ntl_mean

[Abdulazizbek]

data = bm_extract(roi = gdf, 
                      product_id = "VNP46A2",
                      date_range = pd.date_range("2021-10-02", "2021-11-01", freq="D"), 
                      bearer = bearer,
                     )

When download data, it provides ntl_mean value.
I have found some additional information what does it mean: ntl_mean, but I'm not sure.
My question is: what is the exact interpretation of ntl_mean:
Thank you beforehand,

[g4brielvs]

@Abdulazizbek Thanks! BlackMarblePy's bm_extract returns zonal statistics. Zonal statistics summarize raster data by aggregating (e.g., adding up) the values of the raster cells that fall within each zone defined by the vector geometries. By default (see documentation), the average is be returned. You may select other valid functions, e.g., sum or median.

[Abdulazizbek]

Thank you for detailed explanation.
Is it possible to interpret ntl_mean value from bm_extract (unit of the lights measured in nighttime lights?) like this version:
(Giga) Watts luminosity for NxN km

[g4brielvs]

Thank you for detailed explanation. Is it possible to interpret ntl_mean value from bm_extract (unit of the lights measured in nighttime lights?) like this version: (Giga) Watts luminosity for NxN km

@Abdulazizbek The returned values are zonal statistics, in other words, the average value of all the cells within the zone. The data values represent the intensity of nighttime lights; thus, the zonal statistics would represent average light intensity within each zone.