Clear‐sky Atmospheric Radiative Transfer: A Model Intercomparison for Shortwave Irradiances

Wang, P.; Knap, Wouter; Munneke, Peter Kuipers; Stammes, P.

doi:10.1063/1.3116930

Cited by 2 publications

(6 citation statements)

References 4 publications

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“…For evaluation purposes, the broadband version of DAK has been compared with SMARTS (Simple Model of the Atmospheric Radiative Transfer of Sunshine) [ Gueymard , 2001] for cloudless model atmospheres [ Wang et al , 2009]. SMARTS performed well in the Michalsky et al [2006] comparisons.…”

Section: Radiative Transfer Modelmentioning

confidence: 99%

“…For atmospheres containing LOWTRAN aerosols the differences are within 10 W/m 2 . Wang et al [2009] attribute the differences to the fact that the settings of aerosol optical properties in SMARTS and DAK are not identical. The aerosol optical properties in SMARTS are based on fitting tabulated data, whereas DAK uses original tables.…”

Section: Radiative Transfer Modelmentioning

confidence: 99%

“…[10] For evaluation purposes, the broadband version of DAK has been compared with SMARTS (Simple Model of the Atmospheric Radiative Transfer of Sunshine) [Gueymard, 2001] for cloudless model atmospheres [Wang et al, 2009] The key quantities needed to run the DAK model in clear-sky mode are the aerosol optical properties and their wavelength dependence, water vapor and ozone columns, and the surface albedo. These will be described in turn.…”

Section: Radiative Transfer Modelmentioning

confidence: 99%

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Clear‐sky shortwave radiative closure for the Cabauw Baseline Surface Radiation Network site, Netherlands

et al. 2009

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[1] In this paper a clear-sky shortwave closure analysis is presented for the Baseline Surface Radiation Network (BSRN) site of Cabauw, Netherlands (51.97°N, 4.93°E). The analysis is based on an exceptional period of fine weather during the first half of May 2008, resulting in a selection of 72 comparisons, on 6 days, between BSRN measurements and Doubling Adding KNMI (DAK) model simulations of direct, diffuse, and global irradiances. The data span a wide range of aerosol properties, water vapor columns, and solar zenith angles. The model input consisted of operational Aerosol Robotic Network (AERONET) aerosol products and radiosonde data. The wavelength dependence of the aerosol optical thickness, single scattering albedo, and asymmetry parameter was taken into account. On the basis of these data, excellent closure was obtained: the mean differences between model and measurements are 2 W/m 2 (+0.2%) for the direct irradiance, 1 W/m 2 (+0.8%) for the diffuse irradiance, and 2 W/m 2 (+0.3%) for the global irradiance. The good results were obtained because of proper specification of the DAK model input and the high quality of the AERONET and BSRN measurements. The sensitivity of the achieved closure to uncertainties in the aerosol optical thickness, single scattering albedo, and asymmetry parameter was examined. Furthermore, several sensitivity experiments related to the wavelength dependence of the aerosol optical properties and the treatment of water vapor were performed. It appeared that a correct description of the wavelength dependence of the aerosol optical properties is important for achieving broadband closure. However, broadband closure can also be obtained by means of using spectrally averaged values of the single scattering albedo and the asymmetry parameter. Cancellation of errors in different parts of the solar spectrum also contributes to the achieved closure.

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Section: Radiative Transfer Modelmentioning

confidence: 99%

Section: Radiative Transfer Modelmentioning

confidence: 99%

Section: Radiative Transfer Modelmentioning

confidence: 99%

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Clear‐sky shortwave radiative closure for the Cabauw Baseline Surface Radiation Network site, Netherlands

et al. 2009

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“…The original version of the DAK model is a line‐by‐line code, covering wavelengths from UV to near‐IR. The k distribution method is implemented in DAK to calculate broadband solar irradiances [ Kuipers Munneke et al , 2008; Wang et al , 2009b]. The global irradiances are calculated for 32 wavelength bands from 240 to 4600 nm using the k distribution coefficients for the absorptions by O 2 , CO 2 , O 3 and water vapor [ Kato et al , 1999].…”

Section: Methodsmentioning

confidence: 99%

“…For an exceptional period of cloudless weather during the first half of the campaign, Wang et al [2009a] obtained excellent shortwave broadband irradiance closure. The radiative transfer calculations were performed with the Doubling‐Adding KNMI (DAK) model [ De Haan et al , 1987; Stammes , 2001; Kuipers Munneke et al , 2008; Wang et al , 2009b], using Aerosol Robotic Network (AERONET) products for the characterization of aerosols and water vapor. The mean differences between model calculations and measurements were 2 W/m 2 (+0.2%) for the direct irradiance, 1 W/m 2 (+0.8%) for the diffuse irradiance, and 2 W/m 2 (+0.3%) for the global irradiance.…”

Section: Introductionmentioning

confidence: 99%

Cloudy sky shortwave radiative closure for a Baseline Surface Radiation Network site

Wang¹,

Knap²,

Stammes³

2011

J. Geophys. Res.

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A shortwave radiative closure analysis for cloudy skies is presented for the Cabauw Baseline Surface Radiation Network (BSRN) site (51.97°N, 4.93°E). The cloudy cases are carefully selected to be overcast, single‐layer, homogeneous, nonprecipitating water clouds. We selected in total 639 cases on 9 days between May 2008 and May 2009 and on 30 January 2007. The Doubling‐Adding KNMI (DAK) code is used to simulate global irradiances. The cloud optical thickness is derived from the cloud liquid water path from microwave radiometer (MWR) measurements and the MODIS L2 cloud effective radius product. The scattering phase matrix of the cloud particles is calculated using a Mie code with the two‐parameter Gamma size distribution. The MWR integrated water vapor column and an aerosol climatology are also used in the simulations. The cloudy cases cover a large range of liquid water path (30–400 g/m2), water vapor column (0.7–3.1 cm), and solar zenith angle (41°–75°). The mean difference between simulated global irradiances and BSRN measurements is 6 W/m2 (5%), with a standard deviation of 14 W/m2 (13%). This difference is within the uncertainties of the model input parameters and measurement errors. The correlation coefficient between the measured and simulated global irradiances is 0.95. The good closure results demonstrate the high quality of the MODIS effective radius data and MWR liquid water path data and the accuracy of the DAK model for the selected water cloud cases. Furthermore, the effects of clouds, aerosols, water vapor, and surface albedo on the global irradiance have been analyzed carefully. The sensitivity study shows that in order to achieve the closure with an uncertainty of a few W/m2, more frequent effective radius data, simultaneous aerosol and cloud measurements, and surface albedo measurements are essential.

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Clear‐sky Atmospheric Radiative Transfer: A Model Intercomparison for Shortwave Irradiances

Cited by 2 publications

References 4 publications

Clear‐sky shortwave radiative closure for the Cabauw Baseline Surface Radiation Network site, Netherlands

Clear‐sky shortwave radiative closure for the Cabauw Baseline Surface Radiation Network site, Netherlands

Cloudy sky shortwave radiative closure for a Baseline Surface Radiation Network site

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