## Characteristic Numbers of Meteorological Data (independent of tides)

### From BAWiki

Graphical representation of various characteristic numbers of meteorological data (with German text only). This graphical representation is also available in Encapsulated PostScript format

## Contents

- 1 Motivation
- 2 Definitions for the Characteristic Numbers
- 2.1 Program NCANALYSE
- 2.1.1 Maximum Wind Speed
- 2.1.2 Time of Maximum Wind Speed
- 2.1.3 Residual Wind Speed
- 2.1.4 Mean Magnitude of Wind Speed
- 2.1.5 Standard Deviation of Wind Speed
- 2.1.6 Variance of Wind Speed
- 2.1.7 Duration of High Wind Speed
- 2.1.8 Duration of Low Wind Speed
- 2.1.9 Relative Frequency Distribution of Wind Speed
- 2.1.10 Cumulative Frequency Distribution of Wind Speed
- 2.1.11 Exceedance Frequency of Wind Speed Limits
- 2.1.12 Underflow Frequency of Wind Speed Limits
- 2.1.13 Quantiles of Wind Speed

- 2.2 Program LZKAF

- 2.1 Program NCANALYSE

## Motivation

Knowledge of spatial as well as temporal variations of wind velocity and direction in coastal areas and estuaries is a prerequisite for any proper (numerical) simulation of water level and current velocity for wind-influenced tides and especially under storm surge conditions. For questions arising in coastal engineering work calculation of a few characteristic numbers for meteorological data may contribute to give better answers. Therefore derived quantities from e.g. synoptic wind field data help to characterize single as well as to distinguish between different wind situations.

**An automatic analysis of all Characteristic Numbers of Meteorological Data is carried through by the computer programs LZKAF and NCANALYSE.**

## Definitions for the Characteristic Numbers

### Program NCANALYSE

#### Maximum Wind Speed

Highest (local) value of wind speed within the period of data analysis.

Data analysis: NCANALYSE.

#### Time of Maximum Wind Speed

Difference in time between local time of max. wind speed and the max. wind speed at a reference station.

Data analysis: NCANALYSE.

#### Residual Wind Speed

Residual value of wind speed (computed from addition of vectors) within the period of data analysis.

Data analysis: NCANALYSE.

#### Mean Magnitude of Wind Speed

Mean magnitude of wind speed within the period of data analysis.

Data analysis: NCANALYSE.

#### Standard Deviation of Wind Speed

Standard deviation of wind speed within the period of data analysis.

Data analysis: NCANALYSE.

#### Variance of Wind Speed

Variance of wind speed within the period of data analysis.

Data analysis: NCANALYSE.

#### Duration of High Wind Speed

Period of the time during which local wind speed lies above a given wind speed limit.

Data analysis: NCANALYSE.

#### Duration of Low Wind Speed

Period of the time during which local wind speed lies below a given wind speed limit.

Data analysis: NCANALYSE.

#### Relative Frequency Distribution of Wind Speed

Relative frequency of wind speed within given velocity intervals.

Data analysis: NCANALYSE.

#### Cumulative Frequency Distribution of Wind Speed

Cumulative frequency of wind speed within given velocity intervals.

Data analysis: NCANALYSE.

#### Exceedance Frequency of Wind Speed Limits

Exceedance frequency of wind speed limits within the period of data analysis.

Data analysis: NCANALYSE.

#### Underflow Frequency of Wind Speed Limits

Underflow frequency of wind speed limits within the period of data analysis.

Data analysis: NCANALYSE.

#### Quantiles of Wind Speed

Wind speed out of a time series which is not exceeded of a certain percentage of present wind speed values.

Data analysis: NCANALYSE.

### Program LZKAF

#### Maximum Wind Speed

Highest value of (local) wind speed within the period of data analysis

Example: Maximum Wind Velocity in the North Sea

#### Time of Maximum Wind Speed

Difference in time between local time of max. wind speed and the max. wind speed at a reference station.

Example: Time of Maximum Wind Velocity in the North Sea

#### Duration of High Wind Speed

Period of the time during which local wind speed lies above a given thershold

Example: Duration of High Wind Velocity in the North Sea

#### Duration of Low Wind Speed

Period of the time during which local wind speed lies below a given thershold

Example: Duration of Low Wind Velocity in the North Sea

#### Frequency Distribution of Wind Speed

Frequency distribution of local wind speed within arbitrary given intervals and sectors of wind direction

Example: Frequency Distribution of Wind Velocity in the North Sea

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