Assessment of algorithms for computing moist available potential energy

Harris, Bethan L.; Tailleux, Rémi

doi:10.1002/qj.3297

Cited by 9 publications

(10 citation statements)

References 27 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…At each division, the pressure derivative of enthalpy is evaluated at the midpressure of the subdomain and used to order the parcels from top to bottom of the subdomain; the top and bottom halves are then assigned to new subdomains. The divide-and-conquer algorithm has been found to work well in practice (14,42), and in particular it gives a moist MAPE that is almost identical to that calculated using the exact Munkres algorithm for a similar case to the one considered here (14). We use divide and conquer rather than Munkres because divide and conquer is faster and more straightforward to adapt to calculate convective and nonconvective MAPE.…”

Section: Methodsmentioning

confidence: 99%

Changing available energy for extratropical cyclones and associated convection in Northern Hemisphere summer

Gertler

O’Gorman

2019

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

The circulation of the Northern Hemisphere extratropical troposphere has changed over recent decades, with marked decreases in extratropical cyclone activity and eddy kinetic energy (EKE) in summer and increases in the fraction of precipitation that is convective in all seasons. Decreasing EKE in summer is partly explained by a weakening meridional temperature gradient, but changes in vertical temperature gradients and increasing moisture also affect the mean available potential energy (MAPE), which is the energetic reservoir from which extratropical cyclones draw. Furthermore, the relation of changes in mean thermal structure and moisture to changes in convection associated with extratropical cyclones is poorly understood. Here we calculate trends in MAPE for the Northern extratropics in summer over the years 1979–2017, and we decompose MAPE into both convective and nonconvective components. Nonconvective MAPE decreased over this period, consistent with decreases in EKE and extratropical cyclone activity, but convective MAPE increased, implying an increase in the energy available to convection. Calculations with idealized atmospheres indicate that nonconvective and convective MAPE both increase with increasing mean surface temperature and decrease with decreasing meridional surface temperature gradient, but convective MAPE is relatively more sensitive to the increase in mean surface temperature. These results connect changes in the atmospheric mean state with changes in both large-scale and convective circulations, and they suggest that extratropical cyclones can weaken even as their associated convection becomes more energetic.

show abstract

Section: Methodsmentioning

confidence: 99%

Changing available energy for extratropical cyclones and associated convection in Northern Hemisphere summer

Gertler

O’Gorman

2019

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

show abstract

“…If the atmosphere is divided into parcels of equal mass, the changes in the atmosphere can be identified if the redistribution of these parcels is detected. The goal is to find the permutation of the parcels of the atmosphere with the least enthalpy (Harris and Tailleux, 2018). To be able to form parcels with equal mass, an coordinate (following Lorenz) was created that covers different areas starting from the pole, but the mass belonging to them is equal.…”

Section: The Exergy Concept In Atmospheric Energeticsmentioning

confidence: 99%

“…They tested these algorithms for more than 3700 soundings, and they found that best solution of the calculation of the exact is the Munkres algorithm, however, it has long runtime. When the approximation of the is enough Harris and Tailleux (2018) suggest the use of the divide-and-conquer method.…”

Section: The Exergy Concept In Atmospheric Energeticsmentioning

confidence: 99%

“…There are cases, when some algorithms give negative values, which means that the reference state has higher energy than the actual state. The divide-and-conquer algorithm sometimes gives back negative values, but rarer than the top-down or Lorenz' algorithms (Harris and Tailleux, 2018). Peng et al (2015) have chosen a reference state based on a model atmosphere, so it is independent from both the actual and the average state of the atmosphere.…”

Section: The Exergy Concept In Atmospheric Energeticsmentioning

confidence: 99%

See 1 more Smart Citation

Basics of the atmospheric energetics : A brief summary of global and regional atmospheric energetics reflected upon the university curricula

Dávid¹,

Tasnádi²

2021

Időjárás

View full text Add to dashboard Cite

The purpose of this study is to provide an overview of the science and development of atmospheric energetics, its so far matured parts to date, and the direction of the researches. However, we restrict ourselves to the discussion of the very basic results of the researches to reveal the parts the introduction of which can be suggested into the compulsory education of the future meteorologist. This became feasible especially due to the rapid development of the personal computer that makes possible the calculation of the atmospheric energies for students by using their own laptops, so this field of meteorology now can be a tactile reality for them. The founder of atmospheric energetics was Lorenz, who formulated for a global, dry atmosphere the concept of available potential energy, which is the difference between the current energy state of the atmosphere and a reference state with minimum energy. His basic results concerning the global description of atmospheric energetics have already become part of the university curriculum. It is important to be able to describe the energy balance of the atmosphere both locally as well as globally, for which the introduction of enthalpy and exergy seemed appropriate. The advantage of examining the dry atmosphere is that significant simplifications can be applied, but the atmosphere is finally moist, so research has also started in this direction, first with a global and then with a local approach. The key is to find the reference state, which is a complex, computationally demanding task. In this paper, we focus on the most important steps of this process and concentrate on the thermodynamic basis of the new concepts.

show abstract

“…In the former case, z r should be defined either at the top or bottom of the domain depending on the buoyancy of the fluid parcel in the actual state (Tailleux 2013b). The latter case is rarely encountered in the ocean (Saenz et al 2015) but is commonplace in a moist atmosphere (Wong et al 2016;Harris & Tailleux 2018). How to select the solution in this case is still poorly understood, however.…”

Section: Available Energetics Of a Stratified Compressible Binary Fluidmentioning

confidence: 99%

Local available energetics of multicomponent compressible stratified fluids

Tailleux

2018

J. Fluid Mech.

Self Cite

View full text Add to dashboard Cite

We extend the local theory of available potential energy (APE) to a general multicomponent compressible stratified fluid, accounting for the effects of diabatic sinks and sources. As for simple compressible fluids, the total potential energy density of a fluid parcel is the sum of its available elastic energy (AEE) and APE density. These respectively represent the adiabatic compression/expansion work needed to bring it from its reference pressure to its actual pressure and the work against buoyancy forces required to move it from its reference state position to its actual position. Our expression for the APE density is new and derived using only elementary manipulations of the equations of motion; it is significantly simpler than existing published expressions, while also being more transparently linked to the relevant form of APE density for the Boussinesq and hydrostatic primitive equations. Our new framework is used to clarify the links between some aspects of the energetics of Boussinesq and real fluids, as well as to shed light on the physical basis underlying the choice of reference state(s) in local APE theory.

show abstract

Assessment of algorithms for computing moist available potential energy

Cited by 9 publications

References 27 publications

Changing available energy for extratropical cyclones and associated convection in Northern Hemisphere summer

Changing available energy for extratropical cyclones and associated convection in Northern Hemisphere summer

Basics of the atmospheric energetics : A brief summary of global and regional atmospheric energetics reflected upon the university curricula

Local available energetics of multicomponent compressible stratified fluids

Contact Info

Product

Resources

About