[gradsusr] Seemingly corrupt data in grib file

[Kritika Thapa]

Hello all!

I'm a graduate student working with ERA-Interim data and new to grads. I
have been downloading data from ECMWF (
http://apps.ecmwf.int/datasets/data/interim_full_daily/?levtype=pl) in GRIB
format, and using grib2ctl to obtain a ctl file. After that, I run gribmap
-i  <filename>.ctl to obtain an index file.

This has all worked out well as far as getting grads to read the file, but
the data seems distorted. I have so far downloaded the global 2008 monthly
(parameters: specific humidity, U and V components of wind, and
geopotential) data with approximately 120 time values, and the data for the
first 3/4 of the month looks fine. The last 1/4 or so of the month,
however, seems incorrect. This is the case no matter what variable I choose
to display. My calculations (just some simple uses of the vint ()
function), likewise come out useless at these points. The calculations give
me extremely large values for latter half of the month and instead of ring
like contours, I get zebra stripes on the display window.

Does anyone know if this is an issue with grads, the GRIB file, the ctl
file, the idx file, the source of the data, or some other thing I am
unaware of?

Thanks for your help in advance!

Kritika Thapa
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