HARPMERGE "Merged product is empty" warning


While trying to use the harpmerge command line tool, I get an error in Terminal saying WARNING: merged product is empty. I am wondering what this means? I am trying to make daily averages of methane data in Northern Russia for February 2020 with this code:

harpmerge -ap ‘bin(); squash(time, (latitude,longitude))’ -a ‘latitude > 68 [degree_north]; latitude < 72 [degree_north]; CH4_column_volume_mixing_ratio_dry_air_validity>50; bin_spatial(400,68,0.01,500,67,0.01); derive(longitude {longitude});derive(latitude {latitude})’ S5P_OFFL_L2__CH4*.nc /shared/Training/ATMO01_AirQuality_Global/Processing/l3_Bovanenkovo_February1.nc_quality_50.nc

This means that the products for that day did not have any ‘good’ CH4 measurements for the region you have selected. Since CH4 is difficult to measure from space, this situation can indeed happen.

Yes, that is what I suspected was the problem. Thank you for a fast response.