Identification

Title

The impact of temperature vertical structure on trajectory modeling of stratospheric water vapor

Abstract

Lagrangian trajectories driven by reanalysis meteorological fields are frequently used to study water vapor (H₂O) in the stratosphere, in which the tropical cold-point temperatures regulate the amount of H₂O entering the stratosphere. Therefore, the accuracy of temperatures in the tropical tropopause layer (TTL) is of great importance for understanding stratospheric H₂O abundances. Currently, most reanalyses, such as the NASA MERRA (Modern Era Retrospective – analysis for Research and Applications), only provide temperatures with ~ 1.2 km vertical resolution in the TTL, which has been argued to miss finer vertical structure in the tropopause and therefore introduce uncertainties in our understanding of stratospheric H₂O. In this paper, we quantify this uncertainty by comparing the Lagrangian trajectory prediction of H₂O using MERRA temperatures on standard model levels (traj.MER-T) to those using GPS temperatures at finer vertical resolution (traj.GPS-T), and those using adjusted MERRA temperatures with finer vertical structures induced by waves (traj.MER-Twave). It turns out that by using temperatures with finer vertical structure in the tropopause, the trajectory model more realistically simulates the dehydration of air entering the stratosphere. But the effect on H₂O abundances is relatively minor: compared with traj.MER-T, traj.GPS-T tends to dry air by ~ 0.1 ppmv, while traj.MER-Twave tends to dry air by 0.2-0.3 ppmv. Despite these differences in absolute values of predicted H₂O and vertical dehydration patterns, there is virtually no difference in the interannual variability in different runs. Overall, we find that a tropopause temperature with finer vertical structure has limited impact on predicted stratospheric H₂O.

Resource type

document

Resource locator

Unique resource identifier

code

https://n2t.org/ark:/85065/d79c6zmn

codeSpace

Dataset language

eng

Spatial reference system

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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

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West bounding longitude

East bounding longitude

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Temporal extent

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Dataset reference date

date type

publication

effective date

2015-03-31T00:00:00Z

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Conformity

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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

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