The amount of sea ice surrounding the Antarctic continent varies dramatically during the year, and from year to year. The following data, shown in Table 8.9, were obtained from the NASA Earth Observatory website and represent the extent of the sea ice during the September maximum and February (of the following year) minimum. The first line in the table is the mean of data collected over the previous 20 years. (a) Plot both the September values and February values vs. the year, and add a line representing the average ice extent for 1979-2000. (b) Use the find command to determine which years exceeded the average September values for 1979-2000. (c) Use the find command to determine which years were lower than the average February values for 1979-2000. In the previous chapter, the data in this problem were evaluated using the find function. Repeat the calculations, using a nested loop structure. The file lake_powell.dat contains the data listed in Table 8.9.