A Moist Static Energy Budget Analysis of Quasi-2-Day Waves Using Satellite and Reanalysis Data

Abstract

A moist static energy (MSE) budget analysis is applied to quasi-2-day waves to examine the effects of thermodynamic processes on the wave propagation mechanism. The 2-day waves are defined as westward inertia–gravity (WIG) modes identified with filtered geostationary infrared measurements, and the thermodynamic parameters and MSE budget variables computed from reanalysis data are composited with respect to the WIG peaks. The composite horizontal and vertical MSE structures are overall as theoretically expected from WIG wave dynamics. A prominent horizontal MSE advection is found to exist, although the wave dynamics is mainly regulated by vertical advection. The vertical advection decreases MSE around the times of the convective peak, plausibly resulting from the first baroclinic mode associated with deep convection. Normalized gross moist stability (NGMS) is used to examine the thermodynamic processes involving the large-scale dynamics and convective heating. NGMS gradually decreases to zero before deep convection and reaches a maximum after the convection peak, where low (high) NGMS leads (lags) deep convection. The decrease in NGMS toward zero before the occurrence of active convection suggests an increasingly efficient conversion from convective heating to large-scale dynamics as the wave comes in, while the increase afterward signifies that this linkage swiftly dies out after the peak.

Vertical Velocity Profiles in Convectively Coupled Equatorial Waves and MJO: New Diagnoses of Vertical Velocity Profiles in the Wavenumber–Frequency Domain

“…The idea of the importance of the tilt was augmented by some studies with cloud-system resolving models (e.g., Peters and Bretherton 2006;Kuang 2008a). Many observational studies also documented tilted structures in the CCEW members that belong to the fast-moving modes: Kelvin waves (e.g., Kiladis 2002, 2003;Kiladis et al 2009), WIG waves (e.g., Takayabu et al 1996;Haertel and Kiladis 2004;Haertel et al 2008;Kiladis et al 2009;Inoue and Back 2015a;Sumi andMasunaga 2016, 2019), EIG waves (e.g., Kiladis et al 2009), and MRG waves (e.g., Liebmann and Hendon 1990;Takayabu and Nitta 1993;Kiladis et al 2009). In contrast, Kiladis et al (2009) showed vertically stacked structures of the ER wave, which belongs to the slowmoving modes.…”

Atmospheric impacts of local sea surface temperatures versus remote drivers during strong South China Sea winter cold tongue events

“…The MSE is a thermodynamic potential energy term conserved under moist adiabatic processes and hydrostatic balance, making the MSE a useful quantity to understand energetic processes behind moist convection (Yano and Ambaum, 2017). The MSE budget has been widely used as a framework to analyze tropical convective rainfall under cases like MJO (e.g., Maloney, 2009), convective coupled equatorial waves (e.g., Sumi and Masunaga, 2016) and tropical climate phenomen such as Ningaloo Niño (Zheng et al ., 2020). An increase of MSE in an area implies an import of MSE from the surrounding environment, which potentially destabilizes the atmospheric column in that area via heating and moistening processes (i.e., condensation and freezing) that in turn promotes deep convective rainfall.…”

Progress from TRMM to GPM

“…Composite analyses using TRMM and A-train satellites revealed interactions between large scale disturbances and the precipitation systems including convective mass flux (Masunaga 2012(Masunaga , 2013Masunaga and Luo 2016). A moisture budget has also been analyzed to show the structure of equatorial inertia-gravity waves (Sumi and Masunaga 2016). Another example is the relationship between precipitation characteristics in the Baiu front and the subtropical jet using TRMM PR, and reanalysis data (Yokoyama et al 2014(Yokoyama et al , 2017.…”