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Run the WEMo Wave Energy Model

Source: R/wemo.R
WEMo.Rd

wemo() Combines fetch, bathymetry, and wind data to estimate wave height and energy metrics at each site using WEMo (Wave Energy Model) from wind-waves.

First, the function builds a wind-wave over input bathymetry and returns an estimate of final wave height and related wave characteristics (e.g., wave energy index, wave period, wave number, celerity).

Then, the function summarizes the waves from every direction for each site and computes the summary statistic RWE.

Usage

wemo(fetch)

Arguments

fetch

A data frame or sf object containing fetch geometry and required variables: efetch, depths, distances, speed, proportion. Expects the output from prepare_wemo_inputs(). Each row corresponds to a fetch ray.

Value

A list of two elements:

wemo_details

the original fetch object with the following stats about each wave arriving at the site from the direction of the fetch ray added:

  • wave_height_final - Final wave height at the end of the fetch (m)

  • WEI - Wave Energy Index

  • wave_period - Estimated wave period (s)

  • wave_number - Average wave number (rad/m)

  • celerity_final - Final wave phase speed (m/s)

  • nnumber_final - Final group velocity coefficient

wemo_final

sf object with all the variables from site_point in addition to the following:

  • RWE - Total relative wave exposure at the site

  • avg_wave_height - Mean wave height across all fetch rays (m)

  • max_wave_height - Maximum wave height across all fetch rays (m)

  • direction_of_max_wave - Direction(s) of maximum wave height (Degrees from North)

Details

This function builds and propagates waves arriving at the site from each fetch ray segment-by-segment, adjusting for shoaling, wave breaking, and changing depth. Deep and shallow water regimes are handled using different formulas. The function uses a Newton-Raphson method to compute wave number. The values in the wemo_final return are calculated from summarizing (mean and max wave height) of all fetch rays. Relative Wave Energy (RWE) is calculated by multiplying the REI from each wave by the proportion of time that wind blows from the direction of the ray each ray and summing for all fetch rays

See also

prepare_wemo_inputs()

Examples

if (FALSE) { # \dontrun{
# Example assumes fetch object includes efetch, depths, distances, speed, and direction
result <- wemo(fetch = fetch, site_points = site_pts)
details <- result$wemo_details
summary <- result$wemo_output
} # }