imated by the following function:

$T=T_{\text{m}\text{e}\text{a}\text{n}}+(T_{\text{p}\text{e}\text{a}\text{k}}-T_{\text{m}\text{e}\text{a}\text{n}})cos((t-t_{\text{p}\text{e}\text{a}\text{k}}))$

where $T_{\text{m}\text{e}\text{a}\text{n}}=$ the average annual temperature, $T_{\text{p}\text{e}\text{a}\text{k}}=$ the peak temperature, $=$ the frequency of the annual variation