Large‐Scale Precipitation Systems: Essential Elements of the Madden‐Julian Oscillation

2021 ◽  
Author(s):  
Guiwan Chen ◽  
Shuyi S. Chen ◽  
Jian Ling ◽  
Chongyin Li
Keyword(s):  
Large Scale ◽  
Essential Elements ◽  
Madden Julian Oscillation

scholarly journals Kelvin/Rossby Wave Partition of Madden-Julian Oscillation Circulations

Climate ◽  
2020 ◽  
Vol 9 (1) ◽  
pp. 2
Author(s):  
Patrick Haertel
Keyword(s):  
Rossby Wave ◽  
Large Scale ◽  
Atmospheric Model ◽  
Circulation System ◽  
System Of Equations ◽  
Wave Component ◽  
Madden Julian Oscillation ◽  
Kelvin Wave ◽  
Realistic View ◽  
State Of Rest

The Madden Julian Oscillation (MJO) is a large-scale convective and circulation system that propagates slowly eastward over the equatorial Indian and Western Pacific Oceans. Multiple, conflicting theories describe its growth and propagation, most involving equatorial Kelvin and/or Rossby waves. This study partitions MJO circulations into Kelvin and Rossby wave components for three sets of data: (1) a modeled linear response to an MJO-like heating; (2) a composite MJO based on atmospheric sounding data; and (3) a composite MJO based on data from a Lagrangian atmospheric model. The first dataset has a simple dynamical interpretation, the second provides a realistic view of MJO circulations, and the third occurs in a laboratory supporting controlled experiments. In all three of the datasets, the propagation of Kelvin waves is similar, suggesting that the dynamics of Kelvin wave circulations in the MJO can be captured by a system of equations linearized about a basic state of rest. In contrast, the Rossby wave component of the observed MJO’s circulation differs substantially from that in our linear model, with Rossby gyres moving eastward along with the heating and migrating poleward relative to their linear counterparts. These results support the use of a system of equations linearized about a basic state of rest for the Kelvin wave component of MJO circulation, but they question its use for the Rossby wave component.

Structural elaboration in police organizations: an exploration

2017 ◽  
Vol 40 (2) ◽  
pp. 351-365 ◽  
Author(s):  
Alicia L. Jurek ◽  
Matthew C. Matusiak ◽  
Randa Embry Matusiak
Keyword(s):  
Large Scale ◽  
Structural Complexity ◽  
Essential Elements ◽  
Multiple Time ◽  
Police Departments ◽  
Content Type ◽  
Police Organizations ◽  
The Usa ◽  
Multiple Time Points ◽  
American Police

Purpose The current research explores the structural elaboration of municipal American police organizations, specifically, the structural complexity of police organizations and its relationship to time. The purpose of this paper is to describe and test essential elements of the structural elaboration hypothesis. Design/methodology/approach The authors explore the structural elaboration hypothesis utilizing a sample of 219 large police departments across the USA. Data are drawn from multiple waves of the Law Enforcement Management and Administrative Statistics survey and are analyzed using tobit and OLS regression techniques. Findings While there is some evidence that police departments are becoming more elaborate, little evidence for the structural elaboration hypothesis as a function of time is found. Originality/value This project is the first to specifically explore the structural elaboration hypothesis across multiple time points. Additionally, results highlight structural trends across a panel of large American police organizations and provide potential explanations for changes. Suggestions for large-scale policing data collection are also provided.

Contractual Reconstructions

2020 ◽  
pp. 365-386
Author(s):  
Albert Weale
Keyword(s):  
Utility Theory ◽  
Large Scale ◽  
Contract Theory ◽  
Thought Experiment ◽  
Single Agent ◽  
Essential Element ◽  
Essential Elements ◽  
Veil Of Ignorance ◽  
Practical Syllogism ◽  
Mutual Advantage

