Effects of Land Use and Land Cover Change On The Cloud Formation in East Java

The Islands in the Maritime Continent (MC) have undergone substantial land use and land cover (LULC) change in the last 2 decades, especially near the coast. While LULC associated with large-scale deforestation over an area generally leads to a warmer and drier climate, the response over the MC has not been shown to follow this trend. Numerical deforestation experiments have indicated that the deforestation in the MC region leads to increases in both surface temperature and local precipitation. The island of Java, the most populated island in the world, has experienced substantial LULC change in terms of urbanization and deforestation. While West Java has undergone rapid growth of urbanization, East Java has been characterized by changes in deforestation and crop types. We perform a long-term statistical analysis of observations based on satellite retrievals and reanalysis data to examine the effect of LULC change on the boundary layer clouds in East Java. Initial results indicate a statistically significant (p=9.7x10-4) increase in the normalized difference vegetation index (NDVI) between the decades 2001–2010 and 2011-2020, particularly surrounding mountainous regions. NDVI increase (+0.15) is associated with changes between the crops and plantation over the rural regions, and an increase of greening over the mountainous areas. Land surface temperature (LST) varies in accordance with the NDVI changes over the majority of the area, with a decrease in the LST (-1.5oC) induced by a decrease in sensible heat fluxes over elevated NDIV, indicated by the reanalysis dataset. Further examination of the large scale flow characteristics suggests an increase in the water vapor availability near the surface, both onshore and offshore. We further perform modeling experiments over the Java Island, replacing the LULC between the two decades, to examine the effects of the surface energy budget changes induced by the LULC change on the distribution of cloud patterns.