<html><head><meta http-equiv="Content-Type" content="text/html; charset=us-ascii"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class="">You can use your sensitivity experiments to select an optimized set of horizontal and vertical viscosities, and other empirical model parameters, for your model configuration as is done here: <a href="https://journals.ametsoc.org/mwr/article/133/5/1224/67525/Using-Green-s-Functions-to-Calibrate-an-Ocean" class="">https://journals.ametsoc.org/mwr/article/133/5/1224/67525/Using-Green-s-Functions-to-Calibrate-an-Ocean</a><div class=""><br class=""><div><blockquote type="cite" class=""><div class="">On Oct 11, 2020, at 8:36 PM, kunal madkaiker <<a href="mailto:kunal.madkaiker02@gmail.com" class="">kunal.madkaiker02@gmail.com</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><meta http-equiv="Content-Type" content="text/html; charset=utf-8" class=""><div dir="ltr" class=""><div class="">Dear All,</div><div class=""><br class=""></div><div class="">I need some help in setting up my model viscosities. Few model studies done in Arabian Sea and N. Indian ocean suggest that horizontal viscosity can be in the range of 5.E3 to 5.E4 m2/s whereas vertical viscosity can be set as 1.E-3 m2/s in this region. (My model setup has delT=120s, delX=delY=3000m)<br class=""></div><div class=""><br class=""></div><div class="">After going through the formulae in mom_calc_visc.F, I found 'viscAh=5.E3' computes to be 'viscAhgrid=0.26' (for consideration, selecting viscAhgrid=0.2), which satisfies stability and CFL criteria (Manual, Section 4.3.2.1, eq. 4.24, 4.26). Also, using viscAz=0.03, which satisfies eq. 4.28 for min delZ of 5m. I find this setup to be most stable (KE oscillations are the least) <br class=""></div><div class=""><br class=""></div><div class="">Now, manual suggests to setup viscAz=0.003, which is 1 order less than my computed value. Also, considering Munk eq. 4.27, ratio of (Ah/Mw^3) computes to be in order of 4x10^-13. So, for Mw=3000 m (delx/dely), Ah becomes 0.0127 m2/s, which is again an order less.</div><div class=""><br class=""></div><div class="">Can anyone shed some light on this? Incase second combination is more robust, I feel viscAhgrid value will be too small (Ah itself is in order of 1.E-2)<br class=""></div><div class=""></div><div class=""><br class=""></div><div class="">After doing some preliminary experiments, I observed the below mentioned points:</div><div class=""></div><div class="">1. Increasing vertical viscosity definitely subdues oscillations in the KE, but same may not be said for horizontal viscosity.<br class="">2. Reducing vertical viscosity is making the surface currents much stronger.</div><div class=""><br class=""></div><div class="">Kindly assist.</div><div class=""><br class=""></div><div class="">Regards</div><div class="">Kunal<br class=""></div><div class=""><span style="font-size:12pt;line-height:107%;font-family:"Times New Roman","serif"" class=""><span class=""></span></span>
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