Seminars

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Theresa Nohl, University of Münster: Carbonate Chemistry

Live in 1309 Exploratory Hall

Virtual simulcast in Zoom: https://gmu.zoom.us/j/95726202745

Thursdays 4:30-5:45 pm

Lenny Smith, Virginia Tech

Wed, 1 Feb, 1:30-2:30 - POSTPONED, New Date TBA

JC Room G and via Zoom (contact bklinger@gmu.edu for link)

On the Evaluation and Tuning of Probability Forecasts: Why RMSE is Evil and Anomalies are Silly

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João Trabucho Alexandre, University of Utrecht: Mud Sedimentology

Live in 1309 Exploratory Hall

Virtual simulcast in Zoom: https://gmu.zoom.us/j/95726202745

Thursdays 4:30-5:45 pm

Craig Ferguson, U Albany

Wed 8 Feb, 1:30-2:30

Only via Zoom (note change in venue; contact bklinger@gmu.edu for link)

Effects of large-scale soil moisture gradients on the Great Plains low-level jet

A realistic model representation of coupled land-atmospheric processes, like vegetation-shallow cumulus and soil moisture-precipitation feedbacks, is critical to resolving the diurnal cycle over land, resolving fine-scale horizontal gradients in precipitation, and predicting climate at subseasonal-to-seasonal timescales. This talk will provide an overview of efforts to understand and quantify the impact of soil moisture anomalies on local, regional, and circumglobal precipitation patterns. Major themes include the Great Plains low-level jet as an upscaling agent of local land-atmosphere coupling and current efforts to enhance ground and space-based boundary layer observing systems. 

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John Singleton, Colorado State University : Structural Geology

Live in 1309 Exploratory Hall

Virtual simulcast in Zoom: https://gmu.zoom.us/j/95726202745

Thursdays 4:30-5:45 pm

Venu Vuruputur, Indian Institute of Science

Wed 15 Feb, 1:30-2:30

JC Room G and via Zoom (contact bklinger@gmu.edu for link)

A Midlatitude Tale on the Tail of Indian Monsoon Rainfall

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Ben Keisling, University of Texas at Austin: Geoscience Justice

Live in 1309 Exploratory Hall

Virtual simulcast in Zoom: https://gmu.zoom.us/j/95726202745

Thursdays 4:30-5:45 pm

Colin Zarzycki, Pennsylvania State U

Wed, 22 Feb, 1:30-2:30

JC Room G and via Zoom (contact bklinger@gmu.edu for link)

Could it happen? Evaluating extreme weather risks with high-resolution climate storyline simulations

In this talk, we discuss using global Earth system model simulations of short, high-resolution, "storylines" to evaluate and communicate climate risk and potential changes in their associated hazards in the future. In particular, we focus on two flavors of storylines: gray swan tropical cyclones (physically plausible, but historically unrealized events extracted from multi-decadal climate ensembles) and rain-on-snow floods in a warmer world (resimulation of the 1996 Mid-Atlantic floods under different climate scenarios). We discuss scientific insights gained from these simulations, the strengths and limitations of this approach, and the potential benefits of using them to communicate with stakeholders and the general public.

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John Grant, Smithsonian: Planetary Geology

Live in 1309 Exploratory Hall

Virtual simulcast in Zoom: https://gmu.zoom.us/j/95726202745

Thursdays 4:30-5:45 pm

*Please Note Room Change*

V “Ram” Ramaswamy, NOAA Geophysical Fluid Dynamics Laboratory

Wed, 1 Mar, 1:30-2:30

JC Room B and via Zoom (contact bklinger@gmu.edu for link)

Climate Forcings and Changes in the Hydrologic Cycle

A lot of attention has been given to the prospect of the surface temperature increase under the increased imbalance in the Earth’s radiation budget and climate change, and the downstream impacts e.g., continental-scale and marine heat waves. But what about the changes in the hydrologic cycle including evaporation and precipitation? What is our understanding about the changes concerning water over the 20th Century, and where does this take us to anticipate outcomes in the 21st Century? Can we improve upon the predictions and projections of extremes, including being able to do them across timescales? Can we provide substantive actionable information on climate adaptation, vulnerabilities, and mitigation, especially related to extremes concerning water, to the diverse array of stakeholders in the US and across the globe?

