Validation of the ATSR Reprocessing for Climate (ARC) Dataset Using Data from Drifting Buoys and a Three-Way Error Analysis

Abstract

he Along-Track Scanning Radiometer (ATSR) Reprocessing for Climate (ARC) project aims to create an independent climate data record of sea surface temperatures (SSTs) covering recent decades that can be used for climate change analysis. Here, the ARC SSTs are assessed using comparisons with collocated drifting buoy observations and a three-way error analysis that also includes Advanced Microwave Scanning Radiometer for Earth Observing System (AMSR-E) data. The SSTs using the three-channel nighttime retrievals in the ARC data at 1-m depth are found to have a warm bias of 0.054 K (standard deviation 0.151 K) with respect to the drifting buoy data for the 1995?2009 time period using ATSR-2 and Advanced Along-Track Scanning Radiometer (AATSR) instrument data. However, when studying the two-channel retrievals, the ATSR-1 data are found to be less stable and with more extreme values than in later years. Some dependence on latitude, season, and fields such as total column water vapor is found in the ATSR-2 and AATSR period. An assessment of the ARC SST uncertainty shows a stable bias for low uncertainty values but more deviation above 0.6 and 0.35 K for the two- and three-channel nighttime retrievals, respectively. The three-way error analysis reveals a standard deviation of error of 0.14 K for the ARC 1-m depth SSTs using the three-channel nighttime retrieval. Estimates of the standard deviation of error for the drifting buoys are also produced and show evidence of improvement in the buoy network in the years 2003?09 from 0.19 to 0.15 K.