---
title: "Global oceanic barrier model on the sphere"
author: Alba Fuster-Alonso^[afuster@icm.csic.es, Institut de Ciències del Mar (ICM) - CSIC, Barcelona, Spain.] $\;$  Elias T Krainski^[King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia.] $\;$  Haavard Rue^[King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia.] $\;$ Finn Lindgren^[University of Edinburgh (UoE), Edinburgh, Scotland.]
format:
  html:
    page-layout: full
    fig-width: 11.5
    fig-height: 8.5
    embed-resources: true
    self-contained-math: true
    toc: true
    toc-location: left
    toc-title: Outline
    toc-expand: 1
    toc_float: 
      collapsed: true
    code-fold: true
    code-tools: true
    number-sections: true
editor_options: 
  chunk_output_type: console
output: rmarkdown::pdf_document
vignette: >
  %\VignetteIndexEntry{Global oceanic barrier model on the sphere}
  %\VignetteEncoding{UTF-8} 
  %\VignetteEngine{knitr::rmarkdown}
---

```{=html}
<style> body {text-align: justify} </style>
```
<!-- Justify text. -->

```{r setup, include=FALSE}
set.seed(123)
library(INLA)
##inla.setOption(num.threads="4:1")
##inla.setOption(smtp="taucs")
##if (file.exists("myinit.R")) source("myinit.R")
library(knitr)
library(rmarkdown)
knitr::opts_chunk$set(echo=TRUE, cache=FALSE, message=FALSE, warning=FALSE)
knitr::opts_chunk$set(fig.path="figures/barrier-global/")
```

# Introduction

In this tutorial, we illustrate the implementation of the barrier
model proposed in Bakka et al. (2019) in the sphere. It considers the
problem of modeling over a spatial domain, taking into account
physical barriers and the spherical shape of the Earth. Since we are
working on the global oceans, continents can be considered as physical
barriers, and this aspect has to be taken into account in the
modeling. When using a barrier model, the range is not only determined
by the distance to points. If there is a barrier between two points,
the range should decrease quickly, and the correlation over the
barrier should approach zero. Additionally, the Earth's spherical
shape is a crucial factor in this particular case, as considering a
planar approximation can bias the results when working on a global
scale. Therefore, this tutorial is developed using a projection onto a
sphere. We are using the new implementation of the INLA package.


**Since the compiled vignette is large is size, we do not include it the
R-INLA package, but you can download the vignette source and
downloaded data, at
``[https://github.com/hrue/r-inla/tree/devel/rinla/vignettes/barrier-global](https://github.com/hrue/r-inla/tree/devel/rinla/vignettes/barrier-global)''
and compile it yourself.**

