Otis B. Brown

Sea-surface temperature measurements from the Moderate-Resolution Imaging Spectroradiometer (MODIS) on Aqua and Terra

The Terra and Aqua satellites are the flagships of the NASA Earth Observing System and carry suites of sensors designed to provide measurements of the climate system suitable for many research applications. Each satellite carries a Moderate-Resolution Imaging Spectroradiometer (MODIS), which are very complex imaging radiometers operating in both the visible and infrared parts of the electromagnetic spectrum. One of the primary variables that is derived from some of the infrared measurements of MODIS is sea-surface temperature (SST). There are two spectral intervals located where the atmosphere is relatively transparent, at about 4 and 11 micrometer wavelengths, where SST measurements can be made in cloud-free conditions, although the contamination of the shorter wavelength measurements by reflected sunlight limits these to the night-time part of each orbit. The atmospheric correction algorithms used to derive SSTs are described, along with radiometric and sub-surface measurements used to determine the error characteristics of the retrieved fields

Propagation of thermal fronts in the somali current system

Abstract Surface ship-of-opportunity and satellite remotely sensed sea-surface temperature (SST) data were obtained during the mature phase of the Southwest Monsoon in the north-western Indian Ocean for the years 1976–1979. Large wedge-like areas of upwelled water are observed at 5°N and 10°N after Somali Current spinup, indicative of a two-gyre circulation in the Somali Current system. Several months later the southern separation region is observed to translate poleward (5–75 cm/s) in three of the four years. This translation occurs in several distinct phases over a one-month interval with the southern wedge eventually coalescing with the northern wedge between 8 and 10°N (1976, 1979). (In 1978 the northern wedge translated past Socotra and dissipated in the Arabian Sea). The thermal signature of the “new” northern wedge becomes indistinct over a period of two to three months later.

Sea-surface temperature measured by the Moderate Resolution Imaging Spectroradiometer (MODIS)

The Moderate Resolution Imaging Spectroradiometer (MODIS) on the NASA Earth Observing System satellites Terra and Aqua include infrared bands that are designed for the accurate measurement of sea-surface temperature (SST). In addition to the conventional split-window bands in the 10-12 /spl mu/m atmospheric window (similar in spectral properties to the corresponding channels of the heritage instrument, the Advanced Very High Resolution Radiometer (AVHRR)) the MODIS also has three bands in the 3.5 to 4.2 /spl mu/m interval for SST measurement. We present a validation of the MODIS SSTs, derived from the conventional measurements at the 10-12 /spl mu/m window, by comparison with radiometrically-derived skin temperatures from ships, and with bulk measurements from buoys. These show the MODIS SSTs are comparable in accuracy to the AVHRR Pathfinder SST fields.