Identification

Title

Measurement of HOâ‚‚NOâ‚‚ in the free troposphere during the Intercontinental Chemical Transport Experiment - North America 2004

Abstract

The first direct in situ measurements of HO₂NO₂ in the upper troposphere were performed from the NASA DC-8 during the Intercontinental Chemical Transport Experiment-North America 2004 with a chemical ionization mass spectrometer (CIMS). These measurements provide an independent diagnostic of HOx chemistry in the free troposphere and complement direct observations of HOx, because of the dual dependency of HO₂NO₂ on HOx and NOx. On average, the highest HO₂NO₂ mixing ratio of 76 pptv (median = 77 pptv, σ = 39 pptv) was observed at altitudes of 8-9 km. Simple steady state calculations of HO₂NO₂, constrained by measurements of HOx, NOx, and J values, are in good agreement (slope = 0.90, R² = 0.60, and z = 5.5-7.5 km) with measurements in the midtroposphere where thermal decomposition is the major loss process. Above 8 km the calculated steady state HO&#x2082NO&#x2082 is in poor agreement with observed values (R2 = 0.20) and is typically larger by a factor of 2.4. Conversely, steady state calculations using model-derived HOx show reasonable agreement with the observed HO₂NO₂ in both the midtroposphere (slope = 0.96, intercept = 7.0, and R² = 0.63) and upper troposphere (slope = 0.80, intercept = 32.2, and R² = 0.58). These results indicate that observed HO₂ and HO₂NO₂ are in poor agreement in the upper troposphere but that HO₂NO₂ levels are consistent with current photochemical theory.

Resource type

document

Resource locator

Unique resource identifier

code

https://n2t.org/ark:/85065/d7gb24bt

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

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

2007-02-10T00:00:00Z

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

Copyright 2007 American Geophysical Union.

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

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 date

2025-12-26T15:39:25.647733

Metadata language