Aerosol Direct Radiative Effect Sensitivity Analysis

Thorsen, Tyler J.; Ferrare, R. A.; Kato, Seiji; Winker, David M.

doi:10.1175/jcli-d-19-0669.1

Cited by 46 publications

(45 citation statements)

References 104 publications

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“…The dust extinction coefficient, single-scattering albedo (SSA), and asymmetry factor vary as a function of the dust size and composition, and these parameters were taken from the lookup table of Randles et al (2017). The dust aerosols were assumed to be well mixed within each layer of the modeled atmosphere; the overall extinction coefficients, SSAs, and asymmetry factors were calculated following Equations A1-A3 of Thorsen et al (2020).…”

Section: Rrtmgmentioning

confidence: 99%

Saharan Dust Effects on North Atlantic Sea‐Surface Skin Temperatures

et al. 2021

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Introduction and BackgroundSkin sea-surface temperatures (SST skin ) provide a key indicator of the air-sea exchanges at the ocean surface as well as the acquisition, storage, transport, and release of heat. The majority of the incoming solar radiation is absorbed in the upper ocean; most of the resulting heat gain is released to the lower atmosphere, helping to drive weather and climate. The Surface Radiative Fluxes (SRF) are influenced by the atmospheric state (Kato et al., 2020;Wild et al., 2013;Yamada & Hayasaka, 2016). The Saharan Air Layer (SAL) is a particular atmospheric anomaly that frequently occurs at large scales in the tropical North Atlantic Ocean and has consequences on the surface radiation budget (

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Section: Rrtmgmentioning

confidence: 99%

Saharan Dust Effects on North Atlantic Sea‐Surface Skin Temperatures

et al. 2021

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“…For this purpose partial derivatives (e.g., Soden et al, 2008;Shell et al, 2008;Thorsen et al, 2020) ∂ ∂x on a function f (x, . .…”

Section: Irradiance and Reari Kernelsmentioning

confidence: 99%

“…Similar to the analysis of Thorsen et al (2020), the size of the perturbation is chosen as an 1 % increase to the base value (δx = 0.01x). These approximated partial derivatives will be computed for GHI, DNI and REari and referred as irradiance kernels and REari kernel, respectively.…”

Section: Irradiance and Reari Kernelsmentioning

confidence: 99%

“…uated versus ground based observations (e.g., Inness et al, 2019b;Witthuhn et al, 2020;Zhang et al, 2020;Gueymard and Yang, 2020). Bulk absorption properties (e.g., single scattering albedo) has, to our knowledge, not been evaluated yet, despite its major impact on REari calculation (Thorsen et al, 2020). The REari is simulated with the TROPOS (Leibniz Institute of Tropospheric Research) -Cloud and Aerosol Radiative effect Simulator (T-CARS) using the CAMS RA data as input to the offline version of the ECMWF radiation scheme (ecRad) (Hogan and Bozzo, 2018).…”

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Aerosol properties and aerosol–radiation interactions in clear sky conditions over Germany

Witthuhn¹,

Hünerbein²,

Filipitsch³

et al. 2021

Preprint

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Abstract. The clear-sky radiative effect of aerosol-radiation interactions is of relevance for our understanding of the climate system. The influence of aerosol on the surface energy budget is of high interest for the renewable energy sector. In this study, the radiative effect is investigated in particular with respect to seasonal and regional variations for the region of Germany and the year 2015 at the surface and top of atmosphere using two complementary approaches. First, an ensemble of clear-sky models which explicitly consider aerosols is utilized to retrieve the aerosol optical depth and the surface direct radiative effect of aerosols by means of a clear sky fitting technique. For this, short-wave broadband irradiance measurements in the absence of clouds are used as a basis. A clear sky detection algorithm is used to identify cloud free observations. Considered are measurements of the shortwave broadband global and diffuse horizontal irradiance with shaded and unshaded pyranometers at 25 stations across Germany within the observational network of the German Weather Service (DWD). Clear sky models used are MMAC, MRMv6.1, METSTAT, ESRA, Heliosat-1, CEM and the simplified Solis model. The definition of aerosol and atmospheric characteristics of the models are examined in detail for their suitability for this approach. Second, the radiative effect is estimated using explicit radiative transfer simulations with inputs on the meteorological state of the atmosphere, trace-gases and aerosol from CAMS reanalysis. The aerosol optical properties (aerosol optical depth, Ångström exponent, single scattering albedo and assymetrie parameter) are first evaluated with AERONET direct sun and inversion products. The largest inconsistency is found for the aerosol absorption, which is overestimated by about 0.03 or about 30 % by the CAMS reanalysis. Compared to the DWD observational network, the simulated global, direct and diffuse irradiances show reasonable agreement within the measurement uncertainty. The radiative kernel method is used to estimate the resulting uncertainty and bias of the simulated direct radiative effect. The uncertainty is estimated to −1.5 ± 7.7 and 0.6 ± 3.5 W m−2 at the surface and top of atmosphere, respectively, while the annual-mean biases at the surface, top of atmosphere and total atmosphere are −10.6, −6.5 and 4.1 W m−2, respectively. The retrieval of the aerosol radiative effect with the clear sky models shows a high level of agreement with the radiative transfer simulations, with an RMSE of 5.8 W m−2 and a correlation of 0.75. The annual mean of the REari at the surface for the 25 DWD stations shows a value of −12.8 ± 5 W m−2 as average over the clear sky models, compared to −11 W m−2 from the radiative transfer simulations. Since all models assume a fixed aerosol characterisation, the annual cycle of the aerosol radiation effect cannot be reproduced. Out of this set of clear sky models, the largest level of agreement is shown by the ESRA and MRMv6.1 models.

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“…Alternatively, high-quality AOD obtained at high temporal scales are needed for process-oriented studies 27 , 28 and radiative closure experiments with the main goal to determine the precision with which a radiative transfer model can predict both direct and diffuse irradiances 29 , 30 . Finally, information on the uncertainty of the measured AOD is critical for the aerosol radiative forcing and its error estimation 31 – 33 .…”

Section: Background and Summarymentioning

confidence: 99%

Harmonized and high-quality datasets of aerosol optical depth at a US continental site, 1997–2018

et al. 2021

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Aerosol optical depth (AOD) characterizes the aerosol burden in the atmosphere, while its wavelength dependence is a sign of particle size. Long-term records of wavelength-resolved AOD with high quality and suitable continuity are required for climate change assessment. Typically, climate-related studies use AOD products provided by several, and perhaps different, ground-based instruments. The measurements from these instruments often have different accuracy and temporal resolution. To preserve the advantages of these products (high quality) and to reduce their disadvantages (patchy records), we generate a merged dataset obtained from four instruments deployed at a US continental site in which a nearly-continuous AOD record is found at two wavelengths (500 and 870 nm) with high quality and high temporal resolution (1-min) for a 21-yr period (1997–2018). The combined dataset addresses: (1) varying data quality and resolution mismatch of the individual AOD records, and (2) the uncertainty of the merged AOD and its relevance for user-specified needs. The generated dataset will be beneficial for a wide range of applications including aerosol-radiation interactions.

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Aerosol Direct Radiative Effect Sensitivity Analysis

Cited by 46 publications

References 104 publications

Saharan Dust Effects on North Atlantic Sea‐Surface Skin Temperatures

Saharan Dust Effects on North Atlantic Sea‐Surface Skin Temperatures

Aerosol properties and aerosol–radiation interactions in clear sky conditions over Germany

Harmonized and high-quality datasets of aerosol optical depth at a US continental site, 1997–2018

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