Observations of the Earth`s radiation budget in relation to atmospheric hydrology 4. Atmospheric column radiative cooling over the world`s oceans
- Colorado State Univ., Ft. Collins, CO (United States)
- Hadley Center for Climate Prediction and Research, Bracknell (United Kingdom)
- Brookhaven National Lab., Upton, NY (United States)
This paper introduces a simple method for deriving climatological values of the longwave flux emitted from the clear sky atmosphere to the ice-free ocean surface. Simulations of the clear sky longwave fluxes to space and to the surface are employed in this study to assist in the development of this flux retrieval which requires monthly averaged column-integrated water vapor w and the clear sky top-of-atmosphere (TOA) outgoing longwave flux (both available from satellite measurements). It is shown using both theory and data from simulations how the ratio of the surface to TOA flux is a simple function of w and a validation of the simple relationship is presented based on a limited set of surface flux measurements. The rms difference between the retrieved surface fluxes and the simulated surface fluxes is approximately 6 W m{sup {minus}2}. The clear sky column cooling rate of the atmosphere is derived from the Earth Radiation Budget Experiment (ERBE) values of the clear sky TOA flux and the surface flux retrieved using Special Scanning Microwave Imager (SSM/I) measurements of w together with ERBE clear sky fluxes. While a more global assessment of the cloud effect must await use of new satellite data that will allow the authors to estimate the contributions by clouds to these surface fluxes, it is shown in this paper how the longwave effects of clouds in a moist atmosphere where the column water vapor exceeds approximately 30 kg m{sup {minus}2} may be estimated from presently available satellite data with an uncertainty estimated to be approximately 0.2 K d{sup {minus}1}. Based on an approach described in this paper, the authors show how clouds in these relatively moist regions decrease the column cooling by almost 50% of the clear sky values and the existence of significant longitudinal gradients in column radiative heating across the equatorial and subtropical Pacific Ocean. 34 refs., 13 figs., 2 tabs.
- DOE Contract Number:
- FG02-89ER69027
- OSTI ID:
- 86687
- Journal Information:
- Journal of Geophysical Research, Vol. 99, Issue D9; Other Information: PBD: 20 Sep 1994
- Country of Publication:
- United States
- Language:
- English
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