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# mjo_cross_coh2pha

Calculate space-time coherence-squared and phase using the array returned by mjo_cross_segment .

## Prototype

```	procedure mjo_cross_coh2pha (
STC [*][*] : numeric,
opt         : integer
)
```

## Arguments

STC

A three dimensional variable array as returned by mjo_cross_segment.

opt

Currently, not used. Set to 0.

## Description

The only time this is used is when elements (0:7,:,:) have been averaged over multiple segments. This will compute the coherence-squared and phase using averaged power and cross-power quantities. The input array, STC, will be updated appropriately. The following will not be changed:

```         ( 0,:,:)  -  symmetric power spectrum of x
( 1,:,:)  -  asymmetric power spectrum of x
( 2,:,:)  -  symmetric power spectrum of y
( 3,:,:)  -  asymmetric power spectrum of y
( 4,:,:)  -  symmetric cospectrum
( 5,:,:)  -  asymmetric cospectrum
( 6,:,:)  -  symmetric quadrature spectrum
( 7,:,:)  -  asymmetric quadrature spectrum
```
The following will be computed using the input power and cross power quantities:
```         ( 8,:,:)  -  symmetric coherence-squared spectrum
( 9,:,:)  -  asymmetric coherence-squared spectrum
(10,:,:)  -  symmetric phase spectrum
(11,:,:)  -  asymmetric phase spectrum
(12,:,:)  -  symmetric component-1 phase spectrum
(13,:,:)  -  asymmetric component-1 phase spectrum
(14,:,:)  -  symmetric component-2 phase spectrum
(15,:,:)  -  asymmetric component-2 phase spectrum
```
The coordinate frequencies span 0.0 to 0.5. The coordinate wavenumbers span -M/2 to M/2 where M is the number of longitudes.

See the Level 2 diagnostics description titled MULTI-SCALE INTERACTIONS at the US-CLIVAR MJO diagnostics website.

## Examples

See Example 11 of the Madden-Julian Oscillation web page.