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<center>Go To: <a href="#temp">Temporal Coverage</a> | <a href="#spat">Spatial Coverage</a> | <a href="#levels">Levels</a> | <a href="#up">Update Schedule</a> | <a href="#plot">Download/Plot Data</a> | <a href="#restrict">Restrictions</a> |  <a href="#detail">Details</a> | <a href="#caveat">Caveats</a> |  <a href="#name">File Naming</a> | <a href="#citations">Citation</a> | <a href="#references">References</a>  | <a href="#source">Original Source</a> | <a href="#contact">Contact</a></center></font>
<h1>NCEP/NCAR Reanalysis Monthly Means and Other Derived Variables</h1>

<h4 class="data"><a name="short">One-Line Description:</a></h4><ul class="data">
	<li> NCEP/NCAR Reanalysis Monthly Means and Other Derived Variables..</li></ul>

<h4 class="data"><a name="temp">Temporal Coverage:</a></h4>
<ul class="data">
<li>Daily and Monthly Values for 1948/01 - present.</li>
<li>Long term monthly means, derived from data for years 1968 - 1996.</li>
</ul>

<h4 class="data"><a name="spat">Spatial Coverage:</a></h4>
<ul class="data">
<li>T62 Gaussian grid with 192x94 points</li>
<li>88.542N-88.542S, 0E-358.125E</li>
</ul>

<b>Temporal coverage:</b>
<ul>
<li>1/1/1958 - 11/2001 monthly means (not in CDAS update)
<li>Daily psi and chi: Jan 1 1948 to "present".
<li>Long-Term term monthly mean files are averaged over 1968-1996
</ul>

<h4 class="data"><a name="levels">Levels:</a></h4>
<ul class="data">
<li>2 Sigma levels: 0.995,0.2101 for monthly means and monthly LTMs.</li>
<li>5 sigma levels 0.995 , 0.8458 , 0.2582 , 0.2101 , 0.1682  for  chi & psi in daily, daily LTMs, and monthly means forms.</li>
</ul>

<h4 class="data"><a name="up">Update Schedule:</a></h4>
	<ul class="data">
<li>Monthly and daily for daily data.</li>
</ul>


<h4 class="data"><a name="plot">Download/Plot Data:</a></h4>

<table border="1">
<tr>
<th>Variables:</th>
<th>File</th>
<th>Units</th>
<th>Statistics Available</th>
</tr>

<tr>
<td><a hreflang="en" href="/psd/cgi-bin/db_search/DBSearch.pl?Variable=Divergence&Dataset=CDC+Derived+NCEP+Reanalysis+Products+Sigma+Level+Data">Divergence</a></td>
<td>div</td>
<td>1./s</td>
<td>mon mean,ltm</td>
</tr>
<tr>
<td><a hreflang="en" href="/psd/cgi-bin/db_search/DBSearch.pl?Variable=Relative+Vorticity&Dataset=CDC+Derived+NCEP+Reanalysis+Products+Sigma+Level+Data">Relative Vorticity</a></td>
<td>vort</td>
<td>1./s</td>
<td>mon mean,ltm</td>
</tr>

<tr>
<th>Derived</th>
<th>File</th>
<th>Units</th>
<th>Statistics Available</th>
</tr>
<tr>
<td><a hreflang="en" href="/psd/cgi-bin/db_search/DBSearch.pl?Variable=Velocity+Potential&Dataset=CDC+Derived+NCEP+Reanalysis+Products+Sigma+Level+Data&Dataset=CDC+Derived+NCEP+Reanalysis+Products+Daily+Sigma+Level+Data">Velocity Potential</a></td>
<td>chi</td>
<td>m*m/s</td>
<td>mon mean,ltm,day</td>
</tr>
<tr>
<td><a hreflang="en" href="/psd/cgi-bin/db_search/DBSearch.pl?Variable=Streamfunction&Dataset=CDC+Derived+NCEP+Reanalysis+Products+Sigma+Level+Data&Dataset=CDC+Derived+NCEP+Reanalysis+Products+Daily+Sigma+Level+Data">Streamfunction</a></td>
<td>psi</td>
<td>m*m/s</td>
<td>mon mean,ltm,day</td>
</tr>

