Table 1. Summary of publicly available, quasi-operational, quasi-global precipitation estimates that are produced by combining input data from several sensor types, including satellite sensors and precipitation gauges. Where appropriate, the algorithms applied to the individual input data sets are mentioned. Solid shading indicates products that are not yet available. [Last updated 31 July 2021, G.J. Huffman]

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Algorithm	Input data	Space/time grid	Areal coverage/start date	Update frequency	Latency	Producer (Developer) URL
CAMS/OPI	CMAP-OPI, gauge	2.5°/ monthly 2.5°/ pentad	Global/1979	Monthly Pentad	5 days 1 day	NOAA/ NWS CPC (Xie)[1]
CHIRPS preliminary	IR, CHPclim, submonthly/ monthly stations	0.05°/ daily, pentad, monthly	50°N-S/1981	prelim: pentad	2 days	U. C. Santa Barbara (Funk) [2]
CHIRPS final				final: month	2 weeks
CMAP	OPI, SSM/I, SSMIS, GPI, MSU, gauge, model	2.5°/ monthly	Global/1979 - Nov. 2011	Seasonal	3 months	NOAA/ NWS CPC (Xie)[3]
	OPI, SSM/I, GPI, MSU, gauge, model	2.5°/ pentad	Global/1979 - Nov. 2011	Seasonal	3 months	NOAA/ NWS CPC (Xie)[4]
	OPI, SSM/I, GPI, gauge	2.5°/ pentad-RT	Global/2000	Pentad	1 day	NOAA/ NWS CPC (Xie)[5]
CMORPH V1.0_CRT (Bias corrected)	TMI, AMSR-E, AMSR-2, SSM/I, SSMIS, AMSU, MHS, MWRI, IR vectors, CPC Gauge, GPCP Pentad	8x8 km2/30 min	60°N-S/1998	NRT: hourly final post-processed: monthly	NRT: 2,12,18 hours final: 4 months	NOAA/ CPC (Xie)[6]
CMORPH CDR (Same as final CMORPH V1_CRT)V1.0_CRT	TMI, AMSR-E, AMSR-2, SSM/I, SSMIS, AMSU, MHS, MWRI, IR vectors, CPC Gauge, GPCP Pentad	8x8 km2/30 min 0.25°/hourly 0.25°/daily	60°N-S/1998	Monthly	5 months	NOAA/ CPC (Xie)[7]
CMORPH V1.0_BLD	TMI, AMSR-E, AMSR-2, SSM/I, SSMIS, AMSU, MHS, MWIR, IR vectors, daily gauge	0.25°/daily	60°N-S regional/1998	Daily	18 hours	NOAA/ CPC (Xie)[6]
GPCP pentad (Version 1.1)	OPI, SSM/I, GPI, MSU, gauge, GPCP monthly	2.5°/ 5-day	Global/1979	Monthly	3 months	NOAA/ NWS CPC (Xie)[8]
GPCP Version 2.3 Satellite-Gauge (SG)	GPCP-OPI, GPCC gauge 1/79-7/87, 12/87, thereafter SSMI- & SSMIS-AGPI (IR), GPCC gauge, TOVS, AIRS	2.5°/ monthly	Global/1979	Monthly	2 months	UMCP/ESSIC (Adler, Huffman) [9]
GPCP Version 3.1 Satellite-Gauge (SG)	SSMI- & SSMIS-PERSIANN-CDR, GPCC gauge, TOVS, AIRS, TCC & MCTG climatology	0.5°/ monthly	Global/1992	Monthly	2 months	NASA/GSFC (Huffman) [10]
GSMaP Gauge-calibrated (GSMaP_Gauge) V7	GMI, AMSR-2, AMSU, MHS, IR vectors, NOAA CPC daily gauge analysis	0.1°/ hourly	Global - 60°N-S/Mar. 10, 2014	Hourly	3 days	JAXA/EORC (Kubota) [11]
GSMaP Reanalysis Gauge-calibrated (GSMaP_RNL_Gauge) V6	TMI, SSM/I, SSMIS, AMSR-E, GMI, AMSR-2, AMSU, MHS, IR vectors, NOAA CPC daily gauge analysis	0.1°/ hourly	Global - 60°N-S/Mar. 2000	Hourly	Reprocess after major version upgrade	JAXA/EORC (Kubota) [11]
