东北农田扩张对气候影响的数值模拟

摘要

基于1990、2005年两期不同土地利用/覆盖资料，利用区域环境集成模拟系统（RIEMS2.0）分别进行2次连续15年数值模拟，探讨东北土地利用/覆盖变化对气候的影响，分析集中于气温和降水等要素变化上，并对结果进行统计显著性检验。结果表明：（1）东北农田扩张后，东北夏季和冬季平均气温降低，降水减少，并且农田面积扩张的范围越大，气温变化幅度也越大。在夏季，黑河西部、呼伦贝尔南部部分地区降温超过0.5°C，并通过显著性检验（P＜0.05），大兴安岭南部、黑河西部等地区夏季降水减少20%左右，其中产生减少的大部分区域通过显著性检验（P＜0.05）。（2）东北农田扩张通过影响潜热通量的变化和净吸收辐射通量的变化来影响气温的变化，其中东北南部土地利用/覆盖类型变化主要表现为短草类型转变为农田类型，这使得夏季蒸散发增加，潜热通量增加，气温降低。（3）东北农田扩张也影响大气环流场的变化，并与降水的变化有密切的关系。辽宁西部和东北北部部分地区夏季蒸散发增加，大气中水汽增加，但是由于大气环流场变化，降水在这两个地区并未增加。%Two simulations in 1990 and 2005 of land-use and land-cover in Northeast China were used to investigate the impact of land-use and land-cover change (LUCC) on climate. Using a regional environmental system integration model (RIEMS2.0) the authors simulated two consecutive 15-year periods to explore effects of the Northeast China LUCC on climate, focusing on temperature and precipitation changes, and testing their statistical significance. Results show that the expansion of northeast farmland had the following impacts on climate:(1) Mean temperatures in summer and winter in Northeast China were reduced, and precipitation decreased. The expansion of farmland areas also brought about increased changes in amplitude. Temperature changes of more than 0.5 °C is statistically significant (P<0.05) in summer in the west of Heihe and in the southern cooling areas of Hulun Buir. In summer in the south of Da Hinggan Ling and west of Heihe precipitation decreased by 20%, the greatest decrease of the regions that showed statistically significant changes (P<0.05). (2) The expansion of farmland has an influence on mean temperature through changes in the latent heat flux and the net absorption of the radiation flux. In the south of Northeast China, in which land cover type converted from mainly short grass to farmland, total summer evapotranspiration increased, the latent heat flux increased, and the temperature decreased. (3) Farmland expansion in Northeast China also results in changes in atmospheric circulation, and precipitation changes are closely related to the circulation changes. In the west of Liaoning and the northern part of Northeast China, summer water vapor in the atmosphere increased, but atmospheric circulation change at these areas did not result in an increase in precipitation in these two areas.