Temperature Correction: Get Accurate Wall Surface Temperature

[Minka Aduse-Poku]

Dear All,
I have collected temperature data for a period of about 4 months with a device called ibutton attached to the surface of a concrete wall. My problem is the button is made of Stainless steel 305 and exposed to sunlight.
I am interested in obtaining the wall surface temperature and at the same time i know the effect of the sunlight would affect temperature readings (if i am not wrong).
does anyone know or have an idea on how i can correct these readings if i have to?

 

[Minka Aduse-Poku]

Data available to me at the moment are: average irradiance of the location, specific heat of the stainless steel 305 and that of the concrete wall (including temperature values)

 

[phyzguy]

Can you shade the temperature sensor and compare readings in and out of sunlight? Or can you compare readings on cloudy days vs clear days?