TESTS OF THE DIAGNOSTIC-CYCLE ROUTINE IN THE INTERPRETATION OF LAYER-CLOUD EVOLUTIONS

Abstract

A Routine is described which is a collection of computer-programed techniques designed for the interpretation of meteorological satellite videograph observations. From the inferred evolution of the mass-structure distribution, the Routine diagnoses the horizontal velocity distribution for one or more isentropic surfaces. Using the horizontal velocity distribution as input, the Routine further derives net horizontal and net, vertical, parcel-displacements (in the synoptic range of scale) for specified regions and periods of time. This permits pattern configurations of layer-cloudiness to be remapped to later positions which arc consistent with the mass-motion evolutions. The use of the Routine for interpreting satellite cloud observations is illustrated by the presentation of two case studies. The layer-cloudiness distributions for the initial and terminal times of each case are analyzed primarily from the TIROS operational nephanalysis. The initial distribution of layer-cloudiness is remapped in accordance with the net horizontal displacement field. The cloud evolutions are shown and comparisons are made between the joint 24-hr. cloud displacement and net vertical, parcel-displacement patterns and the verifying 1ayer-cloudiness distributions. A close correspondence is found between the terminal position of the displaced cloudiness and the verifying cloudiness distributions. The patterns evolved in the horizontally displaced cloudiness are realistic reflections of the stages of development associated with vortex cloud patterns. Net vertical, parcel-displacement fields are generated which are consistent with conventional synoptic desiderata and the observed cloudiness. The, results indicate that the major portion of layer-cloudiness distributions in the synoptic range of scale in extratropical latitudes can be accounted for by the time-integrated, horizontal and vertical parcel-displacements. The implications of these results to the objective use of satellite data are discussed.