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<p class="MsoNormal"><span style="font-size:12.0pt">Dear Yaohua,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt">I can try responding and others more familiar with the relevant files can correct me if I say something wrong. There is no ocean bottom pressure data available before the GRACE launch. If there is a gridded
OBP data file covering the whole period of the ECCO estimation, it should have NaNs or some other fake value for the period prior to GRACE.
<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt">However, if you are interested in ocean bottom pressure values before 2002, you can use the estimates provided by the ECCO solutions (Release 4 covers
</span>1992.1.1 to 2017.12.31). <span style="font-size:12.0pt">These estimates are constrained by the GRACE data when such data exists, as well as by all the other data (altimetry, Argo, etc.) that we use in the ECCO optimization. <o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="color:black">--<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="color:black">Rui </span><span style="font-size:12.0pt"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt"><o:p> </o:p></span></p>
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<p class="MsoNormal"><b><span style="font-size:12.0pt;color:black">From: </span></b><span style="font-size:12.0pt;color:black"><ecco-support-bounces@mit.edu> on behalf of "yhzhu@fio.org.cn" <yhzhu@fio.org.cn><br>
<b>Reply-To: </b>"ECCO support list, wider membership" <ecco-support@mit.edu><br>
<b>Date: </b>Thursday, February 25, 2021 at 2:42 PM<br>
<b>To: </b>ecco-support <ecco-support@mit.edu><br>
<b>Subject: </b>[ecco-support] Where does OBP data before 2002 come from?<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal"><span style="font-size:12.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal">Dear Sir/madam,<o:p></o:p></p>
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<p class="MsoNormal">We have noticed that the ECCO4 product uses the Ocean Bottom Pressure (OBP) data from 1992.1.1 to 2017.12.31. However, the GRACE satellite was launched in 2002. We are wondering how the grided OBP data before 2002 were obtained? Could you
please list some references which validate or examine these data? Also, what is the difference between the grided OBP data from ECCO website (1992~2017) and those from NASA JPL website (starting in 2002 only)? If we are interested in the OBP data in the South
China Sea region, can we use the one downloaded from ECCO4 between 1992.1.1 and 2017.12.31, or, better use the segment after 2002?<o:p></o:p></p>
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<p class="MsoNormal">Your help is much appreciated.<o:p></o:p></p>
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<p class="MsoNormal">Best regards,<o:p></o:p></p>
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<p class="MsoNormal">Yaohua Zhu<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Verdana",sans-serif">yhzhu@fio.org.cn<o:p></o:p></span></p>
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