In the twilight of utilitarianism contract theorist sought to respond to the problems that utilitarianism had thrown up. How successful were they? Our review of contract theory has shown that it is not possible to base a contract theory on a utility theory of rationality, even though some have claimed that such a theory states the essential elements of rational behaviour. The axioms of utility theory are controversial in themselves, and do not give an account of prudence. To have an account of prudence, we need to turn to the deliberative account of rationality, and the idea of intelligibility. The practical syllogism will only take us so far, however, and will not deal with cases where interests conflict. There is no need to make a sharp distinction between contract theories in which there is a plurality of agents, without a veil of ignorance, and a single agent behind a veil of ignorance. The singular veil of ignorance construction can be regarded as a more abstract thought experiment in situation of moral perplexity. Similarly, the distinction between mutual advantage theories, which involve essential reference to a baseline of non-cooperation, and baseline independent theories is not clear, since much depends on the character of the baseline. The problem of obligation remains unresolved, but its lack of resolution underlines a conclusion of Hart to the effect that coercion is an essential element of a large-scale society.

scholarly journals Detecting and Tracking Coastal Precipitation in the Tropics: Methods and Insights into Multiscale Variability of Tropical Precipitation

2020 ◽  
Vol 33 (15) ◽  
pp. 6689-6705
Author(s):  
David Coppin ◽  
Gilles Bellon ◽  
Alexander Pletzer ◽  
Chris Scott
Keyword(s):  
Diurnal Cycle ◽  
Large Scale ◽  
Madden Julian Oscillation ◽  
Maritime Continent ◽  
Total Rainfall ◽  
Tropical Precipitation ◽  
Precipitation Estimates ◽  
Summer Hemisphere ◽  
The Tropics ◽  
Climate Prediction Center

AbstractWe propose an algorithm to detect and track coastal precipitation systems and we apply it to 18 years of the high-resolution (8 km and 30 min) Climate Prediction Center CMORPH precipitation estimates in the tropics. Coastal precipitation in the Maritime Continent and Central America contributes to up to 80% of the total rainfall. It also contributes strongly to the diurnal cycle over land with the largest contribution from systems lasting between 6 and 12 h and contributions from longer-lived systems peaking later in the day. While the diurnal cycle of coastal precipitation is more intense over land in the summer hemisphere, its timing is independent of seasons over both land and ocean because the relative contributions from systems of different lifespans are insensitive to the seasonal cycle. We investigate the hypothesis that coastal precipitation is enhanced prior to the arrival of the Madden–Julian oscillation (MJO) envelope over the Maritime Continent. Our results support this hypothesis and show that, when considering only coastal precipitation, the diurnal cycle appears reinforced even earlier over islands than previously reported. We discuss the respective roles of coastal and large-scale precipitation in the propagation of the MJO over the Maritime Continent. We also document a shift in diurnal cycle with the phases of the MJO, which results from changes in the relative contributions of short-lived versus long-lived coastal systems.

scholarly journals Influence of the Stratospheric Quasi-Biennial Oscillation on the Madden–Julian Oscillation during Austral Summer

2017 ◽  
Vol 74 (4) ◽  
pp. 1105-1125 ◽  
Author(s):  
Eriko Nishimoto ◽  
Shigeo Yoden
Keyword(s):  
Large Scale ◽  
Statistical Significance ◽  
Austral Summer ◽  
Horizontal Wind ◽  
Convective System ◽  
Madden Julian Oscillation ◽  
Quasi Biennial Oscillation ◽  
Enso Events ◽  
Convective Region ◽  
Biennial Oscillation

Abstract Influence of the stratospheric quasi-biennial oscillation (QBO) on the Madden–Julian oscillation (MJO) and its statistical significance are examined for austral summer (DJF) in neutral ENSO events during 1979–2013. The amplitude of the OLR-based MJO index (OMI) is typically larger in the easterly phase of the QBO at 50 hPa (E-QBO phase) than in the westerly (W-QBO) phase. Daily composite analyses are performed by focusing on phase 4 of the OMI, when the active convective system is located over the eastern Indian Ocean through the Maritime Continent. The composite OLR anomaly shows a larger negative value and slower eastward propagation with a prolonged period of active convection in the E-QBO phase than in the W-QBO phase. Statistically significant differences of the MJO activities between the QBO phases also exist with dynamical consistency in the divergence of horizontal wind, the vertical wind, the moisture, the precipitation, and the 100-hPa temperature. A conditional sampling analysis is also performed by focusing on the most active convective region for each day, irrespective of the MJO amplitude and phase. Composite vertical profiles of the conditionally sampled data over the most active convective region reveal lower temperature and static stability around the tropopause in the E-QBO phase than in the W-QBO phase, which indicates more favorable conditions for developing deep convection. This feature is more prominent and extends into lower levels in the upper troposphere over the most active convective region than other tropical regions. Composite longitude–height sections show similar features of the large-scale convective system associated with the MJO, including a vertically propagating Kelvin response.