IMERG Final Run V06	TMI, SSM/I, SSMIS, AMSR-E, GMI, AMSR-2, AMSU, MHS, SAPHIR, ATMS, IR, MERRA-2 / GEOS FP TQV vectors, GPCP monthly	0.1°/ half-hourly 0.1°/monthly	Global/June 2000	30 min; 1 month	3.5 months	NASA/GSFC PPS (Huffman) [12]
MSWEP	ERA5, IMERG, GridSat, CHELSA, GSOD, GHCN-D, various national gauge databases	0.1°/ 3-hourly	Global/1979	Yearly	months	GloH2O (Beck) [13]
PERSIANN-CDR	GRIDSAT-IRWIN, GPCP Monthly Precipitation	0.25°/ daily	60°N-S/1983	Monthly	3 months	UC Irvine (Sorooshian)[14]
PERSIANN-CCS-CDR	GridSat-IRWIN, GPCP Monthly Precipitation	0.04°/ 3-hour	60°N-S/1983	Monthly	3 months	UC Irvine (Sorooshian)[15]
RFE	GPI, NOAA-SSM/I, gauge	10 km/ daily	Africa/Oct 2000	Daily	6 hours	NOAA/NWS CPC (Xie)[16]
		10 km/daily	South Asia/Apr 2001	Daily	6 hours	NOAA/ NWS CPC (Xie)[17]
TRMM Plus Other Data (3B43 Version 7)	TCI, TMI, SSM/I, SSMIS, AMSR-E, AMSU, MHS, MW-VAR (IR), gauge	0.25°/ monthly	Global - 50°N-S/Jan 1998-2019	Monthly	Replaced by IMERG Final	NASA/ GSFC PPS (Huffman, Adler)[18]
TRMM Plus Other Satellites (3B42 Version 7)	TCI, TMI, SSM/I, SSMIS, AMSR-E, AMSU, MHS, MW-VAR (IR), V.7 3B43	0.25°/ 3-hourly	Global - 50°N-S/Jan 1998-2019	Monthly	Replaced by IMERG Final	NASA/ GSFC PPS (Huffman, Adler)[19]

[1] ftp://ftp.cpc.ncep.noaa.gov/precip/data-req/cams_opi_v0208/ - Pingping Xie
[2] https://chc.ucsb.edu/data/chirps - Chris Funk
[3] ftp://ftp.cpc.ncep.noaa.gov/precip/cmap/monthly/ - Pingping Xie
[4] ftp://ftp.cpc.ncep.noaa.gov/precip/cmap/pentad/ - Pingping Xie
[5] ftp://ftp.cpc.ncep.noaa.gov/precip/cmap/pentad_rt/ - Pingping Xie
[6] ftp://ftp.cpc.ncep.noaa.gov/precip/CMORPH_V1.0 - Pingping Xie
[7] ftp://ftp.cpc.ncep.noaa.gov/precip/GPCP_PEN/ - Pingping Xie
[8] ftp://ftp.cpc.ncep.noaa.gov/precip/GPCP_PEN/ - Pingping Xie
[9] https://www.ncdc.noaa.gov/cdr/atmospheric/precipitation-gpcp-monthly - Robert Adler
[10]https://doi.org/10.5067/DBVUO4KQHXTK - George Huffman [11] http://sharaku.eorc.jaxa.jp/GSMaP/ - Takuji Kubota [12] Level 3 tab, click on "IMERG Final Run" - https://gpm.nasa.gov/contact [13] http://www.gloh2o.org/mswep/ [note: commercial use requires a license] - Hylke Beck [14] https://www.ncdc.noaa.gov/cdr/atmospheric/precipitation-persiann-cdr - Kuolin Hsu
[15] http://chrsdata.eng.uci.edu - Kuolin Hsu
[16] ftp://ftp.cpc.ncep.noaa.gov/fews/newalgo_est/before 2001; ftp://ftp.cpc.ncep.noaa.gov/fews/fewsdata/africa/rfe2 thereafter - Pingping Xie
[17] ftp://ftp.cpc.ncep.noaa.gov/fews/S.Asia/ - Pingping Xie
[18] https://doi.org/10.5067/TRMM/TMPA/MONTH/7 - George Huffman; superseded by IMERG Final Run monthly
[19] https://doi.org/10.5067/TRMM/TMPA/3H/7 - George Huffman; superseded by IMERG Final Run monthly