DS127.0 represents a dataset implemented and computed by NCAR's Data Support Section, and forms an essential part of efforts undertaken in late 2004, early 2005, to produce an archive of selected segments of ERA-40 on standard transformation grids.

In this case, forty six ERA-40 6-hourly surface and single level analysis variables were transformed from a reduced N80 Gaussian grid to a 320x160 regular Gaussian grid. (These are designated as SURFACE, or SURFACE/SINGLE LEVEL, or SFC/sfc, variables below.) All fields were transformed using routines from the ECMWF EMOS library, including 10 meter winds which were treated as scalars because of a lack of 10 meter spectral vorticity and divergence. A missing value of 9.999e+20 occurs in the sea surface temperature and sea ice (SSTK and CI) fields to mask grid points occurring over land. Fields formerly archived as whole integers, such as vegetation indices and cloud cover, occur as integers plus a fractional part in the T106 version due to interpolation.

In addition, twenty seven ERA-40 6-hourly surface and single level 6-hour forecast variables were transformed from a reduced N80 Gaussian grid to a 320x160 regular Gaussian grid. (These are designated as OTHER, or othr, variables below.) All variables are valid 6 hours after the forecast was initiated. Thus, 00Z 6-hour forecast evaporation is valid at 06Z. Four of the variables are instantaneous variables, and the remaining twenty three variables are accumulated over the 6-hour forecast time. Divide the accumulated variables by 21600 seconds to obtain instantaneous values. (Multiplication by minus one may also be necessary to match the sign convention one is accustomed to.) All fields were transformed using routines from the ECMWF EMOS library, including three pairs of stresses which were treated as scalars because of a lack of spectral precursors.