Impact of radiatively interactive dust aerosols in the NASA GEOS‐5 climate model: Sensitivity to dust particle shape and refractive index

By Peter R. Colarco, E. Nowottnick, C. Randles, Bingqi Yi, Ping Yang, Kyu-Myong Kim, J. A. Smith, C. Bardeen. 2014

169 citations recorded by the source corpus.

The radiative effects of Saharan dust aerosols are investigated in the NASA GEOS‐5 atmospheric general circulation model. A sectional aerosol microphysics model (CARMA) is run online in GEOS‐5. CARMA treats the dust aerosol lifecycle, and its tracers are radiatively coupled to GEOS‐5. A series of AMIP‐style simulations are performed, in which input dust optical properties (particle shape and refractive index) are varied. Simulated dust distributions for summertime Saharan dust compare well to observations, with best results found when the most absorbing dust optical properties are assumed. Dust absorption leads to a strengthening of the summertime Hadley cell circulation, increased dust lofting to higher altitudes, and a strengthening of the African easterly jet, resulting in increased dust atmospheric lifetime and farther northward and westward transport. We find a positive feedback of dust radiative forcing on emissions, in contrast with previous studies, which we attribute to our having a relatively strong longwave forcing caused by our simulating larger effective particle sizes. This longwave forcing reduces the magnitude of midday net surface cooling relative to other studies, and leads to a nighttime warming that results in higher nighttime wind speeds and dust emissions. The radiative effects of dust particle shape have only minor impact on transport and emissions, with small (~5%) impact on top of atmosphere shortwave forcing, in line with previous studies, but relatively more pronounced effects on shortwave atmospheric heating and surface forcing (~20% increase in atmospheric forcing for spheroids). Shape effects on longwave heating terms are of order ~10%.

Subfields: Atmospheric Science, Global and Planetary Change

View Paper: https://www.semanticscholar.org/paper/3ed883ae9f15b7b9eaa47642efa095b9dfe42d0b

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Citations in the corpus

The MERRA-2 Aerosol Reanalysis, 1980 - onward, Part I: System Description and Data Assimilation Evaluation. (2017, background): “due to their orbit and/or cloud contamination), contextual biases such as ”clear-sky” bias, and biases due to assumptions made in retrieval algorithms (Zhang and Reid 2009; Shi et al. 2011; Colarco et al. 2014).”
Using the OMI aerosol index and absorption aerosol optical depth to evaluate the NASA MERRA Aerosol Reanalysis (2014, background): “As detailed in Colarco et al. (2014), an alternative set of refractive indices is derived from the observationbased database (referred to hereafter as “observation-based”) constructed from Colarco et al. (2002) in the UV, Kim et al. (2011) in the visible and Shettle and Fenn (1979) in the infrared…”