</table><p>

<h4 class="data"><a name="restrict">Availability and Usage Restrictions:</a></h4>

<ul>
<li>Files are by anonymous FTP from ftp.cdc.noaa.gov in 
<a href="ftp://ftp.cdc.noaa.gov/Datasets/ncep.reanalysis.derived/sigma">
/Datasets/ncep.reanalysis.derived/sigma.</a>
<li>No usage restrictions.
</ul>

<h4 class="data"><a name="detail">Detailed Description:</a></h4>

<ul class="data"><li>
The NCEP/NCAR Reanalysis 1 project is using a state-of-the-art analysis/forecast
system to perform data assimilation using past data from 1948 to the present.
A large subset of this data is available from PSD in its original 4 times
daily format and as daily averages.  However, the data from 1948-1957 is
a little different, in the regular (non-Gaussian) gridded data.  That data
was done at 8 times daily in the model, because the inputs available in that
era were available at 3Z, 9Z, 15Z, and 21Z, whereas the 4x daily data has
been available at 0Z, 6Z, 12Z, and 18Z.  These latter times were forecasted
and the combined result for this early era is 8x daily.  The local
ingestion process took only the 0Z, 6Z, 12Z, and 18Z forecasted values, and
thus only those were used to make the daily time series and monthly means here.
</li>
	</ul>

<h4 class="data"><a name="caveat">Caveats:</a></h4>
<ul class="data">
	<li>None</li>
</ul>

<h4 class="data"><a name="name">Related File Naming &amp; Structure Information:</a></h4>
<p class="indent1">
<u>File Names:</u>
<ul class="data">
	<li>var.time.stat.nc &nbsp;&nbsp;<em>(In directory: /Datasets/ncep.reanalysis.derived/sigma/)</em></li>
</ul>
</p>


<p class="indent1">
<u>Dataset Format and Size</u>:<ul>

<li>All data are stored in netCDF files
<li>The data are divided by variable and type
<li>There are 119 files currently
<li>Sizes range are 1.7 Mbytes and 253.5 Mbytes
<li>Current total of about 8.2 Gbytes

</ul>
</p>

<p class="indent1">
<u>Missing Data:</u>
<ul>
	<li>Missing data is flagged with a value of 32767s for most.</li>
	<li>Chi & Psi monthly LTMs use 1.0e+30f.</li>
	<li>Monthly means and other LTMs us -9.96921e+36f</li>
</ul>
</p>

<h4 class="data"><a name="citations">Citation:</a></h4>
<ul class="data">
<li>For dataset source, please cite:Kalnay et al.,The NCEP/NCAR 40-year reanalysis project, Bull. Amer. Meteor. Soc., 77, 437-470, 1996. 
</li><li>



<strong>Please note:</strong>  If you acquire NCEP Reanalysis Derived
data products from PSD, we ask that you acknowledge us in your use of the 
data. This may be done by including text such as
<em>NCEP Reanalysis Derived data provided by the NOAA/OAR/ESRL PSD, Boulder, Colorado, USA, from their Web site at 
http://www.esrl.noaa.gov/psd/</em> in any documents or publications using
these data. We would also appreciate receiving a copy of the relevant
publications.  This will help PSD to justify keeping the 
NCEP Reanalysis Derived data set freely available online in the
future.  Thank you!

</li>
</ul>


<h4 class="data"><a name="references">References:</a></h4>
<ul class="data">
<li>"The NCEP/NCAR 40-years Reanalysis Project" (Bulletin of the American
Meteorological Society, Vol. 77, No. 3, March 1996).  This can be found
online at:
    <a
href="http://dss.ucar.edu/datasets/ds090.0/docs/publications/bams1996mar/?time=d">
http://dss.ucar.edu/datasets/ds090.0/docs/publications/bams1996mar/?time=d</a>
</li>

</ul>



<h4 class="data"><a name="contact">Contact:</a></h4>
<ul class="data">
	<li>
Physical Sciences Division: Data Management<br>
NOAA/ESRL/PSD<br>
325 Broadway<br>
Boulder, CO 80305-3328<br>
<a href="mailto:esrl.psd.data@noaa.gov"><em>esrl.psd.data@noaa.gov</em></a>

</li>
</ul>

      
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