Implement climatological anomalies

[aazuspan]

• Create a wxee.TimeSeries.climatology_anomaly method
• Include args for frequency and whether or not to standardize
• Implementation:
  • To calculate anomalies, mean climatological normals will be required. Climatological standard deviations will be required for standardized anomalies.
  • For flexibility, this should probably be implemented with required arguments for climatological mean and standard deviation TimeSeries objects. Users would run wxee.TimeSeries.climatology_mean and wxee.TimeSeries.climatology_std to generate those inputs and then pass those and another TimeSeries to calculate anomalies from.

Something like:

ts = wxee.TimeSeries("IDAHO_EPSCOR/GRIDMET").filterDate("1981", "2011").select("pr")
mean = ts.climatology_mean("month")
std = ts.climatology_std("month")
anom = ts.climatology_anomaly("month", mean, std, standardize=True) 

Reference