Global distribution of moisture, evaporation-precipitation, and diabatic heating rates
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Global archives were established for ECMWF 12-hour, multilevel analysis beginning 1 January 1985; day and night IR temperatures, and solar incoming and solar absorbed. Routines were written to access these data conveniently from NASA/MSFC MASSTOR facility for diagnostic analysis. Calculations of diabatic heating rates were performed from the ECMWF data using 4-day intervals. Calculations of precipitable water (W) from 1 May 1985 were carried out using the ECMWF data. Because a major operational change on 1 May 1985 had a significant impact on the moisture field, values prior to that date are incompatible with subsequent analyses.Keywords:
Diabatic
Precipitable water
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Global diabatic heating is estimated using fields of directly computed heating components, in particular those due to shortwave radiation, longwave radiation, sensible heating, and latent heating produced every 6 hours. The role of average fields of diabatic heating in the generation of available potential energy is examined. It is observed that latent heating is most significant in generating available potential energy.
Diabatic
Longwave
Shortwave
Radiant energy
Shortwave radiation
Outgoing longwave radiation
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This paper examines a technique for retrieving from geostationary IR data the vertical profiles of heating and cooling due to moist diabatic processes. First, GOES IR imagery is used to estimate precipitation fields which are independent of fields inferred from residuals in heat budget analysis based on the FGGE level III-b data. Vertical distributions of the associated heating are then obtained using thermodynamic data from the level III-b analysis, one-dimensional cloud models, and the satellite-estimated precipitation. The technique was applied to infer heating in the South Pacific convergence zone during a portion of FGEE SOP-1, and the results were compared with heat-budget calculations made using the ECMWF analyses.
Diabatic
Intertropical Convergence Zone
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Annual cycle
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A two year run with the GLAS climate model with prescribed but seasonally varying boundary conditions provided mean monthly fluxes of sensible heat, latent heat, and radiative energy. These fluxes were analyzed to examine the energy exchange processes between the atmosphere and the ice-free ocean. A mean annual plot of monthly zonal fuxes of sensible heat, latent heat, and net radiation was produced. From these, northward transport of heat flux that would follow if the GCM simulated fluxes were consistent with oceanic circulation were produced. These results are compared with observations.
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The effects of two different evaporation parameterizations on the climate sensitivity to solar constant variations are investigated by using a zonally averaged climate model. The model is based on a two-level quasi-geostrophic zonally averaged annual mean model. One of the evaporation parameterizations tested is a nonlinear formulation with the Bowen ratio determined by the predicted vertical temperature and humidity gradients near the earth's surface. The other is the linear formulation with the Bowen ratio essentially determined by the prescribed linear coefficient.
Solar constant
Potential evaporation
Constant (computer programming)
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Nomograms of mean column heating, due to surface sensible and latent heat fluxes, have been developed from Stage and Businger's (1981a,b) boundary-layer model for cold air outbreaks over warm water. Mean sensible heating of the cloud-free region is related to the cloud-free path (CFP, the distance from the shore to the first cloud formation) and the difference between land-air and sea-surface temperatures θ1 and θ0, respectively. Mean latent heating is related to the CFP and the difference between land-air and sea-surface specific humidities q1 and q0, respectively. Results are also applicable to any path within the cloud-free region. Corresponding heat fluxes may be obtained by multiplying the mean heating by the mean wind speed in the boundary layer. The sensible heating, estimated by the present method, is found to be in good agreement with that computed from the bulk transfer formula. The sensitivity of the solutions to the variations in the initial coastal soundings and large-scale subsidence is also investigated. The results are not sensitive to divergence, but are affected by the initial lapse rate of potential temperature; the greater the stability, the smaller the heating, other factors being equal. Unless one knows the lapse rate at the shore, this requires another independent measurement. For this purpose, we propose to use the downwind slope of the square of the boundary layer height, the mean value of which is also directly proportional to the mean sensible heating. The height of the boundary layer should be measurable by future spaceborne lidar systems. The general behavior of the mean sensible heating, the potential temperature, and the height of the boundary layer as a function of downwind distance within the cloud-free region, and their relations to several important parameters are studied analytically in the Appendix. By-products include the finding that the sensible (latent) heat flux is virtually linear with the contrast in land-air and sea-surface temperatures (specific humidities), thus providing a new kind of flux parameterization in lieu of the classical bulk transfer formulas. The applicability of the results to lake-effect snowstorms is also noted. Finally, the method can be used in reverse to check the validity of boundary-layer models.
Precipitable water
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Carbon assimilation
Water balance
Carbon fibers
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Moisture transport in the atmosphere is one of the most significant components in the hydrological cycle. Under stationary condition, ocean surface fresh water flux, which is the difference between precipitation (P) and evaporation (E), is balanced by the divergence of column-integrated moisture transport (IMT) in the atmosphere. Characterizing accurately a global picture of IMT from observation is a difficult task. It requires measurements of vertical profiles for wind vector and humidity. More specifically, IMT can be defined as the integration in pressure coordinates the product of specific humidity q and wind vector u, where g is the gravitational acceleration, and p, is the atmospheric pressure at ocean surface.In this study, a statistical relationship is derived between u, and u(sub)s using data from numerical weather prediction model. The relationship is then validated using surface and vertical profile from radiosonde data, before applied to spacebased measurements.
Water cycle
Precipitable water
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Abstract The authors quantify systematic differences between modern observation- and reanalysis-based estimates of atmospheric heating rates and identify dominant variability modes over tropical oceans. Convergence of heat fluxes between the top of the atmosphere and the surface are calculated over the oceans using satellite-based radiative and sensible heat fluxes and latent heating from precipitation estimates. The convergence is then compared with column-integrated atmospheric heating based on Tropical Rainfall Measuring Mission data as well as the heating calculated using temperatures from the Atmospheric Infrared Sounder and wind fields from the Modern-Era Retrospective Analysis for Research and Applications (MERRA). Corresponding calculations using MERRA and the European Centre for Medium-Range Weather Forecasts Interim Re-Analysis heating rates and heat fluxes are also performed. The geographical patterns of atmospheric heating rates show heating regimes over the intertropical convergence zone and summertime monsoons and cooling regimes over subsidence areas in the subtropical oceans. Compared to observation-based datasets, the reanalyses have larger atmospheric heating rates in heating regimes and smaller cooling rates in cooling regimes. For the averaged heating rates over the oceans in 40°S–40°N, the observation-based datasets have net atmospheric cooling rates (from −15 to −22 W m−2) compared to the reanalyses net warming rates (5.0–5.2 W m−2). This discrepancy implies different pictures of atmospheric heat transport. Wavelet spectra of atmospheric heating rates show distinct maxima of variability in annual, semiannual, and/or intraseasonal time scales. In regimes where deep convection frequently occurs, variability is mainly driven by latent heating. In the subtropical subsidence areas, variability in radiative heating is comparable to that in latent heating.
Atmospheric Infrared Sounder
Intertropical Convergence Zone
Atmospheric Circulation
Atmospheric models
Atmospheric temperature
Earth's energy budget
Lapse rate
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This study focuses on the observations of global atmospheric heat distributions using satellite measurements. Major heat components such as radiation energy, latent heat and sensible heat are considered. The uncertainties and error sources are assessed. Results show that the atmospheric heat is basically balanced, and the observed patterns of radiation and latent heat from precipitation are clearly related to general circulation.
Atmospheric Circulation
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