Table 2. Summary of publicly available, quasi-operational, quasi-global precipitation estimates that are produced by combining input data from several satellite sensor types. Where appropriate, the algorithms applied to the individual input data sets are mentioned. The TCI is available as a separate product from the Goddard DISC, in addition to the 3G68 compilation. Gray shading indicates products that are not yet available. Yellow shading indicates entries that have not been updated recently [Last updated 13 July 2022, G.J. Huffman]

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Algorithm	Input data	Space/time grid	Areal coverage/start date	Update frequency	Latency	Producer (Developer) URL
GPCP One-Degree Daily (Version 1.3)	SSM/I- & SSMIS-TMPI (IR), TOVS, AIRS, GPCP V2.3 monthly	1°/daily	Global/Oct. 1997	Monthly	3 months	UMCP/ESSIC (Adler, Huffman) [1]
GPCP pentad (Version 1.1)	OPI, SSM/I, SSMIS, GPI, MSU, gauge, GPCP monthly	2.5°/5-day	Global/1979	Seasonal	3 months	NOAA/NWS CPC (Xie) [2]
GPCP Version 3.1 Daily	IMERG, GPCP V3.1 monthly	0.5°/daily	Global/June 2000	3 months	3-6 months	NASA/GSFC (Huffman) [3]
GSMaP Near-Real-Time (GSMaP_NRT)	GMI, AMSR-2, AMSU, MHS, IR vectors	0.1°/hourly	60°N-S/Oct. 2007	1 hour	4 hours	JAXA (Kubota)[4]
GSMaP Realtime (GSMaP_NOW)	GMI, AMSR-2, AMSU, MHS, IR vectors	0.1°/hourly	60°N-S/ Nov. 2015	30 min.	0 hour	JAXA (Kubota)[5]
GSMaP Standard (GSMaP_MVK) V7	TMI, AMSR-E, AMSR, SSM/I, SSMIS, GMI, AMSR-2, AMSU, MHS, IR vectors	0.1°/hourly	60°N-S/Mar. 2014	1 hour	3 days	JAXA/EORC (Kubota) [4]
GSMaP Reanalysis (GSMaP_RNL) V7	TMI, AMSR-E, AMSR, SSM/I, SSMIS, GMI, AMSR-2, AMSU, MHS, IR vectors	0.1°/hourly	60°N-S/MAR. 2000	1 hour	Reprocess after major version upgrade	JAXA/EORC (Kubota) [4]
IMERG Early Run V06	TMI, SSMI, SSMIS, AMSR-E, GMI, AMSR2, AMSU, MHS, SAPHIR, ATMS, IR, MERRA-2/GEOS FP TQV vectors	0.1°/30 min.	Global/June 2000	30 min.	4 hours	NASA/GSFC PPS (Huffman) [6]
IMERG Late Run V06	TMI, SSMI, SSMIS, AMSR-E, GMI, AMSR2, AMSU, MHS, SAPHIR, ATMS, IR, MERRA-2/GEOS FP TQV vectors	0.1°/30 min.	Global/June 2000	30 min.	14 hours	NASA/GSFC PPS (Huffman) [7]
MPE	IR 10.8 channel: SEVIRI on Meteosat 8, 9 (9 takes over the Indian Ocean Data Coverage [IODC] in 2022), and Meteosat 10 (Rapid Scanning Service [RSS]); microwave imager data: SSM/I, SSMIS	IODC: original pixels on full earth disk/15-min	Nadir 41.5°E; 26°W-109°E, 67.5°N-S	15-min	10 min	EUMETSAT [8]
		RSS: original pixels on a third of the earth disc/5-min	Nadir 9.5°E; 45°W-65°E, 15°-70°N-S	5-min	10 min	EUMETSAT [9]
MSWEP NRT	ERA5, GDAS, IMERG, GSMaP	0.1°/3-hour	Global/ 2021	Hourly	3 hours	GloH2O (Beck) [10]
PERSIANN	(TMI, AMSR-E, SSM/I, SSMIS, AMSU, MHS)-cal. IR	0.25°/30-min	60°N-S/ March 2000	Hourly	1 day	UC Irvine (Sorooshian) [11]
