Multi-Radar Multi-Sensor (MRMS) v12.2.0 Updated Products

General information can be found on MRMS’s VLab community page

at https://vlab.noaa.gov/web/mrms/

Canadian C-band and S-band Radars

• Removing all remaining C-band (single pol) radars provided by Canada’s radar network.

• Adding new S-band (dual pol) radars from Canada’s upgraded radar network.

• Affected products: Adding the new S-band Canadian radars to the MRMS system will not result in any new products. However, the S-band radars are more fully integrated into MRMS than the C-bands. See Table 1 for a list of products that previously lacked input from Canadian radars but will include the S-bands with MRMS v12.2. All GRIB2 and GeoTIFF formatted products are available via LDM and NCEP web services. NIDS products are available via LDM only.

Table 1. List of products that previously did not include any Canadian radars but will include S-bands with MRMS v12.2 

For reference, the vertical levels are: 00.50, 00.75, 01.00, 01.25, 01.50, 01.75, 02.00, 02.25, 02.50, 02.75, 03.00, 03.50, 04.00, 04.50, 05.00, 05.50, 06.00, 06.50, 07.00, 07.50, 08.00, 08.50, 09.00, 10.00, 11.00, 12.00, 13.00, 14.00, 15.00, 16.00, 17.00, 18.00, 19.00 km MSL.

Special note: Given the nature of the top down volume scanning of the new S-Band Canada radar, there is the potential for higher tilts to be missing in the calculation of the following products –
 
MergedReflectivityQComposite (max method)
MergedReflectivityComposite (unQC)
ReflectivityAtLowestAltitude (unQC)
 
Caution should be exercised in using these products as they may contain muted values. NSSL is currently working on improving the accuracy of these products and will update accordingly.

Velocity Dealiasing and Circulation

• Dealiasing logic was updated to use the techniques of Build 19 ORPG and address minor bugs.

• Improved stability of circulation calculations.

• Affected products are listed in Table 2.  All GRIB2 formatted products are available via LDM and NCEP web services. NIDS products are available via LDM only.

Table 2. List of products that will benefit from updates to dealiasing and circulation algorithms.

Radar Quality Control

• Added quality control customized for Canadian S-band radars

• Added checks to identify and remove bad observations due to hardware issues

• Improved removal of wind farm residual clutter.

• Corrected an error in the Kdp derivation caused by range folding returns found in high elevation scans.

• Affected products: Nearly all MRMS products will be affected by the update to Radar QC with the following exceptions:  

All raw (unQC’d) fields 

Model_0degC_Height

Model_SurfaceTemp

Model_WetBulbTemp

WarmRainProbability 

BrightBandTopHeight 

BrightBandBottomHeight 

LVL3_HREET

LVL3_HighResVIL 

NLDN_GC_[001,005,015,030]min_AvgDensity 

Quantitative Precipitation Estimates (QPE) and Related Products

• (Seamless HSR) Upgraded the method for identifying and correcting areas of bright band contamination.  As a result, the radar QPE overestimation bias near the radar for low melting layer events is mitigated and underestimation at far ranges is significantly reduced.  Uncertainties in the radar QPE are also reduced.

• (PrecipFlag) Updated PrecipFlag to mitigate false convective identifications in strong bright band areas.

• (Dual pol QPE) Refined R(A) and R(KDP) QPE calculations and significantly reduced QPE variability.

• (Dual pol QPE) Improved melting layer estimates, which enhanced the mitigation of ice contamination for precipitation estimated via specific attenuation and extended the range of the application of polarmetric QPE.

• (Dual pol QPE) Reduced precip rate overestimates in the Western CONUS by refining the identification of deep convection.

• Affected products are listed in Table 3.  All GRIB2 and GeoTIFF formatted products are available via LDM and NCEP web services. NIDS products are available via LDM only.

Table 3. List of products that will benefit from improvements to MRMS’s QPE-related algorithms.

XMRG HRAP QPE Adjustments 

• Applied a QPE minimum threshold of 0.3 mm (~0.01 inch) for QPEs in XMRG HRAP format for the Northeast and Lower Mississippi River Forecast Centers.

• NOTE: XMRG HRAP files for other RFCs / FOs and QPE written in other formats (e.g., GRIB2) will not be thresholded.

• Affected products are listed in Table 4.  XMRG products are available via LDM only.

Table 4. XMRG formatted products with new thresholding applied.

QPE Corrections - Hawaii only

• Corrected grid coordinates for Hawaii’s Multi-Sensor QPE and Gauge Influence Index products (Pass1 and Pass2).  Prior to this correction, the products were offset by half a grid cell (0.0025 degree latitude/longitude or ~250m)

• Affected products are listed in Table 5.  All GRIB2 formatted products are available via LDM and NCEP web services.

Table 5. List of products with small grid coordinate correction.

Gauge Processing

• Improved gauge processing and reference data to allow for more gauges to be integrated into MRMS and done so with greater accuracy and reliability.

• Affected products are listed in Table 6.  All GRIB2 formatted products are available via LDM and NCEP web services.

Table 6. List of products that will benefit from MRMS v12.2’s improved gauge processing.