An independent assessment of pathfinder AVHRR sea surface temperature accuracy using the Marine Atmosphere Emitted Radiance Interferometer (MAERI)

The remotely sensed sea surface temperature (SST) estimated from the 4-km-r esolution Pathfinder SST algorithm is compared to a SST locally measured by the Marine Atmospheric Emitted Radiance Interferometer (MAERI) during five oceanographic cruises in the Atlantic and Pacific Oceans, in conditions ra nging from Arctic to equatorial. The Pathfinder SST is a product of the sat ellite-based Advanced Very High Resolution Radiometer, while the MAERI is a n infrared radiometric interferometer with continuous onboard calibration t hat can provide highly accurate (better than 0.05 degrees C) in situ skin t emperatures during extended shipboard deployments. Matchups, which are coll ocated (within 4 km) and coincident (+/-40 min during the day; +/-120 min d uring the night) data, from these two different sources under cloud-free co nditions are compared. The average difference between the MAERI and Pathfin der SSTs is found to be 0.07+/-0.31 degrees C from 219 matchups during the low- and midlatitude cruises; inclusion of 80 more matchups from the Arctic comparisons produces an average global difference of 0.14+/-0.36 degrees C . The MAERI-Pathfinder differences compare favorably with the average midla titude differences between the MAERI skin SST and other bulk SST estimates commonly available for these cruises such as the research vessels' thermosa linograph SST(0.12+/-0.17 degrees C) and the weekly National Centers for En vironmental Prediction optimally interpolated SST analysis (0.41+/-0.58 deg rees C). While not representative of all possible oceanic and atmospheric r egimes, the accuracy of the Pathfinder SST estimates under the conditions s ampled by the five cruises is found to be at least twice as good as previou sly demonstrated.