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Brooks, Precious Metals

Live in 1309 Exploratory Hall

Virtual simulcast in Zoom: https://gmu.zoom.us/j/95726202745

Thursdays 4:30-5:45 pm

Mukund Gupta, California Institute of Technology

Thu, 2 Mar, 1:15-2:15 Exploratory Hall 3301

and via Zoom (contact bklinger@gmu.edu) for link

Coupled interactions between ocean and sea ice: from basin to floe scale

Sea ice is a layer of frozen ocean waters that forms in winter over polar latitudes due to cold atmospheric temperatures. This layer of ice plays a critical role in the climate system by reflecting incoming solar radiation, helping store carbon dioxide into the ocean and mediating global weather patterns via teleconnections. Over the past decades, sea ice area in the Arctic Ocean has declined sharply, and Antarctica is expected to follow suite within this century. Climate models currently underestimate the downward trend in Arctic sea ice extent, in part due to the misrepresentation of fine scale (< 100 km) processes within the pack. These uncertainties involve poorly-constrained interactions between individual sea ice floes and (sub-)mesoscale turbulence in the ocean, which notably affect the seasonal melt/freeze cycle of sea ice, ocean stratification and surface mixing processes.

Here, I present studies leveraging satellite inferences, Discrete Element Models and Large Eddy Simulations to uncover novel interactions between ocean and sea ice across scales. Altimetric observations reveal that basin-wide mechanical and thermal forcings exert a strong control on the three-dimensional properties of sea ice floes and their spatial distribution within the pack. The spring season emerges as a sharp transition period, during which the size, shape and motion of floes are strongly influenced by ocean mesoscale currents. In turn, modeled interactions between ocean eddies and sea ice floes reveal that floe size, ice/ocean drag, and ice breakage tightly mediate the melt rate of the pack and its bulk rheological properties. As marginal ice zones continue to widen, this two-way coupling in the ice/ocean system is set to gain prominence over the coming decades and motivates the need to develop data-informed floe-scale parametrization of sea ice within global climate models.

Paul Dirmeyer, George Mason U

Wed, 8 Mar, 1:30-2:30

JC Room E and via Zoom (contact bklinger@gmu.edu for link)

Global Land-Atmosphere Coupling Metrics: Accounting for Measurement Noise in Satellite Data

Scott W. Powell, Naval Postgraduate School

Growth Mechanisms of Cumulonimbus Clouds

Thu, 9 Mar, 1:15pm

Exploratory Hall 3301 and via Zoom (contact zboybeyi@gmu.edu for link)

Moist convection in the atmosphere frequently takes the form of cumuliform clouds. Most of the time, such clouds arise from eddies in the boundary layer that reach the lifting condensation level and form shallow convection early in the cloud life cycle. The majority of cumulus (non-precipitating) clouds that develop remain shallow, but some of them are able to grow into taller—and often wider—cumulonimbus (precipitating) clouds. It is these deep and wide clouds that are linked to many types of severe weather events such as supercells and tropical cyclones. They also have profound impacts on the global atmospheric circulation through their extensive release of latent heat throughout the troposphere. In addition, they impact cloud-radiative feedbacks that result from the lateral development of cumulonimbi into broad stratiform regions containing extensive cirrus anvil clouds in the middle-to-upper troposphere.

Representing such clouds in numerical models of the atmosphere is particularly challenging. Cumulus clouds often form from updrafts no more than a few hundred meters wide, meaning that climate models and operational global weather models cannot resolve them. As a result, numerical models use cumulus parameterizations to capture the behavior of a population of many cumuliform clouds that can co-populate a single model grid cell. However, these parameterizations have significant limitations, among which are 1) vertical mass fluxes are often inconsistent with mass fluxes computed from observations and higher-resolution models; and 2) important processes, such as the onset of convection and entrainment of environmental air into convection, are usually sensitive to only the thermodynamic properties of the atmosphere and do not consider other important dynamic processes (such as pressure gradient accelerations) or cloud properties that might impact those processes (such as cloud size). The limitations in parameterizations mean that numerical models struggle to accurately depict both small-scale and large-scale weather and climate processes that depend on cumuliform clouds. This seminar will highlight a variety of Dr. Powell’s ongoing research that leverages both observations and high-resolution numerical modeling to investigate the timing and location of shallow to deep cumuliform cloud transitions.

