Climate Dynamics

, Volume 42, Issue 7, pp 1715–1732

Sensitivity of a coupled climate model to canopy interception capacity

  • T. Davies-Barnard
  • P. J. Valdes
  • C. D. Jones
  • J. S. Singarayer
Article

DOI: 10.1007/s00382-014-2100-1

Cite this article as:
Davies-Barnard, T., Valdes, P.J., Jones, C.D. et al. Clim Dyn (2014) 42: 1715. doi:10.1007/s00382-014-2100-1

Abstract

The canopy interception capacity is a small but key part of the surface hydrology, which affects the amount of water intercepted by vegetation and therefore the partitioning of evaporation and transpiration. However, little research with climate models has been done to understand the effects of a range of possible canopy interception capacity parameter values. This is in part due to the assumption that it does not significantly affect climate. Near global evapotranspiration products now make evaluation of canopy interception capacity parameterisations possible. We use a range of canopy water interception capacity values from the literature to investigate the effect on climate within the climate model HadCM3. We find that the global mean temperature is affected by up to −0.64 K globally and −1.9 K regionally. These temperature impacts are predominantly due to changes in the evaporative fraction and top of atmosphere albedo. In the tropics, the variations in evapotranspiration affect precipitation, significantly enhancing rainfall. Comparing the model output to measurements, we find that the default canopy interception capacity parameterisation overestimates canopy interception loss (i.e. canopy evaporation) and underestimates transpiration. Overall, decreasing canopy interception capacity improves the evapotranspiration partitioning in HadCM3, though the measurement literature more strongly supports an increase. The high sensitivity of climate to the parameterisation of canopy interception capacity is partially due to the high number of light rain-days in the climate model that means that interception is overestimated. This work highlights the hitherto underestimated importance of canopy interception capacity in climate model hydroclimatology and the need to acknowledge the role of precipitation representation limitations in determining parameterisations.

Keywords

InterceptionGCMLand–atmosphere interactionsEvapotranspirationCanopy storage capacity

Supplementary material

382_2014_2100_MOESM1_ESM.pdf (2 mb)
Supplementary material 1 (PDF 2033 kb)

Copyright information

© Springer-Verlag Berlin Heidelberg 2014

Authors and Affiliations

  • T. Davies-Barnard
    • 1
  • P. J. Valdes
    • 1
  • C. D. Jones
    • 2
  • J. S. Singarayer
    • 3
  1. 1.School of Geographical SciencesUniversity of BristolBristolUK
  2. 2.Met Office Hadley CentreExeterUK
  3. 3.Department of MeteorologyUniversity of ReadingReadingUK