Identification

Title

Distinct surface response to black carbon aerosols

Abstract

For the radiative impact of individual climate forcings, most previous studies focused on the global mean values at the top of the atmosphere (TOA), and less attention has been paid to surface processes, especially for black carbon (BC) aerosols. In this study, the surface radiative responses to five different forcing agents were analyzed by using idealized model simulations. Our analyses reveal that for greenhouse gases, solar irradiance, and scattering aerosols, the surface temperature changes are mainly dictated by the changes of surface radiative heating, but for BC, surface energy redistribution between different components plays a more crucial role. Globally, when a unit BC forcing is imposed at TOA, the net shortwave radiation at the surface decreases by -5.87 +/- 0.67 W m(-2) (W m(-2))(-1) (averaged over global land without Antarctica), which is partially offset by increased downward longwave radiation (2.32 +/- 0.38 W m(-2) (W m(-2))(-1) from the warmer atmosphere, causing a net decrease in the incoming downward surface radiation of -3.56 +/- 0.60 W m(-2) (W m(-2))(-1). Despite a reduction in the downward radiation energy, the surface air temperature still increases by 0.25 +/- 0.08 K because of less efficient energy dissipation, manifested by reduced surface sensible (-2.88 +/- 0.43 W m(-2) (W m(-2))(-1)) and latent heat flux (-1.54 +/- 0.27 W m(-2) (W m(-2))(-1)), as well as a decrease in Bowen ratio (-0.20 +/- 0.07 (W m(-2))(-1)). Such reductions of turbulent fluxes can be largely explained by enhanced air stability (0.07 +/- 0.02 K (W m(-2))(-1)), measured as the difference of the potential temperature between 925 hPa and surface, and reduced surface wind speed (-0.05 +/- 0.01 m s(-1) (W m(-2))(-1)). The enhanced stability is due to the faster atmospheric warming relative to the surface, whereas the reduced wind speed can be partially explained by enhanced stability and reduced Equator-to-pole atmospheric temperature gradient. These rapid adjustments under BC forcing occur in the lower atmosphere and propagate downward to influence the surface energy redistribution and thus surface temperature response, which is not observed under greenhouse gases or scattering aerosols. Our study provides new insights into the impact of absorbing aerosols on surface energy balance and surface temperature response.

Resource type

document

Resource locator

Unique resource identifier

code

http://n2t.net/ark:/85065/d7p84gcb

codeSpace

Dataset language

eng

Spatial reference system

code identifying the spatial reference system

Classification of spatial data and services

Topic category

geoscientificInformation

Keywords

Keyword set

keyword value

Text

originating controlled vocabulary

title

Resource Type

reference date

date type

publication

effective date

2016-01-01T00:00:00Z

Geographic location

West bounding longitude

East bounding longitude

North bounding latitude

South bounding latitude

Temporal reference

Temporal extent

Begin position

End position

Dataset reference date

date type

publication

effective date

2021-09-17T00:00:00Z

Frequency of update

Quality and validity

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Conformity

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name of format

version of format

Constraints related to access and use

Constraint set

Use constraints

Limitations on public access

None

Responsible organisations

Responsible party

contact position

OpenSky Support

organisation name

UCAR/NCAR - Library

full postal address

PO Box 3000

Boulder

80307-3000

email address

opensky@ucar.edu

web address

http://opensky.ucar.edu/

name: homepage

responsible party role

pointOfContact

Metadata on metadata

Metadata point of contact