For background information, please refer to the following pages for each dataset:
-  Version 1.1: https://podaac.jpl.nasa.gov/dataset/CCMP_MEASURES_ATLAS_L4_OW_L3_0_WIND_VECTORS_FLK
 Version 2.0: http://www.remss.com/measurements/ccmp
Without diving too deep into the details, perhaps the most important difference between V1.1 and V2.0 is the baseline calibration of the microwave radiometer and scatterometer sensor data that has been assimilated. V1.1 uses a variety of calibration versions throughout it's time series whereas Version 2.0 utilizes a consistent calibration known as RSS V7.
Furthermore, perhaps the next important issue is the change in the background analysis that is used. In V1.1, CCMP utilized the uropean Center for Medium-Range Weather Forecasts (ECMWF) Reanalysis ERA-40 as the background first-guess wind field from 1987 through 1998. From 1999 until 2011, V1.1 utilized the ECMWF Operational Analysis wind fields as the first-guess. With V2.0, CCMP utilizes the latest ECMWF Interim-Reanalysis as the first guess, which unlike the previous ERA-40 and Operational Analysis is processed on a consistent 0.25 degree grid. More information on the ECMWF Interim Analysis may be obtained here: http://www.ecmwf.int/en/research/climate-reanalysis/era-interim
Below is a summary of all other upgrades for V2.0 that are not present in V1.1:
- Extension of the CCMP data set to July 2015 with plans to provide bi-annual extensions and updates to the dataset.
- Addition of winds from new instruments: ASCAT Metop-A, AMSR2, and GMI.
- Use of improved moored buoy data with better quality control, including winds from NDBC, TAO, TRITON, RAMA, PIRATA, and Canadian buoys.
- Upgrade of the data file format to netCDF4 with CF-1.6 metadata.
- Each daily file contains four 6-hourly wind analyses and self-describing metadata.