Sensitivity experiments on the role of moisture in the eastward propagation of MJO

2022 ◽  
Author(s):  
Xiaoyu Zhu ◽  
Zhong Zhong ◽  
Yimin Zhu ◽  
Yijia Hu ◽  
Yao Ha ◽  
...  
Keyword(s):  
Sensitivity Experiments

scholarly journals On the Role of Asymmetric Convective Bursts to the Problem of Hurricane Intensification: Radiation of Vortex Rossby Waves and Wave–Mean Flow Interactions

2014 ◽  
Vol 71 (6) ◽  
pp. 2057-2077 ◽  
Author(s):  
Konstantinos Menelaou ◽  
M. K. Yau
Keyword(s):  
Kinetic Energy ◽  
Thermal Anomaly ◽  
Eddy Kinetic Energy ◽  
Intensity Change ◽  
Mean Flow ◽  
Symmetric Flow ◽  
Thermal Forcing ◽  
Sensitivity Experiments ◽  
Flow Interactions

Abstract The role of asymmetric convection to the intensity change of a weak vortex is investigated with the aid of a “dry” thermally forced model. Numerical experiments are conducted, starting with a weak vortex forced by a localized thermal anomaly. The concept of wave activity, the Eliassen–Palm flux, and eddy kinetic energy are then applied to identify the nature of the dominant generated waves and to diagnose their kinematics, structure, and impact on the primary vortex. The physical reasons for which disagreements with previous studies exist are also investigated utilizing the governing equation for potential vorticity (PV) perturbations and a number of sensitivity experiments. From the control experiment, it is found that the response of the vortex is dominated by the radiation of a damped sheared vortex Rossby wave (VRW) that acts to accelerate the symmetric flow through the transport of angular momentum. An increase of the kinetic energy of the symmetric flow by the VRW is shown also from the eddy kinetic energy budget. Additional tests performed on the structure and the magnitude of the initial thermal forcing confirm the robustness of the results and emphasize the significance of the wave–mean flow interaction to the intensification process. From the sensitivity experiments, it is found that for a localized thermal anomaly, regardless of the baroclinicity of the vortex and the radial and vertical gradients of the thermal forcing, the resultant PV perturbation follows a damping behavior, thus suggesting that deceleration of the vortex should not be expected.

scholarly journals Idealised simulations of cyclones with robust symmetrically unstable sting jets

2020 ◽  
Vol 1 (1) ◽  
pp. 63-91 ◽  
Author(s):  
Ambrogio Volonté ◽  
Peter A. Clark ◽  
Suzanne L. Gray
Keyword(s):  
Conceptual Model ◽  
Environmental Conditions ◽  
Positive Relationship ◽  
Initial State ◽  
Sensitivity Experiments ◽  
Fracture Region ◽  
Wide Range ◽  
Peak Speed ◽  
Insight Into

Abstract. Idealised simulations of Shapiro–Keyser cyclones developing a sting jet (SJ) are presented. Thanks to an improved and accurate implementation of thermal wind balance in the initial state, it was possible to use more realistic environments than in previous idealised studies. As a consequence, this study provides further insight into SJ evolution and dynamics and explores SJ robustness to different environmental conditions, assessed via a wide range of sensitivity experiments. The control simulation contains a cyclone that fits the Shapiro–Keyser conceptual model and develops a SJ whose dynamics are associated with the evolution of mesoscale instabilities along the airstream, including symmetric instability (SI). The SJ undergoes a strong descent while leaving the cloud-head banded tip and markedly accelerating towards the frontal-fracture region, revealed as an area of buckling of the already-sloped moist isentropes. Dry instabilities, generated by vorticity tilting via slantwise frontal motions in the cloud head, exist in similar proportions to moist instabilities at the start of the SJ descent and are then released along the SJ. The observed evolution supports the role of SI in the airstream’s dynamics proposed in a conceptual model outlined in a previous study. Sensitivity experiments illustrate that the SJ is a robust feature of intense Shapiro–Keyser cyclones, highlighting a range of different environmental conditions in which SI contributes to the evolution of this airstream, conditional on the model having adequate resolution. The results reveal that several environmental factors can modulate the strength of the SJ. However, a positive relationship between the strength of the SJ, both in terms of peak speed and amount of descent, and the amount of instability occurring along it can still be identified. In summary, the idealised simulations presented in this study show the robustness of SJ occurrence in intense Shapiro–Keyser cyclones and support and clarify the role of dry instabilities in SJ dynamics.

scholarly journals Sensitivity Experiments on the Role of Water Vapor in the Eastward Propagation of MJO

2021 ◽  
Author(s):  
Xiaoyu Zhu ◽  
Zhong Zhong ◽  
Yimin Zhu ◽  
Yijia Hu ◽  
Yao Ha ◽  
...  
Keyword(s):  
Water Vapor ◽  
Zonal Wind ◽  
Climate Model ◽  
Regional Climate ◽  
Atmospheric Stability ◽  
Wrf Model ◽  
Low Frequency ◽  
Cumulus Parameterization ◽  
Sensitivity Experiments

Abstract In this study, we employed the nudging assimilation of the Weather Research and Forecasting (WRF) model to conduct a set of sensitivity experiments on the role of water vapor in the Madden-Julian Oscillation (MJO) eastward propagation, focusing on the eastward propagating 30-60d low-frequency component in the tropical atmosphere from the Indian Ocean to the western Pacific Ocean during September-November 2004. Using 11 different cumulus parameterization schemes, the simulation results show that the ability of the regional climate model in simulating the MJO eastward propagation is sensitive to the cumulus scheme: A suitable scheme can well reproduce the MJO eastward propagation characteristics, while most schemes show no skill for the MJO eastward propagation. When the water vapor in the model domain was assimilated using reanalysis data with nudging technique, we found that the low-frequency evolution of the tropical zonal wind exhibits MJO features well, and the low-frequency phase of water vapor is ahead of the zonal wind by about 6-7 days, which suggests that the atmospheric water-vapor distribution is the key factor for the eastward propagation of the MJO, and the effect of water-vapor field via affecting the atmospheric stability. When the atmospheric temperature assimilation was conducted, there was almost no improvement in the skill of MJO simulation.

