ABSTRACT

In this paper, time extension methods, originally designed for clear-sky land surface conditions, are used to estimate high-spatial resolution surface daily longwave (LW) radiation from the instantaneous Global LAnd Surface Satellite (GLASS) longwave radiation product. The performance of four time methods were first tested by using ground based flux measurements that were collected from 141 global sites. Combined with the accuracy of daily LW radiation estimated from the instantaneous GLASS LW radiation, the linear sine interpolation method performs better than the other methods and was employed to estimate the daily LW radiation as follows: The bias/Root Mean Square Error (RMSE) of the linear sine interpolation method were −6.30/15.10 W/m² for the daily longwave upward radiation (LWUP), −1.65/27.63 W/m² for the daily longwave downward radiation (LWDN), and 4.69/26.42 W/m² for the daily net longwave radiation (LWNR). We found that the lengths of the diurnal cycle of LW radiation are longer than the durations between sunrise and sunset and we proposed increasing the day length by 1.5 h. The accuracies of daily LW radiation were improved after adjusting the day length. The bias/RMSE were −4.15/13.74 W/m² for the daily LWUP, −1.3/27.52 W/m² for the daily LWDN, and 2.85/25.91 W/m² for the daily LWNR. We are producing long-term surface daily LW radiation values from the GLASS LW radiation product.

摘要

在本文中，最初为晴空地表条件设计的时间扩展方法用于估计来自瞬时全球陆地和地面卫星 (GLASS) 长波辐射产品的高空间分辨率地面日长波 (LW) 辐射。四种时间方法的性能首先通过使用从 141 个全球站点收集的基于地面的通量测量结果进行测试。结合从瞬时 GLASS LW 辐射估计的日 LW 辐射的准确性，线性正弦插值方法比其他方法表现更好，用于估计日 LW 辐射如下： 偏差/均方根误差 (RMSE)线性正弦插值法为-6.30/15.10 W/m ²每日长波向上辐射（LWUP），-1.65/27.63 W/m²日常长波向下辐射（LWDN），和4.69 / 26.42 W /米²的日常净长波辐射（LWNR）。我们发现 LW 辐射的昼夜周期长度比日出和日落之间的持续时间长，我们建议将白天长度增加 1.5 小时。调整日长后，日长波辐射的准确度有所提高。每日 LWUP的偏差/RMSE 为 -4.15/13.74 W/m ²，每日 LWDN 为 -1.3/27.52 W/m ²，每日 LWNR 为 2.85/25.91 W/m ²。我们正在从 GLASS LW 辐射产品中生成长期的表面每日 LW 辐射值。