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Unformatted text preview: 39 HURRICANE IDA WIND RECORD 156 39 Hurricane Ida Wind Record The remnants of Hurricane Ida swept through Norfolk, Virginia during the period 10-15 November 2009, with 25cm of rain and high winds.The data file homework9.txt contains wind data recorded at Weather Station Larchmont-Cornicks, in Norfolk. There are three columns, with average wind direction in degrees (CW positive from north; zero is wind coming from the north), average wind speed u in miles per hour, and gust wind speed u , also in miles per hour. and u are average values taken over five-minute intervals, and u denotes the peak speeds taken over these same intervals. Each row corresponds with one five-minute period. 1. Make some nice annotated plots of the data, and write a few paragraphs to describe what features you can see in the three data channels. Notice that there are approxi- mately six days worth of data here- it was a long storm! Between calm wind conditions, this weather event lasted about 7000 minutes, or 4.8 days. The wind started from the northeast and then gradually came around the the north- west. Interestingly, there was a short period of no wind direction data near time 1700 minutes (lack of noise is a dead giveaway), and also some odd five-degree quantization effects near the zero direction. Looking at the speeds now, we see immediately a one-mph quantization in the gust speed. In the intensifying phase there was a temporary drop in wind speed at time 2000 minutes, but winds quickly built up again by time 3000 minutes. The mean wind speed reached a maximum value of fifty miles per hour, near time 4000 minutes, with a gust in that bin of 57 mph. In the first half of the storm event, gust speed beyond the mean speed seems to be about ten mph, whereas in the second half of the event, it is less; this may indicate that turbulence was highest at the beginning of the storm and lower at the end. Also, we notice that starting at about 4000...
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