# Different altitudes?

**URL:** <https://openradar.discourse.group/t/different-altitudes/641>\
**Category:** Retrievals\
**Tags:** pydda\
**Created:** [August 27, 2025, 4:17pm UTC](https://openradar.discourse.group/t/different-altitudes/641 "2025-08-27T16:17:56Z")\
**Posts on this page:** 3\
**Page:** 1

<div class="post-metadata">

**Author:** ![imd](https://yyz2.discourse-cdn.com/free1/user_avatar/openradar.discourse.group/imd/32/380_2.png) [@imd](https://openradar.discourse.group/u/imd)\
**Post date:** [August 27, 2025, 4:17pm UTC](https://openradar.discourse.group/t/different-altitudes/641/1 "2025-08-27T16:17:56Z")

</div>

How does PyDDA handle data from two radars with different altitudes? Specifically, I’m working with data from a C-band radar at 673 m MSL and an X-band radar at 272 m MSL?

---

<div class="post-metadata">

**Author:** ![rcjackson](https://yyz2.discourse-cdn.com/free1/user_avatar/openradar.discourse.group/rcjackson/32/14_2.png) [@rcjackson](https://openradar.discourse.group/u/rcjackson)\
**Post date:** [August 27, 2025, 5:06pm UTC](https://openradar.discourse.group/t/different-altitudes/641/2 "2025-08-27T17:06:54Z")

</div>

Hello. PyDDA assumes that the heights from both radar grids represent the same altitudes above sea level. If you are using PyART to grid your radars, I would ensure that the origin\_altitude is the same for both radars (I would go with a grid centered around the X-band with an origin\_altitude of 0 m). If you specify PyART to grid with such a configuration, then the PyART gridding technique will adjust the heights of the gates in the grid to account for the different radar heights.

---

<div class="post-metadata">

**Author:** ![imd](https://yyz2.discourse-cdn.com/free1/user_avatar/openradar.discourse.group/imd/32/380_2.png) [@imd](https://openradar.discourse.group/u/imd)\
**Post date:** [August 27, 2025, 7:16pm UTC](https://openradar.discourse.group/t/different-altitudes/641/3 "2025-08-27T19:16:08Z")

</div>

Thank you for your response. Could you please clarify how to set the origin for the grid\_from\_radars function? Should I use the X-band radar’s latitude and longitude as the origin, like this:

origin = (radar\_ktlx.latitude[‘data’].filled(), radar\_ktlx.longitude[‘data’].filled()) ## X-band

grid\_ktlx = pyart.map.grid\_from\_radars([radar\_ktlx], grid\_limits=grid\_limits, grid\_shape=grid\_shape, grid\_origin=origin)

grid\_kict = pyart.map.grid\_from\_radars([radar\_kict], grid\_limits=grid\_limits, grid\_shape=grid\_shape, grid\_origin=origin)

I appreciate guidance on setting the origin correctly.