Identification

Title

Dynamical tropopause based on isentropic potential vorticity gradients

Abstract

Since its inception, the dynamical tropopause based on potential vorticity (PV) is identified by the PV gradient on isentropes. Conceptually, significant isentropic gradients shown on the middle world PV maps reflect the underlying transport barrier associated with the tropopause, formed by jet streams that separate tropospheric air masses at low latitudes and stratospheric air masses at high latitudes. Largely owing to the lack of a general method, the dynamical tropopause has often been represented by a PV value chosen ad hoc without any temporal or spatial differentiation. In this work, we present a method for determining the PV isoline of the dynamical tropopause based on the isentropic PV gradients. Using 1 year of data from the European Centre for Medium–Range Weather Forecasts, the spatial and temporal variability of this PV gradient-based dynamical tropopause is examined. The results show that in general there is a broad distribution of PV values at the dynamical tropopause, ranging from 1.5 to 5 potential vorticity units. Therefore, a fixed PV surface for all isentropes and seasons does not accurately represent the location of the tropopause barrier. The PV at the dynamical tropopause increases with increasing potential temperature. This increase is more pronounced in the Southern Hemisphere than in the Northern Hemisphere. The seasonal cycle shows higher PV values at the dynamical tropopause during summer than during winter. This seasonal cycle is larger on higher isentropes. The dispersion of the PV at the dynamical tropopause about its mean is twofold larger during summer and autumn than during winter and spring in both hemispheres.

Resource type

document

Resource locator

Unique resource identifier

code

http://n2t.net/ark:/85065/d7k64jjs

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

2011-01-14T00:00:00Z

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