We will investigate trends in the temperature and CO2 data sets. Clearly the CO2 data shows a long-term trend, although a seasonal variation can also be seen. The long-term trend in temperature record is less obvious. All function calls and plotting requested below should be done in your main script assign1.m. You will write a function getstats.m that will return a running mean and a measure of seasonal variability of CO2. The function should take as input the CO2 record, and window length IN THAT ORDER, and return as output the running mean and seasonal variability IN THAT ORDER. Details:
1. Figure will contain 3 subplots. Plot the CO2 data vs. time using green symbols in the top subplot.
2. Use your running mean function from the week 8 lab to calculate a running annual mean (i.e., a running yearly average) for the CO2 data (your mean will be over a period that is slightly longer or shorter than a year - why?). Plot your running mean on top of the original data using a black line.
3. We can estimate the seasonal variability in CO2 measurements within each year by a variabilty of methods. Two good choices would be to use either the standard deviation or the peak-to-peak variations CO2 in a year. This is easy to do now that you have your running mean function. Modify the running mean function to return both the running mean and your choice of measure (peak-to-peak or standard deviation) of seasonal "variability". Rename your modi?ed function getstats.m
4. Plot your seasonal variability in CO2 versus time in the second subplot. Label your plot clearly. (You can include more than one way of estimating seasonal variability if you like.) Calculate the mean seasonal CO2 variability for the 1960-2008 period. Hint: The MATLAB function isnan is helpful.
5. Now, use your annual running mean to calculate the annual change (e.g., from January to January of successive years) in CO2 concentration. (Hint: logical indexing into ?elds of your structure co2 is useful.) Plot your results in the third subplot. Calculate the average annual change for the 1960-2010 period.
6. Answer the following questions using your results:
(a) For every year that you have an estimate of the annual change in CO2, is CO2 increasing? How did you decide this?