The High Resolution Dynamics Limb Sounder (HIRDLS) cloud detection and cloud top determination algorithm is described and applied to 2005-2007 HIRDLS radiance profiles. Statistical averages of HIRDLS and correlative cloud data are highly correlated. The 1998-2005 Halogen Occultation Experiment (HALOE) and HIRDLS time averaged cloud top pressures have a correlation coefficient of 0.87 and 0.93 in the tropics and midlatitudes, respectively. Time series of the temperature T < 195 K hemispherical area, on the 450 K potential temperature surface, and the total number of polar stratospheric clouds observed by the HIRDLS experiment in January and February 2005 have a correlation coefficient of 0.92. HALOE and HIRDLS normalized distributions of cloud counts, expressed as a function of outgoing longwave radiation (OLR), have a correlation coefficient of 0.99. Tropical averages of 1998-2005 HALOE and HIRDLS cloud occurrence frequencies at 82 and 100 hPa are within 25% of each other, and the morphology of latitude-longitude contour maps of cloud frequency are similar. Colocated Stratospheric Aerosol and Gas Experiment (SAGE III) and HIRDLS cloud top pressure values in 2005 have a correlation coefficient of 0.85 when the distance between observations is less than 100 km and the time difference is less than 6 h. Correlations between colocated SAGE III and HIRDLS cloud top pressures improve as space and time differences decrease.
