<div dir="ltr"><p>
Forgot:</p><p><br></p><p>CFSR uses:</p><p><br></p><p>  P_k = A_k + B_k*P_sfc<br></p><p><br></p><p>NCL's pres_hybrid_ccm uses a slightly different formulation. It uses<br></p><p>   the formula 
<i>p = a(k)*p0 + b(k)*ps</i>.
</p><p>
The CFSR uses, <i>ap(k) [=a(k)*p0]</i>, which has units
of pressure. <br></p><p>You must nake a(k) dimensionless prior to use. <br></p><p><br></p><p>Good luck<br></p></div><div class="gmail_extra"><br><div class="gmail_quote">On Mon, Jun 4, 2018 at 4:44 PM, Dennis Shea <span dir="ltr"><<a href="mailto:shea@ucar.edu" target="_blank">shea@ucar.edu</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><div id="m_4688570880874251445m_227792296267701757gmail-model-levels" style="display:block"><ul><br>You did not give any information on the source dataset you are using. Hence, hard to answer.<br>Maybe the following will help:<br><br>Source: <a href="https://rda.ucar.edu/datasets/ds093.1/docs/FAQs_hrly_timeseries.html" target="_blank">https://rda.ucar.edu/datasets/<wbr>ds093.1/docs/FAQs_hrly_timeser<wbr>ies.html</a><br><br>The Climate Forecast System uses a hybrid vertical coordinate that is defined by:
<ul>
P_k = A_k + B_k*P_sfc<br>
where P_k is the pressure at level k, and P_sfc is the surface pressure
</ul>
The values of A_k and B_k (units are Pa) are given in the following table:
<ul><table cellspacing="0" cellpadding="3" border="0">
<tbody><tr><th>k</th><th>A</th><th>B</th><th><br></th></tr>
<tr><td align="center">0</td><td align="center">0.0</td><td align="center">1.0</td><td><br></td></tr>
<tr><td align="center">1</td><td align="center">0.0</td><td align="center">0.99467117</td><td>(This is Hybrid Level 1)</td></tr>
<tr><td align="center">2</td><td align="center">0.57499999</td><td align="center">0.99862660</td><td><br></td></tr>
<tr><td align="center">3</td><td align="center">5.7410002</td><td align="center">0.98174226</td><td><br></td></tr>
<tr><td align="center">4</td><td align="center">21.516001</td><td align="center">0.97386760</td><td><br></td></tr>
<tr><td align="center">5</td><td align="center">55.712002</td><td align="center">0.96482760</td><td><br></td></tr>
<tr><td align="center">6</td><td align="center">116.89900</td><td align="center">0.95443410</td><td><br></td></tr>
<tr><td align="center">7</td><td align="center">214.01500</td><td align="center">0.94249105</td><td><br></td></tr>
<tr><td align="center">8</td><td align="center">356.22299</td><td align="center">0.92879730</td><td><br></td></tr>
<tr><td align="center">9</td><td align="center">552.71997</td><td align="center">0.91315103</td><td><br></td></tr>
<tr><td align="center">10</td><td align="center">812.48901</td><td align="center">0.89535499</td><td><br></td></tr>
<tr><td align="center">11</td><td align="center">1143.9880</td><td align="center">0.87522358</td><td><br></td></tr>
<tr><td align="center">12</td><td align="center">1554.7889</td><td align="center">0.85259068</td><td><br></td></tr>
<tr><td align="center">13</td><td align="center">2051.1499</td><td align="center">0.82731885</td><td><br></td></tr>
<tr><td align="center">14</td><td align="center">2637.5530</td><td align="center">0.79930973</td><td><br></td></tr>
<tr><td align="center">15</td><td align="center">3316.2170</td><td align="center">0.76851469</td><td><br></td></tr>
<tr><td align="center">16</td><td align="center">4086.6140</td><td align="center">0.73494524</td><td><br></td></tr>
<tr><td align="center">17</td><td align="center">4945.0288</td><td align="center">0.69868290</td><td><br></td></tr>
<tr><td align="center">18</td><td align="center">5884.2061</td><td align="center">0.65988702</td><td><br></td></tr>
<tr><td align="center">19</td><td align="center">6893.1172</td><td align="center">0.61879963</td><td><br></td></tr>
<tr><td align="center">20</td><td align="center">7956.9082</td><td align="center">0.57574666</td><td><br></td></tr>
<tr><td align="center">21</td><td align="center">9057.0508</td><td align="center">0.53113484</td><td><br></td></tr>
<tr><td align="center">22</td><td align="center">10171.712</td><td align="center">0.48544332</td><td><br></td></tr>
<tr><td align="center">23</td><td align="center">11276.348</td><td align="center">0.43921080</td><td><br></td></tr>
<tr><td align="center">24</td><td align="center">12344.490</td><td align="center">0.39301825</td><td><br></td></tr>
<tr><td align="center">25</td><td align="center">13348.671</td><td align="center">0.34746850</td><td><br></td></tr>
<tr><td align="center">26</td><td align="center">14261.435</td><td align="center">0.30316412</td><td><br></td></tr>
<tr><td align="center">27</td><td align="center">15056.342</td><td align="center">0.26068544</td><td><br></td></tr>
<tr><td align="center">28</td><td align="center">15708.893</td><td align="center">0.22057019</td><td><br></td></tr>
<tr><td align="center">29</td><td align="center">16197.315</td><td align="center">0.18329623</td><td><br></td></tr>
<tr><td align="center">30</td><td align="center">16503.145</td><td align="center">0.14926878</td><td><br></td></tr>
