1. IEM Information
  2. Real-time IEM data feeds with LDM HOWTO

This page will show you all the steps necessary to set up a LDM data feed from the Iowa Environmental Mesonet [IEM]. Currently, we are offering the SchoolNet (KCCI-TV8) dataset and Roadway Weather Information System (RWIS) dataset via LDM.

STEP 1: Send an Email
Send us an email requesting a LDM feed. You can send this email to me, Daryl Herzmann (akrherz@iastate.edu) . You should include contact information and the DNS/IP of the host that you will be using to connect to the IEM LDM. We would like to keep track of who is requesting data and what they are using the data for, so please include that as well.

STEP 2: Download GEMPAK surface tables
Here are the GEMPAK surface tables needed to point dcmetr at. You should download these files and place them somewhere accessible by your decoders.
SchoolNet and RWIS

STEP 3.1: Configure LDM (ldmd.conf)
For the purposes of this HOWTO, I am assuming that you have administrative knowledge of LDM. You will want to edit your ldmd.conf file to request the data feeds from the IEM. Remember the tabs! 

 # Request Iowa Mesonet RWIS data, filename IA.rwisDDHHMM.sao
request	EXP	"^IA\.rwis......\.sao"	mesonet.agron.iastate.edu
 # Request Iowa Mesonet SchoolNet data, filename IA.snetDDHHMM.sao
request	EXP	"^IA\.snet......\.sao"	mesonet.agron.iastate.edu

STEP 3.2: Configure LDM (pqact.conf)
Since you have went through all this effort to request the data, you should at least process it somehow! The datafiles are in METAR collectives with a fake WMO header. (KISU is used, referring to Iowa State). Here are samples of what you can do with your pqact.conf file. Remember the tabs! 

  # Process Iowa Mesonet SchoolNet data
  # Product name: IA.snetDDHHMM.sao, where DD is day HH is hour, MM is minute
  # Data is inserted at :17, :37 and :57 after the hour.
#EXP	^IA\.snet......\.sao
#	PIPE	dcmetr -b 3 -m 72 -s /path/to/surf/file/IA.snet.stn
#		-t 1200 -d data/gempak/logs/dcmetr_IAsnet.log -a 0
#		data/gempak/surface/exp/YYYYMMDD_IAsnet.gem
  # Process Iowa Mesonet RWIS data
  # Product name: IA.rwisDDHHMM.sao, where DD is day HH is hour, MM is minute
  # Data is inserted every 10 minutes starting at :06 after
#EXP	^IA\.rwis......\.sao
#	PIPE	dcmetr -b 3 -m 72 -s /path/to/surf/file/IA.rwis.stn
#		-t 1200 -d data/gempak/logs/dcmetr_IArwis.log -a 0
#		data/gempak/surface/exp/YYYYMMDD_IArwis.gem
  # Do something fancy, and combine them in one file!
EXP	^IA\.(rwis|snet)......\.sao
	PIPE	dcmetr	-b 3 -m 72 -s /path/to/combined/file
		-t 1200 -d data/gempak/logs/dcmetr_IEM.log -a 0
		data/gempak/surface/YYYYMMDD_IEM.gem

SchoolNet data files are generated every 20 minutes. RWIS files are generated every 10 minutes. You may want to be a bit more creative with the LDM request and pqact.conf configuration to limit the number of products decoded. The products are marked with a timestamp (DayDayHourHourMinuteMinute) .

Now, hopefully by this time, I has responded to your email and set up the IEM LDM to accept your data connection. You may want to try a simple LDM command to see if your connection is allowed. 
$ notifyme -v -l - -h mesonet.agron.iastate.edu -f EXP
It may take 5-10 minutes before a new data product hits the IEM data queue. If this command worked, you are probably all set! Restart LDM and see what breaks!

STEP 4: Sign up for IEM bulletin (optional)
You don't have to complete this step, but you can keep up-to-date with IEM news and events with the IEM Daily Bulletin. You can sign up for it here. If this service generates enough interest, I will set up a dedicated email list for it.

CAVEATS!!!

Current Data Users:
NCAR-RAP Surface Data, Boulder, CO
Storm Prediction Center, Norman, OK
NWS WFO Des Moines, IA
NWS WFO Rapid City, SD
NWS WFO Sioux Falls, SD
University of Albany, NY
College of DuPage, IL
West Texas Mesonet, TX

Daryl Herzmann
(akrherz@iastate.edu)
Rev: 26 Dec 2002