Observation error diagnostics and applicability evaluation of MHS brightness temperatures in RMAPS CA
Observation error diagnostics and applicability evaluation of MHS brightness temperatures in RMAPS CA
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RMAPS CA 中 MHS 亮温观测误差诊断及适用性评估
DOI：
10.1080/01431161.2021.1929544
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发表时间：
2021
影响因子：
3.4
通讯作者：
马玉芬
中科院分区：
文献类型：
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作者：
马玉芬
由于常规观测的不连续性和偏差校正的有效性，仍有必要将极轨道卫星的数据同化到中亚有限区域快速更新多尺度分析和预报系统（RMAPS-CA）中。通过与社区辐射传输模式（CRTM）模拟的微波湿度探测器（MHS）辐射亮温（BT）的比较，诊断了多平台MHS辐射亮温的观测误差。结果表明，与模拟BT相比，MHS BT的大部分偏置福尔斯落在−1.5-2.0 K范围内，并随着峰值能量贡献高度（PECH）的增加而增加。不同探测站对MHS同一通道和同一卫星的偏差差异不明显，但对不同卫星的同一通道的偏差差异明显。此外，大多数GFS BT高于MHS BT，MHS BT随PECH增加。此外，所观察到的MHS BT偏置相对于GFS BT的几乎所有PDF分布形成接近高斯分布，其中通道3和4的中心值为正。然后通过两次为期一个月的回顾运行对MHS在RMAPS-CA中的初始应用进行评估，并根据观察结果验证从有和没有MHS的分析中初始化的预测。结果表明，与未同化观测资料的自然运行相比，同化MHS可使位势高度提高约55.3%，对初始时间的平均RMSE，气温、比湿和200 hPa以下风速的平均RMSE分别提高沿着12.8%、4.7%和2.3%。对2 m处的SPFH和10 m处的风速分别有2.9%和3.3%，对小、中、大雨的24 h降水量分别有11.3%、28.7%和20.0%，但对暴雨预报无明显影响。
Due to the insufficiencies of conventional observations and the effectiveness of bias corrections, it is still necessary to assimilate data from polar orbit satellites into a limited-area rapidly updated multiscale analysis and prediction system for Central Asia (RMAPS-CA). This study diagnoses the observation errors of the radiation brightness temperature (BT) of satellite Microwave Humidity Sounder (MHS) from multiple platforms through comparisons to the simulated BTs by the Community Radiative Transfer Model (CRTM) with soundings and a GFS input separately. The results show that the majority BIAS of the MHS BT compared with the simulated BT falls within −1.5–2.0 K and increases with an increase in the peak energy contribution height (PECH). No significant bias differences for the same channel of MHS and the same satellite are found across the different sounding stations, but obvious differences are found for the same channel from different satellites. Additionally, most of the GFS BTs are higher than the MHS BTs, which increase with the PECH. Moreover, almost all PDF distributions of the observed MHS BT bias relative to the GFS BT form a nearly Gaussian distribution, with the centre value being positive for channels 3 and 4. An assessment of the initial applications of MHS to RMAPS-CA is then conducted through two one-month retrospective runs, and forecasts initialized from analyses with and without MHS are verified against the observations. The results show that compared to the natural run for which no observations are assimilated, an improvement in the geopotential height of approximately 55.3% can be obtained by the assimilation of MHS, along with improvements of 12.8%, 4.7% and 2.3% for temperature, specific humidity (SPFH), and wind speeds below 200 hPa, respectively, for an average RMSE with initial time, which is valued at 2.9% and 3.3% for the SPFH at 2 m and wind speed at 10 m, respectively In addition, significant improvements in 24-h precipitation of 11.3%, 28.7% and 20.0% are obtained for light, medium and heavy rain, respectively, while no positive effects are obtained for rainstorm forecasts.