NASA Logo - GSFC + NASA Homepage
+ Goddard Homepage
Korean QPE

Comparisons of rainrates from 3B42, IMERG and Korean QPE

TMPA 3B42

TMPA 3B42 files are avaliable from the NASA Goddard Earth Sciences Data and Information Services Center (GES DISC). These gridded estimates are on a 3-hour temporal resolution and a 0.25-degree by 0.25-degree spatial resolution in a global belt extending from 50S to 50N. The 3B42 estimates are produced in four stages:
    (1) the microwave precipitation estimates are calibrated and combined;
    (2) infrared precipitation estimates are created using the calibrated microwave precipitation;
    (3) the microwave and IR estimates are combined;
    (4) rescaling to monthly data is applied. Each precipitation field is best interpreted as the precipitation rate effective at the nominal observation time.
Click here to download 3B42_web-description.doc (Word.Document) by algorithm developer Dr. George Huffman.

IMERG

Integrated Multi-Satellite Retrievals for GPM (IMERG) Algorithm is intended to intercalibrate, merge, and interpolate "all" satellite microwave precipitation estimates, together with microwave-calibrated infrared (IR) satellite estimates, precipitation gauge analyses, and potentially other precipitation estimators at fine time and space scales for the TRMM and GPM eras over the entire globe. The system is run several times for each observation time, first giving a quick estimate and successively providing better estimates as more data arrive. The final step uses monthly gauge data to create research-level products. Background information and references are provided to describe the context and the relation to other similar missions. Issues involved in understanding the accuracies obtained from the calculations are discussed. Throughout, a baseline Day-1 product is described, together with options and planned improvements that might be instituted before or after launch depending on maturity and project constraints.

The IMERG gridded estimates are on a 30-minute temporal resolution and a 0.1-degree by 0.1-degree spatial resolution extending from 180W to 180E and 90S to 90N.

For more information about IMERG, download IMERG_ATBD_V4.1.pdf

Thanks to George Huffman and David T. Bolvin for providing nearly one-month (03-28 Jun 2012) pre-launch "test-version" of IMERG data and IMERG Early-Run, Late-Run, and Final-Run products.

Korean QPE

Korea Meteorological Administration(KMA) has developed a Real-time ADjusted Radar-AWS (Automatic Weather Station) Rainrate (RAD-RAR) system using eleven radars over the South Korea. The Korean QPE data are on a 1-hour temporal resolution and a 1-km by 1-km spatial resolution extending from 119.883E to 136.316E and 29.1906N to 45.7572N.

Thanks to Geunhyoerk Ryu at KMA for providing Korean QPE data for this study.

Comparisons among 3B42, IMERG and Korean QPE

Korean QPE available: Jun 01 - Dec 31, 2012; Mar 01, 2014- Nov 30, 2016 (as of Feb 17, 2017).
IMERG Early-Run and Late-Run Products available: Apr 1, 2015 - present
IMERG Final-Run Product available: Jun 03 - Jun 28, 2012 (pre-launch test-version); Mar 12, 2014 - Jan 31, 2016 (as of this update on Jan 6, 2017).
3B42 available: Jan 1, 1998 - Oct 31, 2016.

The comparisons are conducted over the area (124.5E-130.5E, 32.5N-39N) for Jun 2012 and Mar 2014- Jan 2016. At 3-hourly scale, 3B42, IMERG and Korean QPE data are used. At hourly scale, only IMERG and Korean QPE data are used as 3B42 is at 3-hour resolution.
  • Area-averaged daily rainfall
    All data (rain and no rain) from each product at its native resolution (QPE: 1km, 1h; 3B42: 0.25o, 3h; IMERG: 0.1o, 0.5h) are accumulated to daily rainfall, and averaged over the entire domain (124.5E-130.5E, 32.5N-39N).
    The daily rainfall cutoff time is 2300Z for QPE, 2230Z for 3B42 and IMERG. There is a 30-minute offset.

  • Scatter plot for area-averaged 3-hourly or hourly rainrates

  • PDF by 3-hourly (0.25o) or hourly (0.1o) rain occurrence and volume for different rain and RQI thresholds


  • Daily rainfall [mm] contours at 1km, 0.25- and 0.1-degree resolutions for QPE, 3B42 and IMERG, respectively
    Daily rainfall for each product is accumulated from its native temporal resolutions (1h for QPE, 3h for 3B42, 0.5h for IMERG) at its native spatial resolution(QPE: 1km; 3B42: 0.25o; IMERG: 0.1o). 0- and non-0 rain rates are all included. No mask or rain types are used yet.
    The daily rainfall cutoff time is 2300Z for QPE, 2230Z for 3B42 and IMERG. There is a 30-minute offset

  • 3-hourly rainrate [mm/h] contours at 1-km, 0.25o and 0.1o resolutions for QPE, 3B42 and IMERG, respectively
    Three-hourly rainrate for each product is accumulated from its native temporal resolutions (1h for QPE, 3h for 3B42, 0.5h for IMERG) at its native spatial resolution(QPE: 1km; 3B42: 0.25o; IMERG: 0.1o). 0- and non-0 rain rates are all included. No mask or rain types are used yet.
    The 3-hourly rainrate cutoff time is 0200, 0500,..., 2300Z for QPE, 0130, 0430, ..., 2230Z for 3B42 and IMERG. There is a 30-minute offset.


FirstGov logo Privacy Policy and Important Notices NASA logo Web Curator: David A. Marks    NASA Official: David B. Wolff