From: Chad Herman <chad.herman.us_at_nyahnyahspammersnyahnyah>

Date: Tue May 10 2011 - 00:21:24 MDT

Date: Tue May 10 2011 - 00:21:24 MDT

I've been building some NCL functions to simplify calculations I do on a

daily basis. I often use CRUTEM's netCDf data and find it annoying that

there is a redundant dimension (t, unspecified, latitude, longitude).

That inspired me to write a function ("squeeze") that will strip out

redundant dimensions while preserving dimension names, coordinate

variables and meta data.

I also found that the current crop of climatology functions didn't do

what I needed. clmMonTLL will calculate the climatology, but I needed to

specify the minimum number of years to calculate a valid mean. I

sometimes deal with single time series which need to transformed into

anomalies. There's no function do that, so I was motivated to write my

own functions.

I've create two generic functions: clmMonTXXX and calcMonAnomTXXX.

Whether you have a single 1D time series (like station data), maybe an

irregular 2D time series (multiple stations), 3D like (time, lat, lon)

or 4D (time, lev, lat, lon), clmMonTXXX will inspect the input

variable's rank and figure out how to calculate the climatology. You can

specify how many years of data must be present to calculate a valid

mean. This function also updates (if necessary) variable attributes like

valid_min, valid_max or valid_range.

calcMonAnomTXXX will take a given 1D, 2D, 3D or 4D variable as well as

the result of clmMonTXXX and calculate anomalies. It will also update

the aforementioned meta data.

I needed more summary statistics in my linear regression calculations so

I wrote a regression function ("linreg") to return a lot more

information than regcoef and regline. I'm planning on extending this

function or creating a new one to accommodate multiple explanatory

variables.

I hope these functions find good use in the NCL community. If you

uncover any bugs or have useful suggestions, let me know. That's what

the "reply all" button is for.

Chad

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