Shortwave radiative closure studies for clear skies during the Atmospheric Radiation Measurement 2003 Aerosol Intensive Observation Period

[1] The Department of Energy's Atmospheric Radiation Measurement (ARM) program sponsored a large aerosol intensive observation period (AIOP) to study aerosol during the month of May 2003 around the Southern Great Plains (SGP) Climate Research Facility (CRF) in north central Oklahoma. Redundant measurements of aerosol optical properties were made using different techniques at the surface as well as in vertical profile with sensors aboard two aircraft. One of the principal motivations for this experiment was to resolve the disagreement between models and measurements of diffuse horizontal broadband shortwave irradiance at the surface, especially for modest aerosol loading. This paper focuses on using the redundant aerosol and radiation measurements during this AIOP to compare direct beam and diffuse horizontal broadband shortwave irradiance measurements and models at the surface for a wide range of aerosol cases that occurred during 30 clear-sky periods on 13 days of May 2003. Models and measurements are compared over a large range of solar-zenith angles. Six different models are used to assess the relative agreement among them and the measurements. Better agreement than previously achieved appears to be the result of better specification of input parameters and better measurements of irradiances than in prior studies. Biases between modeled and measured direct irradiances are in the worst case 1%, and biases between modeled and measured diffuse irradiances are less than 1.9%.

[1]  Warren J. Wiscombe,et al.  The backscattered fraction in two-stream approximations. , 1976 .

[2]  Arild Gulbrandsen,et al.  On the Use of Pyranometers in the Study of Spectral Solar Radiation and Atmospheric Aerosols , 1978 .

[3]  L. J. Cox.  Optical Properties of the Atmosphere , 1979 .

[4]  F. X. Kneizys,et al.  THEORETICAL LINE SHAPE FOR H 2 O VAPOR; APPLICATION TO THE CONTINUUM , 1980 .

[5]  R. Goody.  Prospects for Atmospheric Radiation , 1987 .

[6]  K. Stamnes,et al.  Numerically stable algorithm for discrete-ordinate-method radiative transfer in multiple scattering and emitting layered media. , 1988, Applied optics.

[7]  C. McKay,et al.  Rapid calculation of radiative heating rates and photodissociation rates in inhomogeneous multiple scattering atmospheres , 1989 .

[8]  Eric P. Shettle,et al.  Atmospheric Aerosols: Global Climatology and Radiative Characteristics , 1991 .

[9]  A. Lacis,et al.  A description of the correlated k distribution method for modeling nongray gaseous absorption, thermal emission, and multiple scattering in vertically inhomogeneous atmospheres , 1991 .

[10]  J. Michalsky,et al.  Automated multifilter rotating shadow-band radiometer: an instrument for optical depth and radiation measurements. , 1994, Applied optics.

[11]  J. C. Liljegren,et al.  TWO-CHANNEL MICROWAVE RADIOMETER FOR OBSERVATIONS OF TOTAL COLUMN PRECIPITABLE WATER VAPOR AND CLOUD LIQUID WATER PATH , 1994 .

[12]  R. Kurucz.  Synthetic Infrared Spectra , 1994 .

[13]  E. Clothiaux,et al.  Uncertainties in modeled and measured clear‐sky surface shortwave irradiances , 1997 .

[14]  Gail P. Anderson,et al.  Comparison of model estimated and measured direct-normal , 1997 .

[15]  Catherine Gautier,et al.  SBDART: A Research and Teaching Software Tool for Plane-Parallel Radiative Transfer in the Earth's Atmosphere. , 1998 .

[16]  A. Smirnov,et al.  AERONET-a federated instrument network and data archive for aerosol Characterization , 1998 .

[17]  A. Berk,et al.  Models overestimate diffuse clear‐sky surface irradiance: A case for excess atmospheric absorption , 1998 .

[18]  Alexander Smirnov,et al.  Comparison of aerosol optical depth from four solar radiometers during the fall 1997 ARM intensive observation period , 1999 .

