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Defining Snow Presence Based On Air Temperature


bernard
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Hi,
I would like to conduct an analysis of fixed tilt Photovoltaic array.
I need a weather file for particular location. It can not be found in the PV*SOL Climate data.
But Meteonorm has it. The problem is that this Meteonorm weather file does not contain data about snow depth nor albedos.

I was wondering if I could approximate this by somehow defining an albedo to be 0.6 (ground covered with wet snow) in cases when air temperature is bellow some value.
Which value would that be? Something bellow 0°C. Basically when this air temperature value is present, there is snow on the ground, and when it's higher than this value, there's no snow.

 

RETscreen advices using 0.7 albedo for -5°C temperatures, and interpolated albedo values from 0.7 to 0.2 for air temperatures between -5°C and 0°C (example: -4°C - 0.6, -3°C - 0.5, -2°C - 0.4, -1°C - 0.3, 0°C - 0.2, 1°C - 0.2...).
Do you think this is correct?

Any recommendations please?

Thank you for the reply.

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Dear Bernard,

 

Of course there will be an impact, due to the different number of ice crystals in the snow and meltwater on the surface.

But unfortunately we do not have any studies about it.

 

For us, your approach is a comprehensible way, but it has to be ensured that there is always snow, at temperatures below 0 °. 

 

Best regards

 

Your Technical Support & Service

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Thank you for the reply hotline tm,

The problem is that Meteonorm can export its weather data for this location but without the snow depth and albedo information.

Is there some other way you would recommend on "be ensured that there is always snow"?
Can it somehow be approximated by checking for the precipipations depth along with air temperature?

 

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Dear Bernard,

 

We don't have any recommendations on that issue. Of course precipitation and low air temperatures are an indication for snow. But it also depends for example on wind and vertical air circulations, especially at temperatures around 0°C.

 

To be really sure you need snow information.

 

Your Technical support

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