caveat on converts ERA to ARL format

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ryanxia
Posts: 14
Joined: July 1st, 2016, 1:05 pm
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caveat on converts ERA to ARL format

Post by ryanxia » June 22nd, 2017, 2:59 pm

Hi,

I am able to convert ERA-Interim to ARL-readable file for back trajectory analysis.
However, I found there are several options before running conversion:
1. select projection conversion method
2. input a latitude and longitude

If I choose Extract (set slider bars), what are the values of lat-lon I should select on the slider bars? If I run back-trajectory from a single point, does that mean I should (or was recommended) use the lot-lon of that point as the center for map projection? Any caveat on choosing the best projection conversion method? How's the option of None - Input lat-lon grid?

Thanks,
Ryan

alicec
Posts: 36
Joined: February 8th, 2016, 12:56 pm
Registered HYSPLIT User: Yes

Re: caveat on converts ERA to ARL format

Post by alicec » June 22nd, 2017, 4:46 pm

Use the default None - Input Lat-Lon Grid unless you have a specific reason to do otherwise.
You should almost always use None because HYSPLIT uses a Lat-Lon grid. Only
under special circumstances would you want to interpolate the lat-lon grid to a projection.

If you use the None default then the slider bars will not do anything.
The "Input Lat lon Grid" just refers to using the Lat-Lon grid used by the (Input) meteorological file.
So you do not need to input a latitude and longitude.
For more information about ECMWF ERA-INTERIM grid see here
https://software.ecmwf.int/wiki/display ... +reference

Cheers,
Alice

ryanxia
Posts: 14
Joined: July 1st, 2016, 1:05 pm
Registered HYSPLIT User: No

Re: caveat on converts ERA to ARL format

Post by ryanxia » June 27th, 2017, 2:31 pm

Hi Alice,

Thank you for your reply. Now I could easily convert ERA interim file to ARL readable.

However, I have a new question about ERA meteorology files that I converted; it is supposed to be asked in trajectory model forum, but probably you could answer my question.

I add converted ERA meteorology files for trajectory setup. I tried some different trajectory generation runs. I want to compare the ERA results with NCAR and GDAS dataset.
However, I could generate trajectory only for particular days. For example, I set the starting time like at 16 12 10 05, then it could be run. But if I just change the date, to 16 12 13 05, then it could not be run. It get stuck. I don't know the reason. It will be like:

Model started ...
HYSPLIT4 - Initialization
Last Changed Rev: 854
Last Changed Date: 2017-01-12 10:47:54 -0500 (Thu, 12 Jan 2017)

NOTICE: using namelist file
SETUP.CFG

Calculation Started ... please be patient



Then, it get stuck. I wait with patience for 10 min but it doesn't go through the running. It is supposed to be finished within 2 seconds.
I randomly tried other dates, if set the start date to 16 12 12 05, it still could work; but if 16 12 14 05, it get stuck again. I could not understand why it happened. Could you help me?

btw, if I run the daily run for that month using ERA meteo data, then I found error message for the days that cannot be run:

HYSPLIT4 - Initialization
Last Changed Rev: 854
Last Changed Date: 2017-01-12 10:47:54 -0500 (Thu, 12 Jan 2017)

NOTICE: using namelist file
SETUP.CFG

Calculation Started ... please be patient
900
HYSPLIT4 - Initialization
Last Changed Rev: 854
Last Changed Date: 2017-01-12 10:47:54 -0500 (Thu, 12 Jan 2017)

NOTICE: using namelist file
SETUP.CFG

Calculation Started ... please be patient
900
while executing
"exec $exec_dir/hyts_std.exe"
(procedure "make_traj" line 62)
invoked from within
"make_traj"
invoked from within
".autotraj.bot.save invoke"
("uplevel" body line 1)
invoked from within
"uplevel #0 [list $w invoke]"
(procedure "tk::ButtonUp" line 24)
invoked from within
"tk::ButtonUp .autotraj.bot.save"
(command bound to event)


Best,
Ryan

miriam
Posts: 9
Joined: February 14th, 2017, 4:40 pm
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Re: caveat on converts ERA to ARL format

Post by miriam » July 11th, 2017, 11:44 am

Hi Ryan,

I am having a similar issue. I find that trajectories for ERA-Interim data get stuck on certain days for each month, generally around the 14th-16th. Were you able to find a solution?

If not, can anyone else share some insight?

Thanks,
Miriam

ryanxia
Posts: 14
Joined: July 1st, 2016, 1:05 pm
Registered HYSPLIT User: No

Re: caveat on converts ERA to ARL format

Post by ryanxia » July 11th, 2017, 4:52 pm

Hi Miriam,

I posted the same question in trajectory forum:
viewtopic.php?f=27&t=1265

Alice said it is likely that the meteo file is too large and need to cut them into smaller chunks.
I will try it later to see if that works.

I also notice you had same question before.

Ryan

alicec
Posts: 36
Joined: February 8th, 2016, 12:56 pm
Registered HYSPLIT User: Yes

Re: caveat on converts ERA to ARL format

Post by alicec » July 11th, 2017, 5:57 pm

Are you converting a whole month of of ecmwf data at once?
The monthly datasets are probably too large. You will need to break them down into smaller chunks.
Please keep your grib files under 2GB.
See the following thread:

viewtopic.php?f=14&t=202&p=2779#p2779

You can use the profile program (either from command line) or in the GUI (using Meterology, display data, text profile).
Then put in the time offset and time increment and a location and you will get output from the ARL met file at that location
starting at your time offset and then every time increment forward.
This will give you an idea of what is happening on the day the trajectory gets stuck.

Usually we see this problem when people try to convert grib files which are larger than 2GB.

Let us know how it goes.

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