Extension of explicit radiance observations by the Stratospheric Sounding Unit into the lower stratosphere and lower mesosphere

It is shown that radiance observations centred at four additional levels in the stratosphere and lower mesosphere can be synthesized utilizing the measured limb‐brightening of the radiance observations of the Stratospheric Sounding Unit (SSU). These additional radiance measurements double the vertical range of explicit radiance observations from the SSU. As a series of Stratospheric Sounding Units have been flown on the TIROS‐N series of NOAA satellites, observations of zonal mean radiance, with higher vertical resolution than has generally been obtainable with nadir‐viewing satellite radiometers, are available since 1979 from the lower stratosphere to the lower mesosphere. The additional radiances have allowed operational monitoring of the long term climatology of the lower mesosphere by means of satellite observations to commence.