# searoughness

Surface height standard deviation for sea

Since R2021a

## Syntax

``hgtsd = searoughness(scale)``
``hgtsd = searoughness(scale,'ScaleType',scaletype)``
``[hgtsd,beta0,windvelocity] = searoughness(___)``

## Description

example

````hgtsd = searoughness(scale)` returns the standard deviation of the surface height, `hgtsd`, for the specified sea state number as a scalar in meters.`hgtsd = searoughness(scale,'ScaleType',scaletype)` specifies the scale type.`[hgtsd,beta0,windvelocity] = searoughness(___)` returns additional outputs: `beta0` — Slope of the sea type in degrees. `beta0` is 1.4 times the root mean square (RMS) surface slope. The surface σ0 value for sea clutter reflectivity is computed based on the NRL Sea Clutter Model by Gregers-Hansen and Mittal`windvelocity` — Wind velocity in meters per second ```

## Examples

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Obtain the surface height standard deviation in meters assuming a sea state of 2.

`hgtsd = searoughness(2)`
```hgtsd = 0.1000 ```

## Input Arguments

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If you set `scaletype` to `'SeaState'`, `scale` is interpreted as the sea state, specified as a nonnegative scalar between [0,8]. If you set `scaletype` to `'WindScale'`, `scale` is interpreted as the Beaufort wind scale, specified as a positive scalar between [1,9].

#### Dependency

The interpretation of the `scale` argument depends on the value of `scaletype` name-value pair.

Scale type, specified as either:

• `'SeaState'` — The function uses the Sea State model. When you specify this option, the `scale` input scale must be a nonnegative scalar between [0,8].

• `'WindScale'` — The function uses the Beaufort Wind Scale model. When you specify this option, the `scale` input scale must be a positive scalars between [1,9].

Example: `'WindScale'`

## Output Arguments

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Standard deviation of the surface height, returned as a scalar. The model for height deviation, surface slope, and wind velocity is based on a model by Barton. Units are in meters.

Slope of the sea type β0, in degrees, returned as a scalar.

Wind velocity, returned as a scalar. The model for the height deviation, surface slope, and wind velocity is based on a model by Barton. Units are in meters per second.

 Barton, David K. Radar Equations for Modern Radar. Norwood, MA: Artech House, 2013.