| Microphysical Retrieval from Doppler Radar Reflectivity Using Variational Data Assimilation |
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| 作者姓名： | LI Yongping ZHU Guofu XUE Jishan |
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| 作者单位： | Shanghai Typhoon Institute of China Meteorological Administration，Chinese Academy of Meteorological Sciences，Chinese Academy of Meteorological Sciences Shanghai 200030，Beijing 100081，Beijing 100081 |
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| 基金项目： | Supported by the National Key Program of Science and Technology of China under Grant No. 2001BA607B01
the NSFC Key Project under Grant No. 40233036. |
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| 摘 要： | One of the microphysical variables, the rainwater mixing ratio qr, is retrieved from the observed reflectivity of Doppler radar by a 3D variational data assimilation system. The qr as an analysis variable is obtained by minimizing a cost function defined as the difference between observed radar reflectivity and its retrieval from qr, plus the difference between qr and its background field from a mesoscale model's prediction. Covariance matrix of the background field's error is determined by the so-called NMC method. A method called the second-order auto-regression (SOAR) is used to calculate the coefficients of regressive filtering to fit in with small spatial scale such as cumulus in the process of spatial transformation. An ideal experiment demonstrates the correctness of this system and a sensitivity experiment proves that the random error of observed reflectivity has effect on the analyzed results. At last an experiment with observed data from the Doppler radar at Ma'anshan City in Anhui Province on 19 June 2002 was performed. The retrieved analysis variable qr in this test shows structures in detail, which coincide with the distribution of the echo picture observed by the radar.
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| 关 键 词： | 多普勒雷达 变分同化技术 微观物理变量 数据恢复 反射率 |
| 收稿时间： | 2006/1/12 0:00:00 |
Microphysical Retrieval from Doppler Radar Reflectivity Using Variational Data Assimilation |
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| LI Yongping,ZHU Guofu,XUE Jishan.Microphysical Retrieval from Doppler Radar Reflectivity Using Variational Data Assimilation[J].Acta Meteorologica Sinica,2006,20(1):20-27. |
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| Authors: | LI Yongping ZHU Guofu XUE Jishan |
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| Institution: | [1]Shanghai Typhoon Institute of China Meteorological Administration, Shanghai 200030 [2]Chinese Academy of Meteorological Sciences, Beijing 100081 |
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| Abstract: | One of the microphysical variables, the rainwater mixing ratio qr, is retrieved from the observed reflectivity of Doppler radar by a 3D variational data assimilation system. The qr as an analysis variable is obtained by minimizing a cost function defined as the difference between observed radar reflectivity and its retrieval from qr, plus the difference between qr and its background field from a mesoscale model's prediction. Covariance matrix of the background field's error is determined by the so-called NMC method. A method called the second-order auto-regression (SOAR) is used to calculate the coefficients of regressive filtering to fit in with small spatial scale such as cumulus in the process of spatial transformation. An ideal experiment demonstrates the correctness of this system and a sensitivity experiment proves that the random error of observed reflectivity has effect on the analyzed results. At last an experiment with observed data from the Doppler radar at Ma'anshan City in Anhui Province on 19 June 2002 was performed. The retrieved analysis variable qr in this test shows structures in detail, which coincide with the distribution of the echo picture observed by the radar. |
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| Keywords: | variational assimilation Doppler radar reflectivity microphysical variable |
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