The process you are looking is called mosaic. You can do it for a single date with `.mosaic()`. For multiple dates, I create a property storing year and DOY and then I iterate the image collection mosaicking. Something like:

```

var setdoy = function(image) {

var date_ = image.date().format('y-D');

return image.set('yearDOY', date_);

};

var col2 = col.map(setdoy);

var dates = ee.List(col2.aggregate_array('yearDOY')).distinct();

var by_date = function(lst){

var col_temp = col2.filterMetadata('yearDOY','equals',lst)

var temp_name = col_temp.first().get('yearDOY')

col_temp = col_temp.mosaic();

col_temp = col_temp.set('name', ee.String('date_').cat(temp_name));

return col_temp;

};

var mosaic_col = ee.ImageCollection(dates.map(by_date));

```

Dear Aldo

Many thanks for your response

I will try it