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Re: Status

Hello Linda and Robb,

In response to your e-mail, here is where we stand: the LDM software was
installed on one of our external servers which is frequently used as host
for outgoing data. Now we would like to run some tests by sending data to
another IDD server, some of your machines for instance. 

Technicalities

In general, we would like to send over the IDD system output from our
regional GEM model in grib format. As a starting point, we propose the
following subset of the GEM output to be sent to the UNIDATA users. Feel
free to feedback your suggestions/comments.

Fields (49 in total):

- geopotential height at 1000, 850, 700, 500, 400, 250, 150, and 100 hPa
- air temperature at the same pressure levels + at the model surface 
- wind components projected on the x- and y- axies of the grid at the
  same pressure levels + at the model surface 
- dew-point temperature at the same pressure levels + at the model
  surface 
- sea-level pressure 
- pressure vertical velocity at 700 hPa 
- surface pressure 
- accumulated precipitation 
- instantaneous rainfall rate 
- total column cloud cover

Grid:

A polar-stereographic grid over Canada, the U.S. and the adjacent waters.
135x94 points, horizontal resolution of 60km at 60N.

The regional operational model is run twice per day based on 00Z and 12Z
data, to produce 48-hour forecast. We would like to send the the 0-48 hour
forecasts of the above fields from both runs, at a temporal resolution of
6 hours. This will make for 882 fields/products with a volume of ~ 17Mb
per day. This seems reasonable, having in mind that the model output from
the NMC and ECMWF models you disseminate accounts for 20,000 products and
75 MB per day. However, you may have restrictions for experimental data.

As far as I understood from the documentation, each field is sent as a
separate file/product so that the users can select the fields they need.
Is this so, or can we group several fields as one product ? Say, all
fields for a certain forecast hour ? It seems to me that this will make
for less trafic.

As for GRIB encoding, we use an in-house encoder which is consistent with
the WMO GRIB (edition 1) standards. I will get your GRIB decoder from the
UNIDATA site and check whether it works with our GRIB data. Is your GRIB
decoder decoding into ASCII or some other internal format ? If so, the
decoding test should probably be run at your site, as we may not be
familiar with the internal format.

As a simple test, I guess I can use the pqinsert/pqsend utilities to send
you a few files using the LDM software ? I can use the -f option to
specify an EXP feedtype. I will also need the address of the remote
server I am to send the data to. 

I'll appreciate any advice about how to use the LDM, what test we can make
and how to finish the set-up. Thanks in advance,

Ekaterina

 

______________________________________________________

Division de l'implementation et services operationnels
   Centre meteorologique canadien
Implementation and Operational Services Division
   Canadian Meteorological Centre

e-mail: address@hidden
tel: (514) 421-4646
______________________________________________________

On Fri, 3 Dec 1999, Linda Miller wrote:

> Hi Ekaterina,
> 
> I wondered if  you've made any progress with the installation and testing of
> the LDM for distribution of the GEM data to U.S. universities.  I talked with
> Robb Kambic of Unidata and he said that he answered an initial email from you,
> but we were unsure if you are having problems with it.  Be sure to contact us
> if there's anything we can do to assist.
> 
> It would be wonderful to get the data moving to university users.
> 
> Thanks, in advance, for any update you can provide.
> 
> Linda
> 
> Linda Miller - address@hidden
> External Liaison, Unidata
> University Corporation for Atmospheric Research
> P.O. Box 3000
> Boulder, CO 80307-3000
> 303 497-8646 fax: 303-497-8690
> URL:  http://www.unidata.ucar.edu/staff/lmiller/un.act.html
> 
>