The NOAA Track-Wise Wind Retrieval Algorithm and Product Assessment for CyGNSS
The NOAA Track-Wise Wind Retrieval Algorithm and Product Assessment for CyGNSS
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NOAA Track-Wise Wind 反演算法和 CyGNSS 产品评估
DOI：
10.1109/tgrs.2021.3087426
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发表时间：
2022
影响因子：
8.2
通讯作者：
P. Chang
中科院分区：
文献类型：
--
作者：
Faozi Saïd;Z. Jelenak;Jeonghwang Park;P. Chang
提出了一种新的方法来解决气旋全球导航卫星系统（CyGNSS）的星间和GPS相关的校准问题，基于跟踪的<inline-formula><tex-math notation="LaTeX">$\sigma ^{o}$</tex-math></inline-formula>偏差校正方法。该方法利用数值天气预报模式的辅助数据和半经验地球物理模型函数。注意，因此跟踪方向的<inline-formula><tex-math notation="LaTeX">$\sigma ^{o}$</tex-math></inline-formula>偏差校正保持CyGNSS信号灵敏度。经过校正后，卫星间和GPS相关的校准问题都得到了解决。在整个CyGNSS使命期间观察<inline-formula><tex-math notation="LaTeX">到的</tex-math></inline-formula>长期下降趋势大大降低。使用校正后的<inline-formula><tex-math notation="LaTeX">$\sigma ^{o}$</tex-math></inline-formula>测量，风反演方法和其产品进行了全面评估，为三年期对欧洲中期天气预报中心（ECMWFs），先进的散射仪（ASCAT）A/B，先进的微波扫描辐射计（AMSR）-2，GMI，WindSat，飓风天气研究和预报（HWRF）模式，和步进频率微波辐射计（SFMR）风。相对于ECMWF的总风速偏差和误差标准差（stde）分别为0.16和1.19 m/s，而相对于ASCAT A/B的总风速偏差和误差标准差分别为-0.11和1.12 m/s。AMSR-2/GMI/WindSat（组合）的相同度量分别为-0.19和1.11 m/s。对土壤水分主动被动（SMAP）的偏差和标准分别为-0.38和1.90 m/s。在热带气旋环境中，相对于HWRF的偏差和标准差分别为−0.54和2.90 m/s，相对于SFMR的偏差和标准差分别为−4.71和5.88 m/s。最后，在下雨的情况下测量了CyGNSS的风力性能。在10 m/s以下，CyGNSS和ECMWF之间的偏差随着降雨率的增加而增加。在10到15 m/s之间，偏差基本上不存在。高于15米/秒，结果是不确定的，由于数量较少的雨水样本。总体而言，所呈现的CyGNSS风速产品具有一致性和可靠性，显示出将GNSS-R导出的风用于业务目的的前景。
A novel approach in addressing cyclone global navigation satellite system (CyGNSS) intersatellite and GPS-related calibration issues is proposed, based on a track-wise <inline-formula> <tex-math notation="LaTeX">$\sigma ^{o}$ </tex-math></inline-formula> bias correction method. This method makes use of both ancillary data from numerical weather prediction models and a semiempirical geophysical model function. Care is taken, so the track-wise <inline-formula> <tex-math notation="LaTeX">$\sigma ^{o}$ </tex-math></inline-formula> bias correction maintains CyGNSS signal sensitivity. Both intersatellite and GPS-related calibration issues are removed after correction. Long-term <inline-formula> <tex-math notation="LaTeX">$\sigma ^{o}$ </tex-math></inline-formula> downward trend, observed throughout the CyGNSS mission, is greatly reduced. Using the corrected <inline-formula> <tex-math notation="LaTeX">$\sigma ^{o}$ </tex-math></inline-formula> measurements, a wind retrieval method is also presented and its product thoroughly assessed for a three-year period against European Centre for Medium-Range Weather Forecasts (ECMWFs), Advanced Scatterometer (ASCAT) A/B, Advanced Microwave Scanning Radiometer (AMSR)-2, GMI, WindSat, hurricane weather research and forecasting (HWRF) model, and the stepped frequency microwave radiometer (SFMR) winds. The overall wind speed bias and standard deviation of the error (stde) against ECMWF are 0.16 and 1.19 m/s, while these are −0.11 and 1.12 m/s against ASCAT A/B, respectively. The same metrics against AMSR-2/GMI/WindSat (combined) are −0.19 and 1.11 m/s, respectively. The bias and stde against soil moisture active passive (SMAP) are −0.38 and 1.90 m/s, respectively. In the tropical cyclone environment, the bias and stde against HWRF are −0.54 and 2.90 m/s, and −4.71 and 5.88 m/s with SFMR. Finally, CyGNSS wind performance is gauged in the presence of rain. Below 10 m/s, the bias between CyGNSS and ECMWF increases as the rain rate increases. Between 10 and 15 m/s, biases are mostly absent. Above 15 m/s, results are inconclusive due to the low number of collocated rain samples. Overall, the presented CyGNSS wind speed product both exhibits consistency and reliability, showing promise of using GNSS-R derived winds for operational purposes.