The Moist Entropy Budget of Terminating Madden–Julian Oscillation Events

2021 ◽  
Vol 34 (11) ◽  
pp. 4243-4260
Author(s):  
Brett Chrisler ◽  
Justin P. Stachnik
Keyword(s):  
Heat Fluxes ◽  
Identification Algorithm ◽  
Relative Role ◽  
Radiative Fluxes ◽  
Event Identification ◽  
Horizontal Advection ◽  
Vertical Advection ◽  
Entropy Budget ◽  
Static Energy

AbstractRecent studies have examined moist entropy (ME) as a proxy for moist static energy (MSE) and the relative role of the underlying processes responsible for changes in ME that potentially affect MJO propagation. This study presents an analysis of the intraseasonally varying (ISV) ME anomalies throughout the lifetime of observed MJO events. A climatology of continuing and terminating MJO events is created from an event identification algorithm using common tracking indices including the OLR-based MJO index (OMI), filtered OMI (FMO), real-time multivariate MJO (RMM), and velocity potential MJO (VPM) index. ME composites for all indices show a statistically significant break in the wavenumber-1 oscillation at day 0 for terminating events in nearly all domains except RMM phase 6 and phase 7. The ME tendency is decomposed into horizontal and vertical advection, sensible and latent heat fluxes, and shortwave and longwave radiative fluxes using ERA-Interim data. The relative role of each processes toward the eastward propagation is discussed as well as their effects on MJO stabilization. Statistically significant differences occur for all terms by day −10. A domain sensitivity test is performed where eastward propagation is favored for vertical advection given a larger, asymmetric domain for continuing events. A reduced eastward propagation from vertical advection is evident 2–3 days before similar differences in horizontal advection for terminating events. The importance of horizontal advection for the eastward propagation of the MJO is discussed in addition to the relative destabilization from vertical advection in the convectively suppressed region downstream of future terminating MJOs.

scholarly journals Moist Static Energy Budget of the MJO during DYNAMO

2014 ◽  
Vol 71 (11) ◽  
pp. 4276-4291 ◽  
Author(s):  
Adam Sobel ◽  
Shuguang Wang ◽  
Daehyun Kim
Keyword(s):  
Indian Ocean ◽  
Energy Budget ◽  
Active Phase ◽  
Turbulent Fluxes ◽  
Radiative Heating ◽  
Moist Static Energy ◽  
Horizontal Advection ◽  
Vertical Advection ◽  
Moist Static Energy Budget ◽  
Static Energy

Abstract The authors analyze the column-integrated moist static energy budget over the region of the tropical Indian Ocean covered by the sounding array during the Cooperative Indian Ocean Experiment on Intraseasonal Variability in the Year 2011 (CINDY2011)/Dynamics of the Madden–Julian Oscillation (DYNAMO) field experiment in late 2011. The analysis is performed using data from the sounding array complemented by additional observational datasets for surface turbulent fluxes and atmospheric radiative heating. The entire analysis is repeated using the ECMWF Interim Re-Analysis (ERA-Interim). The roles of surface turbulent fluxes, radiative heating, and advection are quantified for the two MJO events that occurred in October and November using the sounding data; a third event in December is also studied in the ERA-Interim data. These results are consistent with the view that the MJO’s moist static energy anomalies grow and are sustained to a significant extent by the radiative feedbacks associated with MJO water vapor and cloud anomalies and that propagation of the MJO is associated with advection of moist static energy. Both horizontal and vertical advection appear to play significant roles in the events studied here. Horizontal advection strongly moistens the atmosphere during the buildup to the active phase of the October event when the low-level winds switch from westerly to easterly. Horizontal advection strongly dries the atmosphere in the wake of the active phases of the November and December events as the westerlies associated with off-equatorial cyclonic gyres bring subtropical dry air into the convective region from the west and north. Vertical advection provides relative moistening ahead of the active phase and drying behind it, associated with an increase of the normalized gross moist stability.

scholarly journals A Potential Problem with the Application of Moist Static Energy in Tropical Cyclone Studies

