Extracting temperature values in Google Earth Engine

Question

I am attempting to print the average temperature for inputting coordinates in the format of a string. Currently, I have only managed to showcase the temperature on the map and extract it from manually clicking on a pixel on the map.

For the Hycom dataset:

// Import the time series of global images, filter 15 days in August, 2018.

var dataset = ee.ImageCollection('HYCOM/sea_temp_salinity') .filter(ee.Filter.date('2018-08-01', '2018-08-15'));

// Select water temperature at 0 meters and scale to degrees C.

var seaWaterTemperature = dataset.select('water_temp_0')
    .map(function scaleAndOffset(image) {
      return ee.Image(image).multiply(0.001).add(20);
    });

// Define visualization parameters.

var visParams = {
  min: -2.0,  // Degrees C
  max: 34.0,
  palette: ['000000', '005aff', '43c8c8', 'fff700', 'ff0000'],
};

// Display mean 15-day temperature on the map.

Map.setCenter(-88.6, 26.4, 1);
Map.addLayer(seaWaterTemperature.mean(), visParams, 'Sea Water Temperature');

Answer 1

This tutorial covers many of the functions required to extract the values of a raster located under a point. Though I suspect that the steps described may be overkill for what you need.

https://developers.google.com/earth-engine/tutorials/community/extract-raster-values-for-points

A simpler approach would be to generate the point feature, then use the reduce region function.

First you will want to create the point of interest

var poi = ee.Feature(ee.Geometry.Point([-118.6010, 37.0777]), {plot_id: 1})

The coordinates for the point can be entered manually, or substituted for a variable. Then run the reduce region function with the raster and point geometry to extract the value of the pixel which the point falls upon.

var ras_value = image.reduceRegion({
  reducer: ee.Reducer.mean(),
  geometry: poi.geometry(),
  scale: 30,
  maxPixels: 1e9
});

The result will be a dictionary of the pixel values for each band. The desired value can the be printed out.

Note: if reduce region is being run on a single point then the mean, min, or max reducers should all work as it will just sample a single pixel.

https://developers.google.com/earth-engine/guides/reducers_reduce_region