Simulation of Diurnal Rainfall Variability over the Maritime Continent with a High-Resolution Regional Climate Model

Abstract

The characteristics of diurnal precipitation variability are evaluated over the tropical Maritime Continent (MC) from both satellite observations and high-resolution simulations performed using the Weather Research and Forecasting (WRF) model.Simulations using the Kain-Fritsch convective scheme showed a slight improvement in representing the precipitation diurnal cycle compared with those using the other two schemes examined here. The influence of boundary forcing was compared between the National Center for Environmental Prediction-Final Analysis (NCEP-FNL) and the Norwegian Earth System Model (NorESM). In these experiments, simulations with NCEP-FNL data as lateral boundary conditions outperformed those with NorESM boundary conditions. All WRF simulations exaggerated the amplitude of diurnal precipitation over the land. However, the WRF captured the principal shape of the observed diurnal cycle well. An empirical orthogonal function (EOF) analysis was applied and the first two modes from satellite data explained up to about 80 % of the total diurnal variance. The results confirm that the land-sea breeze circulation plays a significant role in the diurnal cycle of precipitation. The radiatively induced land-sea breeze circulation and its timing were well reproduced in the WRF simulations. These results suggest that higher resolution simulations that reproduce heterogeneous local-scale processes are likely necessary in order to resolve diurnal variability of precipitation and its future changes over the MC.

A 10-Year Austral Summer Climatology of Observed and Modeled Intraseasonal, Mesoscale, and Diurnal Variations over the Maritime Continent

“…The WRF Model showed a strong wet bias over the land and dry bias over the water relative to satellite precipitation estimates, consistent with many previous studies in both tropical and midlatitude regions (e.g., Skok et al 2016;Bhatt et al 2016;Vincent and Lane 2016a), but it was consistent with the satellite estimates in many aspects of the spatial variation in rainfall (Fig. 2).…”

“…The data have a temporal resolution of 3 h and a spatial resolution of 0.258 3 0.258. TRMM data have been widely used in characterizing the MJO over the MC (e.g., Peatman et al 2014) and for comparison with and validation of mesoscale and regional climate model simulations and other precipitation datasets (e.g., Vincent and Lane 2016a;Bhatt et al 2016;Skok et al 2016;Koo and Hong 2010;Hassim et al 2016).…”

Influences of Lake Malawi on the spatial and diurnal variability of local precipitation

“…This seesaw pattern of daytime rainfall over land and nighttime rainfall over the lake is quite similar to the pattern described by sea-land contrast in the tropics (e.g. Teo et al, 2011;Bhatt et al, 2016). The EOF second mode has 15.77 % of the total variance and its spatial pattern and PC score do not indicate a propagation mode from land to lake (not shown).…”

“…The northeastward moisture flux provides some of the summer precipitation over north-eastern Africa and South Asia (e.g. Segele et al, 2009a;Viste and Sorteberg, 2013;Gleixner et al, 2017;Bohlinger et al, 2017). Conversely, the south-westward Indian winter monsoon generates a large convergence of vertically integrated moisture flux over the tropical south-east of Africa (November to March, as shown in Fig.…”

Interaction of Urban Heating and Local Winds During the Calm Intermonsoon Seasons in the Tropics

“…Convective raining usually occurs during the late afternoon in the April and nighttime in October (Oki & Musiake, 1994). Such diurnal rainfall signal is common in the MC due to the presence of mountain near the coastline in the region (Bhatt, Sobolowski, & Higuchi, 2016;Sow et al, 2011;Teo et al, 2011).…”