HelioFTH: combining cloud index principles and aggregated rating for cloud masking using infrared observations from geostationary satellites
HelioFTH: combining cloud index principles and aggregated rating for cloud masking using infrared observations from geostationary satellites
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DOI：
10.5194/amt-6-1883-2013
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发表时间：
2013-08
影响因子：
3.8
通讯作者：
B. Dürr;M. Schröder;R. Stöckli;R. Posselt
中科院分区：
文献类型：
--
作者：
B. Dürr;M. Schröder;R. Stöckli;R. Posselt
抽象的。本文提出了一种基于云掩模和云覆盖率的反演方案HelioFTH。该算法是自校准的，并依赖于红外（IR）窗口通道观察。它不需要数值天气预报（NWP）或辐射传输模式的输入，也不需要其他卫星平台的输入。该方案适用于气象卫星可见光和红外成像仪（MVIRI）和旋转增强可见光和红外成像仪（SEVIRI）传感器的全时间和空间分辨率。主要的重点是基于内部云顶压力（CTP）产品将中层和高层云覆盖（HCC）与低层云分离。CFC检索采用基于聚合评级方案的IR仅云掩模。CTP检索是基于MVIRI IR通道的Heliosat样云指数。来自HelioFTH、国际卫星云气候学项目（ISCCP）DX和气候监测卫星应用设施（CM SAF）的CFC与来自基线地面辐射网络（BSRN）和阿尔卑斯地面辐射收支（ASRB）网络的CFC进行了验证。HelioFTH CFC与CM SAF CFC相差不超过5-10%，但高于ISCCP-DX CFC。特别是与ISCCP-DX相比，HelioFTH检测无云像素的条件概率提高了约35%。HelioFTH CFC能够再现在地面观察到的日常变化。此外，HelioFTH HCC与CM SAF和ISCCP-DX在不同地区和台站进行了相互比较。在整个磁盘区域上，与CM SAF HCC产品相比，无云HCC像素的错误检测概率与ISCCP-DX的顺序相同。HelioFTH可用于生成云物理特性的独立气候数据记录，一旦其一致性和均匀性在整个气象卫星时间序列中得到验证。
Abstract. In this paper a cloud mask and cloud fractional coverage (CFC) retrieval scheme called HelioFTH is presented. The algorithm is self-calibrating and relies on infrared (IR) window-channel observations only. It needs no input from numerical weather prediction (NWP) or radiative transfer models, nor from other satellite platforms. The scheme is applicable to the full temporal and spatial resolution of the Meteosat Visible and InfraRed Imager (MVIRI) and the Spinning Enhanced Visible and InfraRed Imager (SEVIRI) sensors. The main focus is laid on the separation of middle- and high-level cloud coverage (HCC) from low-level clouds based on an internal cloud-top pressure (CTP) product. CFC retrieval employs a IR-only cloud mask based on an aggregated rating scheme. CTP retrieval is based on a Heliosat-like cloud index for the MVIRI IR channel. CFC from HelioFTH, the International Satellite Cloud Climatology Project (ISCCP) DX and the Satellite Application Facility on Climate Monitoring (CM SAF) were validated with CFC from the Baseline Surface Radiation Network (BSRN) and the Alpine Surface Radiation Budget (ASRB) network. HelioFTH CFC differs by not more than 5–10% from CM SAF CFC but it is higher than ISCCP-DX CFC. In particular the conditional probability to detect cloud-free pixels with HelioFTH is raised by about 35% compared to ISCCP-DX. The HelioFTH CFC is able to reproduce the day-to-day variability observed at the surface. Also, the HelioFTH HCC was inter-compared to CM SAF and ISCCP-DX over different regions and stations. The probability of false detection of cloud-free HCC pixels is in the same order as ISCCP-DX compared to the CM SAF HCC product over the full-disk area. HelioFTH could be used for generating an independent climate data record of cloud physical properties once its consistency and homogeneity is validated for the full Meteosat time series.