Significant difference in temperature data between Meteonorm 7.2 & NASA-SSE

[Muthuraj]

Hi,

I am currently using PVsyst 6.86 where I tried to compare meteo data from Meteonorm 7.2 and NASA-SSE for a high altitude site.

Although GHI values roughly match, significant difference (13 to 20 deg C) is observed in monthly values of temperature which leads to following questions.

(1) NASA-SSE database contains different temperature values like earth skin temperature, air temperature at 10m (min, max, avg), etc. Which one is used in PVsyst 6.86?

(2) Similarly, Meteonorm also contains different temperature values like surface temperature, air temperature at 2m, etc. Which one is used in PVsyst 6.86?

(3) Although NASA-SSE dataset's spatial resolution is large (1 lat x 1 long), for most of the low altitude sites that I have seen, temperature values match roughly. Is this a problem only in high altitude regions? Any specific reasons.

Thanks.

[LauraH]

Temperature varies with elevation, and most high-altitude regions are mountainous, which is to say that the elevation varies rapidly in space. Thus the temperature at individual locations cannot be represented accurately using an average over 1 deg x 1 deg.