check.DeponsShips: Check if ships move at unrealistic speeds

In jacobnabe/DEPONS2R: Read, Plot and Analyse Output from the DEPONS Model

Check if ships move at unrealistic speeds

Description

Checks if calculateds speeds in DeponsShips objects are unrealistic, which may result from inaccurate AIS positional records. As ship speed in DEPONS directly influences the amount of noise generated, it is advisable to detect and remove such instances to avoid the creation of extreme noise sources.

Usage

check.DeponsShips(x, threshold = 35, fix = F, replacements = NA)

Arguments

x	DeponsShips object
threshold	The speed (knots) above which calculated values are considered unrealistic/excessive. Defaults to 35 knots.
fix	Logical. If FALSE (default), the function returns a data frame of ship tracks containing speeds that exceed the threshold; if TRUE, the function returns a DeponsShips object where these instances have been replaced.
replacements	Named list, where names are ship types and values are replacement speeds (knots) for speeds above the threshold within those types. Only ship types named in the list are processed. If NA (default), reference speeds from Table 1 in MacGillivray & de Jong (2021) are used.

Details

The default replacement speeds (knots) for recognized ship types are as follows (class reference speeds from MacGillivray & de Jong, 2021, Table 1): Fishing, 6.4; Tug, 3.7; Naval, 11.1; Recreational, 10.6; Government/Research, 8; Cruise, 17.1; Passenger, 9.7; Bulker, 13.9; Containership, 18.0; Tanker, 12.4; Dredger, 9.5; Other, 7.4.

Value

If fix = FALSE, a data frame with columns "route number", "name", "type", "length", and "speed", containing one entry for each ship where an excessive speed occurred. If fix = True, a DeponsShip object where instances of excessive speed have been replaced.

Reference

MacGillivray, A., & de Jong, C (2021). A reference spectrum model for estimating source levels of marine shipping based on Automated Identification System data. Journal of Marince Science and Engineering, 9(4), 369. doi:10.3390/jmse9040369

See Also

ais.to.DeponsShips for creation of DeponsShips objects (including calculated speeds) from AIS data

jacobnabe/DEPONS2R documentation built on Nov. 30, 2024, 7:51 p.m.