Identification

Title

Characterizing CO and NOy sources and relative ambient ratios in the Baltimore area using ambient measurements and source attribution modeling

Abstract

Modeled source attribution information from the Community Multiscale Air Quality model was coupled with ambient data from the 2011 Deriving Information on Surface conditions from Column and Vertically Resolved Observations Relevant to Air Quality Baltimore field study. We assess source contributions and evaluate the utility of using aircraft measured CO and NOy relationships to constrain emission inventories. We derive ambient and modeled CO:NOy ratios that have previously been interpreted to represent CO:NOy ratios in emissions from local sources. Modeled and measured CO:NOy are similar; however, measured CO:NOy has much more daily variability than modeled values. Sector-based tagging shows that regional transport, on-road gasoline vehicles, and nonroad equipment are the major contributors to modeled CO mixing ratios in the Baltimore area. In addition to those sources, on-road diesel vehicles, soil emissions, and power plants also contribute substantially to modeled NOy in the area. The sector mix is important because emitted CO:NOx ratios vary by several orders of magnitude among the emission sources. The model-predicted gasoline/diesel split remains constant across all measurement locations in this study. Comparison of CO:NOy to emitted CO:NOy is challenged by ambient and modeled evidence that free tropospheric entrainment, and atmospheric processing elevates ambient CO:NOy above emitted ratios. Specifically, modeled CO:NOy from tagged mobile source emissions is enhanced 5-50% above the emitted ratios at times and locations of aircraft measurements. We also find a correlation between ambient formaldehyde concentrations and measured CO:NOy suggesting that secondary CO formation plays a role in these elevated ratios. This analysis suggests that ambient urban daytime CO:NOy values are not reflective of emitted ratios from individual sources.

Resource type

document

Resource locator

Unique resource identifier

code

http://n2t.net/ark:/85065/d7j9693j

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

2018-03-27T00:00:00Z

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