土壤湿度对东亚夏季气候潜在可预报性影响的数值模拟

李忠贤，陈海山，倪东鸿，曾刚

(南京信息工程大学气象灾害省部共建教育部重点实验室，江苏南京210044)

土壤湿度对东亚夏季气候潜在可预报性影响的数值模拟

李忠贤，陈海山，倪东鸿，曾刚

(南京信息工程大学气象灾害省部共建教育部重点实验室，江苏南京210044)

利用全球大气环流模式NCAR CAM3进行了在给定的观测海温条件下的22 a(1979—2000年)5—8月的2组集合试验。运用方差分析方法，分析了在气候态和年际变化的表层土壤湿度情况下，CAM3模式模拟的东亚夏季气候潜在可预报性及其差异。结果表明:在给定的观测海温条件下，采用气候态的土壤湿度时，CAM3模式模拟的东亚夏季气候的潜在可预报性偏低;而采用年际变化的土壤湿度时，模拟的夏季气候潜在可预报性有所提高，尤其是在中国西北地区;后者模拟的中国西北地区夏季降水和气温的潜在可预报性比前者的模拟结果提高0.1以上。其原因可能是:采用年际变化的土壤湿度时，模式可以更好地模拟出中国西北地区的地表蒸发量和湍流热通量的年际变化，进而使得模式对该地区夏季气候的预报技巧得到提高。

潜在可预报性;夏季气候;土壤湿度;数值模拟

Abstract:Two ensemble simulations for 22 boreal－summer seasons(1979—2000)are conducted by the Community Atmosphere Model version 3(CAM3)with the specified observed sea surface temperature (SST).Impacts of surface soil moisture(SSM)on the simulation of potential predictability of East Asian summer climate are investigated by the model with interannually varying SSM(ISSM)and climatological SSM(CSSM)，respectively，based on the variance analysis method.Results show that，under the specified observed SST，the potential predictability of East Asian summer climate simulated by the CAM3 with ISSM is better than that with CSSM over East Asia，especially over Northwest China.The potential predictability of summer precipitation and air temperature over Northwest China from ISSM simulations is 0.1 higher than that from CSSM simulations.A possible mechanism of influence of soil moisture on potential predictability of summer climate in Northwest China is proposed.The interannual variability of ground evaporation and surface turbulent heat flux can be simulated by CAM3 with ISSM better than with CSSM in Northwest China，leading to the model forecast skill of the summer climate improved by the model with ISSM.

Key words:potential predictability;summer climate;surface soil moisture;numerical simulation

0 引言

中国地处东亚季风区，受东亚季风年际变化影响，气候灾害发生频率较高，旱、涝灾害极大地影响国民经济建设和社会发展，对月、季时间尺度旱、涝气候，尤其是汛期旱、涝趋势的预测是中国气象学家的一项重要课题(丑纪范和徐明，2001)。研究气候年际变化的规律和可预测性对预测短期气候变化具有重要意义，这也是国际CLIVAR计划(气候变率及可预测性计划)的目标。……