# Is it necessary to interpolate the atmospheric data to CRTM pressure levels?

**URL:** <https://forums.jcsda.org/t/is-it-necessary-to-interpolate-the-atmospheric-data-to-crtm-pressure-levels/170>\
**Category:** CRTM\
**Created:** [September 23, 2021, 8:25pm UTC](https://forums.jcsda.org/t/is-it-necessary-to-interpolate-the-atmospheric-data-to-crtm-pressure-levels/170 "2021-09-23T20:25:05Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**Author:** ![Jun](https://yyz1.discourse-cdn.com/flex031/user_avatar/forums.jcsda.org/jun/32/122_2.png) [@Jun](https://forums.jcsda.org/u/Jun)\
**Post date:** [September 23, 2021, 8:25pm UTC](https://forums.jcsda.org/t/is-it-necessary-to-interpolate-the-atmospheric-data-to-crtm-pressure-levels/170/1 "2021-09-23T20:25:05Z")

</div>

Do I need to interpolate the atmospheric data to CRTM pressure levels and layers before feeding them into the CRTM Atmosphere structure? Another radiative transfer model, RTTOV, has a fixed set of levels (54 or 101) and it automatically interpolate the input file data onto the fixed levels. I’m wondering if CRTM does the same way?  
Thanks!

---

<div class="post-metadata">

**Author:** ![BenjaminTJohnson](https://yyz1.discourse-cdn.com/flex031/user_avatar/forums.jcsda.org/benjamintjohnson/32/19_2.png) [@BenjaminTJohnson](https://forums.jcsda.org/u/BenjaminTJohnson)\
**Post date:** [September 27, 2021, 4:49pm UTC](https://forums.jcsda.org/t/is-it-necessary-to-interpolate-the-atmospheric-data-to-crtm-pressure-levels/170/2 "2021-09-27T16:49:46Z")

</div>

CRTM has variable number of levels, so you can provide the profiles with however many levels you like.  
For more specific information, please email me at bjohns@ucar.edu.