<tr><td align="center">31</td><td align="center">16611.604</td><td align="center">0.11881219</td><td><br></td></tr>
<tr><td align="center">32</td><td align="center">16511.736</td><td align="center">0.092166908</td><td><br></td></tr>
<tr><td align="center">33</td><td align="center">16197.967</td><td align="center">0.069474578</td><td><br></td></tr>
<tr><td align="center">34</td><td align="center">15683.489</td><td align="center">0.050646842</td><td><br></td></tr>
<tr><td align="center">35</td><td align="center">14993.074</td><td align="center">0.035441618</td><td><br></td></tr>
<tr><td align="center">36</td><td align="center">14154.316</td><td align="center">0.023555880</td><td><br></td></tr>
<tr><td align="center">37</td><td align="center">13197.065</td><td align="center">0.014637120</td><td><br></td></tr>
<tr><td align="center">38</td><td align="center">12152.937</td><td align="center">0.082940198</td><td><br></td></tr>
<tr><td align="center">39</td><td align="center">11054.853</td><td align="center">0.041067102</td><td><br></td></tr>
<tr><td align="center">40</td><td align="center">9936.6143</td><td align="center">0.016359100</td><td><br></td></tr>
<tr><td align="center">41</td><td align="center">8832.5371</td><td align="center">0.0043106001</td><td><br></td></tr>
<tr><td align="center">42</td><td align="center">7777.1499</td><td align="center">0.00036969999</td><td><br></td></tr>
<tr><td align="center">43</td><td align="center">6804.8740</td><td align="center">0.0</td><td><br></td></tr>
<tr><td align="center">44</td><td align="center">5937.0498</td><td align="center">0.0</td><td><br></td></tr>
<tr><td align="center">45</td><td align="center">5167.1460</td><td align="center">0.0</td><td><br></td></tr>
<tr><td align="center">46</td><td align="center">4485.4932</td><td align="center">0.0</td><td><br></td></tr>
<tr><td align="center">47</td><td align="center">3883.0520</td><td align="center">0.0</td><td><br></td></tr>
<tr><td align="center">48</td><td align="center">3351.4600</td><td align="center">0.0</td><td><br></td></tr>
<tr><td align="center">49</td><td align="center">2883.0381</td><td align="center">0.0</td><td><br></td></tr>
<tr><td align="center">50</td><td align="center">2470.7881</td><td align="center">0.0</td><td><br></td></tr>
<tr><td align="center">51</td><td align="center">2108.3660</td><td align="center">0.0</td><td><br></td></tr>
<tr><td align="center">52</td><td align="center">1790.0510</td><td align="center">0.0</td><td><br></td></tr>
<tr><td align="center">53</td><td align="center">1510.7111</td><td align="center">0.0</td><td><br></td></tr>
<tr><td align="center">54</td><td align="center">1265.7520</td><td align="center">0.0</td><td><br></td></tr>
<tr><td align="center">55</td><td align="center">1051.0800</td><td align="center">0.0</td><td><br></td></tr>
<tr><td align="center">56</td><td align="center">863.05798</td><td align="center">0.0</td><td><br></td></tr>
<tr><td align="center">57</td><td align="center">698.45697</td><td align="center">0.0</td><td><br></td></tr>
<tr><td align="center">58</td><td align="center">554.42401</td><td align="center">0.0</td><td><br></td></tr>
<tr><td align="center">59</td><td align="center">428.43399</td><td align="center">0.0</td><td><br></td></tr>
<tr><td align="center">60</td><td align="center">318.26599</td><td align="center">0.0</td><td><br></td></tr>
<tr><td align="center">61</td><td align="center">221.95799</td><td align="center">0.0</td><td><br></td></tr>
<tr><td align="center">62</td><td align="center">137.78999</td><td align="center">0.0</td><td><br></td></tr>
<tr><td align="center">63</td><td align="center">64.247002</td><td align="center">0.0</td><td><br></td></tr>
<tr><td align="center">64</td><td align="center">0.0</td><td align="center">0.0</td><td><br></td></tr>
</tbody></table></ul></ul></div></div><div class="gmail_extra"><br><div class="gmail_quote"><div><div class="h5">On Mon, Jun 4, 2018 at 2:33 PM, Matt Masarik <span dir="ltr"><<a href="mailto:mattmasarik@boisestate.edu" target="_blank">mattmasarik@boisestate.edu</a>></span> wrote:<br></div></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div><div class="h5"><div dir="ltr"><div>I'm interested in plotting PV on isentropic surfaces from the NCEP CFSRR (reforecast) data set.  I'm planning to interpolate variables to isentropes using (<a href="http://www.ncl.ucar.edu/Applications/Scripts/isent_1.ncl" target="_blank">http://www.ncl.ucar.edu/Appli<wbr>cations/Scripts/isent_1.ncl</a>) and then calculate PV on those surfaces using (<a href="http://www.ncl.ucar.edu/Document/Functions/Contributed/pot_vort_hybrid.shtml" target="_blank">http://www.ncl.ucar.edu/Docum<wbr>ent/Functions/Contributed/pot_<wbr>vort_hybrid.shtml</a>).</div><div><br></div><div>A helper function in there (pres_hybrid_ccm) requires Hybrid A and Hybrid B coefficients for mid- model levels.  I haven't been able to find anything for these constants in CFS on www..  Can someone point me to how I can find these?</div><div><br></div><div>Thank you,</div><div>Matt<br></div></div>
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