Tuesday, March 1, 2011

Lab #7- March 2, 2011

Most gauging stations in LA County showed that there is not much difference between the normal rainfall and the current total rainfall in a season. The majority of the gauging stations had a difference of about 2 or 3 inches; the gauging station with the largest difference was the Tanbark station, which usually has about 28 inches in a normal season, has a total of about 44 inches this season. This makes a difference of approximately 16 inches, which is a large difference. Overall, however, the total and normal rainfalls are not too dissimilar.

The current rainfall in Los Angeles seems to be higher than normal for this time of year. Many of the gauging stations already had current totals that are higher than the normal totals for the entire rainfall season, and the season is not over yet. A fair number of gauging stations already have 3 about 3 inches more rainfall than in a normal season.The high total probably has to do with the heavy rainfall that happened in December, January and February in Los Angeles.

I think that Spline is the best interpolation technique for the data, because it creates a smooth surface that passes exactly through the input points. IDW seems to be better when interpolating a smaller distance, as greater distances give the cell less influence on the output value. I did not use Kriging, because the tutorial said that it was best used for geology and that it assumes there is no trend for the data. Spline seems to give the most accurate data for rainfall, because the set of points was not dense enough for IDW to be super accurate, and Spline gives a better estimation.

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