README on MIDAS Velocity fields

When using these velocities in publications please cite:

Blewitt, G., C. Kreemer, W.C. Hammond, and J. Gazeaux (2016). MIDAS robust trend estimator for accurate GPS station velocities without step detection, Journal of Geophysical Research, 121, doi:10.1002/2015JB012552

This paper is open access and can be found here:
http://onlinelibrary.wiley.com/doi/10.1002/2015JB012552/full 

The MIDAS velocity files are automatically updated weekly from the GPS time series generated by the Nevada Geodetic Laboratory.
Columns on the MIDAS velocity files are as follows:
column 1 - 4 character station ID
column 2 - MIDAS version label 
column 3 - time series first epoch, in decimal year format. 
column 4 - time series last epoch, in decimal year format (See http://geodesy.unr.edu/NGLStationPages/decyr.txt for translation to YYMMMDD format).
column 5 - time series duration (years).
column 6 - number of epochs of data, used or not
column 7 - number of epochs of good data, i.e. used in at least one velocity sample 
column 8 - number of velocity sample pairs used to estimate midas velocity
column 9-11 - east, north, up mode velocities (m/yr)
column 12-14 - east, north, up mode velocity uncertainties (m/yr)
column 15-17 - east, north, up offset at at first epoch (m)
column 18-20 - east, north, up fraction of outliers
colums 21-23 - east, north, up standard deviation velocity pairs 
column 24 - number of steps assumed, determined from our steps database
column 25-27 - latitude (degrees), longitude (degrees) and height (m) of station.


The MIDAS velocities are provided in a number of tectonic plate-based reference frames. These are specified by a code and include:

IGS14 - IGR14 Reference Frame
AF - Africa
AN - Antarctica
AR - Arabia
AU - Australia
BU - Burma
CA - Caribbean
CO - Cocos
EU - Eurasian
IN - Indian
MA - Mariana
NA - North America
NB - North Bismark
NZ - Nazca
OK - Okhotsk
ON - Okinawa
PA - Pacific
PM - Panama
PS - Philippine Sea
SA - South America
SB - South Bismark
SC - Scotia
SL - Shetland
SO - Somalia
SU - Sunda
WL - Woodlark