abnormal temperature with LMD_MIXING

[jake]

I run a model with LMD_MIXING. In other time, the temperature is normal, but in August, the surface (several layer near surface) temperature becomes abnomal (fig1). I'm confused about this. The fig2 is the diagnostic result of temperature vertical diffusion term. It seems that it is the vertical mixing scheme that causes this. If I use MY25_mixing, the temperature will be normal. Does anyone can tell me why?