Change in Input Precipitation Type to Noah LSM

• Based on study by Lackmann et al. (2002 WAF)

  • Before: precipitation type based on air temperature in the lowest model layer (Tsfc)
    • Snow if Tsfc < 0C, rain otherwise
  • Change: precipitation type based on model microphysics (Ffroz, fraction of frozen precipitation)
    • Snow if Ffroz ≥ 0.5, rain otherwise

• Should lead to:

  • Warmer surface temperatures in freezing rain events (latent heating warming ground, self-limiting process)
  • Cooler surface temperatures when snow falls on surface above 0ºC (melting of snow cooling ground)