Suburban-rural energy balance comparisons for Vancouver,B.C.: An extreme case?

Synchronous observations of the energy balances of a suburban and a rural area in the Vancouver region are used to investigate the impact of urbanization on energy exchange. Net radiation and rural soil heat flux density were directly measured, suburban heat storage was parameterized, and the turbulent heat flux densities were evaluated using the Bowen ratio-energy balance method. Most comparisons were conducted during a period of drying following an unusually wet early summer. These conditions produced atypical but very interesting results. With cloudless skies and high radiant input, suburban-rural differences of both net radiation and evapotranspiration were contrary to previous results and intuition. In both cases, suburban values were greater than their rural counterparts. In most respects the rural site behaved as expected, and the explanation for these findings is thought to be related to advective assistance of evapotranspiration from the suburban area. Under lesser radiant forcing the suburban budget acted in greater conformity with past experience and suburban-rural differences were similarly more in agreement with expectation.