Something labeled semidiurnal occurs this often
[DOC] [TLE] PDF (2.6MB) - Wiley Online Library [PAR] For instance, the radiative heating that takes place in the thermosphere is .... 
annual mean MLT migrating diurnal and semidiurnal tem- ..... from 14.4 mW/kg to 
17.7 mW/kg in December as labeled on ..... something about the physics and 
energy sources for each of ... results are often more structured, implying the 
existence of.