Representing anthropogenic dust in E3SMv1: Implementation, evaluation,
and assessment of their radiative forcing
Abstract
Dust emissions related to anthropogenic activities (i.e., anthropogenic
dust (AD)) is not represented in most global climate models and its
radiative impact remains unassessed. In this study, we develop a new and
physically based method to parameterize AD emission based on the DOE’s
Energy Exascale Earth System Model version 1 (E3SMv1). This method
relates AD emission to the crop land use fraction in the E3SMv1 land
component. Major AD sources simulated by our parameterization include
those over Central America, the Sahel, North India, and North China. The
annual averaged AD emission is 567 Tg yr-1 in present-day (year 2000),
which contributes to 13.3 % of total dust emission. Model evaluation
against satellite and ground-based observations shows that the new
parameterization can represent AD emissions and global dust cycle
reasonably well. We find that the total dust emission increases by 13 %
(495 Tg yr-1) from 1850 to 2000 mainly due to the cropland land use
fraction changes, which induces a net dust direct effective radiative
forcing of -0.041 W m-2 at top of the atmosphere. This AD-induced
cooling exceeds 10% of the total anthropogenic aerosol direct effective
radiative forcing from 1750 to 2014 estimated by the Intergovernmental
Panel on Climate Change Sixth Assessment Report. Our findings indicate
an important role of AD in the regional and global climate changes,
which should be included in future climate change assessments.