[wxqc] Calibrating anemometers

[Victor Engel]

After preliminary data analysis, it seems my initial impressions may have
been faulty. Here are the results of my analysis.

In this first report, I list mean DIFSPEED (my neighbor's reported speed
minus my reported speed) for each of the coded directions. Apparently, my
wind readings are actually higher than his. Units are miles per hour.

DIFSPEED WindDirection
   -1.46         North
    -.36           NNE
    -.37            NE
    -.33           ENE
    -.69          East
    -.16           ESE
   -1.17            SE
   -1.01           SSE
    -.84         South
    -.33           SSW
    -.37            SW
    -.91           WSW
   -1.17          West
     .13           WNW
   -1.16            NW
    -.29           NNW
    -.70       AVERAGE

On the other hand, his speeds are higher for wind gust data. I think that is
where I got the impression his readings were higher.

    1.83         North
    1.57           NNE
    1.55            NE
    1.38           ENE
    1.69          East
    1.72           ESE
    1.03            SE
    1.49           SSE
    1.47         South
    1.49           SSW
    1.59            SW
     .35           WSW
    -.04          West
     .40           WNW
    1.79            NW
    1.82           NNW
    1.47       AVERAGE

Finally, here is a count of total data points used for these statistics.

North 83
  NNE 96
   NE 119
  ENE 176
East 166
  ESE 98
   SE 147
  SSE 270
South 169
  SSW 45
   SW 46
  WSW 34
West 23
  WNW 15
   NW 43
  NNW 99
TOTAL 1629

Something that probably skews the top chart a little bit is that I only
selected data for which windspeed was nonzero at my station. Here is the
procedure I used:

I downloaded all weatherunderground data (CSV charts) for our two weather
stations over the period of time my station has been active. Since the times
are sometimes every minute and sometimes every five minutes, I took only the
first data points on or after 5 minute boundaries. Then, I selected only
data for which both stations had values for the timeframe.

I wonder if my setup is missing wind gusts for some reason or other. If the
Davis WIND station itself does not keep track of gusts, then gusts would
have to be captured by software, and gaps between readings could possibly
miss gusts.

Victor
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