Functions to make spatial averages and anomaly time series

[andrew-edwards]

Travis's SST bccm example is for Area 126. Extends from coast to way offshore. After discussion at IOS, we settled on making a function to output an average for shallower water (< 200 m) and for deeper water (> 200 m). Angelica pointed out simply using 200 m isobath gets fiddly with the canyons, so has a masking for the shelf that she can send us.

• [x] Start spatial averaging function to be based on a geographic area (based on Travis's current approach); Travis.
• [x] Can probably pick 200 m for now, and output shallow and deep averages; Travis.
• [x] Make a general anomaly function (that acts on a time series), to use for any time series.
• [x] Make anomaly plot similar to indices ones (may have to give the output of the averaging function it's own class); just use all the years to generate the climatology and then the anomalies. Andy.
• [x] Include Angelica's shelf masking when she sends it.

[andrew-edwards]

Didn't do fourth box above (Andy adapting his anomaly plots), and Travis has done some. Think @travistai2 has done all the rest yes? If so tick off and close!