Comparison of Moist Static Energy and Budget between the GCM-Simulated Madden–Julian Oscillation and Observations over the Indian Ocean and Western Pacific

• Published in: Journal of climate Vol. 26; no. 14; pp. 4981 - 4993
• Main Authors: Wu, Xiaoqing, Deng, Liping
• Format: Journal Article
• Language: English
• Published: Boston, MA American Meteorological Society 01.07.2013
• Subjects: Advection; Anomalies; Atmosphere; Atmospheric moisture; Budgeting; Budgets; Climate; Climate models; Climatology. Bioclimatology. Climate change; Clouds; Computer simulation; Convection; Convection, turbulence, diffusion. Boundary layer structure and dynamics; Convective momentum transport; Datasets; Earth, ocean, space; Energy; Exact sciences and technology; External geophysics; General circulation models; Heat flux; Heat transfer; Horizontal; Horizontal advection; Indian Ocean; Latent heat; Latent heat flux; Lower troposphere; Madden-Julian Oscillation; Marine; Meteorology; Middle troposphere; Modeling; Moist static energy; Momentum; Momentum transport; Observational studies; Oceans; Phase relationships; Precipitation; Propagation; Simulation; Simulations; Studies; Transport; Troposphere; Wind; Zonal winds; Indian Ocean; West Pacific; Pacific Ocean; ISW, Indian Ocean; I, Pacific; IW, Pacific; USA, Iowa; Atmospheric convection; parametrization; General circulation models; tropical zone; Observation data; climate variability; energy balance; digital simulation; Intraseasonal oscillation; Madden Julian oscillation; Composite analysis
• ISSN: 0894-8755; 1520-0442
• DOI: 10.1175/JCLI-D-12-00607.1

The moist static energy (MSE) anomalies and MSE budget associated with the Madden–Julian oscillation (MJO) simulated in the Iowa State University General Circulation Model (ISUGCM) over the Indian and Pacific Oceans are compared with observations. Different phase relationships between MJO 850-hPa zonal wind, precipitation, and surface latent heat flux are simulated over the Indian Ocean and western Pacific, which are greatly influenced by the convection closure, trigger conditions, and convective momentum transport (CMT). The moist static energy builds up from the lower troposphere 15–20 days before the peak of MJO precipitation, and reaches the maximum in the middle troposphere (500–600 hPa) near the peak of MJO precipitation. The gradual lower-tropospheric heating and moistening and the upward transport of moist static energy are important aspects of MJO events, which are documented in observational studies but poorly simulated in most GCMs. The trigger conditions for deep convection, obtained from the year-long cloud-resolving model (CRM) simulations, contribute to the striking difference between ISUGCM simulations with the original and modified convection schemes and play the major role in the improved MJO simulation in ISUGCM. Additionally, the budget analysis with the ISUGCM simulations shows the increase in MJO MSE is in phase with the horizontal advection of MSE over the western Pacific, while out of phase with the horizontal advection of MSE over the Indian Ocean. However, the NCEP analysis shows that the tendency of MJO MSE is in phase with the horizontal advection of MSE over both oceans.