help needed using mixed resolutions meteo files

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croc
Posts: 6
Joined: January 22nd, 2015, 10:25 am
Registered HYSPLIT User: Yes

help needed using mixed resolutions meteo files

Post by croc » July 18th, 2019, 11:01 am

Dear HYSPLIT forum,
I'd like to run backtrajectories starting in the period 28 Feb - 2 Mar 2012
using GDAS p05 meteo files. Unfortunately, the file 20120301_gdas0p5
is missing. As in similar cases in the past, I downloaded the p1
(gdas1.mar12.w1) since HYSPLIT can use mixed grids. This time,
however, hyts_std refuses to start giving the usual error:

*ERROR* metpos: start point not within (x,y,t) any data file
- start time before start of meteorology data
- start time after end of meteorology data

The CONTROL file has 12 02 29 22 as the starting time and the
list of all the needed meteo files starting with 20120301_gdas0p5,
20120229_gdas0p5, 20120228_gdas0p5 (note that I symbolic link
the 20120301_gdas0p5 to the gdas1.mar12.w1).
The chk_info utility gives

File start time: 12 3 1 0 0
File ending time: 12 3 7 21 0

Last record number : 9184
Record length bytes: 65210
Meteo data model : GDAS
Grid size x,y,z : 360 181 24

for gdas1.mar12.w1 and

*WARNING*: metini - vertical velocity missing, switching to divergence
Input data file: 1 1 GHDA

File start time: 12 2 29 0 0
File ending time: 12 2 29 21 0

Last record number : 1888
Record length bytes: 259970
Meteo data model : GHDA
Grid size x,y,z : 720 361 56
Vertical coordinate: 4
First forecast hour: 0
Last forecast hour : 3
Records per time : 236
Minutes between : 180

for 20120229_gdas0p5.
I also tried to substitute gdas1.feb12.w5 to the 20120229_gdas0p5
and the trajectory is propagated but just for one day.
I am starting to think that there might be some incompatibility
between GHDA and GDAS meteo files.
Could you please help me?
Thanks in advance. Regards
Stefano

alicec
Posts: 163
Joined: February 8th, 2016, 12:56 pm
Registered HYSPLIT User: Yes

Re: help needed using mixed resolutions meteo files

Post by alicec » July 19th, 2019, 3:12 pm

Please use an additional gdas1 file so that there is an overlap in time between the two met datasets.
See below for an example. HYSPLIT will automatically use the finer resolution (gdas0p5/ GHDA) during the overlap time.

2 03 01 00 00
1
42.768 -86.149 100.0
-24
0
10000.0
5
/tdir/gdas0p5/
20120227_gdas0p5
/tdir/gdas0p5/
20120228_gdas0p5
/tdir/gdas0p5/
20120229_gdas0p5
/tdir/gdas1.v1/
gdas1.feb12.w5
/tdir/gdas1.v1/
gdas1.mar12.w1
./
tdump


MESSAGE FILE OUTPUT

NOTICE metgrd: (kg, xyr,xy1) - 2 10 10 270 129
NOTICE metinp: GDAS 2 1 10 10 270 129 58992480 12 3 1 0
NOTICE metinp: GDAS 2 1149 10 10 270 129 58992300 12 2 29 21

NOTICE advrng: (kg ,xyr,xy1) - 1 12 12 543 261
NOTICE advrng: (kg ,xyr,xy1) - 2 10 10 270 129
NOTICE main: Initial time step (min) -60
NOTICE main: 58992420 1 2 -60 274.49457 133.73793 0.99657983
NOTICE advrng: (kg ,xyr,xy1) - 1 12 12 542 261
NOTICE advrng: (kg ,xyr,xy1) - 2 10 10 270 129
NOTICE main: 58992360 1 2 -120 274.13840 133.60075 0.99733561
NOTICE advrng: (kg ,xyr,xy1) - 1 12 12 542 261
NOTICE advrng: (kg ,xyr,xy1) - 2 10 10 270 129
NOTICE main: 58992300 1 2 -180 273.73550 133.38596 0.99783152
NOTICE advrng: (kg ,xyr,xy1) - 1 12 12 541 260
NOTICE advrng: (kg ,xyr,xy1) - 2 10 10 269 129
NOTICE metpos: (mtime,ftime) - 58992300 0
NOTICE metpos: (mtime,ftime) - 58992120 0
NOTICE metgrd: (kg, xyr,xy1) - 1 12 12 543 261
NOTICE metinp: GHDA 1 1653 12 12 543 261 58992300 12 2 29 21
NOTICE metinp: GHDA 1 1417 12 12 543 261 58992120 12 2 29 18

NOTICE main: 58992240 1 1 -240 545.40283 265.24933 0.99804646
NOTICE advrng: (kg ,xyr,xy1) - 1 12 12 540 260

alicec
Posts: 163
Joined: February 8th, 2016, 12:56 pm
Registered HYSPLIT User: Yes

Re: help needed using mixed resolutions meteo files

Post by alicec » July 19th, 2019, 3:57 pm

Please also see the following documentation for more detail on how meteorological grids should be specified.
It can get quite complex!

https://www.ready.noaa.gov/hysplitusersguide/S262.htm

- Number of input data grids

Default: 1

Number of simultaneous input meteorological files. The following two entries (directory and name) will be repeated this number of times. A simulation will terminate when the computation is off all of the grids in either space or time. Trajectory calculations will check the grid each time step and use the finest resolution input data available at that location at that time. When multiple meteorological grids have different resolution, there is an additional restriction that there should be some overlap between the grids in time, otherwise it is not possible to transfer a trajectory position from one grid to another. If multiple grids are defined and the model has trouble automatically transferring the calculation from one grid to another, the sub-grid size may need to be increased to its maximum value.

While not available in the GUI, if the user is creating the CONTROL file themselves, two numbers can be specified here: the first being the number of unique grids and the second being the number of files in each grid. For example, an entry of 2 12 would mean that there are met files for 2 different grids (e.g., a regional and a global grid), and that there are 12 files being specified for each grid. The grids should be specified in order of resolution, with the highest resolution grids (i.e, the smallest horizontal spacing between grid points) being specified before lower resolution grids. The two entries for each file (directory and filename) are repeated for each file in the first grid, and then for each file in the second grid, and so on, for any subsequent grids. Note that the same number of files are required for each grid in this approach. Without the use of this approach (i.e., when only one number is specified) the maximum number of files that can be used in the simulation is relatively small, but with this second approach, a much larger number of files can be used in the simulation.

croc
Posts: 6
Joined: January 22nd, 2015, 10:25 am
Registered HYSPLIT User: Yes

Re: help needed using mixed resolutions meteo files

Post by croc » July 24th, 2019, 9:22 am

Dear alicec,
thank you very much for your prompt answer which is turning out to be correct. I am presently testing your suggestion and it seems that I won't need neither to specify the number of unique grids since the program is able to use the finest available grid. This was a feature I already exploited in the past but unfortunately this time I did not try to add the second lower resolution file to provide some overlap in time.
Thanks again for the help!
Regards,

Stefano Crocchianti

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