Search Results

You are looking at 1 - 2 of 2 items for :

  • Author or Editor: Roger W. Saunders x
  • Journal of Atmospheric and Oceanic Technology x
  • Refine by Access: All Content x
Clear All Modify Search
Anne G. O’Carroll
,
John R. Eyre
, and
Roger W. Saunders

Abstract

Using collocations of three different observation types of sea surface temperatures (SSTs) gives enough information to enable the standard deviation of error on each observation type to be derived. SSTs derived from the Advanced Along-Track Scanning Radiometer (AATSR) and Advanced Microwave Scanning Radiometer for Earth Observing System (EOS; AMSR-E) instruments are used, along with SST observations from buoys. Various assumptions are made within the error theory, including that the errors are not correlated, which should be the case for three independent data sources. An attempt is made to show that this assumption is valid and that the covariances between the different observations because of representativity error are negligible. Overall, the spatially averaged nighttime AATSR dual-view three-channel bulk SST observations for 2003 are shown to have a very small standard deviation of error of 0.16 K, whereas the buoy SSTs have an error of 0.23 K and the AMSR-E SST observations have an error of 0.42 K.

Full access
Anne G. O’Carroll
,
Roger W. Saunders
, and
James G. Watts

Abstract

A near-continuous series of global retrievals of sea surface temperature (SST) has been made from the Along-Track Scanning Radiometer (ATSR) series of instruments from 1991 to 2005. To analyze possible long-term trends in the global or regional SST throughout the period daily anomalies are computed using a 1961–90 daily climatology, averaged into global monthly means, and plotted as a global time series. To evaluate any biases in these anomalies they are compared with other satellite SST datasets that have been computed and compared over the same time period. Global infrared satellite SST data have been received from the Advanced Very High Resolution Radiometer (AVHRR) series, microwave SST data from the Tropical Rainfall Measuring Mission (TRMM) Microwave Imager (TMI), and global microwave SST data from the Advanced Microwave Sounding Radiometer (AMSR)-E on Aqua. Additionally, the anomalies have also been compared with the Hadley Centre Global Sea Ice Coverage and Sea Surface Temperature (HadISST1) anomalies. HadISST1 is a globally complete 1° SST analysis compiled from in situ and bias-corrected AVHRR SSTs at the Met Office (UK).

The results of the study show the high accuracy of the Advanced Along Track Scanning Radiometer (AATSR) SSTs, but there are concerns with the NOAA-14 AVHRR data (1996–2000) being biased cold, especially in the Northern Hemisphere, and the AMSR-E SSTs (version 4), which show unexplained biases. Since 1999 TMI SSTs appear to have a consistently warm (∼0.2 K) bias relative to the infrared sensors and HadISST1.

The time series in (A)ATSR SSTs indicate the possibility of warming trends between 0.1 and 0.2 K decade−1, but the remaining ATSR-1 data are required to confirm this.

Full access