Satellite Based Downward Long Wave Radiation by Various Models in Northeast Asia

Abstract

Satellite-based downward long wave radiation measurement under clear sky conditions in Northeast Asia was conducted using five well-known physical models (Brunt 1932, Idso and Jackson 1969, Brutsaert 1975, Satterlund 1979, Prata 1996 with a newly proposed global R ld model (Abramowitz et al. 2012). Data from two flux towers in South Korea were used to validate downward long wave radiation. Moderate resolution imaging spectroradiometer (MODIS) atmospheric profile products were used to develop the R ld models. The overall root mean square error (RMSE) of MODIS R ld with respect to two ecosystem-type flux towers was determined to be ≈ 20 W m -2 . Based on the statistical analyses, MODIS R ld estimates with Brutsaert (1975) and Abramowitz et al. (2012) models were the most applicable for evaluating R ld for clear sky conditions in Northeast Asia. The Abramowitz R ld maps with MODIS T a and e a showed reasonable seasonal patterns, which were wellaligned with other biophysical variables reported by previous studies. The MODIS R ld map developed in this study will be very useful for identifying spatial patterns that are not detectable from ground-based R ld measurement sites.

Comparison of Cloudy‐Sky Downward Longwave Radiation Algorithms Using Synthetic Data, Ground‐Based Data, and Satellite Data

“…Empirical and parameterized algorithms have been compared by many researchers over different land surfaces (Choi et al, ; Iziomon et al, ; Kjaersgaard et al, ; Niemelä et al, ; Wu et al, ). However, these comparisons mainly used meteorological data; algorithm assessments using satellite data are rare, especially for cloudy conditions, because satellites cannot provide accurate near‐surface atmospheric properties (Chiacchio et al, ; Sur et al, ; Wu et al, ). To assess the performance of current cloudy‐sky algorithms, and find the optimal algorithm for DLR computation, three types of algorithms for all‐sky DLR were evaluated in this study.…”