# Retrievals **URL:** https://openradar.discourse.group/c/retrievals/9.md [Latest](https://openradar.discourse.group/latest.md) · [Categories](https://openradar.discourse.group/categories.md) · [Tags](https://openradar.discourse.group/tags.md) --- ## [About the Retrievals category](https://openradar.discourse.group/t/about-the-retrievals-category/93)
**Author:** [@mgrover1](https://openradar.discourse.group/u/mgrover1)\ **Replies:** 0
Do you need to retrieve something from your radar dataset? For example: How do I calculate the precipitation rate from my data? How do I calculate or recalculate the specific differential phase (KDP) How do I determine… --- ## [On the use of FFTs for remapping points](https://openradar.discourse.group/t/on-the-use-of-ffts-for-remapping-points/684)
**Author:** [@scollis](https://openradar.discourse.group/u/scollis)\ **Replies:** 11\ **Last updated:** [August 25, 2026, 4:18pm UTC](https://openradar.discourse.group/t/on-the-use-of-ffts-for-remapping-points/684 "2026-08-25T16:18:34Z")
Ok,. This is, I hope, the start of a great conversation on how we can work more in the spectral space for a whole heap of features across packages. This is motivated by a conversation I had with @aladinor and @swnesbitt … --- ## [Producing "inverted" CAPPI maps](https://openradar.discourse.group/t/producing-inverted-cappi-maps/642)
**Author:** [@gene\_cgha](https://openradar.discourse.group/u/gene_cgha)\ **Replies:** 0\ **Last updated:** [August 28, 2025, 10:22am UTC](https://openradar.discourse.group/t/producing-inverted-cappi-maps/642 "2025-08-28T10:22:16Z")
Hi all, I’m currently working with CfRadial data and trying to generate a CAPPI of reflectivity using Py-ART. I followed the example here: Compare PPI vs CAPPI — Py-ART 2.1.0 documentation However, when plotting with c… --- ## [Different altitudes?](https://openradar.discourse.group/t/different-altitudes/641)
**Author:** [@imd](https://openradar.discourse.group/u/imd)\ **Replies:** 2\ **Last updated:** [August 27, 2025, 7:16pm UTC](https://openradar.discourse.group/t/different-altitudes/641 "2025-08-27T19:16:08Z")
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? --- ## [Wavelength simulation/conversion](https://openradar.discourse.group/t/wavelength-simulation-conversion/621)
**Author:** [@afunk](https://openradar.discourse.group/u/afunk)\ **Replies:** 2\ **Last updated:** [June 25, 2025, 1:49pm UTC](https://openradar.discourse.group/t/wavelength-simulation-conversion/621 "2025-06-25T13:49:41Z")
Is anyone aware of open source radar software that will help simulate data from a particular wavelength using another? For instance, I’d like to simulate Ka-band retrievals from X-band data. Thanks. --- ## [Separating multiple scans from same Lidar](https://openradar.discourse.group/t/separating-multiple-scans-from-same-lidar/604)
**Author:** [@SunnysChan](https://openradar.discourse.group/u/SunnysChan)\ **Replies:** 1\ **Last updated:** [June 3, 2025, 2:10pm UTC](https://openradar.discourse.group/t/separating-multiple-scans-from-same-lidar/604 "2025-06-03T14:10:34Z")
Hi, I am running PyDDA with doppler Lidars. One thing I notice iss that " pydda.retrieval.get\_dd\_wind\_field" always requires reflectivity. Looking at the source code shows the reflectivity is used for correcting vertical… --- ## [On making CFAD over a specific area/domain](https://openradar.discourse.group/t/on-making-cfad-over-a-specific-area-domain/608)
**Author:** [@gene\_cgha](https://openradar.discourse.group/u/gene_cgha)\ **Replies:** 1\ **Last updated:** [June 3, 2025, 2:04pm UTC](https://openradar.discourse.group/t/on-making-cfad-over-a-specific-area-domain/608 "2025-06-03T14:04:35Z")
I’m currently working on generating a CFAD (Contoured Frequency by Altitude Diagram) using Py-ART over a specific geographic domain, similar to this visualization of Chen et al. (2019) in Figure 6. I’ve already written a… --- ## [Generate Geotiff from Rainbow file with wradlib](https://openradar.discourse.group/t/generate-geotiff-from-rainbow-file-with-wradlib/231)
**Author:** [@d-siden](https://openradar.discourse.group/u/d-siden)\ **Replies:** 10\ **Last updated:** [March 7, 2025, 6:42am UTC](https://openradar.discourse.group/t/generate-geotiff-from-rainbow-file-with-wradlib/231 "2025-03-07T06:42:24Z")
Hi, I’m trying to follow this tutorial in order to get data from a Rainbow (.vol) file and export it to a Geotiff file. However the tutorial refers to RADOLAN dataset, and I’m having difficulties in figuring out how to … --- ## [Retrives using pydda](https://openradar.discourse.group/t/retrives-using-pydda/539)
