Can you tell me, the differences between AgMERRA and APHRODITE datasets?

The AgMERRA and AgCFSR climate forcing datasets were created as an element of the Agricultural Model Intercomparison and Improvement Project (AgMIP) to provide consistent, daily time series over the 1980-2010 period with global coverage of climate variables required for agricultural models. The datasets are stored at 0.25 degree*0.25 degree horizontal resolution (~25km), with global coverage and daily values from 1980-2010 in order to form a "current period" climatology.

The AgMERRA corrects to gridded temperature (maximum, minimum, and mean) and precipitation, incorporates satellite precipitation, and replaces solar radiation with NASA/GEWEX SRB to cover the 1980-2010 period, in daily time scale. Also it shows relative humidity (maximum), and wind speed. The spatial resolution for every of variable are different, namely precipitation (mm), Wind Speed (m/s), and Relative Humidity are in 0.25 degree, Solar Radiation (MJ/m2/day) is in 1 degree, Mean, Min and Max Temperature (C) are in 0.5 degree.

You can use this source of in various fields of studies, such as drought monitoring, Assessing floods, crop yield and other samples. You can refer to this paper in field of drought concept. (Estimation of meteorological drought indices based on AgMERRA precipitation data and station-observed precipitation data)

The APHRODITE (Asian Precipitation-Highly-Resolved Observational Data Integration Towards Evaluation) (Yatagai et al., 2009) can present only precipitation data in daily time scale, with 0.25 and 0.5 degree resolutions. This gauge can present dataset only for Asia. APHRODITE's (Asian Precipitation - Highly-Resolved Observational Data Integration Towards Evaluation) daily gridded precipitation is the only long-term (1951 onward) continental-scale daily product that contains a dense network of daily rain-gauge data for Asia including the Himalayas, South and Southeast Asia and mountainous areas in the Middle East. The number of valid stations was between 5000 and 12,000, representing 2.3 to 4.5 times the data available through the Global Telecommunication System network, which were used for most daily grid precipitation products. The products are available on a regional basis(UCAR's site).

We have compared different guages in a paper that you can read the paper for better understanding which entitled (Evaluation of different gridded rainfall datasets for rainfed wheat yield prediction in an arid environment)