Ying Cui, Montclair State University: Stable Isotope Geochemistry

Live in 1309 Exploratory Hall

Virtual simulcast in Zoom: https://gmu.zoom.us/j/95726202745

Thursdays 4:30-5:45 pm

Lais Fernandes, Portland State U

Wed, 22 Mar, 1:30-2:30

via Zoom (contact bklinger@gmu.edu for link)

The interaction between El Niño-Southern Oscillation (ENSO) and Madden-Julian Oscillation (MJO) in South America: observations and model simulations

The investigation shows how the ENSO phenomenon influences the impact of the Madden-Julian Oscillation (MJO) on South America during the summer monsoon season. Observations show that the MJO extratropical teleconnection and its impacts on South America intensify during El Niño (EN) and La Niña (LN) and weaken in neutral ENSO years. Simulations with ENSO also show that active ENSO states more efficiently trigger stronger MJO teleconnections than simulations without ENSO, indicating nonlinear ENSO effects on MJO-related anomalies. Convection over the source region, which triggers the extratropical teleconnection, is enhanced later in EN than in LN and is shifted slightly eastwards. Hence, the most significant impacts on South American precipitation happen later and more to the east in EN than LN.

Chistopher Kinsley, Berkeley Geochronology Center: Geochronology

Live in 1309 Exploratory Hall

Virtual simulcast in Zoom: https://gmu.zoom.us/j/95726202745

Thursdays 4:30-5:45 pm

Yifei Guan, Rice University

Tue, 28 Mar, 1:30-2:30 Room TBA and via Zoom (contact bklinger@gmu.edu for link)

Data-driven subgrid-scale models for large-eddy simulation of turbulence

Fabien Solmon, Laboratoire D’Aérologie

Wed, 29 Mar, 1:30-2:30

JC Room C and via Zoom (contact bklinger@gmu.edu for link)

Aerosol - Monsoon interactions analyzed through regional climate modelling.

Understanding Monsoon Systems (MS) and their connection to global and regional climate has been a subject of intense research for decades. One important aspect of MS development is connected to the regional variability of diabatic and moisture sources affecting meridional energy gradients and rainfall distribution. This presentation will examine how natural and anthropogenic aerosol can interact with monsoon systems at the regional scale through feedback involving radiation, cloud and surface adjustments. A regional climate modelling approach will be introduced applied to studying how large quantities of aerosols from emitted dust and biomass burning can interact with West African monsoon dynamics and associated rainfall.

Greg Newmann, NASA: Planetary Physics

Live in 1309 Exploratory Hall

Virtual simulcast in Zoom: https://gmu.zoom.us/j/95726202745

Thursdays 4:30-5:45 pm

Edwin Schneider, AOES

Wed, 5 Apr, 1:30-2:30

JC Room E and via Zoom (contact bklinger@gmu.edu for link)

The Role of Atmospheric Noise in Decadal SST Variability

Decadal SST variability is investigated in a 500-year constant external forcing CGCM simulation. Comparison with a simulation made with an Interactive Ensemble (IE) version of the CGCM indicates that all decadal SST and AMOC variability is probably forced by surface fluxes produced by internal atmospheric noise. An approximate upper ocean heat budget is used to in conjunction with results from the IE to point to the resolution of a controversy concerning the relative roles of atmospheric noise net surface heat flux and ocean dynamics in internal decadal AMV variability. The result in the CGCM is that the atmospheric noise and ocean dynamics forcings of SST are about the same size, and that the ocean dynamics forcing has a longer time scale.

Schneider, E. K., B. Kirtman, and N. Perlin 2023: The role of atmospheric noise in decadal climate variability, J. Climate, 37, 2147-2166, DOI 10.1175/JCLI-D-22-0399.1.

