摘要：Observational evidence suggests that compared to non-forested areas, forests have a cooling effect on
daytime land surface temperature (LST) and a warming effect on nighttime LST in many regions of the
world, thus implying that forests dampen the diurnal temperature range. This feature is not captured
by current climate models. Using the Community Land Model 5.0 (CLM5.0), we show that this
diurnal behavior can be captured when accounting for biomass heat storage (BHS). The nighttime
release of energy absorbed by the vegetation biomass during the day increases both nighttime LST and
ambient air temperature in forested regions by more than 1 K. The daytime cooling is weaker than the
nighttime warming effect, because the energy uptake by the biomass is compensated by a reduction in
the turbulent heat fluxes during day. This diurnal asymmetry of the temperature response to BHS
leads to a warming of daily mean temperatures, which is amplified during boreal summer warm
extremes. Compared to MODIS, CLM5.0 overestimates the diurnal LST range over forested areas.
The inclusion of BHS reduces this bias due to its dampening effect on diurnal LST variations. Further,
BHS attenuates the negative bias in the nighttime LST difference of forest minus grassland and
cropland, when compared to MODIS observations. These results indicate that it is essential to
consider BHS when examining the influence of forests on diurnal temperature variations. BHS should
thus be included in land surface models used to assess the climatic consequences of land use changes
such as deforestation or afforestation.
关键词：biomass heat storage; land use change; land surface modeling
