5:15 PM - 7:15 PM
[AAS08-P10] Sensitivity of the Coupled Atmosphere-Ocean System to Vegetation Height Distribution in the MIROC Climate Model
★Invited Papers
Vegetation canopy height is a key determinant of low-level wind speed through its influence on surface roughness. In the MIROC series of climate models, canopy height has traditionally been prescribed as a constant based on fixed land cover types. However, in 2018, NASA launched the spaceborne LiDAR mission GEDI, which provides accurate measurements of forest vertical structure. GEDI’s footprint diameter is better suited for forest observations compared to the previously used ICESat/GLAS, enhancing data accuracy. Recently, several global gridded canopy height datasets have been developed to complement GEDI’s sparse horizontal coverage by incorporating satellite optical observations.
In this study, we integrate two such datasets—High-resolution Canopy Height Model of the Earth (HRCHME; Lang et al., 2023) and Global Canopy Height Maps (GCHM; Tolan et al., 2024)—into the MIROC6 climate model to assess the impact of more realistic vegetation height representations on climate simulations. We conducted three sets of pre-industrial climate simulations using different boundary conditions for canopy height: default settings (constant based on fixed land cover types), HRCHME, and GCHM. Each simulation was integrated for 100 years.
HRCHME showed a similar canopy height distribution to the default setting, though vegetation height was lower along coastal areas and in savanna regions. GCHM, on the other hand, generally exhibited lower canopy heights in tropical and boreal regions. Climatological 10 m wind speed was enhanced in coastal regions of the maritime continent and the Arctic in both simulations using observational canopy height distributions. In HRCHME, wind speed decreased over savanna areas, while in GCHM, it increased over tropical rainforests. Both sensitivity simulations showed surface temperature increases over tropical forests. In contrast, sea surface temperature decreased along coastal regions of the maritime continent, and convective activity was altered over the warm pool. Arctic temperature rises and sea-ice thinning were observed in boreal summer in both simulations. Detailed results and underlying mechanisms will be discussed in the talk.
In this study, we integrate two such datasets—High-resolution Canopy Height Model of the Earth (HRCHME; Lang et al., 2023) and Global Canopy Height Maps (GCHM; Tolan et al., 2024)—into the MIROC6 climate model to assess the impact of more realistic vegetation height representations on climate simulations. We conducted three sets of pre-industrial climate simulations using different boundary conditions for canopy height: default settings (constant based on fixed land cover types), HRCHME, and GCHM. Each simulation was integrated for 100 years.
HRCHME showed a similar canopy height distribution to the default setting, though vegetation height was lower along coastal areas and in savanna regions. GCHM, on the other hand, generally exhibited lower canopy heights in tropical and boreal regions. Climatological 10 m wind speed was enhanced in coastal regions of the maritime continent and the Arctic in both simulations using observational canopy height distributions. In HRCHME, wind speed decreased over savanna areas, while in GCHM, it increased over tropical rainforests. Both sensitivity simulations showed surface temperature increases over tropical forests. In contrast, sea surface temperature decreased along coastal regions of the maritime continent, and convective activity was altered over the warm pool. Arctic temperature rises and sea-ice thinning were observed in boreal summer in both simulations. Detailed results and underlying mechanisms will be discussed in the talk.