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

Abstract

[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.

Complex experiment on studying the microphysical, chemical, and optical properties of aerosol particles and estimating the contribution of atmospheric aerosol-to-earth radiation budget

“…The analysis also shows that the average differences between empirical data and model calculations are close to results obtained by other authors in other regions (Kato et al, 1997;Henzing et al, 2004;Michalsky et al, 2006;Nowak et al, 2008;Wang et al, 2009;Halthore et al, 1998Halthore et al, , 2004Plakhina et al, 1998;Chubarova et al, 1999). It is important that our results were obtained under the conditions of high and moderate atmospheric transmittance, where the optical depth, scattering phase function, and aerosol single scattering albedo errors increase significantly.…”

Aerosols in the convective boundary layer: Shortwave radiation effects on the coupled land‐atmosphere system

“…With respect to observations, by isolating the aerosol impacts on the SW radiation, Hatzianastassiou et al [2005] and Wang et al [2009] have shown that detailed aerosol temporal evolution and vertical profiles are needed to reproduce the observed direct/diffuse partitioning and global irradiance [see also Meywerk and Ramanathan, 1999;Singh et al, 2010]. The available observational campaigns studying the aerosol impacts on the troposphere [e.g., de Wekker et al, 2004;Johnson et al, 2008] focused mainly on instrument comparisons and data validation without discussing in detail how the aerosols influence the boundary-layer vertical structure and the CBL heat budget.…”

“…Depending on the aerosol characteristics [Liu and Ou, 1990;Wang et al, 2009], chemical composition [Yu and Zhang, 2011], and vertical distribution [Knapp et al, 2002;Raut and Chazette, 2008;Sakaeda et al, 2011], their effects on the surface radiation/energy budgets range from negligible to very significant [see also Kaufman et al, 2002;Matthias and Bosenberg, 2002;Forster et al, 2007;Arneth et al, 2010;Costabile et al, 2013]. More specifically, aerosols modify the convective boundary layer (CBL) dynamics changing its depth, vertical structure, and entrainment zone characteristics [Ackerman, 1977;Venkatram and Viskanta, 1977;Zhang et al, 2010;Barbaro et al, 2013].…”

Comparison between measurements and model simulations of solar radiation at a high altitude site: Case studies for the Izana BSRN station

“…The mean differences of modeled minus observed global SDR are small (<1%) and within the instrumental error. [2] found mean differences between model and measurements of 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 at Cabauw (Netherlands) BSRN site.…”