Planck spectral radiance for wavelengths relevant to sea surface temperature estimation from space

Dependence of Planck spectral radiance (B) on temperature and wavelength in ranges relevant to thermal remote sensing of the oceans. Left panel: B against wavelength for a selection of temperatures relevant to terrestrial observation. Right panel: B curves against temperature for a selection of thermal window wavelengths. For temperatures typical of the terrestrial surface and low clouds, the Planck function per unit wavelength interval peaks around 10 micrometres, i.e., in the vicinity of the main window of high atmospheric transmission. Radiance is much greater in the 10 – 12 micrometres range than around 3.7 micrometres. However, the latter window has the advantage for SST estimation of a much steeper dependence of radiance with temperature.