<div dir="ltr">Hi, All<div><br></div><div>I have tried to do some vertical regridding work with NCL function int2p_n_wrap. I am trying to regrid the OH concentration (in kg/m3) from MERRA 2x2.5 grid (144x91x72) to GISS ModelE F40 (144x90x40). However, I have found some negative values in the regridded grid when I set linlog = -1. The negative values only happen on the first two levels near the surface and the rest of the levels seem to be fine. I think it is mainly because of the extrapolation near the surface. If I set linlog = 1, there will be some missing values in the first several levels near the surface then. I also tried to regrid other units such as mixing ratio and the same thing happens. I am not sure if it is because that the units can not just be interpolated or if there are ways to conserve the mass? I just started to learn how to use NCL and I couldn't figure out how to solve this. If anyone has some comments on how to address this, I would really appreciate it! </div><div><div><br></div><div>Attached is the NCL script used and I have uploaded the files needed to run the script to <i style="color:rgb(0,0,0)"><a href="http://ftp.cgd.ucar.edu/incoming">ftp.cgd.ucar.edu/incoming</a>.</i><span style="color:rgb(0,0,0)"> These files are: </span><font color="#000000"><a href="http://OH_3Dglobal.geos5.72L.2x25.hemco.nc">OH_3Dglobal.geos5.72L.2x25.hemco.nc</a>; <a href="http://pressure.MERRA.nc">pressure.MERRA.nc</a>; <a href="http://pressure.GCAP_2000s.F40.nc">pressure.GCAP_2000s.F40.nc</a>. </font></div><div><font color="#000000"><br></font></div><div><font color="#000000">p.s. I am using NCL version 6.3.0 and the system I am on is linux RHEL6.6x86_64.</font></div><div><font color="#000000"><br></font></div><div><font color="#000000">Thank you so much for your time!</font></div><div>Jessie</div></div>-- <br><div class="gmail_signature"><div dir="ltr">Huanxin (Jessie) Zhang<div>PhD Candidate in Environmental Engineering-Atmospheric Chemistry Modeling</div><div>Dept. of Geological and Mining Engr. & Sciences</div><div>Michigan Technological University</div><div>1400 Townsend Drive, Houghton, MI, 49931</div><div><a href="mailto:huanxinz@mtu.edu" target="_blank">Email: huanxinz@mtu.edu</a></div></div></div>
</div>