 NCL Home > Documentation > Functions > Climatology

clmMonTLLL

Calculates long term monthly means (monthly climatology) from monthly data: (time,lev,lat,lon) version

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 clmMonTLLL (
x [*][*][*][*] : float or double
)

return_val [*][*][*] :  numeric
```

Arguments

x

A four-dimensional array of type float or double. Dimensions must be time, lev, lat, lon. The size of time dimension must be a multiple of 12. The dimensions must be named.

Return value

An array of the same size and type as x except that the leftmost dimension will be of size 12.

Description

Calculate long term monthly means (monthly climatology) from monthly data.

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

Calculate the monthly climatology of u(time,lev,lat,lon) where

```[time | 528] x [lev | 23] x [lat | 128] x [lon | 256]
```
This represent 44 years [44*12=528] of monthly data. Consider the following code snippet:
```      f    = addfile("x.1958-2001.nc, "r")
u    = f->U
uClm = clmMonTLLL( u )
printVarSummary(uClm)
```
The result is:
```variable: uClm
Type: float
Total Size: 36175872 bytes
9043968 values
Number of Dimensions: 4
Dimensions and sizes:   [month | 12] x [lev | 23] x [lat | 128] x [lon | 256]
Coordinates:
month: [0..11]
lev: [1..1000]
lat: [-88.92773..88.92773]
lon: [ 0..358.53]
Number Of Attributes: 7
time_op_ncl : Climatology: 44 years
cell_method : time: mean
standard_name :       eastward_wind
units :       m/s
long_name :   U velocity
_FillValue :  -999
```