[19]  E. Clothiaux,et al.  The k-distribution method and correlated-k approximation for a shortwave radiative transfer model. , 1999 .

[20]  C. Gautier,et al.  Modified correlated k-distribution methods for remote sensing applications , 2000 .

[21]  Brett C. Bush,et al.  Characterization of Thermal Effects in Pyranometers: A Data Correction Algorithm for Improved Measurement of Surface Insolation , 2000 .

[22]  Stephen E. Schwartz,et al.  Comparison of model-estimated and measured diffuse downward irradiance at surface in cloud-free skies , 2000 .

[23]  C. Gueymard.  Parameterized transmittance model for direct beam and circumsolar spectral irradiance , 2001 .

[24]  Nels S. Laulainen,et al.  Multiyear measurements of aerosol optical depth in the Atmospheric Radiation Measurement and Quantitative Links programs , 2001 .

[25]  J. Ogren,et al.  Four years of continuous surface aerosol measurements from the Department of Energy's Atmospheric Radiation Measurement Program Southern Great Plains Cloud and Radiation Testbed site , 2001 .

[26]  M. Haeffelin,et al.  Determination of the thermal offset of the Eppley precision spectral pyranometer. , 2001, Applied optics.

[27]  Ibrahim Reda,et al.  Measurement of Broadband Diffuse Solar Irradiance Using Current Commercial Instrumentation with a Correction for Thermal Offset Errors , 2001 .

[28]  D. M. Powell,et al.  A comparison between modeled and measured clear‐sky radiative shortwave fluxes in Arctic environments, with special emphasis on diffuse radiation , 2002 .

[29]  A. Jefferson,et al.  Spatial variability of submicrometer aerosol radiative properties over the Indian Ocean during INDOEX , 2002 .

[30]  C. Gueymard.  Direct solar transmittance and irradiance predictions with broadband models. Part II: validation with high-quality measurements , 2003 .

[31]  Laurence S. Rothman,et al.  The HITRAN molecular spectroscopic database: edition of 2000 including updates through 2001 , 2003 .

[32]  Ibrahim Reda,et al.  Results from the first ARM diffuse horizontal shortwave irradiance comparison , 2003 .

[33]  R. Marchand,et al.  Simultaneous spectral albedo measurements near the Atmospheric Radiation Measurement Southern Great Plains (ARM SGP) central facility , 2003 .

[34]  R. Ferrare,et al.  In situ aerosol profiles over the Southern Great Plains cloud and radiation test bed site: 1. Aerosol optical properties , 2004 .

[35]  C. Gueymard.  The sun's total and spectral irradiance for solar energy applications and solar radiation models , 2004 .

[36]  Further developments in closure experiments for surface diffuse irradiance under cloud‐free skies at a continental site , 2004 .

[37]  Piet Stammes,et al.  Effect of aerosols on the downward shortwave irradiances at the surface: Measurements versus calculations with MODTRAN4.1 , 2004 .

[38]  J. Michalsky,et al.  Toward the development of a diffuse horizontal shortwave irradiance working standard , 2005 .

[39]  Shepard A. Clough,et al.  The effect of the half-width of the 22-GHz water vapor line on retrievals of temperature and water vapor profiles with a 12-channel microwave radiometer , 2005, IEEE Transactions on Geoscience and Remote Sensing.

[40]  Shepard A. Clough,et al.  Atmospheric radiative transfer modeling: a summary of the AER codes , 2005 .

[41]  C. Flynn,et al.  How well can we Measure the Vertical Profile of Tropospheric Aerosol Extinction , 2005 .

[42]  Beat Schmid,et al.  Comparison of methods for deriving aerosol asymmetry parameter , 2006 .

[43]  Alexander Smirnov,et al.  How well do State-of-the-Art Techniques Measuring the Vertical Profile of Tropospheric Aerosol Extinction Compare? , 2006 .

[44]  Beat Schmid,et al.  Evaluation of daytime measurements of aerosols and water vapor made by an operational Raman lidar over the Southern Great Plains , 2006 .