Time-plot of standard deviation of temperature
 

I have a unsteady closed system, where the temperature is varying with time. I want to plot the standard deviation of the instantaneous temperature field in the system as a function of temperature, which should go on decreasing progressively. For this what I need, as I feel, is to go to : solve-->monitors-->surface-->and check the plot box and define the surface monitor to give reports of static temperature under temperature, but the exact report type which I need is the standard deviation of this temperature. Unfortunately, average, facet average, integral...... are the options only present. How do you think can I accomplish that? Using DEFINE_ADJUST UDF as suggested by one friend might be a solution. I tried that but could not figure out how to get the plot using it. By the way, I still do not know the use of the following: solve--> monitors -->statistic. Is it helpful in my case? Thanks.