We describe a vertically scanning infrared radiometer for measuring the air–sea temperature difference without disturbing the water skin layer. The radiometer operates with a single wavelength channel that is 1.1 μm wide, centered on 14.2 μm, on the short-wavelength edge of a CO<sub>2</sub> atmospheric absorption band. The resulting high atmospheric absorption enables calibration of the horizontal-viewing signal with an <i>in situ</i> air-temperature sensor. The signal at all other scan angles is measured relative to that at the horizontal, providing a differential air–sea temperature measurement that is nearly independent of calibration offsets that can be a problem with independent air- and water-temperature sensors. We show data measured on a ship in the Tropical Western Pacific Ocean during July 1999, which exhibit important discrepancies from <i>in situ</i> data using bulk air-and water-temperature sensors. These discrepancies illustrate important differences between bulk versus skin water temperature.
© 2001 Optical Society of America
(010.0010) Atmospheric and oceanic optics : Atmospheric and oceanic optics
(120.0120) Instrumentation, measurement, and metrology : Instrumentation, measurement, and metrology
(120.0280) Instrumentation, measurement, and metrology : Remote sensing and sensors
(120.5630) Instrumentation, measurement, and metrology : Radiometry
Joseph A. Shaw, Domenico Cimini, Ed R. Westwater, Yong Han, Heather M. Zorn, and James H. Churnside, "Scanning Infrared Radiometer for Measuring the Air-Sea Temperature Difference," Appl. Opt. 40, 4807-4815 (2001)