Wen Song, University of Texas at Austin: Geological Engineering

Live in 1309 Exploratory Hall

Virtual simulcast in Zoom: https://gmu.zoom.us/j/95726202745

Thursdays 4:30-5:45 pm

Xuejin Zhang, NOAA Atlantic Oceanographic and Meteorological Lab (AOML)

Wed, 12 Apr, 1:30-2:30

via Zoom (contact bklinger@gmu.edu for link)

Kai Huang, Climate Dynamics Doctoral Defense

Wed, 12 Apr, 9:00-10:00 

Room TBD 

Ben Linzmeier, University of Southern Alabama: Invertebrate Paleontology

Live in 1309 Exploratory Hall

Virtual simulcast in Zoom: https://gmu.zoom.us/j/95726202745

Thursdays 4:30-5:45 pm

Janak Joshi, Climate Dynamics Doctoral Defense

Mon, 17 Apr, 9:30-10:30

Exploratory Hall 3301

Jack Chen,

Wed, 19 Apr, 1:30-2:30

Zoom (contact bklinger@gmu.edu for link)

Shemin Ge, University of Colorado: Hydrogeology

Live in 1309 Exploratory Hall

Virtual simulcast in Zoom: https://gmu.zoom.us/j/95726202745

Thursdays 4:30-5:45 pm

Douglas Nedza, AOES Climate Dynamics Program

Wed, 26 Apr, 1:30-2:30

JC Room A and via Zoom (contact bklinger@gmu.edu for link)

Understanding Contributions to Variance in North Atlantic Sea Surface Temperatures

Quantifying the relative contributions of external forcing and internal variability to North Atlantic Sea Surface Temperatures (NASST) has important implications for attributing and predicting climate changes around the North Atlantic basin. Virtually all previous methods have approached this problem by estimating the externally forced signal directly, either from climate models or using statistical filtering methods. These methods make strong assumptions about the forced variability which are not universally accepted. In this work, we approach this problem in a fundamentally different way that avoids controversial assumptions about the externally forced variability. Specifically, we estimate internal variability directly and then compute the forced variability as the residual. This approach is a form of dynamical adjustment, although this implementation differs from previous applications.

Live in 1309 Exploratory Hall

Virtual simulcast in Zoom: https://gmu.zoom.us/j/95726202745

Thursdays 4:30-5:45 pm

Kyle Pallozzi, National Weather Service

Wed, 3 May, 1:30-2:30

JC Room C and via Zoom (contact bklinger@gmu.edu for link)

Evaluating & warning for severe thunderstorms/tornadoes

Live in 1309 Exploratory Hall

Virtual simulcast in Zoom: https://gmu.zoom.us/j/95726202745

Thursdays 4:30-5:45 pm

CLIM 408 Students

Wed, 10 May, 1:00-2:30, Research Hall 121

(inside Climate Dynamics Suite)

Erik Swenson, George Mason U

Wed, 31 Aug, 1:30-2:30

EXPL 3301 and via Zoom (contact bklinger@gmu.edu for link)

Indian monsoon teleconnections with ENSO in an ensemble of re-forecasts

The El Niño Southern Oscillation (ENSO) has a significant impact on the Indian summer monsoon, with more dry conditions (relative to normal) expected during El Niño and more wet conditions during La Niña. In this study we examine the ENSO-monsoon relationship in an ensemble of re-forecasts produced with the NCEP CFSv2 and compare with the observed relationship. A large sample size allows for higher-order details of the ENSO-monsoon relationship to be quantified with significance. We examine the seasonal mean relationship in such a way that allows for potential nonlinearity and introduce a novel modification of Principal Component Analysis to incorporate asymmetry. Extending the analysis to sub-seasonal timescales, we further diagnose the impact of ENSO on the monsoon active-break cycle. Preliminary results suggest that ENSO does not systematically alter the active-break phases, and the impact over central India is independent.

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John Tarduno, University of Rochester – Early Earth paleomagnetism

Thursdays, 4:30-5:45 pm

Virtual in Zoom: https://gmu.zoom.us/j/99939787631

Gustavo de Almeida Coelho, Furman U Wed, 7 Sep, 1:30-2:30, via Zoom (contact bklinger@gmu.edu for link)

Towards Flood Resilience in Metropolitan Areas: Planning for Climate Uncertainty and Real-time Flood Forecasting

Urban floods generated by heavy and short-duration rainfall are a major concern due to their potential socioeconomic impacts and threat to life. I will discuss two approaches to support flood resilience in metropolitan areas. (1) In longer-term planning horizon (years to decades) I assess changes in future extreme precipitation due to climate change and present a novel method to incorporate these changes in flood engineering design. This method can support water resources engineers and decision-makers in planning for climate uncertainty. (2) In short-term (hours to days) I explore the predictive capability of flood forecast systems integrating numerical weather prediction to urban scale hydrodynamic models. This research advances urban flood modeling by highlighting key insights on short-range real-time flood predictability that can guide preparedness and response to approaching flood events.

