ABSTRACT

The HY-2B satellite, equipped with the scanning microwave radiometer (SMR), was launched on 25 October 2018 and began observation on 30 October 2018. With the SMR data, we retrieved the sea surface temperature (SST), along with the ocean wind speed (OWS), total columnar water vapour (TCWV), and cloud liquid water (TCLW), within an optimal estimation (OE) Framework. Through the comparison with Argo profiling floats data, mean difference of 0.01°C, and standard deviation of 0.47${ }^{\circ }\mathrm{C}$ are inferred for SST within the latitude range of 60°S–60°N. The contrast against the WindSat standard products also shows an encouraging result, in which the standard deviation for SST, OWS, TCWV, and TCLW are 0.49$$°\text{C}$$, 0.64 m s⁻¹, 1.23 mm, and 0.029 mm, respectively. To investigate the effect of oceanic and atmospheric state on SST retrieval, the sensitivities of brightness temperature (TB) at considered frequency to SST, OWS, TCWV, and TCLW are carefully analysed, and seven combinations of SMR frequencies are tested to retrieve different parameters. The results emphasize the importance of low-frequency observations in retrieving accurate SST and suggest that the influence of wind speed and atmospheric vapour content is non-negligible. It is also indicated that the role of the higher frequency (23.8 and 37 GHz) is limited for SST retrieval. This study presents an assessment for SST retrieval from SMR measured data and provides a reference about frequency selection for measuring SST from passive microwave radiometer.

摘要

装有扫描微波辐射仪（SMR）的HY-2B卫星于2018年10月25日发射，并于2018年10月30日开始观测。利用SMR数据，我们检索了海表温度（SST）以及海风最佳估算（OE）框架内的最大速度（OWS），柱状总水蒸气（TCWV）和云状液态水（TCLW）。通过与Argo分析浮点数据的比较，平均差异为0.01°C，标​​准偏差为0.47${ }^{\circ }\mathrm{C}$推断SST在60°S–60°N纬度范围内。与WindSat标准产品的对比也显示出令人鼓舞的结果，其中SST，OWS，TCWV和TCLW的标准偏差为0.49$$°\text{C}$$，0.64毫秒^-1，分别1.23毫米，0.029毫米。为了研究海洋和大气状态对SST检索的影响，仔细分析了考虑频率下的亮度温度（TB）对SST，OWS，TCWV和TCLW的敏感性，并测试了7种SMR频率组合以检索不同的参数。结果强调了低频观测在检索准确的海表温度中的重要性，并表明风速和大气蒸气含量的影响不可忽略。还表明，较高的频率（23.8和37 GHz）在SST检索中的作用受到限制。这项研究提出了从SMR测量数据中检索SST的评估，并为从无源微波辐射计测量SST的频率选择提供了参考。