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朱士超, 银燕, 金莲姬. 青藏高原一次强对流过程对水汽垂直输送的数值模拟[J]. 大气科学, 2011, 35(6): 1057-1068. DOI: 10.3878/j.issn.1006-9895.2011.06.06
引用本文: 朱士超, 银燕, 金莲姬. 青藏高原一次强对流过程对水汽垂直输送的数值模拟[J]. 大气科学, 2011, 35(6): 1057-1068. DOI: 10.3878/j.issn.1006-9895.2011.06.06
ZHU Shichao, YIN Yan, JIN Lianji. A Numerical Study of the Vertical Transport of Water Vapor by Intense Convection over the Tibetan Plateau[J]. Chinese Journal of Atmospheric Sciences, 2011, 35(6): 1057-1068. DOI: 10.3878/j.issn.1006-9895.2011.06.06
Citation: ZHU Shichao, YIN Yan, JIN Lianji. A Numerical Study of the Vertical Transport of Water Vapor by Intense Convection over the Tibetan Plateau[J]. Chinese Journal of Atmospheric Sciences, 2011, 35(6): 1057-1068. DOI: 10.3878/j.issn.1006-9895.2011.06.06

青藏高原一次强对流过程对水汽垂直输送的数值模拟

A Numerical Study of the Vertical Transport of Water Vapor by Intense Convection over the Tibetan Plateau

  • 摘要: 本文采用中尺度天气研究预测模式(WRF) 模拟了青藏高原那曲地区的一次强对流过程, 分析了强对流对水汽的垂直输送量及对模式不同云微物理参数化方案的敏感性。通过与实测资料的比较, 发现此次模拟在对流发生时间、 地点、 降水时间等方面均与实际接近。敏感性试验表明: 当对流发生时, 对流区域向上的水汽通量随海拔高度呈先增大后减小的趋势, 该趋势对参数化方案不敏感。24小时总水汽垂直输送量随高度的变化也是如此。成因分析表明, 这与云微物理过程参数化对所模拟云中垂直上升运动的影响有关。由于强对流对水汽的垂直输送作用所引起的对流层上层加湿程度和加湿作用持续时间都对云微物理参数化方案敏感, 当选用不同云微物理方案进行模拟时, 对流层上层水汽混合比的过程最大值可造成20.3%的差异, 使对流层上层加湿所持续的时间从1.5到7小时不等。进行24小时平均后, 对流层上层湿度对云微物理方案的敏感性虽然有所减少, 但方案间的最大差异仍有14.3%。因此, 本文利用WRF对个例的模拟结果表明, 在利用WRF数值模式研究强对流对对流层上层区域湿度的影响时, 云微物理方案的不确定性对结果的影响在一天尺度内仍是不可忽视的。

     

    Abstract: The vertical transport of water vapor by a severe convective process occurring in Nagqu area over the Tibetan Plateau has been investigated using the Weather Research Forecast (WRF) model with different cloud microphysical schemes. The simulated characteristics of the storm reveal good agreement with observations, such as the onset and location of convection and precipitation. The results show that when the convective cloud arises, the upward flux of water vapor over the convective region increases at first then declines with altitude, and is not sensitive to cloud microphysical schemes. Similar trend is also found for the total water vapor integrated over a period of 24 hours. A further analysis shows that this trend is correlated to the vertical updraft in the cloud, that is, both the short-time humidifying effect in the upper troposphere and duration are sensitive to cloud microphysical parameterization schemes. The largest difference of the maximum upper tropospheric water vapor mixing ratio can reach 20.3% among different schemes, leading to humidifying lasting from 1.5 to 7 hours. Taking a 24-hour average can reduce the sensitivity of upper troposphere humidity, but the maximum still reaches 14.3%. The results of this study indicate that when the WRF model is used for studies of the effects of deep convection on the upper tropospheric water vapor, the uncertainty induced by using different microphysical schemes cannot be neglected within 24-hour time scale.

     

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