Thermodynamic Modes of Variability over the Maritime Continent

Due to complicated ocean / land topography and sparse data measurements, modeling of atmospheric processes over the Maritime Continent (MC) is notoriously difficult. Because of systematic biases, simply using boundary conditions from reanalysis data sets in smaller scale modeling may not produce reliable results. In this study, vertical thermodynamic profiles generated from the ERA-Interim and MERRA data sets are compared with radiosonde observations from several sites over the MC for the 2008-2015 period. Following the reanalysis evaluation, an examination of the sounding data set is conducted for the purpose of exploring the dominant vertical temperature, humidity, and wind structures in the region. Principal Component Analysis (PCA) is employed to transform vertical patterns present in radiosonde data for these variables into typical thermodynamic profiles for the MC. PCA is repeated for the MERRA and ERA-Interim data sets and both rotated and non-rotated empirical orthogonal functions are considered. The results indicate that the primary modes of thermodynamic variability in the region can be represented in a lower-dimensional subspace, allowing for more realistic model simulations of atmospheric processes, particularly cloud development, convection, and precipitation over the MC.