Group: Team Spaghetti Monster
As we learn in the world of GIS there are several ways to do things, and so here is our second version of the storm tracks. This one is good one as the storm tracks can be seen as continuous lines, instead of being broken apart. We have also kept the data of the line segments of each of the landfall storm tracks because when we dissolve the line segments all the attributes are lost.
Step 1: Download the data from NOAA’S website -
Step 2: Open ArcMap- Select by attributes: year > 1979, so that the storm tracks 1980 onwards are selected
Step 3: Export the selected data
Step 4: Get the map of USA from the ‘I’ drive and project it to North America Albers Equal Area Conic. Also project the storm tracks to the same projection.
Step 5: In order to select the storm tracks at landfall go to Select-Select by Location-‘Intersect’ the hurricane tracks with the map of continental USA. When you select the storm tracks at landfall some of the storm tracks are broken apart and only the parts intersecting with the continent are shown. Since it doesn’t look proper you would want to look at the name of the landfall storm tracks and do a ‘select by attribute’ function. Before doing this, add another field in the attribute table called ‘Name-Year’. Then going into ‘field calculator’ option in the attribute table select name and year and add the values to the column. Then, go into ‘select by attribute’ and write down a sequel like "Name_Year" = 'ALLEN1980' OR "Name_Year" = 'DANIELLE1980' OR "Name_Year" = 'BRET1981' OR "Name_Year" = 'DENNIS1981' OR "Name_Year" = 'SUBTROP11982' OR "Name_Year" = 'CHRIS1982'……. and in this way you can select all the storm tracks which intersect at landfall and they now will show up as small line segments joined together but the whole track is shown and are not broken apart.
Step 6: A 100 km buffer is created around these storm tracks using the Buffer tool in ArcToolbox. They are still shown as segments. We want to keep this information because in the next step when we dissolve it all the other attributes except ‘FID’ , ‘Shape’, and ‘Name_Year’ of the Hurricanes are lost. So, there are now 3139 tracks (before dissolving).
Step 7: In the next step the buffered storm tracks are dissolved and this reduces the total number of storm tracks (since the line segments are all joined up) into 96. So there are actually 96 hurricanes (with a buffer of 100 km) at landfall which hit coastal USA between 1980 and 2006.
Step 8: Out of this 34 storm tracks are selected because they have sufficient data on damage. These are again selected by creating a similar sequel query as in Step 5 so that they are shown up as small segments joined together but not broken apart at landfall. This also keeps all the other attributes of the hurricanes. These are then buffered and dissolved. Since we need the wind speed and category of the hurricane those fields are added in the attribute table after dissolving the 34 hurricane tracks. We added the values of wind speed and category at landfall.
Warning: When you try to buffer or dissolve the hurricanes several times you will get the error message that the geometry of the feature is not defined and it will tell you the FID of the track which is creating the problem. It is necessary to go into the edit mode and delete those rows of storm tracks. It will not affect the results in any way.
Finally, we have a map of the 34 storm tracks at landfall from 1980 to 2006 for which enough data is available.