**hcurl**

`hcurl(`*uexpr,vexpr*)

Calculates the vertical component of the curl (ie, vorticity) at each grid
point using finite differencing on the grids provided. It is assumed that
*uexpr*

gives the U Wind component, and that
*vexpr*

provides the V Wind component.

### Usage Notes

- The alghorithm used for the finite difference calculation is described
as an Example for the
`cdiff`

function.

- The function assumes an X-Y varying dimension environment, and will
not operate unless that is the case. The
`define`

command can
be used in conjunction with the `hcurl`

function to create 3 or
4 dimensional fields of vorticity, from which
vertical cross-sections could be displayed.

- The boundaries of the grid are set to missing.

- The radius of the earth used in the calculation is in meters; thus the
units of the wind expressions provided would normally be m/s.

### Examples

- To display the vorticity:

`d hcurl(u,v) `

- If you want to display a vertical cross section of vorticity, you
first need to calculate it over a 3-Dimensional region:

```
set lon 0 360
```

```
set lat -90 90
```

```
set lev 1000 100
```

```
define vort = hcurl(u,v)
```

```
set lon -90
```

`display vort `