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Dan Segessenman, George Mason University – Precambrian chronostratigraphy

Thursdays, 4:30-5:45 pm

1309 Exploratory Hall

Virtual simulcast in Zoom: https://gmu.zoom.us/j/99939787631

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Max Wyss, International Centre for Earth Simulation – Earthquake risks in the Himalayas

Thursdays, 4:30-5:45 pm

Virtual simulcast in Zoom: https://gmu.zoom.us/j/99939787631

Austin Reed, Nikki Lydeen, and others

Fri, 16 Sep, 11:00-12:00,

Research Hall 121 (CLIM Lab) & via zoom (contact bklinger@gmu.edu for link)

Quasi-monthly AOES discussion of notable recent climate and weather events. Come with an interesting news item. Come to add your two cents. Or just come to listen

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Nohl, Aragonite and Diagenesis

Thursdays, 4:30-5:45 pm

Jiang Zhu, National Center for Atmospheric Research (NCAR)

Wed, 28 Sep, 1:30-2:30,

Johnson Center Mtg Rm G and via Zoom (contact bklinger@gmu.edu for link)

Clearing clouds of uncertainty with the help of paleoclimate

The cloud feedback has long been identified as the leading source of uncertainty in the climate forcing-feedback framework, dominating the inter-model spread in how the global-average temperature responds to CO2 doubling, the equilibrium climate sensitivity (ECS). The increase of cloud feedback in the most recent generation of models is also responsible for the higher ECS than the previous generation of models. It is of paramount importance that we reduce the uncertainties associated with the cloud feedback processes. In this talk, I use the Community Earth System Models as an example to show how we can constrain the cloud parameterizations and feedback through simulation of past climate changes. Specifically, the paleoclimate simulations suggest that models with too strong or too weak cloud feedback may fail to simulate realistic ice age and/or hothouse climates in Earth’s past. I also discuss the potential role of the state dependence of the cloud feedback in the application of paleoclimate constraint

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Simon Goring, University of Wisconsin – Paleoclimate-Paleobiota Interactions

Thursdays, 4:30-5:45 pm

Virtual simulcast in Zoom: https://gmu.zoom.us/j/99939787631

Nathaniel Chaney, Duke U

Modeling the role of surface heterogeneity in land-atmosphere interactions

Wed, 5 Oct, 1:30-2:30 Johnson Center Mtng rm G and via Zoom (contact fhaychap@gmu.edu) for link

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Mike Ackerman, Carnegie Institute for Science – Early Earth Geology

Thursdays, 4:30-5:45 pm

Virtual simulcast in Zoom: https://gmu.zoom.us/j/99939787631

David Straus, George Mason U

Wed, 12 Oct, 1:30-2:30, Johnson Center Mtng Rm G and via Zoom (contact bklinger@gmu.edu for link)

Global consequences of uncertainty in heating within the Madden-Julian Oscillation

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Christian Sidor, University of Washington – Vertebrate Paleontology

Thursdays, 4:30-5:45 pm

Virtual simulcast in Zoom: https://gmu.zoom.us/j/99939787631

Reilly Stiles and others

Fri, 14 Oct, 11:00-12:00,

Research Hall 121 (CLIM Lab) & via zoom (contact bklinger@gmu.edu for link)

Quasi-monthly AOES discussion of notable recent climate and weather events. Come with an interesting news item. Come to add your two cents. Or just come to listen.

Alexey Fedorov, Yale U

The response of the tropical Pacific mean state and ENSO to global warming

Wed, 19 Oct, 1:30-2:30, Johnson Center Mtng Rm C and via Zoom (contact bklinger@gmu.edu for link)

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Amelia Shevenell, University of South Florida – Evolution of Antarctica

Thursdays, 4:30-5:45 pm

Virtual simulcast in Zoom: https://gmu.zoom.us/j/99939787631

Youngji Joh, Princeton U

Stronger decadal variability of the Kuroshio Extension under simulated future climate change

Wed, 26 Oct, 1:30-2:30, via Zoom (contact bklinger@gmu.edu for link)

Understanding the behavior of western boundary current systems is crucial for predictions of biogeochemical cycles, fisheries, and basin-scale climate modes over the midlatitude oceans. In this talk, I will address the response of the North Pacific’s Kuroshio Extension (KE) variability to future climate change scenarios. Large-ensemble climate model simulations show that in response to increasing greenhouse gases, the time scale of KE sea surface height (SSH) shifts from interannual scales toward decadal and longer scales. Greenhouse warming leads to a positive KE state that restricts ocean perturbations, enhancing decadal KE modulations relative to short-time scale variations. Our spectral analyses suggest that anthropogenic forcing may alter the future predictability of the KE system.

