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I would like to get the panel data of the nighttime light in Japan and check the correlation between other economic statistics. In order to do that, I have to get yearly digital number value from each satellite, F10, F12, F14, F15, F16, and F18, and intercalibrate it as Elvidge et al(2009) did.

Here is the code in which I could get the DN value in 1994, the year which F10 and F12 exist at the same time. but I can't identify which satellite are the data from.

So, the question is below:

How can I check which satellite are the data from?

If it is impossible to make sure of it, How to get DN value from a certain satellite?

var dataset = ee.ImageCollection('NOAA/DMSP-OLS/NIGHTTIME_LIGHTS').select('stable_lights');
var v1994 = dataset.filter(ee.Filter.date('1994-01-01', '1994-12-31')).median();
var nighttimeLightsVis = {min: 0.0, max: 60.0};
Map.addLayer(v1994.clip(jpn), nighttimeLightsVis, "Nighttime_1994");
var reducer1 = ee.Reducer.mean();
var reducers = reducer1.combine({reducer2: ee.Reducer.median(), sharedInputs: true})
function ntl(image) {var pas = image.reduceRegions({  collection: jpn,  reducer: reducers,  scale: 500,});return pas}
function export_table (table, description) {var em = Export.table.toDrive({ collection: ee.FeatureCollection(table), description: description, folder:'GIS', selectors:(["CITY_ENG","JCODE","mean"]),});return em}
var nl_v1994 = export_table(ntl(v1994), 'NL_v1994Ejpn');

*I got the border data, "jpn" in this code, from this website

*I tried to use the GeoTIFF image which downloaded from this website, but I got an error: Image.reduceRegions: Unable to find a crs.

  • Can you add a link to Elvidge et al. 2009? – JonasV Sep 30 at 15:12
  • Thank you, Jonas. Here you can download the paper – Takeshi Oct 1 at 3:39
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The satellite is saved in the property system:index. You can acces it like this for a single image:

var dataset = ee.ImageCollection('NOAA/DMSP-OLS/NIGHTTIME_LIGHTS')
                .select('stable_lights');

print(dataset.first().get("system:index"))

If you only want Images from the satellite F14 you can use filterMetadata

print(dataset.filterMetadata("system:index", "contains", "F14"))

When using .mean() or .median() and not filter the satellites beforehand, it will always use all available data from the ImageCollection you give it.

See here for more general info on the dataset.

| improve this answer | |
  • I appreciate your kindness! I can move to the next step. – Takeshi Oct 1 at 15:22

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