Identification

Title

Chemical behavior of the tropopause observed during the Stratosphere-Troposphere Analyses of Regional Transport experiment

Abstract

During the Stratosphere-Troposphere Analyses of Regional Transport (START) experiment in December 2005, the behavior of the extratropical tropopause was examined under a variety of dynamical conditions. Using in situ measurements of ozone and water vapor, on board the new NSF/NCAR research aircraft Gulfstream V, and data from large-scale meteorological analyses, we address issues of the tropopause definitions and sharpness. Comparisons of the data from two flights show that the sharpness of chemical transitions across the tropopause varies with the sharpness of the static stability change across the tropopause. Using tracer correlations, air masses of mixed stratospheric and tropospheric characteristics are identified. The mixed air mass does not form a uniform mixing layer near the tropopause, but rather shows strong spatial variation. A depth of mixed air (~5 km in vertical distribution) is found on the cyclonic side of the polar jet, where the thermal gradient is weak and significant separation occurs between the thermal and the dynamical tropopause. Away from the jet or on the anticyclonic side of the jet, where the stability gradient is strong, the chemical transition across the tropopause was much more abrupt and shows minimum mixing. In both cases (either significant or minimal mixing), the thermal tropopause is shown to be approximately at the center of the mixing layer, and the altitude relative to the thermal tropopause is found to be an effective coordinate for locating the chemical transition. To further understand the role of the thermal and dynamical tropopause as a chemical transport boundary, tracer correlations are used to examine the chemical characteristics, and the trajectory calculations are used to infer the fate of the air mass between the thermal and dynamic tropopauses in the region of significant separation. The tracer correlation analysis shows that the air mass in this region is a mixture of stratospheric and tropospheric air but predominantly of tropospheric characteristics. Trajectory model calculations show that a significant fraction of the air parcels in this region ended in the mid to lower troposphere, which suggest the irreversible nature of the observed stratospheric intrusion.

Resource type

document

Resource locator

Unique resource identifier

code

http://n2t.net/ark:/85065/d71v5g8b

codeSpace

Dataset language

eng

Spatial reference system

code identifying the spatial reference system

Classification of spatial data and services

Topic category

geoscientificInformation

Keywords

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keyword value

Text

originating controlled vocabulary

title

Resource Type

reference date

date type

publication

effective date

2016-01-01T00:00:00Z

Geographic location

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East bounding longitude

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End position

Dataset reference date

date type

publication

effective date

2007-09-26T00:00:00Z

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Conformity

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version of format

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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

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