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Cathy Weitz, Planetary Science Institute – Mars Geology

Thursdays, 4:30-5:45 pm

1309 Exploratory Hall

Virtual simulcast in Zoom: https://gmu.zoom.us/j/99939787631

Randolph A. McBride, George Mason U

The Turnaround from Transgression to Regression of Holocene Barrier Systems in Southeastern Australia: Geomorphology, Geologic framework, and Geochronology

Fri, 28 Oct, 1:30-2:30, via Zoom (contact pdirmeye@gmu.edu for link)

Holocene regressive strandplains that preserve a series of former shorelines are extensive on coasts that were remote from major Pleistocene ice sheets (for example, Australia and Brazil), whereas transgressive barrier islands are typical in glacial forebulge regions (for example, North America and Europe). In strandplains, the regressive phase of strandline development was preceded by a transgressive phase during the final stages of postglacial sea-level rise. This study examines the turnaround from transgression to regression through chronostratigraphic description of three barrier systems in south-eastern Australia: Seven Mile Beach, Bengello Beach and Pedro Beach. The geomorphic and depositional histories are reconstructed using ground-penetrating radar (GPR) and vibracores along transects across the landwardmost ridges, and optically-stimulated luminescence (OSL) and radiocarbon dating (C-14). At the Seven Mile Beach barrier system, extensive washover deposits are preserved that include distinctive, landward-directed, flame-shaped washover fans along the bayside shoreline of the landwardmost ridge. Landward-dipping ground-penetrating radar reflections in radargrams provide evidence of the culmination of the transgressive phase and transition into the regressive phase dominated by progradation, evidenced by the change to seaward-dipping reflections. A similar progradational plain formed at the Bengello Beach barrier system, but transgressive deposits are largely absent at the site investigated, where an eroded headland created limited accommodation space until sand supply was sufficient for progradation. The Pedro Beach barrier system depositional history is more complex. There, a smaller embayment filled rapidly during the mid-Holocene, and transgressive sands were deposited as sea level reached its present level and impounded a wetland. Accommodation space in the embayment was filled by ca 4000 years ago. Overall, results indicate that the Holocene turnaround transition occurred between 8400 and 7000 years ago, and was preserved at the landward margin of these three strandplains. Holocene morphostratigraphy differs among sites primarily as a function of sea level, sediment supply, and antecedent topography.

Daniel Tong, George Mason U

Extreme Air Quality Events and Societal Effects in a Changing Climate

Fri, 28 Oct, 2:45-3:45 via zoom (contact bklinger@gmu.edu for link)

Tim DelSole, George Mason U

Wed, 2 Nov, 1:30-2:30, Johnson Center Mtng Rm G and via Zoom (contact bklinger@gmu.edu for link)

Things I wish I learned in Graduate School: How to choose a scientific problem

Christopher Kinsley, Berkeley Geochronology Center – Geochronology

Thursdays, 4:30-5:45 pm

Virtual simulcast in Zoom: https://gmu.zoom.us/j/99939787631

Maria Molina, U Maryland College Park

Using Machine Learning to Extend Earth System Prediction

Wed, 9 Nov, 1:30-2:30

Johnson Center Mtng Rm G and via Zoom (contact bklinger@gmu.edu for link)

Chaos theory, which is the concept of sensitivity to initial state for numerical weather prediction, is at the root of why the skillful deterministic prediction of weather at the subseasonal-to-seasonal (S2S) timescales using state-of-the-art forecasting models remains extremely challenging. Predictability stemming from atmospheric initial conditions is also substantially reduced beyond approximately two weeks and the ocean generally does not offer added predictability until a trajectory reaches the seasonal timescale. These challenges motivate the use of machine learning methods for S2S prediction. Two approaches for S2S prediction will be highlighted: (1) an unsupervised learning approach and (2) a supervised learning approach. The first study focuses on assessing the representation and predictability of North American weather regimes, which are persistent large-scale atmospheric patterns. The second study focuses on the use of a deep learning model (specifically a U-Net) for bias correction of S2S forecasts of global temperature and precipitation.

