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yyyymmdd_to_yyyyfrac

Converts a one-dimensional array containing yyyymmdd values to yyyy and fractional year.

Prototype

load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/contributed.ncl"  ; This library is automatically loaded
                                                             ; from NCL V6.2.0 onward.
                                                             ; No need for user to explicitly load.

	function yyyymmdd_to_yyyyfrac (
		yyyymmdd  [*] : integer, float, double,  
		dd_offset [1] : integer, float, double   
	)

Arguments

yyyymmdd

A one dimensional array containing yyyymmdd values: yyyy are years (Gregorian); "mm" are months ranging from 1 to 12 corresponding to January to December; the "dd" are calendar day of the month [1 to 31]

NOTE: This function does not recognize the proleptic_gregorian calendar.

dd_offset

A scalar denoting the daily fractional offset. A value of zero indicates no daily offset. A value of 0.5 yields mid-day fractional values. [ 0.0 <= dd_offset < 1.0 ]

Return value

A one dimensional array containing values of the form yyyy plus fractional part of year. If yyyymmdd is type double the return will be type double. Otherwise type float is returned.

Description

For each value of yyyymmdd, the day_of_year is determined. The fractional part is determined by the quantity (day_of_year(yyyy,mm,dd)-1)) divided by the numbers of days in the year [365 or 366].

NOTE: This function does not recognize the proleptic_gregorian calendar.

Examples

The following require that contributed.ncl be loaded prior to invoking the function.

       load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/contributed.ncl"

Example 1

Convert a 1D array yyyymmdd = (/ 19790101 , 19791231, 19840715, 20011201 /) to yyyy and fractional year.

      yrfrac = yyyymmdd_to_yyyyfrac(yyyymmdd, 0.)
      print(yrfrac)

Each of the above yields a 1D array of length 4 values.

(0)     1979
(1)     1979.997
(2)     1984.536
(3)     2001.915

The above with an offset of dd_offset=0.5

      yrfrac = yyyymmdd_to_yyyyfrac(yyyymmdd, 0.5)
      print(yrfrac)