scholarly journals Large-Scale Environmental Characteristics of MJOs that Strengthen and Weaken over the Maritime Continent

2018 ◽  
Vol 31 (14) ◽  
pp. 5731-5748 ◽  
Author(s):  
Casey D. Burleyson ◽  
Samson M. Hagos ◽  
Zhe Feng ◽  
Brandon W. J. Kerns ◽  
Daehyun Kim
Keyword(s):  
Seasonal Cycle ◽  
Large Scale ◽  
Longwave Radiation ◽  
Sea Surface ◽  
Madden Julian Oscillation ◽  
Moist Static Energy ◽  
Maritime Continent ◽  
New Finding ◽  
Field Campaigns ◽  
Static Energy

Abstract The characteristics of Madden–Julian oscillation (MJO) events that strengthen and weaken over the Maritime Continent (MC) are examined. The real-time multivariate MJO (RMM) index is used to assess changes in global MJO amplitude over the MC. The MJO weakens at least twice as often as it strengthens over the MC, with weakening MJOs being twice as likely during El Niño compared to La Niña years and the reverse for strengthening events. MJO weakening shows a pronounced seasonal cycle that has not been previously documented. During the Northern Hemisphere (NH) summer and fall the RMM index can strengthen over the MC. MJOs that approach the MC during the NH winter typically weaken according to the RMM index. This seasonal cycle corresponds to whether the MJO crosses the MC primarily north or south of the equator. Because of the seasonal cycle, weakening MJOs are characterized by positive sea surface temperature and moist-static energy anomalies in the Southern Hemisphere (SH) of the MC compared to strengthening events. Analysis of the outgoing longwave radiation (OLR) MJO index (OMI) shows that MJO precipitation weakens when it crosses the MC along the equator. A possible explanation of this based on previous results is that the MJO encounters more landmasses and taller mountains when crossing along the equator or in the SH. The new finding of a seasonal cycle in MJO weakening over the MC highlights the importance of sampling MJOs throughout the year in future field campaigns designed to study MJO–MC interactions.

scholarly journals Filtering the Stochastic Skeleton Model for the Madden–Julian Oscillation

2016 ◽  
Vol 144 (2) ◽  
pp. 501-527 ◽  
Author(s):  
Nan Chen ◽  
Andrew J. Majda
Keyword(s):  
Large Scale ◽  
Warm Pool ◽  
Model Error ◽  
Small Scale ◽  
Fast Wave ◽  
Madden Julian Oscillation ◽  
Computationally Efficient ◽  
Skeleton Model ◽  
Spatially Extended ◽  
Novel Strategy

Abstract The filtering and prediction of the Madden–Julian oscillation (MJO) and relevant tropical waves is a contemporary issue with significant implications for extended range forecasting. This paper examines the process of filtering the stochastic skeleton model for the MJO with noisy partial observations. A nonlinear filter, which captures the inherent nonlinearity of the system, is developed and judicious model error is included. Despite its nonlinearity, the special structure of this filter allows closed analytical formulas for updating the posterior states and is thus computationally efficient. A novel strategy for adding nonlinear observational noise to the envelope of convective activity is designed to guarantee its nonnegative property. Systematic calibration based on a cheap single-column version of the stochastic skeleton model provides a practical guideline for choosing the parameters in the full spatially extended system. With these column-tuned parameters, the full filter has a high overall filtering skill for Rossby waves but fails to recover the small-scale fast-oscillating Kelvin and moisture modes. An effectively balanced reduced filter involving a simple fast-wave averaging strategy is then developed, which greatly improves the skill of filtering the moisture modes and other fast-oscillating modes and enhances the total computational efficiency. Both the full and the reduced filters succeed in filtering the MJO and other large-scale features with both homogeneous and warm pool cooling/moistening backgrounds. The large bias in filtering the solutions by running the perfect model with noisy forcing is due to the noise accumulation, which indicates the importance of including judicious model error in designing filters.

