ST590G -- FALL 2012 
     
     Class Exercise #2 -- Tuesday, 03 September 2012

     Our Group ___________________________________________________

     In the directory "snow" are files from 28 sites in Norway 
     containing dates and snow depths recorded daily for many years.  
     A subset of the files include:

     asker.txt  bjornholt.txt  kjobli.txt  listafyr.txt oslo.txt

     songli.txt  stavanger.txt tafjord.txt  tromso.txt  utsira.txt

     Choose one of these files (circle it) and turn in (1),(2) and (3).
     Do (4) so that you can picture what's going on.
  
     The first 24 records should be part of the header.  Each record has 
     station number, date recorded as  (xx.xx.xxxx) in European style, 
     the snow depth in centimeters, and a data quality code.  The last 
     date I requested was 30 June 2011, so that should be the last 
     record before the footer.
 
     1) The first step is to check the quality of the data.  
       a) read the dates and snow depth
       b) the snow year starts in 01 July and ends at 30 June, so name 
       each snow year by the calendar year in which it finishes, so today
       would be in snow year 2013
       c) find out the number of zeros and the number of missing values 
       for each snow year in the dataset
       d) also find the maximum snow depth for each snow year

     2) From the number of missing and zeros, construct a list of good 
     years, where a bad year would have either a high number of missing 
     observations, or an unusually large number of zeros.  (We're not 
     sure if some zeros were really misrecorded missing observations.)

     3) Create a frequency table of data quality index by snow year.
     (a description of the quality code/flag is given at
        http://eklima.met.no/Help/examples/html/report66_en.html )


     4) Plot five snow year's data from the 'good' years.  Comment on 
     anything surprising.

     Submit your output and log.  Don't forget your toes!