I am converting ERA5-Land hourly surface solar radiation downwards (SSRD) data from Joules per square meter (J/m²) to Watts per square meter (W/m²), following the guidelines provided on the ECMWF Confluence page (Conversion table for accumulated variables (total precipitation/fluxes) - Copernicus Knowledge Base - ECMWF Confluence Wiki). After applying the conversion formula from the user support section, I obtain reasonable W/m² values for all UTC hours. However, the conversion of SSRD data at 00 UTC (subtracting the 23 UTC value from the 00 UTC value and then dividing by 3600) results in W/m² values ranging from -6839.27 to 7409.66, which are outside the expected range. Could anyone please help me understand why the SSRD values at 00 UTC are not falling within a reasonable range? I used the following formula:
W/m² = (SSRD at 00UTC - SSRD at 23UTC) / 3600
Dr Abdul Malik