A Summary and Comparison of the latest GPCP Daily and Monthly Products (Version 3.2) and the Plan Forward

This presentation is composed of four major parts: (1) a brief overview of the latest Global Precipitation Climatology Project (GPCP) Daily and Monthly products (V3.2) and satellite-gauge input data sets used in them, (2) comparison of the GPCP V3.2 products with the previous version of GPCP Daily (V1.3) and Monthly (V2.3) products and highlighting major changes, (3) assessment of the GPCP V3.2 products over the Oceans using Passive Aquatic Listeners (PALs) and over sea ice using snow depth data from combination of ICESat-2 and Cryosat-2 observations, and (4) a brief description of the plans towards the next generation of the GPCP products. GPCP is a popular combined satellite-gauge precipitation dataset in which the long-term CDR standards of consistency and homogeneity are emphasized, going back to 1983 for GPCP Monthly V3.2. Several major changes occurred in V3.2 including: (1) moving from Monthly 2.5°x2.5° and Daily 1.0°x 1.0° spatial resolution in V2.3 to 0.5°x0.5° for both Daily and Monthly products, (2) addition of more recent satellite data such as the Tropical Rainfall Measuring Mission (TRMM), CloudSat, Global Precipitation Measurement (GPM) mission, and the Gravity Recovery and Climate Experiment (GRACE) mass change observations, and (3) use of new precipitation retrieval and calibration methods. Compared to V2.3, GPCP V3.2 shows about  6.5% increase in global oceanic and about a 4.5% increase in global (land and ocean) precipitation rates with some major changes over the ocean between 40 oS and 60 oS. Similar to V2.3, a near-zero global precipitation trend was observed in V3.2.  However, regional trends, which are substantial, remain generally similar between V2.3 and V3.2. Evaluations over the oceans using PALs showed that GPCP v3.2 substantially outperforms GPCP V2.3 in representing rain occurrence and rain intensity at a daily scale, likely due to the use of IMERG in the daily product of GPCP V3.2. Comparison of the GPCP V3.2 product over sea ice, suggests that GPCP V3.2 generally captures the snowfall accumulation pattern over sea ice, compared to that obtained from the combination of ICESat-2 and Cryosat-2 observations, as well as that from ERA5. However, the products show considerable differences in the amount of snowfall accumulation, with ERA5 often showing the highest values. We will end the presentation by briefly discussing our plans for further improvement of GPCP including higher spatial and temporal resolution, lower latency, and the use of more advanced gauge analysis and precipitation retrieval methods.