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<p class="MsoNormal"><span style="font-size:11.0pt">Hi Wenlan,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">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. <o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">Best regards,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">Ou Wang<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt"><b><span style="font-size:12.0pt;color:black">From:
</span></b><span style="font-size:12.0pt;color:black">ecco-support <ecco-support-bounces@mit.edu> on behalf of
</span><span style="font-size:12.0pt;font-family:"MS Gothic";color:black">范文</span><span style="font-size:12.0pt;font-family:"PingFang TC",sans-serif;color:black">蓝</span><span style="font-size:12.0pt;color:black"> <fwl@whu.edu.cn><br>
<b>Date: </b>Sunday, August 24, 2025 at 2:15</span><span style="font-size:12.0pt;font-family:"Arial",sans-serif;color:black"> </span><span style="font-size:12.0pt;color:black">AM<br>
<b>To: </b>ECCO support list, wider membership <ecco-support@mit.edu><br>
<b>Subject: </b>[EXTERNAL] [ecco-support] Question on tracer cell area calculation<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt">Hi, ecco team,<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt">Thank you again for your previous help in reading grid files; I have a follow-up question.<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt">According to grid variable documentation, I expected the horizontal area of every tracer cell to be<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt"> rA = dxG * dyG.<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt">However, after loading the variables from the grid file, the equality does not hold for any cell. <o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt">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? <o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt">If so, is reading rA directly the more accurate way to get the cell area?<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt">Thank you very much for your help.<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt">Best regards, <o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:9.0pt;font-family:Helvetica;color:black">————————————————<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:9.0pt;font-family:"MS Mincho";color:black">范</span><span style="font-size:9.0pt;font-family:Helvetica;color:black">
</span><span style="font-size:9.0pt;font-family:"MS Mincho";color:black">文</span><span style="font-size:9.0pt;font-family:Helvetica;color:black">
</span><span style="font-size:9.0pt;font-family:"PingFang TC",sans-serif;color:black">蓝</span><span style="font-size:9.0pt;font-family:Helvetica;color:black"><o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:9.0pt;font-family:Helvetica;color:black"><br>
Wenlan Fan, Ph.D Candidate<br>
GNSS Research Center, Wuhan University<br>
Wuhan, 430079, P. R. China<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:9.0pt;font-family:Helvetica;color:black">(+86)15708408018<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:9.0pt;font-family:Helvetica;color:black"><a href="mailto:fwl@whu.edu.cn">fwl@whu.edu.cn</a><o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt"><o:p> </o:p></span></p>
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