**Author:** [@Amani](https://openradar.discourse.group/u/Amani)\ **Replies:** 1\ **Last updated:** [December 4, 2024, 9:54pm UTC](https://openradar.discourse.group/t/retrives-using-pydda/539 "2024-12-04T21:54:07Z")
It is my first time using Pydda, I try to retrieves wind from sounding and radar data using iris sigmet format I try to apply this tutorial https://openradarscience.org/ams-open-radar-2023/notebooks/pydda/Retrieving\_wi… --- ## [Weird Vertical Velocities Post-PyDDA-Retrieval](https://openradar.discourse.group/t/weird-vertical-velocities-post-pydda-retrieval/131)
**Author:** [@adiste5](https://openradar.discourse.group/u/adiste5)\ **Replies:** 5\ **Last updated:** [December 1, 2024, 11:32am UTC](https://openradar.discourse.group/t/weird-vertical-velocities-post-pydda-retrieval/131 "2024-12-01T11:32:46Z")
Hi! I’ve run PyDDA over two PNW coastal radars, KLGX and KRTX. The initial horizontal wind field looks good (Fig. ADS1), but when I try to plot vertical velocity, I get very strange values, especially around the cone of… --- ## [How to calculate cm , co ,cx,xy and cz value?](https://openradar.discourse.group/t/how-to-calculate-cm-co-cx-xy-and-cz-value/530)
**Author:** [@imd](https://openradar.discourse.group/u/imd)\ **Replies:** 8\ **Last updated:** [November 27, 2024, 4:05pm UTC](https://openradar.discourse.group/t/how-to-calculate-cm-co-cx-xy-and-cz-value/530 "2024-11-27T16:05:39Z")
grids\_out, \_ = pydda.retrieval.get\_dd\_wind\_field(\[grid\_kict, grid\_ktlx\], Cm=256.0, Co=1e-2, Cx=1, Cy=1, Cz=1, Cmod=1e-5, model\_fields=\[“hrrr”\], refl\_field=‘DBZ’, wind\_tol=0.5, max\_iterations=50, filter\_window=15, fi… --- ## [PyDDA wind retrieval using single DWR](https://openradar.discourse.group/t/pydda-wind-retrieval-using-single-dwr/475)
**Author:** [@VTIITI](https://openradar.discourse.group/u/VTIITI)\ **Replies:** 3\ **Last updated:** [June 13, 2024, 11:27am UTC](https://openradar.discourse.group/t/pydda-wind-retrieval-using-single-dwr/475 "2024-06-13T11:27:26Z")
Is there any example notebook available to use pydda for single DWR? --- ## [PyDDA retrieve wind](https://openradar.discourse.group/t/pydda-retrieve-wind/462)
**Author:** [@woxiangxin](https://openradar.discourse.group/u/woxiangxin)\ **Replies:** 0\ **Last updated:** [April 23, 2024, 6:04am UTC](https://openradar.discourse.group/t/pydda-retrieve-wind/462 "2024-04-23T06:04:02Z")
Here is my retrieve result. I think there are some issues with this result, especially around the zero-velocity line. The wind direction should be orthogonal to the zero-velocity line, but in the figure, the wind is dire… --- ## [Use wradlib functions with DWD BUFR data](https://openradar.discourse.group/t/use-wradlib-functions-with-dwd-bufr-data/386)
**Author:** [@atmoboran](https://openradar.discourse.group/u/atmoboran)\ **Replies:** 3\ **Last updated:** [January 29, 2024, 11:10am UTC](https://openradar.discourse.group/t/use-wradlib-functions-with-dwd-bufr-data/386 "2024-01-29T11:10:26Z")
Hello everyone, I’m sorry to say, but it’s about BUFR - the format we all admire so much. So I’m trying to handle a dataset from DWD (it’s a ras08 - precipitation scan - DWD BUFR ras08 - Google Drive ; here is an examp… --- ## [PyDDA with more than 2 radars](https://openradar.discourse.group/t/pydda-with-more-than-2-radars/376)
**Author:** [@hvagasky](https://openradar.discourse.group/u/hvagasky)\ **Replies:** 2\ **Last updated:** [January 19, 2024, 10:13pm UTC](https://openradar.discourse.group/t/pydda-with-more-than-2-radars/376 "2024-01-19T22:13:57Z")
Hi, When PyDDA retrieves winds with more than 2 radars does it only conduct the retrieval over regions where all of the radars overlap? I have a case with data from 6 radars. I am finding that the region where winds are… --- ## [CAPPI from DWD volume scans](https://openradar.discourse.group/t/cappi-from-dwd-volume-scans/344)
