Journal cover Journal topic
Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
https://doi.org/10.5194/acp-2018-242
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.
Research article
14 Mar 2018
Review status
This discussion paper is a preprint. A revision of the manuscript is under review for the journal Atmospheric Chemistry and Physics (ACP).
How reliable are CMIP5 models in simulating dust optical depth?
Bing Pu1,2 and Paul Ginoux2 1Atmospheric and Oceanic Sciences Program, Princeton University, Princeton, New Jersey 08544
2NOAA Geophysical Fluid Dynamics Laboratory, Princeton, New Jersey 08540
Abstract. Dust aerosol plays an important role in the climate system by affecting the radiative and energy balances. Biases in dust modeling may result in biases in simulating global energy budget and regional climate. It is thus very important to understand how well dust is simulated in the Coupled Model Intercomparison Project Phase 5 (CMIP5) models. Here seven CMIP5 models using interactive dust emission schemes are examined against satellite derived dust optical depth (DOD) during 2004–2016.

It is found that multi-model mean can largely capture the global spatial pattern and zonal mean of DOD over land in present-day climatology in MAM and JJA. Global mean land DOD is underestimated by −25.2 % in MAM to −6.4 % in DJF. While seasonal cycle, magnitude, and spatial pattern are generally captured by multi-model mean over major dust source regions such as North Africa and the Middle East, these variables are not so well represented by most of the models in South Africa and Australia. Interannual variations of DOD are neither captured by most of the models nor by multi-model mean. Models also do not capture the observed connections between DOD and local controlling factors such as surface wind speed, bareness, and precipitation. The constraints from surface bareness are largely underestimated while the influences of surface wind and precipitation are overestimated.

Projections of DOD change in the late half of the 21st century under the Representative Concentration Pathways 8.5 scenario by multi-model mean is compared with those projected by a regression model. Despite the uncertainties associated with both projections, results show some similarities between the two, e.g., DOD pattern over North Africa in DJF and JJA, an increase of DOD in the Arabian Peninsula in all seasons, and a decrease over northern China from MAM to SON.

Citation: Pu, B. and Ginoux, P.: How reliable are CMIP5 models in simulating dust optical depth?, Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2018-242, in review, 2018.
Bing Pu and Paul Ginoux
Bing Pu and Paul Ginoux
Bing Pu and Paul Ginoux

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Short summary
Biases in dust modeling may result in biases in simulating energy budget and regional climate. Output of seven Coupled Model Intercomparison Project Phase 5 (CMIP5) models is examined. Seasonal cycle and spatial pattern of dust optical depth (DOD) in very dusty regions are largely captured by multi-model mean. But observed connections between DOD and local controlling factors such as bareness are not well represented. Future projections by CMIP5 models and a regression model are also analyzed.
Biases in dust modeling may result in biases in simulating energy budget and regional climate....
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