You should set the scale
and crs
(or crsTransform
and crs
) parameters in the export call. When you reduce an image collection the result has a default projection that has 1-degree pixel size in WGS84 EPSG:4326 coordinate reference system. It does this because it is possible that images in the collection might have mixeddifferent projections. Currently, because your region is pretty small and you are accepting defaults in the export, your exported image has a single 1-degree pixel; set the crs and scale to that of the original data. Read more about the default projection at The default projection.