A global model–measurement evaluation of particle light scattering coefficients at elevated relative humidity
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- Stockholm University (Sweden); Bolin Centre for Climate Research, Stockholm (Sweden)
- University of Colorado, Boulder, CO (United States)
- University of Granada (Spain)
- European Centre for Medium-Range Weather Forecasts, Reading (United Kingdom)
- NASA/Goddard Space Flight Center, Greenbelt, MD (United States); University of Maryland, Baltimore County, MD (United States)
- NASA/Goddard Space Flight Center, Greenbelt, MD (United States); GESTAR/Universities Space Research Association, Columbia, MD (United States)
- Università degli Studi dell’Aquila, L’Aquila (Italy)
- Norwegian Meteorological Institute, Oslo (Norway)
- Finnish Meteorological Institute, Kuopio (Finland)
- Center for International Climate Research, Oslo (Norway)
- Nagoya University (Japan)
- NASA/Goddard Space Flight Center, Greenbelt, MD (United States)
- Royal Netherlands Meteorological Institute, De Bilt (Netherlands)
- Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)
- Paul Scherrer Institute, Villigen (Swtizerland)
- Appalachian State University, Boone, NC (United States)
- Chinese Academy of Meteorological Sciences, Beijing (China)
- Paul Scherrer Institute, Villigen (Switzerland); University of Applied Sciences, Windisch (Switzerland)
Abstract. The uptake of water by atmospheric aerosols has a pronounced effect on the particle light scattering properties which in turn are strongly dependent on the ambient relative humidity (RH). Earth system models need to account for the aerosol water uptake and its influence on light scattering in order to properly capture the overall radiative effects of aerosols. Here we present a comprehensive model-measurement evaluation of the particle light scattering enhancement factor f (RH), defined 5 as the particle light scattering coefficient at elevated RH (here set to 85 %) divided by its dry value. The comparison uses simulations from 10 global aerosol models and a global dataset of surface-based in situ measurements. In general, we find a large diversity in the magnitude of predicted f (RH) amongst the different models which can not be explained by the site types. There is strong indication that differences in the model parameterizations of hygroscopicity are driving at least some of the observed diversity in simulated f (RH). An important finding is that the models show a significantly larger discrepancy with the 10 observations if RHref =0 % is chosen as the model reference RH compared to RHref =40 %. The multi-site average ratio between model outputs and measurements is 1.64 in the former case and 1.16 in the latter. The disagreement is believed to originate from the hygroscopicity parameterisations at the lower RH range which may not implement all phenomenon taking place (i.e. not fully dried particles and hysteresis effects). Our results emphasize the need to consider the measurement conditions in such comparisons and recognize that measurements referred to as ’dry’ may not be dry in model terms.
- Research Organization:
- Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Univ. of Colorado, Boulder, CO (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Biological and Environmental Research (BER). Earth and Environmental Systems Science Division
- Grant/Contract Number:
- SC0016541; AC05-76RL01830
- OSTI ID:
- 1675164
- Alternate ID(s):
- OSTI ID: 1688421
- Report Number(s):
- PNNL-SA-150184
- Journal Information:
- Atmospheric Chemistry and Physics (Online), Vol. 20, Issue 17; Related Information: Burgos, M. A., Andrews, E. J., Titos, G., Benedetti, A., Bian, H., Buchard, V., Curci, G., Kipling, Z., Kirkevåg, A., Kokkola, H., Laakso, A., Letertre-Danczak, J., Lund, M. T., Matsui, H., Myhre, G., Randles, C., van Noije, T., Zhang, K., and Zieger, P.: Aerosol optical properties from ten earth system models for the year 2010, Dataset version 2.0, Bolin Centre Database, https://doi.org/10.17043/burgos-2020-esm-2, 2020Burgos, M. A., Andrews, E., Titos, G., Alados-Arboledas, L., Baltensperger, U., Day, D., Jefferson, A., Kalivitis, N., Mihalopoulos, N., Sherman, J., Sun, J., Weingartner, E., and Zieger, P.: Aerosol light scattering coefficients and scattering enhancement factors at 26 globally distributed stations 1998–2017, EBAS ACTRIS Data Centre, https://doi.org/10.21336/gen.4, 2019.; ISSN 1680-7324
- Publisher:
- European Geosciences UnionCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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