TRMM rainfall measurement for synoptic systems
The Tropical Rainfall Measuring Mission (TRMM) satellite is a single satellite, carrying multiple instruments on board, as described here. It makes a total of 16 orbits/day at a low altitude of 400 km, with different swath widths for each instrument. Thus, the measurement product that you get is not a "continuous" measurement of a single atmospheric phenomenon, but a composite of multiple orbital passes and instruments, where the density of coverage will depend on the time period over which the composite is made.

If you take a look at TRMM data access page, there are 3 levels of data, each level depending on the amount of processing and quality control:


Level 1: Precipitation radar (PR) reflectivity
Level 2: Combined rainfall profile - PR + Microwave interferometer (TMI)
Level 3: 3-hourly composite of the above + additional data from other instruments (satellites, ground measurements, ground radars), with extended range to 60S - 60N. 


Level 1 and 2 data are nearly raw, and are not composites - they give you data from all 16 orbits/day, and each swath cross-section along the orbit will have a timestamp associated with it. Level 3 data will be the most spatially "continuous" of the three, but one must be aware that this is a composite of multiple orbital swaths and multiple instruments, so it is more suitable for slowly evolving (larger scale) systems.

Related: Is there a database of global rainfall time series?