TEMPORAL AND SPATIAL VARIATIONS IN THE PLANETARY-SCALE OUTGOING LONG-WAVE RADIATION AS DERIVED FROM TIROS II MEASUREMENTS

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  • 1 Meteorological Satellite Laboratory, U.S. Weather Bureau, Washington, D.C.
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Abstract

Daily composite charts of outgoing long-wave radiation between latitudes 55°N. and 55°S. were derived from TIROS II measurements for 26 days between late November 1960 and early January 1961. Samples of these charts reveal the wealth of information available about the radiation patterns over the earth and about the synoptic distributions of the major cloud fields. Mean maps of outgoing long-wave radiation for four periods of generally more abundant radiation data portray the broad-scale variations in the radiation pattern both geographically and in time. For the Northern Hemisphere these maps show how the long-wave radiation varied during some very large-scale changes in 700-mb. mean flow which were part of a remarkable energy, or index, cycle in this period. Most pronounced were the sharp decreases in outgoing radiation that accompanied the penetration of westerlies into the subtropics where anticyclones had prevailed previously. In the Southern Hemisphere some sizable temporal variations also occurred; these appeared to be representative of a change in circulation from a zonal to a more meridional type. Average latitudinal profiles of the outgoing radiation for these four mean periods and for the entire 26 days are also presented. The overall distribution shows maxima of outgoing radiation near 20°N. and 20°S. with lower values toward higher latitudes in both hemispheres and in equatorial regions. Comparisons of these measurements from TIROS II with previous estimates of outgoing long-wave radiation by investigators of the heat budget show relatively good agreement.

Abstract

Daily composite charts of outgoing long-wave radiation between latitudes 55°N. and 55°S. were derived from TIROS II measurements for 26 days between late November 1960 and early January 1961. Samples of these charts reveal the wealth of information available about the radiation patterns over the earth and about the synoptic distributions of the major cloud fields. Mean maps of outgoing long-wave radiation for four periods of generally more abundant radiation data portray the broad-scale variations in the radiation pattern both geographically and in time. For the Northern Hemisphere these maps show how the long-wave radiation varied during some very large-scale changes in 700-mb. mean flow which were part of a remarkable energy, or index, cycle in this period. Most pronounced were the sharp decreases in outgoing radiation that accompanied the penetration of westerlies into the subtropics where anticyclones had prevailed previously. In the Southern Hemisphere some sizable temporal variations also occurred; these appeared to be representative of a change in circulation from a zonal to a more meridional type. Average latitudinal profiles of the outgoing radiation for these four mean periods and for the entire 26 days are also presented. The overall distribution shows maxima of outgoing radiation near 20°N. and 20°S. with lower values toward higher latitudes in both hemispheres and in equatorial regions. Comparisons of these measurements from TIROS II with previous estimates of outgoing long-wave radiation by investigators of the heat budget show relatively good agreement.

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