The Madden-Julian oscillation (MJO) is the dominant mode of variability in tropical atmosphere on intraseasonal timescales and planetary spatial scales. Despite primary importance MJO decades research progress since its original discovery, a generally accepted theory for essential mechanisms has remained elusive. Here, we present minimal dynamical model that recovers robustly fundamental features (i.e., "skeleton") intraseasonal/planetary scales: (i) peculiar dispersion relation d omega/dk...

Abstract Purpose of Review: Review our current understanding how precipitation is related to its thermodynamic environment, i.e., the water vapor and temperature in surroundings, implications for changes extremes a warmer climate. Recent Findings: Multiple research threads have i) sought empirical relationships that govern onset strong convective precipitation, or might identify scale with temperature; ii) examined such change global regional climate models under warming scenarios; iii)...

We present a modification of Tully’s fewest-switches (TFS) trajectory surface-hopping algorithm (also called molecular dynamics with quantum transitions) that is the time uncertainty (FSTU) method. The FSTU method improves self-consistency by incorporating into hopping times classically forbidden hops. This allows an electronic transition at some geometry to occur nearby allowed if point reachable within Heisenberg interval uncertainty. increased accuracy verified using challenging set...

Clouds in the tropics can organize circulation on planetary scales and profoundly impact long range seasonal forecasting climate entire globe, yet contemporary operational computer models are often deficient representing these phenomena. On other hand, observations reveal remarkably complex coherent waves vortices interacting across a bewildering of from kilometers to ten thousand kilometers. This paper reviews interdisciplinary contributions over last decade through modus operandi applied...

Abstract A simple stochastic model is designed and analyzed in order to further understand the transition strong convection. The has been characterized recently observational data by an array of statistical measures, including (i) a sharp mean precipitation, peak precipitation variance, at critical value column water vapor (CWV), (ii) approximate power law probability density event size, (iii) exponential tails CWV values, when conditioned on either precipitating or nonprecipitating...

Abstract A minimal, nonlinear oscillator model is analyzed for the Madden–Julian oscillation (MJO) “skeleton” (i.e., its fundamental features on intraseasonal/planetary scales), which includes following: (i) a slow eastward phase speed of roughly 5 m s−1, (ii) peculiar dispersion relation with dω/dk ≈ 0, and (iii) horizontal quadrupole vortex structure. Originally proposed in recent work by authors, mechanism involves neutrally stable interactions between planetary-scale, lower-tropospheric...

Precipitation accumulations, integrated over rainfall events, can be affected by both intensity and duration of the storm event. Thus, although precipitation is widely projected to increase under global warming, a clear framework for predicting accumulation changes has been lacking, despite importance accumulations societal impacts. Theory in probability density function (pdf) presented with an evaluation these climate model simulations. We show that simple set conditions implies roughly...

Abstract Convective momentum transport (CMT) plays a central role in interactions across multiple space and time scales. However, because of the multiscale nature CMT, quantifying parameterizing its effects is often challenge. Here simple dynamic model with features CMT systematically derived studied. The includes between large-scale zonal mean flow convectively coupled gravity waves, convection parameterized using multicloud model. moist convective wave–mean shown here have several...

Abstract The Madden–Julian oscillation (MJO) is the dominant mode of variability in tropical atmosphere on intraseasonal time scales and planetary spatial scales. Despite primary importance MJO decades research progress since its original discovery, a generally accepted theory for essential mechanisms has remained elusive. In recent work by two authors, minimal dynamical model been proposed that recovers robustly most fundamental features (i) slow eastward speed roughly 5 m s−1, (ii)...

Abstract Prototype models are presented for time series statistics of precipitation and column water vapor. In these models, events begin when the vapor reaches a threshold value end it slightly lower value, as motivated by recent observational modeling studies. Using stochastic forcing to parameterize moisture sources sinks, this dynamics reaching is first-passage-time problem that can be solved analytically. Exact event sizes durations, which model predicts probability density function...

Significance Understanding the role that atmospheric wind bursts play in initiation and maintenance of El Niño Southern Oscillation (ENSO) tropics is a crucial problem ocean–atmosphere sciences. We provide insight into by proposing simple ENSO model, amenable to detailed analysis, where burst activity driven stochastic jump process depends on strength western Pacific warm pool. The model captures key features observational record, such as probability density function power spectrum eastern...

Abstract Lagrangian trajectories are widely used as observations for recovering the underlying flow field via data assimilation (DA). However, strong nonlinearity in observational process and high dimensionality of problems often cause challenges applying standard DA. In this paper, a Lagrangian‐Eulerian multiscale DA (LEMDA) framework is developed. It starts with exploiting Boltzmann kinetic description particle dynamics to derive set continuum equations, which characterize statistical...

