I currently have solar radiation data from different coordinates in the Philippines and I would like to compute for cloud cover. I have seen the Angstrom-Savinov equation (H =H0[1−(1−k)C]) but I still need to input key parameters for me to properly use it. Does anyone have an idea where to get these references? If you have other suggestions, that would be amazing. Thank you very much.
That equation is far too simplistic to be useful. If you want to do any serious work, and especially if you need good spatiotemporal resolution, the best is to use actual spaceborne observations of cloud fraction (e.g., from MODIS) or reconstructions from reanalyses (e.g. ERA5) or other methods (e.g. CMSAF).
See https://giovanni.gsfc.nasa.gov/giovanni/#service=TmAvMp&starttime=&endtime=&variableFacets=dataFieldMeasurement%3ACloud%20Fraction%3B
https://wui.cmsaf.eu/safira/action/viewProduktList?dId=1
https://cds.climate.copernicus.eu/cdsapp#!/dataset/reanalysis-era5-pressure-levels?tab=form
Averaged radiation intensity at the surface relates to the cloud cover fraction and solar zenith angle. But the solar radiation field reaching the surface is not uniform in case of broken cloud skies. In that case, scaterred cloud side reflection has to be taken into account to obtain the actual averaged solar radiation intensity reaching the surface.
This may help: https://authors.elsevier.com/c/1cv~B4sIlksnr0
Unfortunately, Rui misunderstood the question. His paper is interesting, but not address the need for cloud fraction data at any location.
- Badges
- Science topic
- Similar topics
- Data Mining
- Classification