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Tom Algeo, University of Cincinnati – Geochemistry

Thursdays, 4:30-5:45 pm

Zoom: https://gmu.zoom.us/j/99939787631

Alia Wofford, Briah’ Davis, and others

Fri, 11 Nov, 11:00-12:00, via Zoom (contact bklinger@gmu.edu for link)

Quasi-monthly AOES discussion of notable recent climate and weather events. Come with an interesting news item. Come to add your two cents. Or just come to listen.

Hsin Hsu, George Mason U

Climate Dynamics Dissertation Defense

Nonlinearity and Regimes in Global Soil Moisture-Surface Heat Flux Coupling

Tue, 15 Nov, 12:00-1:00

Johnson Center Meeting Room E (334) and via zoom (Contact bklinger@gmu.edu for link)

Advisor: Paul Dirmeyer

Feedbacks on the atmosphere induced by soil moisture variability are recognized as an essential component of the Earth system. Coupling between SM and surface heat fluxes, especially the latent heat flux (LE), is the foundation of these feedbacks as it exchanges water and energy between the interface of land and atmosphere. Building upon that, this dissertation aims to understand land-atmosphere interactions by exploring the nonlinearity, multivariable dependency, and regime characteristics in the SM:LE coupling at a global scale. I show that LE is significantly affected by both SM and net radiation not only linearly but also nonlinearly and synergistically. Then, I determine active and inactive regimes in SM:LE sensitivity and confirm spatial patterns of SM:LE dependency during active regimes are consistent among observations and climate models. Nevertheless, the spatial patterns of the existence of local coupling regimes reflecting hydroclimate are diverse. I further find that, under global warming, the locally dominant regime may change, and projected SM variability tends to span more regimes. These changes in the dominant regime are decomposed into contributions from moisture processes and energy processes using a novel framework. Results show moisture processes result in a more moisture-limited world while the energy effect is also significant, but its impact is inconsistent among climate models. The global patterns computed in this research not only shed new light on aspects of land-atmosphere interactions but also raise several follow-up topics worthy of further study.

Vaishali Naik, Princeton U

The role of short-lived climate forcers (SLCFs) in the climate system – key findings from the IPCC AR6

Wed, 9 Nov, 1:30-2:30 Johnson Center Meeting Rm G and via Zoom (contact bklinger@gmu.edu for link)

Barry Klinger, George Mason U
Wed, 30 Nov, 1:30-2:30,
Eastern Boundary Upwelling – Where does the Heat Go?

Johnson Center Meeting Rm G and via Zoom (contact bklinger@gmu.edu for link)

Oceans have distinctive coastal upwelling zones that can be 4^oC cooler than surroundings.  Climate models still struggle to accurately reproduce the zones, which affect the larger climate system by pulling heat out of the atmosphere.  Ultimately the magnitude of this ocean heat gain must be set by a balance with ocean heat loss somewhere else.  Here we examine ocean-only numerical experiments to address the question: Once the heat enters the ocean in the Peruvian Upwelling Zone, where does it go?  To isolate the upwelling effects, we compare simulations with and without upwelling-favorable winds.  Along the way we tour a near-global gyre associated with the coastal wind, an Ekman-layer overturning circulation, and perturbations to northern hemisphere tropical circulation by southern hemisphere wind.

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Sean Brennan, US Geological Survey – CO2 sequestration

Thursdays, 4:30-5:45 pm

1309 Exploratory Hall

Virtual simulcast in Zoom: https://gmu.zoom.us/j/99939787631

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Laura Haynes, Vassar College – Paleoceanography

Thursdays, 4:30-5:45 pm

Virtual simulcast in Zoom: https://gmu.zoom.us/j/99939787631

This week's edition of CCC has been cancelled.

Fri, 16 Sep, 11:00-12:00, Research Hall 121 (CLIM Lab)

Quasi-monthly AOES discussion of notable recent climate and weather events. Come with an interesting news item. Come to add your two cents. Or just come to listen.