This Oberwolfach workshop was dedicated to continuing the sequence on “Atmosphere-Ocean Science” from (2002, 2006, 2010). The spirit of these events is that an open invitation engage in eye-level exchange recent developments and pressing challenges each participating disciplines, explore possible new routes interdisciplinary cooperation. emphasized “model hierarchies” their importance for systematic development both theoretical understanding methods scientific investigation. To limit its...

Abstract The notion of balance has played an important role in data assimilation. However, traditional ideas have been based on dry dynamics, without moisture. Recently, the balanced moisture formulated moist dynamics. Here, goal is to investigate assimilation strategies with moisture, and assess impact accounting for moisture's unbalanced components. To illustrate main ideas, examples are presented using a simple model consisting linear, moist, shallow‐water equations stochastic forcing,...

Abstract Computational inverse problems utilize a finite number of measurements to infer discrete approximation the unknown parameter function. With motivation from setting PDE-based optimization, we study unique reconstruction discretized by examining positivity Hessian matrix.

What is power fixed data observations? How many parameters can one reconstruct? Here describe probabilistic approach, and spell out interplay observation size $(r)$ be uniquely identified $(m)$. The...

Abstract It is known that gravity waves in the troposphere, which are often excited by preexisting convection, can favor or suppress formation of new convection. Here it shown presence wind shear barotropic wind, create a more favorable environment on one side convection than other side. Both nonlinear and linear analytic models developed here show greatest difference favorability between two sides created jet shears, little no profiles with at low levels upper troposphere. A nonzero (or,...

Abstract The Madden–Julian oscillation (MJO) skeleton model offers a theoretical prediction of the MJO’s structure. Here, method is described for identifying this structure in observational data. utilizes projections onto equatorial wave structures, and main question is: Can isolate MJO without using temporal filtering or empirical orthogonal functions? For data projection, wide range incorporated: multiple variables (wind, geopotential height, water vapor, and, as proxy convective activity,...

Abstract For the tropical atmosphere on planetary scales, it is common to model circulation using strong damping. Here with new data analysis techniques, evidence suggests that damping can actually be neglected. Specifically, near equator, east‐west overturning in agreement undamped wave response atmospheric heating. To estimate heating, satellite observations of outgoing longwave radiation (OLR) are used. Frequently, OLR used as a heuristic indicator cloudiness. results further suggest...

The Madden–Julian Oscillation (MJO) is the dominant component of tropical intraseasonal variability, and a theory explaining its structure successful numerical simulation remains major challenge. A model for MJO should have propagation speed 4–7 m/s predicted by theory; wavenumber-2 or -3 planetary-scale, low-frequency envelope with distinct active inactive phases deep convection; an intermittent turbulent chaotic multiscale within planetary involving embedded westward- eastward-propagating...

Simple prototypes for forced advection‐diffusion problems are known to produce passive tracer distributions that exhibit approximately exponential or stretched tails. Having previously found an tail the column integrated water vapor (CWV) distribution under high precipitation conditions, we conjectured if such relevant more complex tropospheric problems, should find tails a wide set of tracers. Here it is shown indeed ubiquitous in observed, model, and reanalysis data sets variety tracers,...

Abstract The authors use linear analysis for a simple model to study the evolution of convectively coupled waves (CCWs) in background shear and moisture mimicking observed structure Madden–Julian oscillation (MJO). This is motivated by observation, an idealized setting, intraseasonal two-way interactions between CCWs wind. It found here that profiles with bottom-heavy content are more favorable development mesoscale/squall line–like whereas synoptic-scale typically sensitive strength. MJO...

Abstract Simulations of precipitating convection would typically use a non-Boussinesq dynamical core such as the anelastic equations, and incorporate water substance in all its phases: vapour, liquid ice. Furthermore, phase be separated into cloud (small droplets suspended air) rain (larger that fall). Depending on environmental conditions, moist may organize itself multiple length time scales. Here we investigate question, what is minimal representation dynamics still reproduces basic...

Abstract A linear stochastic model is presented for the dynamics of water vapor and tropical convection. Despite its formulation, reproduces a wide variety observational statistics from disparate perspectives, including (i) cloud cluster area distribution with an approximate power law; (ii) spectrum spatiotemporal red noise, as in “background spectrum” convection; (iii) suite that resemble statistical physics concepts critical phenomena phase transitions. The physical processes are...

Abstract For tropical rainfall, there are several potential sources of predictability, including synoptic‐scale convectively coupled equatorial waves (CCEWs) and intraseasonal oscillations such as the Madden–Julian Oscillation (MJO). In prior work, predictability these rainfall has mainly been explored using forecast model data. Here, goal is to estimate intrinsic using, instead, observational To accomplish this, Tropical Rainfall Measuring Mission (TRMM) data decomposed into different wave...