06/91 - present
|Along-shelf mean||Along-shelf std||Across-shelf mean||Across-shelf std|
When we compare these values with the whole set of observations for the
summer we can observe that the summer of 2003 has stronger upwelling
favorable winds but the difference with previous years might not be
To determine if the mean winds for 2003 are significantly bigger than
the ones for previous years we use Matlab TTEST2 Hypothesis test.
TTEST2 Hypothesis test: Compares the averages of two samples.
[H,P,CI,STATS] = TTEST2(X,Y,ALPHA,TAIL) performs a t-test to
determine whether two samples from a normal distribution (with
unknown but equal variances) could have the same mean.
The null hypothesis is: "means are equal".
For TAIL = 0 the alternative hypothesis is: "means are not equal."
For TAIL = 1, alternative: "mean of X is greater than mean of Y."
For TAIL = -1, alternative: "mean of X is less than mean of Y."
TAIL = 0 by default.
H=0 => "Do not reject null hypothesis at significance level of alpha."
H=1 => "Reject null hypothesis at significance level of alpha."
|2003 Along-shelf mean||All years Along-shelf mean||means are not equal||mean of 2003 is greater than mean of rest||mean of 2003 is less than mean of rest|
|2003 Across-shelf mean||All years Across-shelf mean||means are not equal||mean of 2003 is greater than mean of rest||mean of 2003 is less than mean of rest|
As can be seen from the along-shelf wind table, the mean wind for the
months of June, July, and August of 2003 is
significantly bigger than the mean wind for the previous years.
To see if the wind during the summer of 2003 was more persistent than
during previous years, we look at the autocorrelation of the wind data.
If the wind was more persistent the correlations for every lag hour are
going to be bigger than usual.
To see if the wind during the summer of 2003 was more persistent in
direction than during previous years, we look at histograms of wind
direction. If the wind was more persistent the histogram during the
summer is going to be narrower than for the rest of the years. The blue
line represents the upwelling favorable wind direction. We can see that
for the summer months of 2003 the wind direction corresponds
approximately with the upwelling favorable direction. The percentage of
upwelling favorable wind in 2003 is higher than in previous years for
June, July and August.