DOI: 10.5061/dryad.zcrjdfnk6
title: Northeast US Regional NEXRAD radar mosaics of winter storms from 1996-2023, part 1

description: This dataset contains over 14,000 hours of regional radar mosaics over the
 northeast US from 600+ winter storm days between 1996-2023. Winter storm
 days are defined when at least 2 out of 15 surface stations in the
 northeast US (see attached map) produced at least 1 inch of snow over the
 24 hour period. Sequences of these mosaics aid in analyzing the
 precipitation area and the structures within winter storms. Radar
 reflectivity data is combined from the first, lowest (0.5 degree)
 elevation angle from 12 NEXRAD WSR-88D radars in the northeast US (see
 attached). The scans occur every 5-10 minutes from each radar depending on
 the radar scan settings.  The time label of the regional map is
 based on the scan time central radar, KOKX (Upton, NY). Scans from other
 radars in the region are used for that time as long as they are within 8
 minutes of the KOKX scan. The polar radar data from each radar is
 interpolated to a regional 1202 km x 1202 km Cartesian grid with 2 km grid
 spacing covering 35.73-46.8 degN and 66.36-81.85 degW. Where the radar
 domains overlap, we take the highest reflectivity value. For dates after
 dual-polarization integration (2012 onwards), files contain the
 correlation coefficient (RHO_HV) field and a binary field  that
 can be used to “image mute” the reflectivity which reduces the visual
 prominence of melting and mixed precipitation commonly mistaken for heavy
 snow. Image muting is applied where radar reflectivity is ≥ 20 dBZ and
 RHO_HV is ≤ 0.97. This product is different from other widely used radar
 mosaics such as the MRMS produced by NOAA since it does not interpolate to
 a constant altitude and thus preserves the finer scale details in the
 reflectivity field. Because the data used to create these mosaics are not
 interpolated to a constant altitude, the altitude varies over the region
 (altitudes of radar scan used at each grid point are provided as a field
 for each data file). This data set is specifically designed to analyze
 fine-scale structures in winter storms. Part 1 contains files pre-dual
 polarization integration (1996-2012)Part 2 contains files post-dual
 polarization integration (2012-2023)
description: # Regional NEXRAD radar mosaics of winter storms from 1996-2023, part 1
 This dataset contains over 14,000 hours of regional radar mosaics over the
 northeast US from 600+ winter storm days between 1996-2023. Winter storm
 days are defined when at least 2 out of 15 surface stations in the
 northeast US (see attached map and .csv) produced at least 1 inch of snow
 over the 24 hour period. Sequences of these mosaics aid in analyzing the
 precipitation area and the structures within winter storms. Radar
 reflectivity data is combined from the first, lowest (0.5 degree)
 elevation angle from 12 NEXRAD WSR-88D radars in the northeast US (see
 attached). The scans occur every 5-10 minutes from each radar depending on
 the radar scan settings. The time label of the regional map is based on
 the scan time central radar, KOKX (Upton, NY). Scans from other radars in
 the region are used for that time as long as they are within 8 minutes of
 the KOKX scan. The polar radar data from each radar is interpolated to a
 regional 1202 km x 1202 km Cartesian grid with 2 km grid spacing covering
 35.73-46.8 degN and 66.36-81.85 degW. Where the radar domains overlap, we
 take the highest reflectivity value. For dates after dual-polarization
 integration (2012 onwards), files contain the correlation coefficient
 (RHO\_HV) field and a binary field that can be used to “image mute” the
 reflectivity which reduces the visual prominence of melting and mixed
 precipitation commonly mistaken for heavy snow. Image muting is applied
 where radar reflectivity is ≥ 20 dBZ and RHO\_HV is ≤ 0.97. This product
 is different from other widely used radar mosaics such as the MRMS
 produced by NOAA since it does not interpolate to a constant altitude and
 thus preserves the finer scale details in the reflectivity field. Because
 the data used to create these mosaics are not interpolated to a constant
 altitude, the altitude varies over the region (altitudes of radar scan
 used at each grid point are provided as a field for each data file). This
 data set is specifically designed to analyze fine-scale structures in
 winter storms. ## Description of the data and file structure [Part
 1](https://doi.org/10.5061/dryad.zcrjdfnk6) contains files pre-dual
 polarization integration (1996-2012) [Part
 2](https://doi.org/10.5061/dryad.rbnzs7hj9) contains files post-dual
 polarization integration (2012-2023) Files are zipped by year (i.e.
 1996.zip, etc.). Part 1 contains 17 `.zip` files and part 2 contains 12
 `.zip` files. `expected_numer_of_files.xlsx` lists the number of expected
 files in each `.zip` file. **File type**: The files in this dataset are
 CF-1.8 compliant netCDF4 files. **Naming convention**: * Files are named
 with the following convention: `YYYYMMDD_hhmmss_stitched.nc`. * For post
 dual-pol dates, files with available correlation coefficient data, and
 thus an image muted field, files are named as follows:
 `YYYYMMDD_hhmmss_stitched_muted.nc` **Combining data from multiple
 radars**: See [section
 2.1](%5Bhttps://amt.copernicus.org/articles/15/5515/2022/#section2%5D) of
 [Tomkins et al. (2022)](https://doi.org/10.5194/amt-15-5515-2022) for full
 details on how the data is combined from multiple radars. **Description of
 variables in each file**: * **ref\_max**: Maximum reflectivity at each
 grid point * **alt\_max**: Altitude of max. reflectivity * **rho\_max**:
 Correlation coefficient corresponding to max. reflectivity *(only
 available for post-dual pol dates)* * **muted\_mask**: Boolean field, True
 where image muted *(only available for post-dual pol dates)* **Radars used
 in the Northeast US regional mosaics**: KBGM, KBOX, KBUF, KCCX, KCXX,
 KDIX, KDOX, KENX, KGYX, KLWX, KOKX, KTYX *(see map.png)* **Central
 radar**: KOKX **Regional map bounds**: N: 46.8 deg, S: 35.73 deg, E:
 -66.36 deg, W: -81.85 deg *(see map.png)* ## Sharing/Access information
 Data was derived from the following sources: * [NOAA Next Generation Radar
 (NEXRAD) Level 2 Base
 Data](https://www.ncei.noaa.gov/access/metadata/landing-page/bin/iso?id=gov.noaa.ncdc:C00345) accessed via [Amazon Web Services (AWS)](https://registry.opendata.aws/noaa-nexrad/) ## Code/Software These files were created using Python 3.6 and the open-source [Py-ART](https://arm-doe.github.io/pyart/) python package. We added a [function to image mute radar objects](https://arm-doe.github.io/pyart/API/generated/pyart.util.image_mute_radar.html#pyart.util.image_mute_radar), beginning with Py-ART version 1.11.8. An example of how to use the function is provided [here](https://arm-doe.github.io/pyart/examples/plotting/plot_nexrad_image_muted_reflectivity.html). Software to create the composites can be found in the `software` folder. Instructions to modify the software to process WSR-88D data from other regions are included. Files can be read with open-source software packages such as `ncdf4` in R and `netCDF4` and `Py-ART` in Python. Examples for reading the files in Python is included below: With `netCDF4`: ```python import netCDF4 data = netCDF4.Dataset('YYYYMMDD_stitched.nc') print(data) ``` With `Py-ART`: ```python import pyart grid = pyart.io.read_grid('YYYYMMDD_stitched.nc') ```