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<p class="MsoNormal">Hi Yongsu,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">One way to obtain raw uncertainties for both data constraints and controls is to remove the grid scaling factor (gamma) from the uncertainties actually used in V4r4’s optimization. Gamma is the square root of fractional grid area defined
as <o:p></o:p></p>
<p class="MsoNormal">gamma(I,j) = sqrt(A(I,j))/max(A(i,j)), where i,j are grid x- and y-index; A is grid cell area (as in RAC.data from model outpu); sqrt is square-root; max is maximum. Raw uncertainties (e_raw) then can be derived from uncertainties (e) that
are actually used in optimization (such as those specified in data.ecco) by using the following equation,
<o:p></o:p></p>
<p class="MsoNormal">e_raw = e*gamma.<o:p></o:p></p>
<p class="MsoNormal">The actual uncertainties (e) are distributed as part of V4r4’s ancillary data
<a href="https://podaac.jpl.nasa.gov/dataset/ECCO_L4_ANCILLARY_DATA_V4R4">https://podaac.jpl.nasa.gov/dataset/ECCO_L4_ANCILLARY_DATA_V4R4</a>.
<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">The raw uncertainties were originally produced by different from a few institutions. That information can be found in V4r4’s synopsis document (<a href="https://ecco-group.org/docs/v4r4_synopsis.pdf">https://ecco-group.org/docs/v4r4_synopsis.pdf</a>).
Since some of the raw uncertainties for V4r4 are the same as those for V4r3, additional information can be found in V4r3’s synopsis document (<a href="https://ecco.jpl.nasa.gov/drive/files/Version4/Release3/doc/v4r3_summary.pdf">https://ecco.jpl.nasa.gov/drive/files/Version4/Release3/doc/v4r3_summary.pdf</a>)
and data document (<a href="https://ecco.jpl.nasa.gov/drive/files/Version4/Release3/doc/v4r3_data.pdf">https://ecco.jpl.nasa.gov/drive/files/Version4/Release3/doc/v4r3_data.pdf</a>). In particular, V4r3’s synopsis describes the rationale behind splitting costs
to time-mean & time-varying parts and applying area-scaling factor, as well as how to derive actual uncertainties used in optimization from raw uncertainties.
<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">For next release (V4r5), we will include instructions about how to generate uncertainties used in optimization from raw uncertainties.
<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Best,<o:p></o:p></p>
<p class="MsoNormal">Ou Wang<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></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 NA Yongsu <ynaab@connect.ust.hk><br>
<b>Date: </b>Tuesday, November 15, 2022 at 12:28 PM<br>
<b>To: </b>ecco-support@mit.edu <ecco-support@mit.edu><br>
<b>Cc: </b>atnguyen@oden.utexas.edu <atnguyen@oden.utexas.edu>, jclmak <jclmak@ust.hk><br>
<b>Subject: </b>[EXTERNAL] [ecco-support] About raw uncertainty fields of v4r4<o:p></o:p></span></p>
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<p class="MsoNormal" style="background:white"><span style="font-size:12.0pt;color:black">Dear ECCO team,<o:p></o:p></span></p>
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<p class="MsoNormal" style="background:white"><span style="font-size:12.0pt;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal" style="background:white"><span style="font-size:12.0pt;color:black">I'm currently setting up a regional state estimate based on ECCOv4r4. I wonder if there is a way to download raw uncertainties (in lat/lon) of target observations (e.g.
satellite) and controls of both oceanic initial conditions and atmospheric forcings (i.e. from Chaudhuri et al. 2013).<o:p></o:p></span></p>
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<p class="MsoNormal" style="background:white"><span style="font-size:12.0pt;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal" style="background:white"><span style="font-size:12.0pt;color:black">Also, it would be great if there is a direction on how to process (e.g. split into time-mean/time-varying components, apply area-weighted scaling while mapping, etc.) the
raw files to make the files that have been distributed in v4r4. Thanks in advance!<o:p></o:p></span></p>
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<p class="MsoNormal" style="background:white"><span style="font-size:12.0pt;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal" style="background:white"><span style="font-size:12.0pt;color:black">Best wishes,<br>
Yongsu Na<o:p></o:p></span></p>
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<p class="MsoNormal" style="background:white"><span style="font-size:12.0pt;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal" style="background:white"><span style="font-size:12.0pt;color:black">-----<o:p></o:p></span></p>
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<p class="MsoNormal" style="background:white"><span style="font-size:12.0pt;color:black">PhD student<br>
Department of Ocean Science<br>
Hong Kong University of Science and Technology<o:p></o:p></span></p>
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<p class="MsoNormal" style="background:white"><span style="font-size:12.0pt;color:black">----- <o:p></o:p></span></p>
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