Multiple-scale modelling of forest snow sublimation: initial findings

✍ Scribed by J. Parviainen; J. W. Pomeroy

• Publisher: John Wiley and Sons
• Year: 2000
• Tongue: English
• Weight: 193 KB
• Volume: 14
• Category: Article
• ISSN: 0885-6087
• DOI: 10.1002/1099-1085(20001030)14:15<2669::aid-hyp85>3.0.co;2-q

✦ Synopsis

Physically based equations describing snow interception and sublimation processes were applied to canopyintercepted snow using a fractal scaling technique to provide a snow-covered forest boundary condition for a onedimensional land surface scheme. Modi®cation of the land surface scheme's calculation of turbulent transfer and within-canopy ambient humidity was required to accommodate this nested control volume approach. Tests in late winter in a southern boreal forest mature jack pine stand against measured sublimation found that the coupled model provides good approximations of sublimation losses on half-hourly and event bases. Daily sublimation averaged 0Á5 kg m À2 daily, with minimum and maximum daily losses of 0Á16 and 0Á72 kg m À2 . Cumulative errors in estimating canopy temperature, humidity and intercepted snow load over 7 days of simulation were À 0Á7 K, À 4Á15% of the average observed vapour pressure, and 0Á103 kg m À2 , respectively. At a nearby regenerating jack pine site, measured peak latent heat ranged from À 14Á6 W m À2 to -40Á9 W m À2 . Testing of the model at this site yielded reasonable estimates of latent and sensible heat ¯uxes during an overnight event, but did not estimate latent heat ¯ux as well during events involving larger snow loads and incoming solar radiation, possibly as a result of errors introduced by solving for within-canopy humidity and neglect of subcanopy snow energetics. Further work to improve heat storage terms, and the inclusion of subcanopy snow energetics could help improve the coupled model performance.