0.2 ℃; In the subtropical humid zone, the precipitation in arid and semi-arid areas decreased significantly, and the precipitation in the dry season, especially in the early monsoon period, was the most significant, reaching 0.3 mm · d -1. The expansion of farmland in India made The average annual heat flux increases and the latent heat flux decreases. The changes of latent heat flux caused by vegetation evapotranspiration, especially the latent heat flux in the pre-monsoon period are obviously decreased, which is the important reason of the regional air temperature increase and precipitation decrease. Making the continent over the continent (at a height of 850 h Pa) controlled by a weak divergent circulation. The divergent descending airflow is another reason for the increase of the local temperature and the decrease of precipitation.