Date: 2023-06-12

# Overview of HurreconR

#### 12 June 2023

## HURRECON Model

The HURRECON model estimates wind speed, wind direction, enhanced Fujita scale wind damage, and duration of EF0 to EF5 winds as a function of hurricane location and maximum sustained wind speed. Results may be generated for a single site or an entire region. Hurricane track and intensity data may be imported directly from the US National Hurricane Center’s HURDAT2 database.

The model is an updated version of the original HURRECON model written in Borland Pascal for use with Idrisi (see below for details).

## Getting Started

Here are the basic steps for using the model. Please see below for more details.

1. Install and load the R package for the model (HurreconR).
2. Create a directory for a set of related model runs with subdirectories for input and output files (as described below).
3. Create a site file (sites.csv) with geographic coordinates for one or more study sites.
4. Download or create geographic and political boundary shapefiles for the desired geographic region. The coordinate system should be latitude/longitude (degrees). Rename these files so the first name of each file is “boundaries”.
5. Create a land-water file (land_water.tif) for the region.
6. Create a parameter file (parameters.csv) with parameters for all hurricanes and (optionally) for particular hurricanes.
7. Create an input hurricane track file (input_tracks.csv) for the geographic region. If desired, this file can be created directly from HURDAT2.
8. Run the model to create site and regional estimates. Use the plot functions to view model results.

## Details

All user functions begin with “hurrecon”. Input CSV files have a single header line that contains variable names (see details below). Model results are generated for two cover types: water and land. Datetimes are assumed to be UTC (GMT). Raster files are in GeoTiff format. Geographic coordinates are assumed to be latitude/longitude (degrees). The following measurement units are used throughout:

    bearing, direction - degrees
    distance - kilometers
    speed - meters/second
    time - minutes or hours

The user specifies a path (hur_path) for a given set of model runs. Input and output files are stored on the following subdirectories of this path:

    hur_path/input
    hur_path/region
    hur_path/region-dt
    hur_path/region-all
    hur_path/site
    hur_path/site-all
    hur_path/vector

The input subdirectory contains input files. The site and region subdirectories contain site and regional output files, respectively. Shapefiles that contain geographic and political boundaries for viewing regional results are stored on the vector subdirectory.

The following input files are required:

    sites.csv
    boundaries.*
    land_water.tif
    parameters.csv
    input_tracks.csv

All input files (except boundary files) are located on the input subdirectory.

The sites file contains the name, location, and cover type (water = 1, land = 2) of each study site. Variables: site_name, latitude, longitude, cover_type.

The boundary files are vector shapefiles that are used for creating maps of regional results. These files are located on the vector subdirectory.

The land-water file is a raster GeoTiff file that specifies the cover type (water = 1, land = 2) for each cell across a region. The geographic coordinates and the number of rows and columns of the land-water file are used to set the geographic window and spatial resolution for regional modeling.

The parameters file contains model parameters (radius of maximum winds and scaling parameter) for all hurricanes and (optionally) for individual hurricanes. Variables: hur_id, rmw, s_par. This file must contain at least one record (hur_id = ALL) that specifies the default values of rmw and s_par. Values typically range from 20 to 100 km for rmw and from 1.2 to 1.5 for s_par, depending on the region.

The input tracks file contains location and maximum wind speed for each position of each hurricane for a given set of model runs. Variables: hur_id, name, date_time, jd, status, latitude, longitude, wind_max.

The input tracks file may be created directly from HURDAT2. Use the hurrecon_reformat_hurdat2 function to reformat a HUTDAT2 file as hurdat2_tracks.csv, rename this file to input_tracks.csv, and copy this file to the input subdirectory.

The hurrecon_extract_tracks function is used to extract the data needed for a particular set of model runs. This function uses the input tracks file and the land-water file to create input files (ids.csv, tracks.csv, tracks-all.csv) required for the hurrecon_model functions.

Examples of input files may be found on the inst/input subdirectory.

To run the model, create the above directories, copy the input files to their respective subdirectories, and use the library function to load HurreconR.

## Model Functions

    hurrecon_reformat_hurdat2

    hurrecon_set_path
    hurrecon_get_path

    hurrecon_create_land_water
    hurrecon_extract_tracks

    hurrecon_model_site
    hurrecon_model_site_all
    hurrecon_model_region
    hurrecon_model_region_dt
    hurrecon_model_region_all

    hurrecon_summarize_land_water
    hurrecon_summarize_tracks
    hurrecon_summarize_site
    hurrecon_summarize_region

    hurrecon_plot_site
    hurrecon_plot_site_all
    hurrecon_plot_tracks
    hurrecon_plot_region
    hurrecon_plot_region_dt
    hurrecon_plot_region_all

The hurrecon_reformat_hurdat2 function reformats data from HURDAT2 for use with HURRECON. This is normally a one-time operation for a given version of HURDAT2. Hurricane IDs in HURDAT2 are reformatted to facilitate sorting by year (e.g. AL031935 becomes AL1935-03).

The hurrecon_set_path function sets the path for the current set of model runs. The hurrecon_get_path function returns the current path. Use hurrecon_set_path before using other functions.

