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<p class="MsoNormal">Yaohua,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">There are *<b>no</b>* ocean bottom pressure (OBP) data before 2002 used in ECCO V4. The GRACE data since 2002 is the only OBP data used. If you referred the OBP files for 1922-2001, e.g. GRACE_jpl_rl05m_20180122_1992…, GRACE_jpl_rl05m_20180122_2001,
in <a href="https://ecco.jpl.nasa.gov/drive/files/Version4/Release4/input_ecco/input_bp">
https://ecco.jpl.nasa.gov/drive/files/Version4/Release4/input_ecco/input_bp</a>, they only contain fill values (-999) and there are no valid data in those files.
<o:p></o:p></p>
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<p class="MsoNormal">Regards,<o:p></o:p></p>
<p class="MsoNormal">Ou<o:p></o:p></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 11:43 AM<br>
<b>To: </b>ecco-support <ecco-support@mit.edu><br>
<b>Subject: </b>[EXTERNAL] [ecco-support] Where does OBP data before 2002 come from?<o:p></o:p></span></p>
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<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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