2015 ◽  
Vol 72 (8) ◽  
pp. 3009-3019 ◽  
Author(s):  
Zhanhong Ma ◽  
Jianfang Fei ◽  
Xiaogang Huang ◽  
Xiaoping Cheng
Keyword(s):  
Boundary Layer ◽  
Tropical Cyclone ◽  
Kinetic Energy ◽  
Energy Transport ◽  
Potential Temperature ◽  
Moist Static Energy ◽  
Horizontal Advection ◽  
Vertical Advection ◽  
Conservation Property ◽  
Static Energy

Abstract The moist static energy (MSE) is derived from the first law of thermodynamics and has been widely used in tropical cyclone (TC) studies because of its energetic and conventionally recognized conservation properties. This study investigates the validation of the MSE application in TC systems based on cloud-resolving numerical simulations. By examining the approximations made in deriving the MSE, neglecting the horizontal advection of pressure (namely, the generation of kinetic energy) relative to the vertical advection of pressure is found to be in error in the boundary layer of TCs with the horizontal advection of pressure even being several times larger than the vertical advection of pressure near the surface. Such a problematic approximation has broken down the conservation property of MSE in adiabatic conditions. An investigation of the energetic characteristics based on an MSE budget equation demonstrates that the MSE has created significant bias in evaluating the energy transport in the inner region of the TC boundary layer. Neglecting the kinetic energy conversion term in the boundary layer leads to a more strengthened cool-pool feature of MSE relative to the equivalent potential temperature; therefore, the interchangeable relationship between these two terms may also be inaccurate in the boundary layer. It is concluded that, although the MSE is an instrumental term for TC studies, caution should be taken when it is used in the boundary layer of TCs.

scholarly journals The Role of Frost Processes in the Retreat of River Banks

Water ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 1812
Author(s):  
Karol Augustowski ◽  
Józef Kukulak
Keyword(s):  
Relative Role ◽  
Freezing And Thawing ◽  
Fine Grained ◽  
Fluvial Processes ◽  
Precise Calculation ◽  
Erosion Pins ◽  
Summer Half ◽  
Lateral Erosion ◽  
Summer Flood

The rate of bank retreat was measured using erosion pins on the alluvial banks of the rivers in the Podhale region (the boundary zone between Central and Outer Carpathians) during the hydrological year 2013/2014. During the winter half-year (November–April), the bank retreat was mainly caused by processes related to the freezing and thawing of the ground (swelling, creep, downfall). During the summer half-year (May–October), fluvial processes and mass movements such as lateral erosion, washing out, and sliding predominated. The share of fluvial processes in the total annual amount of bank retreat (71 cm on average) was 4 times greater than that of the frost phenomena. Erosion on bank surfaces by frost phenomena during the cold half-year was greatest (up to 38 cm) on the upper parts of banks composed of fine-grained alluvium, while fluvial erosion during the summer half-year (exceeding 80 cm) mostly affected the lower parts of the banks, composed of gravel. The precise calculation of the relative role of frost phenomena in the annual balance of bank erosion was precluded at some stations by the loss of erosion pins in the summer flood.

Grain Boundary Segregation in Titanium Dioxide: Evaluation of Relative Driving Forces for Segregation

2002 ◽  
Vol 751 ◽  
Author(s):  
Qinglei Wang ◽  
Guoda D. Lian ◽  
Elizabeth C. Dickey
Keyword(s):  
Titanium Dioxide ◽  
Driving Forces ◽  
Boundary Segregation ◽  
Solute Segregation ◽  
Dielectric Behavior ◽  
Relative Role ◽  
Transmission Electron ◽  
Fundamental Phenomenon ◽  
Versus Strain

ABSTRACTSolute segregation to grain boundaries is a fundamental phenomenon in polycrystalline metal-oxide electroceramics that has enormous implications for the macroscopic dielectric behavior of the materials. This paper presents a systematic study of solute segregation in a model dielectric, titanium dioxide. We investigate the relative role of the electrostatic versus strain energy driving forces for segregation by studying yttrium-doped specimens. Through analytical transmission electron microscopy studies, we quantitatively determine the segregation behavior of the material. The measured Gibbsian interfacial excesses are compared to thermodynamic predictions.

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