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publications

Delineating the Eddy–Zonal Flow Interaction in the Atmospheric Circulation Response to Climate Forcing: Uniform SST Warming in an Idealized Aquaplanet Model

Published in Journal of the Atmospheric Sciences, 2013

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Chen, Gang, Jian Lu and Lantao Sun, 2013: Delineating the Eddy–Zonal Flow Interaction in the Atmospheric Circulation Response to Climate Forcing: Uniform SST Warming in an Idealized Aquaplanet Model, Journal of the Atmospheric Sciences, 70, 2214--2233, doi:10.1175/JAS-D-12-0248.1.

The robust dynamical contribution to precipitation extremes in idealized warming simulations across model resolutions

Published in Geophysical Research Letters, 2014

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Lu, Jian, L. Ruby Leung, Qing Yang, Gang Chen, William D. Collins, Fuyu Li, Z. Jason Hou and Xuelei Feng, 2014: The robust dynamical contribution to precipitation extremes in idealized warming simulations across model resolutions, Geophysical Research Letters, 41, 2971--2978, doi:10.1002/2014GL059532.

The Role of Stratospheric Polar Vortex Breakdown in Southern Hemisphere Climate Trends

Published in Journal of the Atmospheric Sciences, 2014

ABSTRACT: This paper investigates the connection between the delay in the final breakdown of the stratospheric polar vortex, the stratospheric final warming (SFW), and Southern Hemisphere climate trends. We first analyze ERA-Interim reanalysis and three climate model outputs with different climate forcings. Climate trends appear when there is a delay in the timing of SFWs. When regressed onto the SFW dates (which reflects the anomaly when the SFW is delayed for one standard deviation of its onset dates), the anomaly pattern bears a resemblance to the observed climate trends, for all the model outputs, even without any trends. This suggests that the stratospheric and tropospheric circulations are organized by the timing of SFWs, in both the interannual time scale and climate trends due to external forcings.We further explore the role of the SFW using a simplified dynamical model, in which the ozone depletion is mimicked by a springtime polar stratospheric cooling. The responses of zonal-mean atmospheric circ…

Sun, Lantao, Gang Chen and Walter A. Robinson, 2014: The Role of Stratospheric Polar Vortex Breakdown in Southern Hemisphere Climate Trends, Journal of the Atmospheric Sciences, 2335--2353, doi:10.1175/JAS-D-13-0290.1.

Sensitivities of the Lower-Stratospheric Transport and Mixing to Tropical SST Heating

Published in Journal of the Atmospheric Sciences, 2014

ABSTRACT: The sensitivities of the Brewer-Dobson Circulation (BDC) to different distributions of tropical SST heating are investigated in an idealized aqua-planet model. It is found that an increase in tropical SSTs generally leads to an acceleration of tropical upwelling and an associated reduction in the Age of Air (AOA) in the polar stratosphere, and that the AOA near the subtropical tropopause is correlated with local isentropic mixing of tropospheric air with stratospheric air.The zonal distribution of SST perturbations has a major impact on the vertical and meridional structure of the BDC as compared with other SST characteristics. Zonally localized SST heatings tend to generate a shallow acceleration of the stratospheric residual circulation, enhanced isentropic mixing associated with a weakened stratospheric jet, and a reduction in AOA mostly within the polar vortex. Contrarily, SST heatings with a zonally symmetric structure tend to produce a deep strengthening of the stratospheric residual circula…

Yang, Huang, Gang Chen and Daniela I.V. V. Domeisen, 2014: Sensitivities of the Lower-Stratospheric Transport and Mixing to Tropical SST Heating, Journal of the Atmospheric Sciences, 71, 2674--2694, doi:10.1175/JAS-D-13-0276.1.

Variations in Titan's dune orientations as a result of orbital forcing

Published in Icarus, 2016

Wind-blown dunes are a record of the climatic history in Titan's equatorial region. Through modeling of the climatic conditions associated with Titan's historical orbital configurations (arising from apsidal precessions of Saturn's orbit), we present evidence that the orientations of the dunes are influenced by orbital forcing. Analysis of 3 Titan general circulation models (GCMs) in conjunction with a sediment transport model provides the first direct intercomparison of results from different Titan GCMs. We report variability in the dune orientations predicted for different orbital epochs of up to 70°. Although the response of the GCMs to orbital forcing varies, the orbital influence on the dune orientations is found to be significant across all models. Furthermore, there is near agreement among the two models run with surface topography, with 3 out of the 5 dune fields matching observation for the most recent orbital cycle. Through comparison with observations by Cassini, we find situations in which the observed dune orientations are in best agreement with those modeled for previous orbital configurations or combinations thereof, representing a larger portion of the cycle. We conclude that orbital forcing could be an important factor in governing the present-day dune orientations observed on Titan and should be considered when modeling dune evolution.

