A5081828026- Climate variability and models
- Atmospheric and Environmental Gas Dynamics
- Atmospheric Ozone and Climate
- Meteorological Phenomena and Simulations
- Atmospheric aerosols and clouds
- Oceanographic and Atmospheric Processes
- Atmospheric chemistry and aerosols
- Tropical and Extratropical Cyclones Research
- Geology and Paleoclimatology Research
- Geophysics and Gravity Measurements
- Ionosphere and magnetosphere dynamics
- Geological and Geophysical Studies
- Ocean Acidification Effects and Responses
- Cryospheric studies and observations
- Marine and coastal ecosystems
- Solar and Space Plasma Dynamics
- Climate Change Policy and Economics
- Geological and Tectonic Studies in Latin America
- Aeolian processes and effects
- Climate change impacts on agriculture
- Geological and Geochemical Analysis
- Island Studies and Pacific Affairs
- Seismology and Earthquake Studies
- Microtubule and mitosis dynamics
- Advanced Thermodynamics and Statistical Mechanics
University of Virginia
2016-2025
Finnish Meteorological Institute
2024
Indiana University
2020
McCormick (United States)
2019
Lawrence Livermore National Laboratory
2018
University of California, Los Angeles
2018
University of Oxford
2018
Nanjing University
2018
Goddard Space Flight Center
2018
Science Systems and Applications (United States)
2018
Abstract Static stability is a fundamental dynamical quantity that measures the vertical temperature stratification of atmosphere. However, magnitude and structure finescale features in this field are difficult to discern data with low resolution. In study, authors apply more than six years high resolution global positioning system radio occultation profiles document long-term mean variability static stratosphere upper troposphere. The most pronounced feature well-known transition from...
Abstract Previous studies have documented a poleward shift in the subsiding branches of Earth’s Hadley circulation since 1979 but disagreed on causes these observed changes and ability global climate models to capture them. This synthesis paper reexamines number contradictory claims past literature finds that tropical expansion indicated by modern reanalyses is within bounds models’ historical simulations for period 1979–2005. Earlier conclusions were underestimating trends relied defining...
Abstract. In response to increasing greenhouse gases, the subtropical edges of Earth's Hadley circulation shift poleward in global climate models. Recent studies have found that reanalysis trends cell edge over past 30–40 years are within range simulated by Coupled Model Intercomparison Project Phase 5 (CMIP5) models and documented seasonal hemispheric asymmetries these trends. this study, we evaluate whether conclusions hold for newest generation (CMIP6). Overall, find similar...
Abstract By interacting with radiation, clouds modulate the flow of energy through Earth system, circulation atmosphere, and regional climate. We review impact cloud‐radiation interactions for atmospheric in present‐day climate, its internal variability response to climate change. After summarizing cloud‐controlling factors cloud‐radiative effects, we clarify scope limits Clouds On‐Off Klimate Model Intercomparison Experiment (COOKIE) cloud‐locking modeling methods. COOKIE showed that...
Abstract In Coupled Model Intercomparison Project Phase 5 (CMIP5) models, the zonal‐mean tropospheric circulation shifts robustly poleward in Southern Hemisphere extratropics response to increased atmospheric CO 2 concentrations. However, Northern (NH) extratropics, is largely absent zonal mean and instead characterized by complex regional anomalies. This study decomposes forcing CMIP5 models into two components: a direct component due radiative an indirect associated with sea surface...
Abstract There is mounting evidence that the width of tropics has increased over last few decades, but there are large differences in reported expansion rates. This is, likely, part due to wide variety metrics have been used define tropical width. Here we perform a systematic investigation into relationship among nine zonal-mean using preindustrial control and abrupt quadrupling CO 2 simulations from suite coupled climate models. It shown latitudes edge Hadley cell, midlatitude eddy-driven...
Abstract This study quantifies cloud–radiative anomalies associated with interannual variability in the latitude of Southern Hemisphere (SH) midlatitude eddy-driven jet, 20 global climate models from phase 5 Coupled Model Intercomparison Project (CMIP5). Two distinct model types are found. In first class (type I models), total cloud fraction is reduced at SH midlatitudes as jet moves poleward, contributing to enhanced shortwave radiative warming. second II this dynamically induced warming...
Abstract Extratropical cyclones play a principal role in wintertime precipitation and severe weather over North America. On average, the greatest number of track 1) from lee Rocky Mountains eastward across Great Lakes 2) Gulf Stream along eastern coastline However, cyclone tracks are highly variable within individual winters between winter seasons. In this study, authors apply Lagrangian tracking algorithm to examine variability extratropical America during winter. A series methodological...
Abstract. Observational and modeling studies suggest that Earth's tropical belt has widened over the late 20th century will continue to widen throughout 21st century. Yet, estimates of tropical-width variations differ significantly across studies. This uncertainty, an unknown degree, is partly due large variety methods used in width. Here, for eight commonly metrics width are implemented Tropical-width Diagnostics (TropD) code package MATLAB programming language. To consolidate various...