The hurrecon_create_land_water function creates a land-water raster file in GeoTiff format using the specified minimum & maximum latitude & longitude, the number of rows & columns, and vector boundary files in shapefile format used to set the cover type of each cell. The land-water file is used by other functions to get the spatial parameters required for regional modeling. The hurrecon_extract_tracks function extracts data from an input tracks file (which may be derived from HURDAT2) for use with a particular land-water file. Optional parameters may be used to broaden the geographic area or adjust the minimum hurricane intensity when selecting hurricane tracks.

The hurrecon_model functions generate output for a single hurricane and a single site (all datetimes), all hurricanes for a single site (peak values), a single hurricane for a specified geographic region (peak values or specified datetime), and all hurricanes for a specified geographic region (peak values). If save is TRUE (default), results are written to the site, site-all, region, region-dt, or region-all subdirectory as CSV or GeoTiff files. The default time step for site results is 1 minute. The default time step for regional results is calculated as the time required to traverse one cell in the vertical direction at 20 meters per second, rounded to one of these values: 1, 2, 3, 5, 10, 15, 30, or 60 minutes.

The hurrecon_summarize_land_water function displays information about the current land-water file. The hurrecon_summarize_tracks function displays information about the current track files. The hurrecon_summarize_site function displays peak values for a single hurricane and a single site. The hurrecon_summarize_region function summarizes regional output for a single hurricane.

The hurrecon_plot_site functions create time-series and scatter plots for a single hurricane and time-series plots for all hurricanes for a given site. The hurrecon_plot_tracks function creates a map of the land-water file with selected hurricane tracks. The hurrecon_plot_region functions create maps of regional results for a single hurricane or for all hurricanes.

## Examples

Sample commands for the 1935 Florida Keys hurricane and Miami FL:

    hurrecon_reformat_hurdat2(hurdat2_file="hurdat2-1851-2022-050423.txt")
    [copy hurdat2_tracks.csv to input_tracks.cvs on input directory]

    hurrecon_set_path("c:/hurrecon/east_20km")
    hurrecon_get_path()

    hurrecon_create_land_water(nrows=150, ncols=180, xmin=-100, xmax=-59, ymin=23, ymax=50)
    hurrecon_extract_tracks(wind_min=70)

    hurrecon_model_site("AL1935-03", "Miami FL")
    hurrecon_model_site_all("Miami FL")
    hurrecon_model_region("AL1935-03")
    hurrecon_model_region_dt("AL1935-03", "1935-09-03T12:00")
    hurrecon_model_region_all()

    hurrecon_summarize_land_water()
    hurrecon_summarize_tracks()
    hurrecon_summarize_site("AL1935-03", "Miami FL")
    hurrecon_summarize_region("AL1935-03")

    hurrecon_plot_site("AL1935-03", "Miami FL")
    hurrecon_plot_site_all("Miami FL")
    hurrecon_plot_tracks()
    hurrecon_plot_region("AL1935-03")
    hurrecon_plot_region_dt("AL1935-03", "1935-09-03T12:00")
    hurrecon_plot_region_all()

## Model Equations

The sustained wind speed (Vs) at any point P in the northern hemisphere is estimated as:

    [1] Vs = F[Vm - S(1 - sin T)Vh/2] * Sqrt[(Rm/R)^B * exp(1 - (Rm/R)^B)]

    where:

    F = scaling parameter for the effects of friction (water = 1.0, land = 0.8)
    Vm = maximum sustained wind speed over water anywhere in hurricane
    S = scaling parameter for asymmetry due to forward motion of hurricane (1.0)
    T = clockwise angle between forward motion of hurricane and radial line to P
    Vh = forward speed of hurricane
    Rm = radius of maximum winds
    R = radial distance from hurricane center to point P
    B = scaling parameter controlling shape of wind profile curve

The peak wind gust speed (Vg) at point P is estimated as:

    [2] Vg = G * Vs

    where:

    G = gust factor (water = 1.2, land = 1.5)

The wind direction (D) in degrees at point P is estimated as:

    [3] D = Az - 90 - I

    where:

    Az = azimuth from point P to hurricane center
    I = cross-isobar inflow angle (water = 20 degrees, land = 40 degrees)

In the southern hemisphere:

    T = counterclockwise angle between forward motion of hurricane and radial line to P
    D = Az + 90 + I

For more details, see publications below.

## History

The original HURRECON model was written in Borland Pascal and depended on Idrisi for spatial visualization. The model was used in published studies of the ecological impacts of historical hurricanes in New England and Puerto Rico:

- Boose, E. R., Chamberlin, K. E., Foster, D. R. 2001. Landscape and regional impacts of hurricanes in New England. Ecological Monographs 71: 27-48.

- Boose, E. R., Serrano, M. I., Foster, D. R. 2004. Landscape and regional impacts of hurricanes in Puerto Rico. Ecological Monographs 74: 335-352.

New features in the updated version of HURRECON include support for: (1) estimating wind damage on the enhanced Fujita scale, (2) importing hurricane track and intensity data directly from HURDAT2, (3) creating a land-water file with user-selected geographic coordinates and spatial resolution, and (4) creating plots of site and regional results.

The model equations for estimating wind speed and direction, including parameter values for inflow angle, friction factor, and wind gust factor (over land and water), are unchanged from the original HURRECON model.