NMQ: National Mosaic and Multi-Sensor QPE
Comparisons of rainrates from Q3 (MRMS) and GMI, DPR, CMB, KU
GPM surface rainrates
Following three GPM surface rain products are compared with MRMS (or called "Q3").
- GMI
GMI surface rainrates are generated on a pixel by pixel basis from radiometer brightness temperature
data using the Goddard Profiling algorithm GPROF2014.
- DPR
The DPR Level-2A product, 2ADPR, "DPR precipitation", is in a 3-swath structure.
The swaths are normal scans (NS), matched scans (MS), and high sensitivity scans (HS).
- CMB
The Combined Level-2 product, 2BCMB, "Level-2 DPR and GMI Combined", is in a two-swath structure.
The first swath, NS, contains 49 rays that match Ku DPR. The second swath, MS, contains 25 rays that match Ka DPR.
- KU
The Ku Level-2A product, 2AKu, "Ku precipitation", is written as a 1-swath structure (NS).
Comparisons with Q3 (footprint-matched)
The comparisons are conducted over the CONUS during GPM overpasses
from Mar 2014 to most current dates dependent
on the data availability.
Vers 3, Mar 2014 --> Feb 2016 (combined various V-3 versions)
Ver 04A, Mar 2014 --> Jul 2016
ITE109, Jun 2014 --> May 2016 KU, DPR only
ITE110, Mar 2014 --> Jul 2016 GMI only
ITE111, Mar 2014 --> Jul 2016 GMI only
ITE113, Jun 2014 --> Jul 2016 KU, DPR only
ITE114, Jun 2014 --> Jul 2016
ITE117, Mar 2014 --> Jul 2016 GMI only
Ver 05, Mar 2014 --> Jun 2017 ( V05A & B, Mar 2014 --> Apr 2021 for GMI)
ITE601, Mar 2014 --> Jun 2017 , KU, DPR only
ITE607, Apr 2014 --> Jun 2017 , CMB only
Ver 06A, Mar 2014 --> Mar 2021 , KU,DPR,CMB only. No GMI. No DPR_HS after 16Z 21May 2018.
The Q3 instantaneous rainrates are matched with GMI, DPR, CMB, KU rain
products and resampled at the footprint resolution on each overpass,
and then the matched rainrates are averaged to 50km x 50km grids with
following QCs/filters:
- QC0
- QC1
- Rainrates >=0.2 mm/h
- RQI>=0.9
- Liquid precipitation only
- QC2
- Rainrates >=0.0 mm/h
- Set all values < 0.01 mm/h to 0
- QC3
- Rainrates >=0.0 mm/h
- Set all values < 0.01 mm/h to 0
- RQI>=0.9
- Liquid precipitation only
Rainrates less than 0.2 mm/h from all products are not included in the
analysis as the GMI gets a lot of false light rain.
Different rainrate thresholds are used in the following comparison
plots because many researches show the satellite rain bias is a
function of rain intensities.
Note: QC2 and QC3 are only applied to V04A, ITE111 and later versions.
For V04A, GMI rain is set to 0 when GMI POP <40%.
- Scatter plot for different rainrate and rain type categories (Yearly, Mission To Date)
- PDF by rain occurrence and volume for different rainrate and rain type categories (Yearly, Mission To Date)
- Density plot for different rainrate and rain type categories (Yearly, Mission To Date)
- Error Map (Mission To Date)
The mean rain maps for DPR, GMI, CMB or KU rainrates, error maps
(mean relative error, mean absolute error, normalized root
mean squre error for DPR, GMI, CMB or KU rainrates
relative to Q3 rainrates), as well as the sample size, are based on the matched data
at 50km resolution after applying the QCs/filter.
- Rain map
The rain map for GMI surface precipitation (SP), GMI most likely precipitation (MP),
DPR near surface rainrate , CMB surface rainrate, KU near surface rainrate, or Q3
is based on its native spatial resolution (GMI/DPR/KU: ~5km; Q3: 0.01o).
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