MJO-Induced Variability of the Diurnal Cycle of Precipitation over the Maritime Continent

2020 ◽  
Author(s):  
Ajda Savarin ◽  
Shuyi Chen
Keyword(s):  
Diurnal Cycle ◽  
Large Scale ◽  
Complex Nature ◽  
Madden Julian Oscillation ◽  
Maritime Continent ◽  
Convective Envelope ◽  
Modes Of Variability ◽  
Complex Interactions ◽  
The Indian Ocean ◽  
The Western Pacific

<p>Large-scale convection associated with the Madden-Julian Oscillation (MJO) initiates over the Indian Ocean and propagates eastward across the Maritime Continent (MC) into the western Pacific. As an MJO enters the MC, it often weakens or completely dissipates due to complex interactions between the large-scale MJO and the MC landmass and its topography. This is referred to as the MC barrier effect, and it is responsible for the dissipation of 40-50% of observed MJO events. One of the main reasons for the MJO’s weakening and dissipation over the MC is the diurnal cycle (DC), one of the strongest modes of variability in the region. Due to the complex nature of the MJO and the MC’s complicated topography, the interaction between the DC and the MJO is not well understood.</p><p>In this study, we examine the MJO-induced variability of the DC of precipitation over the MC. We use gridded satellite precipitation products (TRMM 3B42 and GPM IMERG) to: (1) track the MJO convective envelope using the Large-scale Precipitation Tracking algorithm (LPT), (2) analyze the changes in the DC of precipitation over the MC relative to the passage of the MJO. We find that the presence of an MJO not only increases the amount of precipitation over the MC, but that the increase is more pronounced over water than over land. The results from observations are compared to those from two reanalysis datasets (ERA5, MERRA-2). The reanalysis datasets are then used to examine the dynamic and thermodynamic changes that drive the variability in the DC of precipitation relative to the MJO. In addition, we separate MJO events into two groups based on whether they cross the MC, and independently examine their influences on the evolution of the DC of precipitation.</p>

scholarly journals Gaia as a complex adaptive system

2002 ◽  
Vol 357 (1421) ◽  
pp. 683-695 ◽  
Author(s):  
Timothy M. Lenton ◽  
Marcel van Oijen
Keyword(s):  
Complexity Theory ◽  
Large Scale ◽  
Adaptive System ◽  
Complex Adaptive System ◽  
Spatial Interaction ◽  
Self Regulation ◽  
Essential Elements ◽  
Adaptive Behaviour ◽  
Complex Adaptive ◽  
Self Organizing

We define the Gaia system of life and its environment on Earth, review the status of the Gaia theory, introduce potentially relevant concepts from complexity theory, then try to apply them to Gaia. We consider whether Gaia is a complex adaptive system (CAS) in terms of its behaviour and suggest that the system is self–organizing but does not reside in a critical state. Gaia has supported abundant life for most of the last 3.8 Gyr. Large perturbations have occasionally suppressed life but the system has always recovered without losing the capacity for large–scale free energy capture and recycling of essential elements. To illustrate how complexity theory can help us understand the emergence of planetary–scale order, we present a simple cellular automata (CA) model of the imaginary planet Daisyworld. This exhibits emergent self–regulation as a consequence of feedback coupling between life and its environment. Local spatial interaction, which was absent from the original model, can destabilize the system by generating bifurcation regimes. Variation and natural selection tend to remove this instability. With mutation in the model system, it exhibits self–organizing adaptive behaviour in its response to forcing. We close by suggesting how artificial life (‘Alife’) techniques may enable more comprehensive feasibility tests of Gaia.

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