Search Results

You are looking at 1 - 10 of 70 items for :

  • Radiative transfer x
  • Meteorological Monographs x
  • All content x
Clear All
Eli J. Mlawer, Michael J. Iacono, Robert Pincus, Howard W. Barker, Lazaros Oreopoulos, and David L. Mitchell

drives the large-scale dynamics that moves energy from the tropics toward the poles. Radiation calculations are therefore essential for climate and weather simulations, but are themselves quite complex even without considering the effects of variable and inhomogeneous clouds. Clear-sky radiative transfer calculations have to account for thousands of absorption lines due to water vapor, carbon dioxide, and other gases, which are irregularly distributed across the spectrum and have shapes dependent on

Full access
V. Ramaswamy, W. Collins, J. Haywood, J. Lean, N. Mahowald, G. Myhre, V. Naik, K. P. Shine, B. Soden, G. Stenchikov, and T. Storelvmo

century, for example, Kirchhoff’s deductions concerning blackbody radiation, and the associated laws by Planck, Wien, Rayleigh–Jeans, and Stefan–Boltzmann. These laws, and the physics of thermal absorption and emission by gases and molecules, were applied to the context of the atmosphere, leading to the formalism of atmospheric longwave radiative transfer [see chapter 2 in Goody and Yung (1995) ]. Discovery and understanding of observed phenomena played a role throughout in the development of

Full access
Sally A. McFarlane, James H. Mather, and Eli J. Mlawer

using atmospheric properties measured or retrieved from other ARM instruments provides a test of how well the ARM measurements are able to characterize the full set of cloud, aerosol, atmospheric state, and surface properties in the vertical column. Such “radiative flux closure” exercises can identify weaknesses in measurements, retrievals, or radiative transfer models and indicate under what conditions ARM measurements are representative of the large-scale atmospheric conditions. While spectral

Full access

atmosphere. Currently, effort is directed toward placing these sensors at CART sites and validating the analysis approaches. The next step is to develop the means to convert the CART remote sensor data stream into the types of derived data quantities that are necessary to comprehend the effects the clouds and clear atmosphere on the IRF and GCM-class radiative transfer models. The IRF scientific questions being addressed with data from the SGP are not really site specific; the same questions could be

Full access
E. J. Mlawer and D. D. Turner

radiative transfer codes be able to reproduce these spectral measurements for a broad range of conditions. This perspective was central to the founding objectives of the ARM Program, provided an essential focus of the program during its early years, and was at the core of many of the program’s important accomplishments during its history. A critical motivation for establishing the Atmospheric Radiation Measurement (ARM) Program was to develop the capability to evaluate and improve line-by-line radiation

Full access
Steven Ghan and Joyce E. Penner

-scatter albedo in terms of droplet radius and the complex refractive index. After the optical properties of the cloud and aerosol layers are determined, these have to be used in radiative transfer models. The radiative transfer in simulated atmospheres containing aerosol, clouds, and gases including interactions with the surface was made substantially more robust with the development of the Rapid Radiative Transfer Model for GCMs (RRTMG) ( Mlawer et al. 1997 ; Iacono et al. 2003 , 2008 ); the history of

Full access

. General circulation model modelers will then be able to better identify the best approaches to improved parameterizations of radiative transfer effects. This is expected to greatly improve the accuracy of long-term general circulation model predictions and the efficacy of those predictions at the important regional scale, as the research community and DOE attempt to understand the effects of greenhouse gas emissions on Earth’s climate. The ARM initiative and field experiment The DOE’s ARM Program is a

Full access

otherwise unchanged from the original document. The Atmospheric Radiation Measurement (ARM) Program has matured into one of the key programs in the U.S. Climate Change Science Program. The ARM Program has achieved considerable scientific success in a broad range of activities, including site and instrument development, atmospheric radiative transfer, aerosol science, determination of cloud properties, cloud modeling, and cloud parameterization testing and development. The focus of ARM science has

Full access
D. D. Turner, E. J. Mlawer, and H. E. Revercomb

instruments (e.g., Raman lidars, global positioning systems, and microwave radiometers). However, because of the critical need to measure water vapor with the precision necessary to improve the accuracy of radiative transfer models, the program decided to deploy multiple instruments sensitive to water vapor at each site. This strategy provided opportunities to compare the different technologies and develop new methods to combine observations to create more accurate water vapor products. This chapter

Full access
Maike Ahlgrimm, Richard M. Forbes, Jean-Jacques Morcrette, and Roel A. J. Neggers

this approach are typically provided by the various ARM permanent and Mobile Facility sites established at locations from the Arctic to the tropics considered to represent key regimes in the earth’s climate and make ARM data invaluable for such long-term evaluation studies. 3. Advances in the parameterization of radiation transfer Radiative transfer calculations are an expensive part of the forecast model in terms of computational cost. Cost-saving compromises such as longer time steps, coarser

Full access