This study utilized the high-spectral resolution radiative transfer model (MODerate resolution atmospheric TRANsmission, MODTRAN6.0.2.5) to compute global clear-sky shortwave (SW) radiative flux and compared it with NASA’s Clouds and the Earth’s Radiant Energy System (CERES) Synoptic Radiative Fluxes and Clouds (SYN1deg) product. The comparison revealed that the global distributions of clear-sky downwelling SW fluxes at the surface from the M6.0 calculations and SYN1 results are similar, with annual means of 246.51 Wm and 242.42 Wm, respectively. Analysis further showed that most of the M6.0 calculations are slightly higher from low to mid-latitudes, particularly in the Northern Hemisphere (NH), but lower in higher latitudes compared to SYN1 results. However, these differences mostly fall within the CERES estimated uncertainty (6 Wm) of monthly mean clear-sky downwelling SW flux at the surface. The sensitivity of clear-sky SW/ fluxes to changes in Precipitable Water Vapor (PWV), represented by the clear-sky water vapor radiative kernel, is about -0.7 Wm/(kgm) over oceans for both M6.0 and CERES SYN1 products, except for SYN1 results over the Southern Hemisphere (SH) ocean. Additionally, the zonal means of land coverage and SW/VIS/NIR albedos from M6.0 calculations indicate that VIS albedos are highest in polar regions (60°), followed by SW and NIR albedos, while NIR albedos become highest from low to mid-latitudes (60°). Generally, SW/VIS/NIR albedos and their differences increase monotonically with increased land coverage from 60°S to 60°N. The consistent clear-sky water vapor radiative kernels derived from both products exceeded our expectations, suggesting their potential use to trace physical signatures in climate model calculations. It is recommended that these model-derived radiative kernels should be validated by the long-term global and regional surface observations in order to enhance confidence to implement these radiative kernels in climate models.

中文翻译：

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追踪计算出的全球晴空光谱短波辐射通量分布中的物理特征


本研究利用高光谱分辨率辐射传输模型（中分辨率大气传输，MODTRAN6.0.2.5）计算全球晴空短波（SW）辐射通量，并将其与NASA的云和地球辐射能系统（CERES）进行比较天气辐射通量和云 (SYN1deg) 产品。比较结果表明，M6.0计算结果和SYN1结果的全球晴空下流SW通量分布相似，年平均值分别为246.51 Wm和242.42 Wm。分析进一步表明，与 SYN1 结果相比，大多数 M6.0 计算结果在低纬度到中纬度地区略高，特别是在北半球 (NH)，但在高纬度地区则较低。然而，这些差异大多落在 CERES 估计的地表月平均晴空下降 SW 通量的不确定性 (6 Wm) 范围内。对于 M6.0 和 CERES SYN1 产品，晴空 SW/通量对可降水水汽 (PWV) 变化（以晴空水汽辐射核为代表）的敏感度约为 -0.7 Wm/(kgm)。 ，南半球 (SH) 海洋上的 SYN1 结果除外。此外，M6.0计算中的土地覆盖和近红外反照率的纬向平均值表明，可见光反照率在极地地区最高（60°），其次是近红外反照率和近红外反照率，而近红外反照率从低到中最高- 纬度（60°）。一般来说，SW/VIS/NIR 反照率及其差异随着土地覆盖范围从 60°S 增加到 60°N 而单调增加。从这两种产品中获得的一致的晴空水蒸气辐射内核超出了我们的预期，表明它们在气候模型计算中追踪物理特征的潜在用途。 建议通过长期的全球和区域表面观测来验证这些模型推导的辐射核，以增强在气候模型中实施这些辐射核的信心。