Search found 365 matches

by barbara.stunder
February 11th, 2013, 3:04 pm
Forum: General questions on meteorological data needed for HYSPLIT
Topic: Why GDAS0P5 data have no w velocity?
Replies: 6
Views: 3759

Re: Why GDAS0P5 data have no w velocity?

Have you tried running the trajectory ensemble for a starting point/time where you get a large difference and a case where they are similar? I wonder if the case with the w-value in the model output would be within the envelope of the ensemble with the gdas0p5? The ensemble provides an estimate of t...
by barbara.stunder
January 15th, 2013, 8:21 am
Forum: General questions on meteorological data needed for HYSPLIT
Topic: Why GDAS0P5 data have no w velocity?
Replies: 6
Views: 3759

Re: Why GDAS0P5 data have no w velocity?

GDAS0P5 are NOT converted from the same GDAS dataset with GDAS1 data. For ARL's GDAS1, NCEP post-processes NCEP GDAS output into 1-degree, pressure level data which includes vertical velocity. ARL takes that and processes it. For ARL's GDAS0P5, ARL post-processes NCEP GDAS output into half-degree, ...
by barbara.stunder
January 8th, 2013, 11:02 am
Forum: General questions on meteorological data needed for HYSPLIT
Topic: Why GDAS0P5 data have no w velocity?
Replies: 6
Views: 3759

Re: Why GDAS0P5 data have no w velocity?

GDAS0P5 are NOT converted from the same GDAS dataset with GDAS1 data. For ARL's GDAS1, NCEP post-processes NCEP GDAS output into 1-degree, pressure level data which includes vertical velocity. ARL takes that and processes it. For ARL's GDAS0P5, ARL post-processes NCEP GDAS output into half-degree, h...
by barbara.stunder
January 7th, 2013, 10:15 am
Forum: General questions on meteorological data needed for HYSPLIT
Topic: GDAS0P5 data extraction
Replies: 11
Views: 5381

Re: GDAS0P5 data extraction

dolces wrote:How can I extract specific vertical layers from GDAS0P5 and re-write into a new ARL format data?
Can MeteoInfo do this? Link to MeteoInfo at http://ready.arl.noaa.gov/HYSPLIT.php
by barbara.stunder
January 7th, 2013, 9:54 am
Forum: General questions on meteorological data needed for HYSPLIT
Topic: GDAS0P5 data extraction
Replies: 11
Views: 5381

Re: GDAS0P5 data extraction

dolces wrote:Are ARL data in ASCII format? Can I use MATLAB to read and re-write them?
Only the header for each record is in ASCII format. See the information and the sample FORTRAN program chk_data.f at the bottom of http://ready.arl.noaa.gov/archives.php

I am not familiar with MATLAB.
by barbara.stunder
December 21st, 2012, 9:30 am
Forum: General questions on meteorological data needed for HYSPLIT
Topic: GDAS0P5 data extraction
Replies: 11
Views: 5381

Re: GDAS0P5 data extraction

The HYSPLIT spatial extract program xtrct_grid, only extracts the lowest X number of levels, you cannot tell it which particular levels to get. The GDAS1 levels are on pressure surfaces and the GDAS0P5 are on hybrid sigma-pressure, so except for the higher levels, the comparison would not be direct...
by barbara.stunder
December 21st, 2012, 9:09 am
Forum: General questions on meteorological data needed for HYSPLIT
Topic: GDAS0P5 data extraction
Replies: 11
Views: 5381

Re: GDAS0P5 data extraction

Yes, with the 'cat' command.
cat day2 >> day1
by barbara.stunder
December 20th, 2012, 8:35 am
Forum: General questions on meteorological data needed for HYSPLIT
Topic: GDAS0P5 data extraction
Replies: 11
Views: 5381

Re: GDAS0P5 data extraction

The HYSPLIT spatial extract program xtrct_grid, only extracts the lowest X number of levels, you cannot tell it which particular levels to get. The GDAS1 levels are on pressure surfaces and the GDAS0P5 are on hybrid sigma-pressure, so except for the higher levels, the comparison would not be direct.
by barbara.stunder
December 7th, 2012, 8:21 am
Forum: Cluster Analysis
Topic: error-origin lat-lon must be identical
Replies: 9
Views: 7573

Re: error-origin lat-lon must be identical

You're positive they all have the same trajectory source latitude-longitude?

If so, please send me your set of trajectories, or a sub-set for which this error occurs and I'll look at it.
by barbara.stunder
December 4th, 2012, 9:23 am
Forum: General questions on meteorological data needed for HYSPLIT
Topic: Where can I get detailed description of GDAS 0.5-deg data?
Replies: 13
Views: 6295

Re: Where can I get detailed description of GDAS 0.5-deg dat

The GDAS output is in spectral coefficients on 64 levels. The resolution is T574 (approx. 27 km, see http://www.nws.noaa.gov/os/notification/tin10-15gfs.txt). There is information on the GFS, which is the forecast component of the the GDAS at http://www.emc.ncep.noaa.gov/GFS/doc.php Other informatio...