Merging climate data based on time in UTC

I have two data, one is of SMAP for 84 days at daily scale and have time band in UTC, other is of era-5 land data for 84 days but at hourly scale and here also time band in UTC for each pixel. Now complexity arise as, SMAP data UTC time vary pixel by pixel (grid-by-grid) at minute scale and whereas ERA-5 data time is constant for each hours in Pixel and have 24 time bands.

Now I have to fill ERA-5 hourly data on SMAP daily data, like ERA-5 06:00 hour data should be filled pixel of SMAP which has ~06:00 hrs, ERA-5 14:00 hour data should be filled pixel of SMAP which has ~14:00 hrs and repeting same for 24 hours. I have to put operation on 84 days data, and all the data files have same grid size (1624X1856).