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# This is the README file for the Intertropical Front (ITF) positional data over Africa.  
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OVERVIEW:  Updated Feb, 2021

This FTP directory lists .txt files containing dekadally (10-day) averaged coordinates of the ITF for every
every 5 degrees longitude from 15W to 35E over Africa.  The ITF data record covers from April, 1989 to 
present, coinciding West Africa monsoon season (Apr-Oct).  ITF data/positions outside of this timeframe 
(Nov-Mar) are not analyzed and maintained. 

Consistent with operational weather analysis in West Africa, the position of the ITF is determined from the
daily subjective analysis of two key weather properties:
  1) Surface dewpoint temperature delineating the 15 degree isodrosotherm
  2) Lower-level (925mb) reanalysis wind streamlines delineating areas/axes of zonal convergence   

Both of these daily inputs are then combined by meteorologists at CPC to result in a mean dekadal (10-day) 
ITF position. 

ITF position climatologies for each dekad are provided and are based on 1991-2020 base period. 
  
Near-real time dekadal ITF products may be found at:
http://www.cpc.ncep.noaa.gov/products/fews/ITCZ/itcz.shtml

 
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*** 1.  Filename Convention:
    
    "YYYY_MMK.txt" 

    YYYY == 4 digit year
    MM   == 2 digit month
    K    == 1 digit dekad number (1-3) 


*** 2.  Content of Data: 
    
    Each .txt file contains dekadally (10-day) averaged coordinates of the ITF for every 5 degrees  
    longitude from 15W to 35E over Africa in comma delimited format.  See example below:
    
    lat,lon
    16.6,-15
    17.1,-10
    17.8,-5
    17.8,-0
    17.3,5
    14.8,10
    14.5,15
    14.6,20
    13.7,25
    13.6,30
    14.1,35

    Additionally, .pdf's which include ITF position maps, time series, and discussions produced during 
    operations are also listed in the "/products" subdirectory at this FTP address. 


*** 3.  Updating: 
    
    The directory is updated with the latest dekadal ITF coordinate data (.txt) and operational product
    file (.pdf) within a few days after the end of the dekad.  This is typically the 1st, 11th, and 21st
    of the month from Apr-Oct.  


*** 4.  Caveats with Data Record:
    
    Prior to 2000, there are several dekads with missing coordinate information due to the unavailability
    of input data.  Missing data is denoted as "NaN".  In sum, missing data accounts for less than 2.5% of
    the entire ITF dataset to date. 

   
*** 5.  Contact: 
  
    Please contact us for any problems or questions regarding this product.  

        Wassila Thiaw
        Climate Prediction Center 
        NOAA Center for Weather and Climate Prediction
        5830 University Research Court 
	  College Park, MD 20740 
        Tel:  301.683.3424
        E-mail:  Wassila.Thiaw@noaa.gov