McDonald, George D., Alexander G. Hayes, Ryan C. Ewing, Juan M. Lora, Claire E. Newman, Tetsuya Tokano, Antoine Lucas, Alejandro Soto and Gang Chen, 2016: Variations in Titan's dune orientations as a result of orbital forcing, Icarus, 270, 197--210, doi:10.1016/j.icarus.2015.11.036.

Examining the Hydrological Variations in an Aquaplanet World Using Wave Activity Transformation

Published in Journal of Climate, 2017

ABSTRACT: Building on the recent advent of the concept of finite-amplitude wave activity, a contour-following diagnostics for column water vapor (CWV) is developed and applied to a pair of aquaplanet model simulations to understand and quantify the higher moments in the global hydrological cycle. The Lagrangian nature of the diagnostics leads to a more tractable formalism for the transient, zonally asymmetric component of the hydrological cycle, with a strong linear relation emerging between the wave activity and the wave component of precipitation minus evaporation (). The dry-versus-wet disparity in the transient hydrological cycle is measured by , and it is found to increase at a super-Clausius–Clapeyron rate at the poleward side of the mean storm track in response to a uniform sea surface temperature (SST) warming and the meridional structure of the increase can be largely attributed to the change of the meridional stirring scale of the midlatitude Rossby waves. Further scaling for indicates that the ra…

Lu, Jian, Koichi Sakaguchi, Qing Yang, L. Ruby Leung, Gang Chen, Chun Zhao, Erik Swenson and Zhangshuan J. Hou, 2017: Examining the Hydrological Variations in an Aquaplanet World Using Wave Activity Transformation, Journal of Climate, 30, 2559--2576, doi:10.1175/JCLI-D-16-0561.1.

Wave Events: Climatology, Trends, and Relationship to Northern Hemisphere Winter Blocking and Weather Extremes

Published in Journal of Climate, 2017

ABSTRACT: Diagnostics of finite amplitude Local Wave Activity (LWA) are applied on the 500-hPa geopotential height field to diagnose persistent synoptic weather events of anomalously large wave activity in the Northern Hemisphere. By considering the cyclonic and anticyclonic components of LWA separately, persistent weather systems associated with large-amplitude troughs and ridges are detected. While anticyclonic wave events are predominantly found over Europe and Alaska, cyclonic wave events are usually occurring over East Asia and Northeastern Canada. Those preferred regions correspond to the location of planetary-scale ridges and troughs, which contribute, together with transient anomalies, to the formation of wave events. Although wave events are not blocking events per definition, they are typically associated with increased blocking in their vicinity. Their spatial relationship to blocking, however, varies depending on their cyclonic or anticyclonic nature and the type of wave-breaking signatures. Wav…

Martineau, Patrick, Gang Chen and D. Alex Burrows, 2017: Wave Events: Climatology, Trends, and Relationship to Northern Hemisphere Winter Blocking and Weather Extremes, Journal of Climate, 30, 5675--5697, doi:10.1175/JCLI-D-16-0692.1.

Enhanced hydrological extremes in the western United States under global warming through the lens of water vapor wave activity

Published in npj Climate and Atmospheric Science, 2018

Download paper: here and journal website

Lu, Jian, Daokai Xue, Yang Gao, Gang Chen, L. Ruby Leung and Paul Staten, 2018: Enhanced hydrological extremes in the western United States under global warming through the lens of water vapor wave activity, npj Climate and Atmospheric Science, accepted, doi:10.1038/s41612-018-0017-9.

Enhanced hydrological extremes in the western United States under global warming through the lens of water vapor wave activity

Published in npj Climate and Atmospheric Science, 2018

Download paper: here and journal website

Lu, Jian, Daokai Xue, Yang Gao, Gang Chen, L. R. Leung and Paul Staten, 2018: Enhanced hydrological extremes in the western United States under global warming through the lens of water vapor wave activity, npj Climate and Atmospheric Science, 1, 7, doi:10.1038/s41612-018-0017-9.

talks

teaching

Teaching experience 1

Undergraduate course, University 1, Department, 2014

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Teaching experience 2

Workshop, University 1, Department, 2015

This is a description of a teaching experience. You can use markdown like any other post.