In recent decades, the subtropical edges of Earth’s Hadley circulation have shifted poleward. Some studies concluded that this observed tropical expansion is occurring more rapidly than predicted by global climate models. However, modeling shown internal variability can account for a large fraction trends, at least in an annual-mean, zonal-mean framework. This study extends these previous results examining seasonal and regional characteristics poleward using seven reanalysis datasets, sea...
Abstract The atmospheric response to increasing CO 2 concentrations is often described in terms of the equilibrium climate sensitivity (ECS). Yet forcing global models not limited an increase global‐mean surface temperature: for example, midlatitude jets shift poleward, Hadley circulation expands, and subtropical dry zones are altered. These changes, which referred here as “dynamical sensitivity,” may be more important practice than temperature. This study examines what degree intermodel...
Abstract We investigate the interannual relationship among clouds, their radiative effects, and two key indices of atmospheric circulation: latitudinal positions Hadley cell edge midlatitude jet. From reanalysis data satellite observations, we find a clear consistent between width high cloud field, statistically significant in nearly all regions seasons. In contrast, shifts jet correlate significantly with only North Atlantic region during winter season. While that season poleward are...
Abstract This study examines the dynamical mechanisms responsible for changes in midlatitude clouds and cloud radiative effects (CRE) that occur conjunction with meridional shifts jet streams over North Atlantic, Pacific, Southern Oceans. When poleward, extratropical cyclones their associated upward vertical velocity anomalies closely follow. As a result, poleward shift contributes to high-topped storm-track longwave CRE. However, when downward increase equatorward of jet, contributing an...
Abstract The width of the tropical Hadley circulation (HC) has garnered intense interest in recent decades, owing to emerging evidence for its expansion observations and models anticipated impacts on surface climate descending branches. To better clarify causes widening, this work generalizes zonal mean HC regional level by defining meridional overturning cells (RC) using horizontally divergent wind. edges RC are more closely connected hydroclimate than traditional metrics (such as sea...
Abstract This study quantifies the response of clouds and radiative budget Southern Hemisphere (SH) to poleward shift in tropospheric circulation induced by development Antarctic ozone hole. Single forcing climate model integrations, which only stratospheric depletion is specified, indicate that (1) high‐level midlevel closely follow SH midlatitude jet (2) low‐level decrease across most Ocean. Similar cloud anomalies are found satellite observations during periods when anomalously poleward....
Abstract Numerous lines of observational evidence suggest that Earth's tropical belt has expanded over the past 30–40 years. It is natural to expect this poleward displacement should be associated with drying on margins subtropics, but it less clear what degree zonally symmetric. This study tests which motion Hadley cell boundary changes in local precipitation or sea level pressure and those are Evidence from both reanalysis data global climate models reveals expansion mostly confined...
Abstract Over the past 15 years, numerous studies have suggested that sinking branches of Earth’s Hadley circulation and associated subtropical dry zones shifted poleward over late twentieth century early twenty-first century. Early estimates this tropical widening from satellite observations reanalyses varied 0.25° to 3° latitude per decade, while global climate models show at lower end observed range. In 2016, two working groups, U.S. Climate Variability Predictability (CLIVAR) group on...
A poleward shift of the Hadley cell (HC) edge in a warming climate, which contributes to expansion drought-prone subtropical regions, has been widely documented. The question addressed here is whether this reversible with CO2 removal. By conducting large-ensemble experiments where concentrations are systematically increased and then decreased present-day level, we show that poleward-shifted HC climate does not return its state when reduced. While Southern Hemisphere remains state, Northern...
The circulation response to climate change shapes regional and extremes. Over the last decade an increasing number of atmospheric signals have been documented, with some attributed human activities. represent exciting opportunity for improving our understanding dynamical mechanisms, testing theories reducing uncertainties. also presented puzzles that better change, its contribution extremes, interactions moisture, connection thermodynamic discrepancies. next is likely be a golden age...
The climatology, seasonality, and intraseasonal to interannual variability of the temperature field near cold‐point tropopause (CPT) are examined using state‐of‐the‐art climate models that participated in Coupled Model Intercomparison Project Phase 5 (CMIP5). Both historical simulations future projections based on Representative Concentration Pathway (RCP) 8.5 scenario used evaluate model performance identify potential changes at CPT focusing 100 hPa zero‐lapse‐rate (ZLR) temperatures. It is...
Abstract This study analyzes Coupled Model Intercomparison Project phase 5 (CMIP5) model output to examine the covariability of interannual Southern Hemisphere Hadley cell (HC) edge latitude shifts and shortwave cloud radiative effect (SWCRE). In control climate runs, during years when HC is anomalously poleward, most models substantially reduce radiation reflected by clouds in lower midlatitude region (LML; ∼28°S–∼48°S), although no such reduction seen observations. These biases HC‐SWCRE...
Abstract This study examines whether the spread in climate sensitivity of Coupled Model Intercomparison Project Phase 5 (CMIP5) models also captures Southern Hemisphere dynamical response to greenhouse gas forcing. Three metrics are proposed quantify “dynamical sensitivity” Hemisphere: poleward expansion Hadley circulation, subtropical dry zone, and shift midlatitude jet. In CMIP5 abrupt 4 × CO 2 integrations, circulation is well correlated with all seasons; contrast, shifts zone jet...