scholarly journals Idealised simulations of cyclones with robust symmetrically-unstable sting jets

2019 ◽  
Author(s):  
Ambrogio Volonté ◽  
Peter A. Clark ◽  
Suzanne L. Gray
Keyword(s):  
Environmental Factors ◽  
Conceptual Model ◽  
Environmental Conditions ◽  
Positive Relationship ◽  
Initial State ◽  
Sensitivity Experiments ◽  
Fracture Region ◽  
Peak Speed ◽  
Symmetric Instability

Abstract. Idealised simulations of Shapiro-Keyser cyclones developing a sting jet (SJ) are presented. Thanks to an improved and accurate implementation of thermal wind balance in the initial state, it has been possible to use more realistic environments than in previous idealised studies. As a consequence, this study provides further insight in SJ evolution and dynamics and explores SJ robustness to different environmental conditions, assessed via a wide and different range of sensitivity experiments. The control simulation contains a cyclone that fits the Shapiro-Keyser conceptual model and develops a SJ whose dynamics are associated with the evolution of mesoscale instabilities including symmetric instability (SI) along the airstream. The SJ undergoes a strong descent while leaving the cloud-head banded tip and markedly accelerating towards the frontal-fracture region, revealed as an area of buckling of the already-sloped moist isentropes. A substantial amount of SI, generated by slantwise frontal motions in the cloud head, is released along the SJ during its descent. This supports the role of SI in the airstream’s dynamics proposed in a conceptual model outlined in a previous study. Sensitivity experiments illustrate that the SJ is a robust feature of intense Shapiro-Keyser cyclones, highlighting a range of different environmental conditions in which SI contributes to the evolution of this airstream, conditional on the model having adequate resolution. The results reveal that several environmental factors can modulate the strength of the SJ. However, a positive relationship between the strength of the SJ, both in terms of peak speed and amount of descent, and the amount of instability occurring along it can still be identified. In summary, the idealised simulations presented in this study show the robustness of SJ occurrence in intense Shapiro-Keyser cyclones and support and clarify the role of dry instabilities in SJ dynamics.

Role of dactinomycin in the improved survival of children with Wilms' tumor

JAMA ◽  
1966 ◽  
Vol 195 (12) ◽  
pp. 1005-1009 ◽  
Author(s):  
D. J. Fernbach
Keyword(s):  
Wilms Tumor

Role of the allergist in diagnosis and management of patients with uveitis

JAMA ◽  
1966 ◽  
Vol 195 (3) ◽  
pp. 167-172 ◽  
Author(s):  
T. E. Van Metre
Keyword(s):  
Diagnosis And Management

The power of norms to sway fused group members

2018 ◽  
Vol 41 ◽  
Author(s):  
Winnifred R. Louis ◽  
Craig McGarty ◽  
Emma F. Thomas ◽  
Catherine E. Amiot ◽  
Fathali M. Moghaddam
Keyword(s):  
Evolutionary Anthropology ◽  
Normative Systems ◽  
Violent Extremism ◽  
Identity Fusion ◽  
Group Members

AbstractWhitehouse adapts insights from evolutionary anthropology to interpret extreme self-sacrifice through the concept of identity fusion. The model neglects the role of normative systems in shaping behaviors, especially in relation to violent extremism. In peaceful groups, increasing fusion will actually decrease extremism. Groups collectively appraise threats and opportunities, actively debate action options, and rarely choose violence toward self or others.

Elaborating the role of reflection and individual differences in the study of folk-economic beliefs

2018 ◽  
Vol 41 ◽  
Author(s):  
Kevin Arceneaux
Keyword(s):  
Decision Making ◽  
Individual Differences ◽  
Cognitive Processes ◽  
Evolutionary History ◽  
Behavioral Responses ◽  
History Of ◽  
Economic Beliefs

AbstractIntuitions guide decision-making, and looking to the evolutionary history of humans illuminates why some behavioral responses are more intuitive than others. Yet a place remains for cognitive processes to second-guess intuitive responses – that is, to be reflective – and individual differences abound in automatic, intuitive processing as well.

The role of affect in feelings of obligation

2020 ◽  
Vol 43 ◽  
Author(s):  
Stefen Beeler-Duden ◽  
Meltem Yucel ◽  
Amrisha Vaish
Keyword(s):  
Positive Emotions ◽  
The Creation ◽  
Sense Of Obligation

Abstract Tomasello offers a compelling account of the emergence of humans’ sense of obligation. We suggest that more needs to be said about the role of affect in the creation of obligations. We also argue that positive emotions such as gratitude evolved to encourage individuals to fulfill cooperative obligations without the negative quality that Tomasello proposes is inherent in obligations.

Refining our understanding of the “elephant in the room”

2020 ◽  
Vol 43 ◽  
Author(s):  
Andrew Whiten
Keyword(s):  
Social Cognition ◽  
Cultural Evolution ◽  
Cognitive Abilities ◽  
Critical Factors ◽  
Technological Culture

Abstract The authors do the field of cultural evolution a service by exploring the role of non-social cognition in human cumulative technological culture, truly neglected in comparison with socio-cognitive abilities frequently assumed to be the primary drivers. Some specifics of their delineation of the critical factors are problematic, however. I highlight recent chimpanzee–human comparative findings that should help refine such analyses.

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