Land-Atmosphere Interactions
We have investigated feedback mechanisms in land-atmosphere interactions and examined the effects of LCLUC on climate to improve our understanding of how the expansion and intensification of LCLUC have affected terrestrial ecosystems and thereby the climate system.
The temperate climate region of southeastern Australia (SEA) suffers from large periodic wildfires. Yaewone Kim, Minjoo Kim, and Eungul Lee found that FFDI95 in the temperate climate region of SEA increased significantly during the fire season (austral summer) throughout the study period. During the prefire season (austral spring), significantly reduced soil moisture enhances heat transfer through sensible heat flux, thus raising the temperature from the surface to the lower troposphere. During the fire season, a thicker troposphere, including the intensification of anticyclonic circulation and subsidence, may promote hot and dry conditions, thus intensifying wildfires.
Unprecedented land cover and land use (LCLU) changes can significantly alter the interactions between the land and atmosphere through biogeophysical processes, potentially changing the monsoon systems. Ahyeong Im, Eungul Lee, and Yanqian He quantified the LCLU transitions with fractional maps produced using the recently developed categorical LCLU maps from 1982 to 2015. The detected LCLU transitions affect the regional warming as demonstrated by correlation, regression and Granger-causality analyses and the related biogeophysical processes. Thus, the identified LCLU transitions can change the regional climate and potentially affect the monsoon systems by changing the contrast in heat between land and ocean.
Transporting and enhancing processes of dust in Korea
Sunyoung Kim, Eungul Lee, and Seungho Lee explored the transporting processes for the Asian dust observed over South Korea. Precipitation and Palmer Drought Severity Index (PDSI) inthe source regions during the previous summer were negatively correlated with the ADDs in South Korea. The intensified winds of northwesterly-northerly-northwesterly over a pathway of the Asian dust from the source regions to South Korea were identified during high ADDs years in South Korea. A dipole pattern of anti-cyclonic and cyclonic anomalies over central and eastern Asia, respectively, supported the Asian dust pathway [Kim et al., 2019, J. of Climate Research].
Changok Han also revealed that high PM10 concentrations are significantly associated with anticyclonic anomalies over the Amur River basin, which induce easterly wind anomalies and promote atmospheric stagnation by weakening prevailing westerlies. This anticyclonic circulation is thermodynamically linked to snow cover reduction in the basin. Decreased surface albedo increases heat transfer to the atmosphere via sensible and latent fluxes, leading to thermal expansion and rising geopotential height [Han et al., In revision].