El niño anomaly – r.iresmi.net

Author

Michaël

Published

2023-11-16

Modified

2023-11-16

A photo of sea waves — Surf – CC-BY-NC-ND by Al Case

Day 16 of 30DayMapChallenge: « Oceania » (previously).

Using data from NOAA. Tried different combinations of {terra}/{stars}/{raster} and {ggplot2}/{tmap}/base::plot and between glitches, projection problems, slow plotting, limited customization, that’s not very satisfying…

library(terra)
library(viridis)

ssta_file <- "ct5km_ssta_v3.1_20231115.nc"

if (!file.exists(ssta_file)) {
  download.file(paste0("https://www.star.nesdis.noaa.gov/pub/sod/mecb/crw/data/5km/v3.1_op/nc/v1.0/daily/ssta/2023/",
                       ssta_file), 
                ssta_file)
}

ssta <- rast(ssta_file) |> 
  project(
   'PROJCS["Sphere_Equal_Earth_Asia_Pacific",
    GEOGCS["GCS_Sphere_GRS_1980_Mean_Radius",
        DATUM["D_Sphere_GRS_1980_Mean_Radius",
            SPHEROID["Sphere_GRS_1980_Mean_Radius",6371008.7714,0.0]],
        PRIMEM["Greenwich",0.0],
        UNIT["Degree",0.0174532925199433]],
    PROJECTION["Equal_Earth"],
    PARAMETER["False_Easting",0.0],
    PARAMETER["False_Northing",0.0],
    PARAMETER["Central_Meridian",200.0],
    UNIT["Meter",1.0]]')

plot(ssta$sea_surface_temperature_anomaly, 
     col = viridis(256), axes = FALSE, 
     main = "Sea surface temperature anomaly 2023-11-15",)

Map of Sea surface temperature anomaly on 2023-11-15 — Figure 1: Sea surface temperature anomaly 2023-11-15 from NOAA Daily Global 5km Satellite Sea Surface Temperature (a.k.a. CoralTemp)

---
title: "El niño anomaly"
description: "Day 16 of 30DayMapChallenge"
author: "Michaël"
date: "2023-11-16T20:00:00"
date-modified: last-modified
categories:
  - R
  - 30DayMapChallenge
  - spatial
  - datavisualization
  - remote sensing
draft: false
freeze: true
editor_options:
  chunk_output_type: console
chunk_output_type: console
execute:
  eval: true
---

[![Surf -- CC-BY-NC-ND by Al Case](images/42968106162_a6b37b6353_c.jpg){fig-alt="A photo of sea waves"}](https://flic.kr/p/28sWLYA)

Day 16 of [30DayMapChallenge](https://30daymapchallenge.com/): « Oceania » ([previously](/#category=30DayMapChallenge)).

Using data from [NOAA](https://coralreefwatch.noaa.gov/product/5km/tutorial/crw05a_sst_product.php). Tried different combinations of {terra}/{stars}/{raster} and {ggplot2}/{tmap}/base::plot and between glitches, projection problems, slow plotting, limited customization, that's not very satisfying...

```{r}
#| label: setup

library(terra)
library(viridis)
```

```{r}
#| label: data
#| results: false

ssta_file <- "ct5km_ssta_v3.1_20231115.nc"

if (!file.exists(ssta_file)) {
  download.file(paste0("https://www.star.nesdis.noaa.gov/pub/sod/mecb/crw/data/5km/v3.1_op/nc/v1.0/daily/ssta/2023/",
                       ssta_file), 
                ssta_file)
}

ssta <- rast(ssta_file) |> 
  project(
   'PROJCS["Sphere_Equal_Earth_Asia_Pacific",
    GEOGCS["GCS_Sphere_GRS_1980_Mean_Radius",
        DATUM["D_Sphere_GRS_1980_Mean_Radius",
            SPHEROID["Sphere_GRS_1980_Mean_Radius",6371008.7714,0.0]],
        PRIMEM["Greenwich",0.0],
        UNIT["Degree",0.0174532925199433]],
    PROJECTION["Equal_Earth"],
    PARAMETER["False_Easting",0.0],
    PARAMETER["False_Northing",0.0],
    PARAMETER["Central_Meridian",200.0],
    UNIT["Meter",1.0]]')
```

```{r}
#| label: fig-map
#| fig-cap: Sea surface temperature anomaly 2023-11-15 from NOAA Daily Global 5km Satellite Sea Surface Temperature (a.k.a. CoralTemp)
#| fig-alt: Map of Sea surface temperature anomaly on 2023-11-15
#| out-width: "100%"
#| fig-width: 7
plot(ssta$sea_surface_temperature_anomaly, 
     col = viridis(256), axes = FALSE, 
     main = "Sea surface temperature anomaly 2023-11-15",)
```