Hi Jitka, When you are using the CDM stack code such as your junit test to get data, then expandGrib1ThinGrids = true must be set because the CDM stack only knows how to handle full grids. Otherwise you will get the exceptions like: java.lang.ArrayIndexOutOfBoundsException: 35718. If expandGrib1ThinGrids = false, you must use your own code to process the data. You could change the setting between calls so the expected type of data would be returned. Hopefully this makes sense. Robb... Ticket Details =================== Ticket ID: EEV-923331 Department: Support netCDF Java Priority: High Status: Open