---
title: "spatialBehaviour"
output: rmarkdown::html_vignette
date: "`r Sys.Date()`"
vignette: >
   %\VignetteIndexEntry{spatialBehaviour}
   %\VignetteEngine{knitr::rmarkdown}
   %\VignetteEncoding{UTF-8}
---

``` {r setup, include = FALSE}
library(StormR)
```

The `spatialBehaviour()` function allows computing wind speed and direction for
each cell of a regular grid (i.e., a raster) for a given tropical cyclone or set
of tropical cyclones. The `product="Profiles"` argument allows producing 2D wind
fields during the lifespan of the cyclone at a temporal resolution of up to 15
minutes. The `spatialBehaviour()` function also allows to compute three
associated summary statistics: the maximum sustained wind speed
(`product="MSW"`), the power dissipation index (`product="PDI"`) and the
duration of exposure to winds reaching defined speed thresholds along the life
span of the cyclones (`product="Exposure"`). Then the `plotBehaviour()` and the
`writeRast()` functions can be used to visualise and export the output.
In the following example we use the `test_dataset` provided with the package to
illustrate how cyclone track data can be used to compute, plot, and export 2D
wind field profiles or summary statistics.

### Computing and plotting spatialBehaviour products

We can compute the behaviour of winds generated by the topical cyclone Pam
(2015) near Vanuatu. First, track data are extracted as follows:

```{r}
sds <- defStormsDataset()
st <- defStormsList(sds = sds, loi = "Vanuatu", names = "PAM", verbose = 0)
plotStorms(st)
```

#### Wind profiles

Using track data and the `spatialBehaviour()` function with the
`product="Profiles` argument we can generate 2D wind fields at any time as
follows:

```{r}
pf <- spatialBehaviour(st, product = "Profiles", verbose = 0)
pf
```

The function returns a `SpatRaster` object with two rasters, one for the wind
speed and one for the wind direction, for each observation or interpolated
observation. Rasters' names follow the following terminology, the name of the
storm in capital letters, "Speed" or "Direction", and the index of the
observation, separated by underscores. Note that actual observations have entire
indices (e.g., 41, 42, ...) while interpolated observation have decimals (e.g.,
41.1, 41.2, ...). Most tropical cyclone track data sets are based on
observations gathered every 3 or 6 hours. Therefore, to be able to compute wind
fields every 1 hour, the observations are interpolated.
Wind direction follows the meteorological convention : it indicates where the wind is blowing from, with 0° at North and increasing clockwise. 

Wind speed and direction profiles at the 41^th^ observation can be plotted as
follows:

```{r}
plotBehaviour(st, pf$PAM_Speed_41)
plotBehaviour(st, pf$PAM_Direction_41)
```

#### Summary statisics

The `spatialBehaviour()` function can compute the different `products` (i.e.,
`"Profiles"`, `"MSW"`, `"PDI"`, `"Exposure"`) either separately or together.
Here, we compute all three summary statistics together as follows:

```{r}
ss <- spatialBehaviour(st, product = c("MSW", "PDI", "Exposure"), verbose = 0)
ss
```

The `spatialBehaviour()` function returns a `SpatRaster` object with eight
rasters: one for the maximum sustained wind speed (`"MSW"`), one for the power
dissipation index (`"PDI"`), and one for each of the six defaults wind
thresholds values set for the duration of exposure (`"Exposure"`).

```{r}
names(ss)
```

By default, the function returns the duration of exposure (in hours) to wind
speeds above the thresholds used by the Saffir-Simpson hurricane wind scale
(i.e., 18, 33, 42, 49, 58, and 70 $m.s^{-1}$). This can be change using the
`wind_threshold` argument.

The maximum sustained wind speed can be plotted as follows:

```{r}
plotBehaviour(st, ss$PAM_MSW)
```

The power dissipation index can be plotted as follows:

```{r}
plotBehaviour(st, ss$PAM_PDI)
```

The duration of exposure to wind stronger than 58 $m.s^{-1}$ (i.e.,
Saffir-Simpson's categories 4 and 5) can be plotted as follows:

```{r}
plotBehaviour(st, ss$PAM_Exposure_58)
```

### Spatio-temporal resolution

As in the WorldClim database (<https://worldclim.org/data/worldclim21.html>)
four spatial resolutions are available. By default the spatial resolution is set
to 2.5 min (~4.5 km at the equator), but a finer spatial resolution of 30 s (~1
km at the equator) and coarser spatial resolutions of 5 min (~9 km at the
equator) or 10 min (~18.6 km at the equator) can be set using the `spaceRes`
argument. The temporal resolution is set to 1 hour by default but finer spatial
resolution of 0.75, 0.50, or 0.25 hour can be set using the `tempRes` argument.
Maximum sustained wind speed can be computed at a 10 min spatial resolution and
a 30 min temporal resolution as follows:

```{r}
ss <- spatialBehaviour(st, product = c("MSW"), verbose = 0, spaceRes = "10min", tempRes = 30)
plotBehaviour(st, ss$PAM_MSW)
```
#### Dynamic plot
`plotBehaviour` function also provide (See ExtractStorms vignette) a dynamic plot.
Here is an example based on the same parameters as above.
```{r}
plotBehaviour(st, ss$PAM_MSW, dynamicPlot = TRUE)
```



### Exporting spatialBehaviour products

The `spatialBehaviour()` function returns rasters stored in a `SpatRaster`
object than can be exported either in ".tiff" or ".nc" (NetCDF) formats using
the `writeRast()` function. Here, we export the maximum sustained wind speed in
the working directory as follows:

```{r}
writeRast(ss$PAM_MSW)
```



