A quasi-Lagrangian coordinate system based on high resolution tracer observations: implementation for the Antarctic polar vortex
Item
Title (Dublin Core)
A quasi-Lagrangian coordinate system based on high resolution tracer observations: implementation for the Antarctic polar vortex
Description (Dublin Core)
In order to quantitatively analyse the chemical and dynamical evolution of the polar vortex it has proven extremely useful to work with coordinate systems that follow the vortex flow. We propose here a two-dimensional quasi-Lagrangian coordinate system {<i>χ</i><sub><i>i</i></sub>, Δ<i>χ</i><sub><i>i</i></sub>}, based on the mixing ratio of a long-lived stratospheric trace gas <i>i</i>, and its systematic use with <i>i</i> = N<sub>2</sub>O, in order to describe the structure of a well-developed Antarctic polar vortex. In the coordinate system {<i>χ</i><sub><i>i</i></sub>, Δ<i>χ</i><sub><i>i</i></sub>} the mixing ratio <i>χ</i><sub><i>i</i></sub> is the vertical coordinate and Δ<i>χ</i><sub><i>i</i></sub> = <i>χ</i><sub><i>i</i></sub>(Θ)−<i>χ</i><sub><i>i</i></sub><sup>vort</sup>(Θ) is the meridional coordinate (<i>χ</i><sub><i>i</i></sub><sup>vort</sup>(Θ) being a vertical reference profile in the vortex core). The quasi-Lagrangian coordinates {<i>χ</i><sub><i>i</i></sub>, Δ<i>χ</i><sub><i>i</i></sub>} persist for much longer time than standard isentropic coordinates, potential temperature Θ and equivalent latitude <i>φ</i><sub>e</sub>, do not require explicit reference to geographic space, and can be derived directly from high-resolution in situ measurements. They are therefore well-suited for studying the evolution of the Antarctic polar vortex throughout the polar winter with respect to the relevant chemical and microphysical processes. By using the introduced coordinate system {<i>χ</i><sub>N<sub>2</sub>O,</sub> Δ<i>χ</i><sub>N<sub>2</sub>O</sub>} we analyze the well-developed Antarctic vortex investigated during the APE-GAIA (Airborne Polar Experiment – Geophysica Aircraft in Antarctica – 1999) campaign (Carli et al., 2000). A criterion, which uses the local in-situ measurements of <i>χ</i><sub><i>i</i></sub>=<i>χ</i><sub><i>i</i></sub>(Θ) and attributes the inner vortex edge to a rapid change (<i>δ</i>-step) in the meridional profile of the mixing ratio <i>χ</i><sub><i>i</i></sub>, is developed to determine the (Antarctic) inner vortex edge. In turn, we suggest that the outer vortex edge of a well-developed Antarctic vortex can be attributed to the position of a local minimum of the <i>χ</i><sub>H<sub>2</sub>O</sub> gradient in the polar vortex area. For a well-developed Antarctic vortex, the Δ<i>χ</i><sub>N<sub>2</sub>O</sub>-parametrization of tracer-tracer relationships allows to distinguish the tracer inter-relationships in the vortex core, vortex boundary region and surf zone and to examine their meridional variation throughout these regions. This is illustrated by analyzing the tracer-tracer relationships <i>χ</i><sub><i>i</i></sub> : <i>χ</i><sub>N<sub>2</sub>O</sub> obtained from the in-situ data of the APE-GAIA campaign for <i>i</i> = CFC-11, CFC-12, H-1211 and SF<sub>6</sub>. A number of solitary anomalous points in the CFC-11 : N<sub>2</sub>O correlation, observed in the Antarctic vortex core, are interpreted in terms of small-scale cross-isentropic dispersion.
Creator (Dublin Core)
Ivanova, E. V.
Volk, C. M.
Riediger, O.
Klein, H.
Sitnikov, N. M.
Ulanovskii, A. E.
Yushkov, V. A.
Ravegnani, F.
Möbius, T.
Schmidt, U.
Date (Dublin Core)
2018-08-09
Type (Dublin Core)
Text
Format (Dublin Core)
application/pdf
Identifier (Dublin Core)
10.5194/acpd-8-16123-2008
https://acp.copernicus.org/preprints/acpd-2008-0284/
Source (Dublin Core)
eISSN: 1680-7324
Language (Dublin Core)
eng
