##### Water Vapor comparison with in situ observations #####

The evaluation is performed for the Water Vapor product of the satellite sensors. 
These satellite data are compared to GTS(Global Telecommunication System) in situ sonde data.
GTS in situ observations are downloaded from the Japan Meteorological Agency.
We calculate bias and standard deviation after making in situ to satellite match-up data.

How to make match-up data is 

To perform Water Vapor comparison, radiosonde observations are collocated with the 30 Satellite observations
within 30 kilometers and 1 hours.

To calculate the bias and standard deviation, satellite observations are collocated  under this condition. 

a. At least 5 footprints are available with good quality and TPW < 70kg/m2.
b. Maximum difference among 30 AMSR2 footprints is less than 5kg/m2 .

If these conditions are satisfied, we calculate the bias and standard deviation 
between radiosonde and average of the nearest 30 available satellite observaions.


How to calculate bias is 
    diff(i)=satellite(i)-insitu(i)
    bias=(diff(1)+.......diff(N-1)+diff(N))/N
How to calculate standard deviation is  
    std*std=((diff(1)-bias)*(diff(1)-bias)+.......�{(diff(N)-bias)*(diff(N)-bias))/(N-1)

The left panels let you choose which direction and date to check. 
At last if you click display bottom, bias and standard deviation are plotted for short span.
If you change the span, you click other plot span.

Plot Span definition is 
 : short  from last 50days
 : Middle from last 1.5years
 : Long   from observation start day