Impact of clouds on atmospheric heating based on the R04 CloudSat fluxes and heating rates data set

Abstract

[1] Among the largest uncertainties in quantifying the radiative impacts of clouds are those that arise from the inherent difficulty in precisely specifying the vertical distribution of cloud optical properties using passive satellite measurements. Motivated by the need to address this problem, CloudSat was launched in April 2006 carrying into orbit the first millimeter wavelength cloud radar to be flown in space. Retrieved profiles of liquid and ice cloud microphysical properties from this Cloud Profiling Radar form the basis of the CloudSat's fluxes and heating rates algorithm, 2B-FLXHR, a standard product that provides high vertical resolution profiles of radiative fluxes and atmospheric heating rates on the global scale. This paper describes the physical basis of the 2B-FLXHR algorithm and documents the first year of 2B-FLXHR data in the context of assessing the radiative impact of clouds on global and regional scales. The analysis confirms that cloud contributions to atmospheric radiative heating are small on the global scale because of a cancelation of the much larger regional heating from high clouds in the tropics and cooling from low clouds at higher latitudes. Preliminary efforts to assess the accuracy of the 2B-FLXHR product using coincident CERES data demonstrate that outgoing longwave fluxes are better represented than those in the shortwave but both exhibit good agreement with CERES on scales longer than 5 days and larger than 5°. Colocated CALIPSO observations of clouds that are undetected by CloudSat further indicate that while thin cirrus can introduce modest uncertainty in the products, low clouds that are obscured by ground clutter represent a far more important source of error in the current 2B-FLXHR product that must be addressed in subsequent versions of the algorithm.

Impacts of 3D Aerosol, Cloud, and Water Vapor Variations on the Recent Brightening during the South Asian Monsoon Season

“…The biases of outgoing shortwave (SW) radiation, outgoing longwave (LW) radiation, surface shortwave radiation (SSR), and surface LW radiation are less than 5.5 (6%), 0.1 (<0.1%), 16 (7%), and 13 W m −2 (4%), respectively. Moreover, the uncertainties in 2B-FLXHR fluxes decrease significantly for long time scale averages [18]. Therefore, the radiative forcing of clouds, derived from CloudSat, have been verified as credible, especially in large space and time scales [18,24].…”

“…Moreover, the uncertainties in 2B-FLXHR fluxes decrease significantly for long time scale averages [18]. Therefore, the radiative forcing of clouds, derived from CloudSat, have been verified as credible, especially in large space and time scales [18,24].…”

“…Although the BUGSrad defines the SW from 0-4 µm, the solar energy at 4-5 µm is excessively Remote Sens. 2018, 10, 651 4 of 17 low (approximately 0.39% of total solar energy) [18]. Therefore, the effect of this difference is ignorable in the definitions of the SW between CERES (0-5 µm) and BUGSrad (0-4 µm).…”

“…L'Ecuyer, et al [18] detected biases between the radiative data of 2B-FLXHR from CloudSat and those from CERES with monthly 5 • means on the global scale. The biases of outgoing shortwave (SW) radiation, outgoing longwave (LW) radiation, surface shortwave radiation (SSR), and surface LW radiation are less than 5.5 (6%), 0.1 (<0.1%), 16 (7%), and 13 W m −2 (4%), respectively.…”

“…The MYD08 and Level 2 aerosol layer products from MODIS and CALIPSO are used to describe the recent changes in aerosol loading in South Asia [16,17]. The CloudSat 2B-CLDCLASS, 2B-CWC-RO, and 2B-FLXHR products are used to quantify the 3D changes in cloud macrophysical and microphysical characteristics and corresponding variable radiative effects of clouds [18]. Moreover, environmental conditions are obtained from the European Centre for Medium-Range Weather Forecast-AUXiliary analysis (ECMWF-AUX) product [19].…”