RESULT ANALYSIS OF OBSERVATIONS BY AIRBORNE MICROWAVE INSTRUMENTS ON MULTI-ALTITUDE FLIGHTS
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摘要: 机载微波大气温度探测仪可以机动灵活地获取大气温度廓线信息。针对一次机载微波大气温度探测仪的多高度飞行观测试验,基于逐线积分模式和大气参数廓线库,建立用于不同飞行高度的快速辐射传输模式,分析了仪器观测亮温的质量并对仪器观测进行了订正;建立了基于神经网络的微波大气温度廓线反演算式,分析了不同高度、不同通道选择对于大气温度廓线反演性能的影响。研究结果表明:(1)较低飞行高度计算得到的各地表敏感通道地表比辐射率之间具有较好的一致性;(2)采用订正算式订正后,不同飞行高度的模拟亮温与观测亮温具有较好的一致性;(3)机载微波大气温度反演最优通道组合依赖于平台飞行高度;(4)采用最优的通道组合,4 200 m、3 200 m和2 500 m高度层温度反演均方根误差范围分别为0.5~1.8 K、0.5~1.3 K和0.4~1.0 K。Abstract: Airborne microwave sounding instruments can get atmosphere temperature flexibly. Using line-by-line calculation model MPM and profile datasets, a fast radiative transfer model was applied to airborne microwave sounding instruments and an artificial neural network numerical simulation scheme was developed, which evaluated the multi-altitude flight examinations of the airborne microwave sounding instruments. A neural network was analyzed by a series of retrieval experiments. The results are shown as follows: (1) Surface emissivity of lower-altitude flight calculation has good consistency; (2) With an adjustment model, the fast radiative transfer model can preferably simulate airborne bright temperatures; (3) With the airborne height changing, the best combination of airborne microwave sounding instruments channels is different; (4) With the best combination of airborne microwave sounding instruments channels, the atmospheric temperature RMS error for 4 200 m, 3 200 m and 2 500 m is between 0.5 K and 1.8 K, 0.5 K and 1.3 K, and 0.5 K and 1.0 K, respectively.
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表 1 大气微波温度探测仪通道特性参数
通道 中心频率/GHz 3 dB带宽/MHz 灵敏度/K 动态范围/K 定标精度/K 1 50.300 000 180 1.2 3~330 1.5 2 51.760 000 400 0.9 3~330 1.5 3 52.800 000 400 0.9 3~330 1.5 4 53.596 000 400 0.9 3~330 1.5 5 54.400 000 400 0.9 3~330 1.5 6 54.940 000 400 0.9 3~330 1.5 7 55.500 000 330 0.9 3~330 1.5 8 57.290 344 330 0.9 3~330 1.5 表 2 不同时次对应的探空数据
气压/hPa 高度/m 10:56:36 11:24:35 温度/K 相对湿度/% 温度/K 相对湿度/% 656.4 3 607.6 274.86 73.3 274.99 72.8 689.3 3 199.6 276.36 64.1 276.64 66.6 702.7 3 054.6 276.8 71.9 276.54 75.8 749.1 2 531.4 278.89 77.7 278.85 81.4 795.1 2 040.9 279.27 86.7 279.06 86.7 840.0 1 586.9 280.80 93.5 280.13 93.8 882.8 1 174.9 282.69 94.7 282.73 82.4 922.5 806.3 285.55 81.7 285.89 73.4 957.4 493.6 288.06 84.3 287.30 77.5 表 3 2 500 m高度层不同通道计算所得的地表比辐射率
高度 50.3 GHz 51.76 GHz 52.8 GHz 2 500 m 0.990 5 0.988 9 0.993 4 表 4 大气温度反演均方根误差(K)整层平均值
高度层/m 8通道 7通道 6通道 5通道 4通道 4 200 1.05 0.90 0.99 1.08 1.10 3 200 1.44 1.08 0.86 0.98 1.12 2 500 1.06 0.87 0.73 0.74 0.91 -
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