**Author:** [@atmoboran](https://openradar.discourse.group/u/atmoboran)\ **Replies:** 1\ **Last updated:** [November 15, 2023, 1:55pm UTC](https://openradar.discourse.group/t/cappi-from-dwd-volume-scans/344 "2023-11-15T13:55:18Z")
Hello everybody, I’m trying to produce CAPPIs from the DWD volume scans (here for the location Essen: Index of /weather/radar/sites/sweep\_vol\_z/ess/hdf5/filter\_polarimetric/ (dwd.de) The problem is, that the codes that… --- ## [Is HRRR assimilating radar velocities?](https://openradar.discourse.group/t/is-hrrr-assimilating-radar-velocities/321)
**Author:** [@jm5791](https://openradar.discourse.group/u/jm5791)\ **Replies:** 1\ **Last updated:** [September 28, 2023, 3:47pm UTC](https://openradar.discourse.group/t/is-hrrr-assimilating-radar-velocities/321 "2023-09-28T15:47:55Z")
Hello all, Looking at some pydda dual doppler wind retrievals examples, I understand that one may typically uses a reanalysis/forecasting model (like HRRR) as a background field. Though, I was wondering: are models lik… --- ## [PyDDA 1.4.0 released](https://openradar.discourse.group/t/pydda-1-4-0-released/297)
**Author:** [@rcjackson](https://openradar.discourse.group/u/rcjackson)\ **Replies:** 0\ **Last updated:** [August 31, 2023, 2:45pm UTC](https://openradar.discourse.group/t/pydda-1-4-0-released/297 "2023-08-31T14:45:17Z")
PyDDA 1.4.0 has been released today! In this version of PyDDA we have: \* Moved to ruff for linting and added pre-commit hooks to better ensure code quality in PRs. \* Expanded unit testing of Jax/TensorFlow cost functio… --- ## [Magnitudes in retrieved Vertical Velocities PyDDA](https://openradar.discourse.group/t/magnitudes-in-retrieved-vertical-velocities-pydda/280)
**Author:** [@hvagasky](https://openradar.discourse.group/u/hvagasky)\ **Replies:** 13\ **Last updated:** [August 23, 2023, 6:58pm UTC](https://openradar.discourse.group/t/magnitudes-in-retrieved-vertical-velocities-pydda/280 "2023-08-23T18:58:05Z")
Hi, I am retrieving winds from KVNX and KICT using PyDDA. The magnitude of the vertical velocity maximizes right near the axis between the radars and decreases with distance in what seems to be an unphysical manner. Do … --- ## [Radar Grid Weighting - PyDDA](https://openradar.discourse.group/t/radar-grid-weighting-pydda/274)
**Author:** [@sdm5607](https://openradar.discourse.group/u/sdm5607)\ **Replies:** 2\ **Last updated:** [July 27, 2023, 6:24pm UTC](https://openradar.discourse.group/t/radar-grid-weighting-pydda/274 "2023-07-27T18:24:43Z")
Hi all, I’m currently working on creating a dual-doppler analysis using PyDDA between a mobile C-band and NEXRAD radar but am having some issues with the resulting 3D wind field. I know the get\_dd\_wind\_field() function … --- ## [Weighing constants for PyDDA](https://openradar.discourse.group/t/weighing-constants-for-pydda/205)
**Author:** [@hvagasky](https://openradar.discourse.group/u/hvagasky)\ **Replies:** 5\ **Last updated:** [July 13, 2023, 7:52am UTC](https://openradar.discourse.group/t/weighing-constants-for-pydda/205 "2023-07-13T07:52:24Z")
Hi. Is there additional documentation or guidance on how to determine the appropriate weights or what is an appropriate range for the weights to use in PyDDA besides Welcome to the PyDDA documentation! — PyDDA 1.2.0 docu… --- ## [Facing difficultyin converting Coordinate system from x,y to lat,lon](https://openradar.discourse.group/t/facing-difficultyin-converting-coordinate-system-from-x-y-to-lat-lon/256)
**Author:** [@SandeepAllampalli](https://openradar.discourse.group/u/SandeepAllampalli)\ **Replies:** 7\ **Last updated:** [July 5, 2023, 2:14pm UTC](https://openradar.discourse.group/t/facing-difficultyin-converting-coordinate-system-from-x-y-to-lat-lon/256 "2023-07-05T14:14:03Z")
I am trying to convert x and y coordinates into latitude and longitude. Can someone here help me in guiding? @kmuehlbauer @mgrover1 Below is the description of the metadata. Thanks in advance. Sandeep dataset\_2017 O… --- ## [3D Wind Retrivals in Stratiform Precipitation](https://openradar.discourse.group/t/3d-wind-retrivals-in-stratiform-precipitation/186)
**Author:** [@hvagasky](https://openradar.discourse.group/u/hvagasky)\ **Replies:** 2\ **Last updated:** [March 14, 2023, 7:23pm UTC](https://openradar.discourse.group/t/3d-wind-retrivals-in-stratiform-precipitation/186 "2023-03-14T19:23:26Z")
I have a project where we are specifically interested in smaller-scale vertical velocities within the stratiform portion of a MCS. Right now we have an older DOE ARM data set called CONVV (ARM Research Facility) . Howeve…