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geoschem / geos-chem

GEOS-Chem "Science Codebase" repository. Contains GEOS-Chem science routines, run directory generation scripts, and interface code. This repository is used as a submodule within the GCClassic and GCHP wrappers, as well as in other modeling contexts (external ESMs).
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[QUESTION] Altitude of GEOS-Chem vertical grid #1308

Closed JinZheeee closed 1 year ago

JinZheeee commented 2 years ago

Hi: I want to know how to obtain the altitudes of the 47 vertical layers. The website (http://wiki.seas.harvard.edu/geos-chem/index.php/GEOS-Chem_vertical_grids) listed the 47-layer altitudes, but are these values fixed for all the grids all the time? 图片

yantosca commented 2 years ago

Thanks for writing @JinZheeee. The example shown below assumes a surface pressure of 1013.25 hPa.

The hybrid grid formula is given in this section on the wiki: http://wiki.seas.harvard.edu/geos-chem/index.php/GEOS-Chem_vertical_grids#Hybrid_grid_definition

Note that above about level 36 or so the levels transition from varying with surface pressure to fixed. So near the top of the atmopshere the levels are the same for all (I,J,L) grid box locations. But near the surface the pressure follows the surface pressure.

yantosca commented 2 years ago

From the wiki, the transition pressure is about 170hPa. Any grid boxes skyward of 170 hPa are on fixed pressure levels.

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