Since high and low clouds ubiquitously overlie the Tropical Western Pacific (TWP) region, the cloud radiative effect (CRE) cannot be influenced by either high or low clouds, but by combinations of the clouds. This study investigates the CRE of multi-layered clouds in TWP via a radiative transfer model, Streamer. We assumed that multi-layered clouds are composed of full coverage of high clouds overlying low clouds with fractional coverage. The simulation results show that low clouds readily change CREs from positive to negative in the case of optically thin high clouds, even if the fraction of low clouds takes 10% of that of high clouds. Also, various combinations of physical properties of multi-layered high and low clouds allow more CRE variability (− 253.76 to 93.10 W m−2) than single-layered clouds do (− 101.62 to 96.95 W m−2). Even in the same conditions (total column cloud optical thickness = 15 and high cloud top pressure = 200 hPa), the multi-layer clouds have various CREs from − 180.55 to 45.64 W m−2, while the single-layer high clouds − 2.00 W m−2. These findings are also comparable with satellite observations from CERES and CALIPSO. The present study suggests that considerable uncertainty of radiative effects of high clouds over TWP can attribute to low clouds below high clouds.

中文翻译：

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热带高云覆盖低云的云辐射效应

由于高低云普遍覆盖热带西太平洋（TWP）区域，因此云辐射效应（CRE）不受高低云的影响，而不受云的组合的影响。本研究通过辐射传输模型Streamer研究了TWP中多层云的CRE。我们假设多层云是由高云的完全覆盖和部分覆盖的低云组成。仿真结果表明，即使在光学上薄的高云的情况下，低云也很容易将CRE从正变为负，即使低云的比例占高云的10％。同样，多层高低云的物理属性的各种组合比单层云（− 101.62至96.95 W m-2）具有更大的CRE变异性（− 253.76至93.10 W m-2）。即使在相同条件下（总柱云光学厚度= 15，高云顶压力= 200 hPa），多层云的CRE也从− 180.55到45.64 W m−2，而单层高云− 2.00 W m-2。这些发现也可与CERES和CALIPSO的卫星观测结果相媲美。本研究表明，在TWP上高云的辐射效应存在很大的不确定性，可归因于高云以下的低云。