Identification

Title

Effects of dust aerosols on tropospheric chemistry during a typical pre-monsoon season dust storm in northern India

Abstract

This study examines the effect of a typical pre-monsoon season dust storm on tropospheric chemistry through a case study in northern India. Dust can alter photolysis rates by scattering and absorbing solar radiation and provide surface area for heterogeneous reactions. We use the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem) to simulate the dust storm that occurred during 17-22 April 2010 and investigate the contribution of different processes on mixing ratios of several key trace gases including ozone, nitrogen oxides, hydrogen oxides, methanol, acetic acid and formaldehyde. We revised the Fast Troposphere Ultraviolet Visible (F-TUV) photolysis scheme to include effects of dust aerosols on photolysis rates in a manner consistent with the calculations of aerosol optical properties for feedback to the meteorology radiation schemes. In addition, we added 12 heterogeneous reactions on the dust surface, for which 6 reactions have relative-humidity-dependent reactive uptake coefficients (γ). The inclusion of these processes in WRF-Chem is found to reduce the difference between observed and modeled O3 from 16 ± 9 to 2 ± 8 ppbv and that in NOy from 2129 ± 1425 to 372 ± 1225 pptv compared to measurements at the high-altitude site Nainital in the central Himalayas, and reduce biases by up to 30% in tropospheric column NO2 compared to OMI retrievals. The simulated dust storm acted as a sink for all the trace gases examined here and significantly perturbed their spatial and vertical distributions. The reductions in these gases are estimated as 5-100%, and more than 80% of this reduction was due to heterogeneous chemistry. The RH dependence of γ is also found to have substantial impact on the distribution of trace gases, with changes of up to 20-25% in O3 and HO2, 50% in H2O2 and 100% in HNO3. A set of sensitivity analyses revealed that dust aging could change H2O2 and CH3COOH levels by up to 50% but has a relatively small impact on other gases.

Resource type

document

Resource locator

Unique resource identifier

code

http://n2t.net/ark:/85065/d7t154k3

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

2014-07-04T00:00:00Z

Frequency of update

Quality and validity

Lineage

Conformity

Data format

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