Hi Penny, Coordinate values are at the middle of the grid cell, so 15-Feb runs from 1-Jan to 1-Apr 15-May runs from 1-Apr to 1-Jul 15-Aug runs from 1-Jul to 1-Oct 15-Feb runs from 1-Jan to 31-Dec The command yes? show axis/t seasonal_reglists the coordinates, the box sizes the date of the lower limit of the axis and the time step, or time coordinate value. The definition of "month" is an ambiguous one, so in order for the grid cells to be evenly spaced, things aren't quite as clean as what I listed above. The axis has four, equally spaced cells, each 1/4 year long.
(Coordinate axes can actually lie anywhere in a grid cell, IF one specifies the edges of the cells as well as the coordinates, with the DEFINE AXIS/EDGES or DEFINE AXIS/BOUNDS qualifier and those edges are then saved in netCDF files. But that's not done on the climatological axes in the Ferret dataset climatological_axes.cdf)
On 12/5/2012 9:50 AM, Oots, Penny C. (LARC-E301)[SCIENCE SYSTEMS AND APPLICATIONS, INC] wrote:
I created a netcdf file by regridding a threads aggregation of monthly data with
time values of integer number of months since 2006-06-01 (i.e. Time values are
7.0 to 66.0) to a seasonal_reg axis. The resulting time axis has the following
values (in hours) that correspond to Feb-15, May-15, Aug-15, and Nov 15.
SEASONAL_REG[4]
1095.7275, 3287.1825, 5478.6375, 7670.0925
yes? show axis seasonal_reg
name axis # pts start end
SEASONAL_REG TIME 4mr 15-FEB 15:43 15-NOV 14:05
T0 =3D 01-JAN-0000 00:00:00
Axis span (to cell edges) =3D 8765.82 (modulo length =3D axis span)
Question 1: Does Feb 15 represent data from Feb 15 to May-15 or from Jan-15 to Apr-15? (Is Feb 15 the mid-point or the beginning point?)
And does Nov 15 represent data from Nov 15 to Feb 15 or from Oct 15 to Dec 15?
And is there a Ferret command that I should have found to display this info?
Question 2: Why is the 15th of the month used instead of the first of the month?
Penny Oots