[ecco-support] [EXTERNAL] Question on tracer cell area calculation

[Wang, Ou (US 329B)]

Hi Wenlan,

Using rA is the correct way to get the grid-cell area. The grid cells are not rectangular, so dxG*dyG is only an approximation of the actual grid cell area, rA.

Best regards,
Ou Wang

From: ecco-support <ecco-support-bounces at mit.edu> on behalf of 范文蓝 <fwl at whu.edu.cn>
Date: Sunday, August 24, 2025 at 2:15 AM
To: ECCO support list, wider membership <ecco-support at mit.edu>
Subject: [EXTERNAL] [ecco-support] Question on tracer cell area calculation
Hi, ecco team,

Thank you again for your previous help in reading grid files; I have a follow-up question.

According to grid variable documentation, I expected the horizontal area of every tracer cell to be

    rA = dxG * dyG.

However, after loading the variables from the grid file, the equality does not hold for any cell.

Does this mean that simply multiplying dxG by dyG is insufficient, and additional corrections (e.g., spherical-geometry factors) are still needed to obtain the true rA?
If so, is reading rA directly the more accurate way to get the cell area?

Thank you very much for your help.

Best regards,

————————————————
范 文 蓝

Wenlan Fan, Ph.D Candidate
GNSS Research Center, Wuhan University
Wuhan, 430079, P. R. China
(+86)15708408018
fwl at whu.edu.cn<mailto:fwl at whu.edu.cn>

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.mit.edu/pipermail/ecco-support/attachments/20250824/64814de2/attachment-0001.htm>