Table 4. Summary of publicly available, quasi-operational, quasi-global precipitation estimates from precipitation gauge data. Where appropriate, the algorithms applied to the individual input data sets are mentioned. Unlike the other tables, "global" implies "land areas", with variable amounts of coverage for islands. [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
APHRODITE Water Resources/ Extreme Events	~12,000 gauges (ratio interpolation with orographic effects)	0.25°, 0.5°/daily	Eurasia/1951 - 2007 (V1101)	-	-	APHRODITE Project (Yatagai) [1]
	~8,000 gauges (ratio interpolation with orographic effects)	0.25°, 0.5°/daily, 0.5°/daily climatology	Monsoon Asia/1979-2015 (V1801R1, V1901)	-	-
CPC Unified Gauge-based Analysis of Global Daily Precip.	> 30,000 gauges (optimal interp. with orographic effects)	0.5°/daily over the global land 0.125°/daily over CONUS	Global/1979-2005	-	-	NOAA/NWS CPC (Chen & Xie)[2]
	> 17,000 gauges real-time (optimal interp. with orographic effects)	0.5°/daily over the global land 0.125°/daily over CONUS	Global/2006	Daily	1 day	NOAA/NWS CPC (Chen & Xie)[3]
CRU Gauge	~10,000 gauges (anomaly interpolation)	2.5°x3.75°, 5°/monthly	Global/1900 - 1998	-	-	CRU at U. East Anglia (Hulme)[4]
CRU TS 3.10.01 Gauge	~10,000 gauges (anomaly interpolation)	0.5°/monthly	Global/1901	Yearly	1-2 years	CRU and BADC (Harris)[5]
GHCN+CAMS Gauge	~3,800 gauges (SPHEREMAP)	2.5°/monthly	Global/1979	Monthly	1 week	NOAA/NWS CPC (Xie)[6]
GPCC First Guess Monthly	~7,500 gauges (SYNOP stations)	1°/ monthly	Global/2004	Monthly	5 days (after end of month)	DWD GPCC (Becker and Schneider)[7]
GPCC First Guess Daily	~7,500 gauges (SYNOP stations)	1°/ daily	Global/2009	Monthly	5 days (after end of month)	DWD GPCC (Becker and Schneider)[8]
GPCC Full Data Daily V.2020	~~84,800 gauges	1°/ daily	Global/1982-2019	about every 2 years	1-2 years	DWD GPCC (Becker and Schneider)[9]
GPCC Full Data Monthly V.2020	~~84,800 gauges	0.5°, 1°, 2.5°/ monthly	Global/1981-2019	Occasional (about every 2 years)	1-2 years	DWD GPCC (Becker and Schneider)[10]
GPCC Monitoring V.2020	~8,000 gauges (climatology-anomaly)	1°,2.5°/monthly	Global/1982 - present	Monthly	2 months	DWD GPCC (Becker and Schneider)[11]
GPCC VASClimo Version 1.1	~9,000 gauges (climatology-anomaly)	0.5°,1°,2.5°/ monthly	Global/1950-2000	Old (will be replaced by HOMPRA)	-	DWD GPCC (Becker)[12]
Rainwatch	~200 gauges	stations/daily	16 African countries/ varies by country	Varies by country	Varies by country	The Walker Inst., U. of Reading (Tarnavsky) [13]

[1] http://aphrodite.st.hirosaki-u.ac.jp/; see also https://climatedataguide.ucar.edu/climate-data/aphrodite-asian-precipitation-highly-resolved-observational-data-integration-towards - Akiyo Yatagai
[2] ftp://ftp.cpc.ncep.noaa.gov/precip/CPC_UNI_PRCP/GAUGE_GLB/V1.0/ - Pingping Xie
[3] ftp://ftp.cpc.ncep.noaa.gov/precip/CPC_UNI_PRCP/GAUGE_GLB/RT/ - Pingping Xie
[4] https://crudata.uea.ac.uk/cru/data/precip/ - Ian "Harry" Harris (ENV - Staff)
[4] https://crudata.uea.ac.uk/cru/data/hrg/ - Ian "Harry" Harris (ENV - Staff)
[6] Pingping Xie
[7] https://opendata.dwd.de/climate_environment/GPCC/first_guess - Udo Schneider
[8] https://opendata.dwd.de/climate_environment/GPCC/first_guess_daily - Udo Schneider
[9] https://opendata.dwd.de/climate_environment/GPCC/full_data_daily_v2020 - Udo Schneider
[10] https://opendata.dwd.de/climate_environment/GPCC/full_data_monthly_v2020 - Udo Schneider
[11] https://opendata.dwd.de/climate_environment/GPCC/monitoring_v2020 - Udo Schneider
[12] https://opendata.dwd.de/climate_environment/GPCC/vasclimo - Udo Schneider
[13] http://walker.ac.uk/rw/, https://zenodo.org/record/3366368#.YLUoDi9Q1iN - Elena Tarnavsky