Identification

Title

Role of convection in redistributing formaldehyde to the upper troposphere over North America and the North Atlantic during the summer 2004 INTEX campaign

Abstract

Measurements of formaldehyde (CH₂O) from a tunable diode laser absorption spectrometer (TDLAS) were acquired onboard the NASA DC-8 aircraft during the summer 2004 INTEX-NA campaign to test our understanding of convection and CH₂O production mechanisms in the upper troposphere (UT, 6 - 12 km) over continental North America and the North Atlantic Ocean. The present study utilizes these TDLAS measurements and results from a box model to (1) establish sets of conditions by which to distinguish "background" UT CH₂O levels from those perturbed by convection and other causes; (2) quantify the CH₂O precursor budgets for both air mass types; (3) quantify the fraction of time that the UT CH₂O measurements over North America and North Atlantic are perturbed during the summer of 2004; (4) provide estimates for the fraction of time that such perturbed CH₂O levels are caused by direct convection of boundary layer CH₂O and/or convection of CH₂O precursors; (5) assess the ability of box models to reproduce the CH₂O measurements; and (6) examine CH₂O and HO₂ relationships in the presence of enhanced NO. Multiple tracers were used to arrive at a set of UT CH₂O background and perturbed air mass periods, and 46% of the TDLAS measurements fell within the latter category. In general, production of CH₂O from CH₄ was found to be the dominant source term, even in perturbed air masses. This was followed by production from methyl hydroperoxide, methanol, PAN-type compounds, and ketones, in descending order of their contribution. At least 70% to 73% of the elevated UT observations were caused by enhanced production from CH₂O precursors rather than direct transport of CH₂O from the boundary layer. In the presence of elevated NO, there was a definite trend in the CH₂O measurement - model discrepancy, and this was highly correlated with HO₂ measurement - model discrepancies in the UT.

Resource type

document

Resource locator

Unique resource identifier

code

https://n2t.org/ark:/85065/d7bc3zq5

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

2008-09-05T00:00:00Z

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