研究目的
To modify the brightness temperatures measured by the AMSR2 to compensate for the difference in sizes of each frequency field of view (FOV) for more accurate geophysical retrievals.
研究成果
The AMSR2 L1R product, developed using the BG method, provides modified brightness temperatures that compensate for the difference in sizes of each frequency FOV, enabling more accurate geophysical retrievals. The quality of the replication was evaluated by the Fit Error, controlled by a smoothing factor (κ), with the most appropriate criterion for κ being to minimize the Fit Error while ensuring the sum of the absolute values of the weighting factors (|ai|) was ≤ 2. The L1R product is recommended for use when multifrequency brightness temperatures are used simultaneously, except when F and G are similar in size.
研究不足
The Fit Error normally did not reach 0, and the modified brightness temperatures (?TB) could have an unexpected value when too many negative components appeared in the weighting factors (a) for a predetermined κ. Additionally, if the target antenna pattern (F) and source antenna patterns (Gs) were similar, the Fit Error for the L1R product was worse than for the L1B product because the center of F was always in the center of the 89.0 GHz (A) channel antenna pattern.