P-IN-SEVIRI PMW (H60B)	HSAF products based on SSMIS, AMSU/ MHS, ATMS, GMI, AMSR-2; MSG-IR	5 km/15 min	MSG full disk/July 2020	15 min	15 min	HSAF (Melfi)[12]
P-AC-SEVIRI-PMW (H61B)	P-IN-SEVIRI-PMW	5 km/hourly	MSG full disk/July 2020	hourly	30 min	HSAF (Melfi)[12]
P-AC-SEVIRI-E (H90)	P-IN-SEVIRI-E	5 km/hourly	MSG IODC full disk/March 2021	hourly	30 min	HSAF (Melfi)[12]
P-AC-SM2R-PMW (H64)	H-AUX-67 (the integration of P-IN-PMW); HSAF Soil Moisture products	0.25 °/daily	60°S-75°N, 60°W-60°E/January 2019	Daily	17 hours	HSAF (Ciabatta, Brocca)[12]
SCaMPR (NESDIS Enterprise Rainfall Rate / QPE)	(GMI, AMSR-2, AMSU-B, MHS)-cal IR	2 km/10 min	Western Hemisphere (70°N-60°S) - Jan 2008 Global - 70°N-60°S / Aug 2020	10 min.	45 min from image time (start of GEO-IR scans)	NOAA/NESDIS (Kuligowski) [13]
TOVS	HIRS, MSU sounding retrievals	1°/daily	Global/1979-April 2005	Daily	N/A	NASA/GSFC 610 (Susskind)[14]
TRMM Real-Time HQ Version 7 (3B40RT)	TMI, SSM/I, SSMIS, AMSR-E, AMSU, MHS	0.25°/3-hourly	Global - 70°N-S/Mar. 2000 - Dec. 2019	3 hours	N/A	NASA/GSFC PPS (Huffman, Adler)[15]
TRMM Real-Time VAR Version 7 (3B41RT)	MW-VAR (IR)	0.25°/hourly	Global - 50°N-S/Mar. 2000 - Dec- 2019	1 hour	N/A	NASA/GSFC PPS (Huffman, Adler)[16]
TRMM Real-Time HQVAR Version 7 (3B42RT)	HQ, MW-VAR (IR)	0.25°/3-hourly	Global - 50°N-S/Mar. 2000 - Dec- 2019	3 hours	N/A	NASA/GSFC PPS (Huffman, Adler)[17]

[1] https://www.ncdc.noaa.gov/cdr/atmospheric/precipitation-gpcp-daily - Robert Adler
[2] ftp://ftp.cpc.ncep.noaa.gov/precip/GPCP_PEN/ - Pingping Xie
[3] https://doi.org/10.5067/MEASURES/GPCP/DATA303 - George Huffman
[4] http://sharaku.eorc.jaxa.jp/GSMaP/ - Takuji Kubota
[5] http://sharaku.eorc.jaxa.jp/GSMaP_NOW// - Takuji Kubota
[6] https://gpm.nasa.gov/data/directory Level 3 tab, click on "IMERG Early Run" - https://gpm.nasa.gov/contact
[7] https://gpm.nasa.gov/data/directory Level 3 tab, click on "IMERG Late Run" - https://gpm.nasa.gov/contact
[8] https://navigator.eumetsat.int/product/EO:EUM:DAT:MSG:MPE-GRIB-IODC?query=MPE&s=simple - EUMETSAT">
[9] https://navigator.eumetsat.int/product/EO:EUM:DAT:MSG:RSS-MPE-GRIB - EUMETSAT>
[10] http://www.gloh2o.org [note: commercial use requires a license] - Hylke Beck
[11] http://chrsdata.eng.uci.edu - Kuolin Hsu
[12] http://hsaf.meteoam.it/User/Register - Davide Melfi, Marco Petracca (product quality assessment), Michal Kasina (hydrological validation)
[13] http://www.star.nesdis.noaa.gov/smcd/emb/ff/SCaMPR.php - Robert (Bob) Kuligowski
[14] https://disc.gsfc.nasa.gov/datasets?keywords=TOVS*&page=1 - Andrey K. Savtchenko [15] https://doi.org/10.5067/TRMM/TMPA/3H-E-MW/7 - George Huffman; superseded by IMERG Early and Late Runs
[16] https://doi.org/10.5067/TRMM/TMPA/3H-E-IR/7 - George Huffman; superseded by IMERG Early and Late Runs
[17] https://doi.org/10.5067/TRMM/TMPA/3H-E/7 - George Huffman; superseded by IMERG Early and Late Runs