HYSPLIT Forum: hysplitbbs.arl.noaa.gov

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 ...

GDAS0P5 are converted from the same GDAS dataset with GDAS1 data, right? Why GDAS1 data have w volocity while GDAS0P5 data don't?

When generating trajectories with GDAS0P5 data, HYSPLIT has to calculate w velocity from diversity, is it possible that the w velocity field calculated from diversity is ...

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

I think so. Look this topic: https://hysplitbbs.arl.noaa.gov/viewtopic.php?f=14&t=60

Can Meteoinfo do this? I mean ...

Are ARL data in ASCII format? Can I use MATLAB to read and re-write them?

How can I extract specific vertical layers from GDAS0P5 and re-write into a new ARL format data?

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 ...

I am doing some comparison on hysplit trajectories generated from GDAS1 and GDAS0P5 data, and now I want a set of data which are in 0.5 degree resolution but with 23 vertical layers as GDAS1 data, how can I extract these data from GDAS0P5 data?

Thanks.

barbara.stunder wrote:The raw GDAS output is not posted to a public server.

In that case, could you please give me a brief description of the raw GDAS data? I need to know the horizontal and vertical distribution of the dataset.

Thanks very much.

NCEP is not creating FNL 1-degree data anymore. NCEP changed nomenclature from FNL to GDAS. Both ARL's GDAS1 and GDAS0p5 are post-processed from the same NCEP GDAS run.

ARL processes NCEP's "raw" GDAS output to create ARL's GDAS0P5.

NCEP processes GDAS output (1 degree grib files) to create the ...

Please see these files at ftp://arlftp.arlhq.noaa.gov/archives/gdas0p5/
readme_gdas0p5_info.txt
readme_gdas0p5_missings.txt

By the way, when I generate trajetories with GDAS 0.5-deg data of 2011, it always shows a warning like this :

WARNING: metini - vertical velocity missing
switching to ...