The Influence of Soil Moisture and Surface Roughness on an Idealized
Tropical Cyclone
Abstract
On occasion, tropical cyclones (TCs) have been shown to strengthen over
land, provided that the land is warm and moist. The emergent hypothesis
is that the moist surface provides sustaining latent heat flux that is
reminiscent of an oceanic environment.. To test this hypothesis,
numerical simulations of idealized TCs with various profiles of soil
moisture availability (SMA) and surface roughness were conducted. SMA
gradients are shown to have a large influence on precipitation beyond
uniform SMA. The sensitivity of accumulated precipitation to SMA is
larger with enhanced friction. The maximum wind speed is more sensitive
to differences in SMA under lower surface roughness. Results provide a
foundation for refining emerging theories about land –atmosphere
interactions with landfalling tropical systems. Additionally, these
findings may inform forecasters to consider land-surface conditions when
assessing intensity trends for landfalling tropical cyclones,
particularly since assimilation of soil moisture and surface
characteristics can yield differing impacts.