AOES Seminars Fall 2015 to Summer 2016
AOES Seminars Summer 2015 to Summer 2016
Geology Seminars Spring 2016
Climate Dynamics Seminars Fall 2015
Geology Seminars Fall 2015
Climate Dynamics Seminars Summer 2015
AOES Seminars
Climate Dynamics Summer 2016
16 Jun: Hongli Ren, Laboratory for Climate Studies, National Climate
Center, Beijing, China
ENSO and annual cycle interaction: The combination mode representation in CMIP5 models
Thu 2-3pm, Research Hall 281 (COLA Conference Rm)
27 Jun: Augustin Vintzileos (NOAA Climate Prediction Center)
Forecasting Excessive Heat Waves at Subseasonal Lead times
Mon 10-11 Research Hall 163
Heatwaves are among the most dangerous, yet invisible, of natural hazards. According to NOAA, the distribution of 30-year based annual mean fatalities from natural hazards in the U.S. ranks as follows; those from heat (130), floods (81), tornadoes (70), lightning (48) and hurricanes (46). Resilience to excessive heat events can be augmented by using multi-scale prognostic systems.
We designed and developed a scalable system for forecasting excessive heat events at lead times beyond Week-1. This system consists of (a) a monitoring/verification component and (b) a forecasting component which in its baseline version uses NOAA’s Global Ensemble Forecast System (GEFS) predictions of temperature and relative humidity from Day-8 to Day-14. In this presentation, we discuss the definition of heat events, sources of predictability and present the forecast skill of the Subseasonal Excessive Heat Outlook System (SEHOS). Finally we argue on the importance of using multi-model approaches in such systems and comment on the possibility to extend forecasts temporally to Weeks 3-4 and geographically to the global tropics and subtropics.
6 Jul: Peitao Peng, (NOAA/NCEP/Climate Prediction Center)
A Comparison of Seasonal SST Forecast Skill: Constructed
Analog vs. NMME
Wed, 1:30-2:30pm, Exploratory Hall 3301
11 Jul: Xuelei Feng, GMU,
Climate Dynamics Dissertation Defense: Understanding Climate Variability and Global Climate Change Using High-resolution GCM Simulations
Mon 1-3pm, Research Hall 281 (COLA Conference Rm)
In this study, two climate processes are examined using long-term simulations from multiple climate models with increasing horizontal resolutions. These simulations include the European Centre for Medium-range Weather Forecasts (ECMWF) atmospheric general circulation model (AGCM) runs (project Athena) and coupled ocean-atmosphere seasonal hindcasts (project Minerva). Both sets are with different AGCM resolutions, the highest at 16 km. A pair of the Community Climate System Model (CCSM) simulations with its ocean general circulation model (OGCM) resolution at 100 and 10 km is also examined, with the latter resolving oceanic mesoscale eddies.
The resolution influence on the precipitation climatology over the Gulf Stream (GS) region is first investigated. In the Athena simulations, the resolution increase generates enhanced mean GS precipitation in both large-scale and subscale rainfalls in the North Atlantic, with the latter more tightly confined near the oceanic front. However, the Minerva runs with the non-eddy resolving OGCM simulates weaker oceanic front in the GS extension, which weaken the mean GS precipitation response. On the other hand, an increase in CCSM oceanic resolutions from non-eddy-resolving to eddy resolving regimes greatly improves the model’s GS precipitation climatology in response to increased SST gradient in the GS extension. Further analyses show that the improvement of the GS precipitation climatology due to resolution increases is caused by the enhanced atmospheric response to sharp SST gradient near the oceanic front, which leads to stronger surface convergence and upper level divergence.
Another focus of this study is the impacts of global warming due to increases in Greenhouse Gases on precipitation using atmospheric Athena model simulations. Two models with spatial resolutions of about 125km and 16 km are examined. During the twenty-first century simulation, there is a higher occurrence of low and heavy rain from the tropics to mid-latitudes at the expense of a decrease in the frequency of moderate rain. In the high latitudes and polar regions, all categories of rain except drizzle increase. The global precipitation amount sensitivities of the high and low-resolution simulations are 1.7%/K and 1.8%/K, comparable to coupled model simulations. The most sensitive response of 6.3-6.8%/K for the heavy rain approaches the Clausius-Clapeyron scaling limit for water vapor. Moreover, in different mean state rainfall areas, the frequency peak of the distribution with intensity linearly increases with climatological regions. The rainfall events within the scope of peak intensities are reduced in a warming climate, while the frequency of events at higher intensities increase in all climatological regions
12 Jul: Emilia Kyung Jin (Korea Inst. of Atmospheric Prediction Systems)
Diurnal Variation of Precipitation during East Asian Summer Monsoon
Tue 1-2pm, Research Hall 163
The realistic simulation of diurnal cycle of precipitating convection, in particular, over land is one of major shortcomings of physical parameterization of NWP models. Over the East Asia region, including Korea, the maximum precipitation is observed in the afternoon and early morning. The observational characteristics of diurnal variations of precipitation are investigated. The impact of cumulus convection parameterization and model resolution on the simulation of diurnal variations of precipitation over East Asia during the summer monsoon period is explored by conducting a suite of ensemble simulations of numerical models.
13 Jul: Karen McKinnon (NCAR)
Sources of subseasonal predictability of US summer temperatures
Wed 10-11am, Research Hall 163
21 Jul: Emerson Nicole LaJoie
Climate Dynamics Dissertation Defense: Changes in Internal Variability Due to Global Warming
Thu 11am-1pm Research Hall Room 163
Extreme weather events can have serious impacts on society, infrastructure, and human life. Evidence is growing that the frequency and intensity of extreme weather events will increase in response to rising greenhouse gas concentrations. However, a consensus has yet to reached as to whether these changes can be explained by a simple shift in the underlying probability distribution, or by a change in shape of the distribution (namely variance) as well. Previous studies have investigated this question by aggregating data across space, but aggregation requires normalizing data in some way to allow data from different geographic regions to be combined into a single distribution. Unfortunately, subsequent studies show that the normalization procedure introduces biases. This dissertation proposes a new methodology for quantifying changes in variance that is rigorous, multivariate,and invariant to linear transformation (and thus independent of normalization). The new methodology is applied to simulations from state-of-the-art climate models and reveals significant changes in seasonal- and annual-mean 2m temperature and precipitation in response to anthropogenic forcing. The models consistently predict decreases in temperature variance in regions of seasonal sea-ice formation and across the Southern Ocean by the end of the twenty- first century. While more than half the models also predict significant changes in variance over ENSO regions, and the North Atlantic Ocean, the direction of this change is model dependent. Models also consistently predict widespread increases to precipitation variability, particularly in the tropics, extratropics, and polar latitudes. Some models predict more than a doubling in variance, raising questions about the adequacy of doubling uncertainty estimates to test robustness in detection and attribution studies.
25 Jul: Yan Jin
Climate Dynamics Dissertation Defense: The Mechanisms Explaining the East Asian Summer Monsoon (EASM) Response to Global Climate Change
Mon, 10-11am, Research Hall Room 281
Global warming induces changes in the mean state of the East Asian Summer Monsoon (EASM) by modifying the western North Pacific Subtropical High (WNPSH). We show that the Super-Parameterized CCSM4 (SP-CCSM4), a coupled climate model which implements a new representation of cloud-scale processes, captures important EASM features better than CCSM4, which has conventional convection parameterization. In a future warmer climate, SP-CCSM4 shows that EASM precipitation and monsoon circulation intensify. Analysis of the simulation reveals a remote air-sea interaction mechanism in which the warming of the boundary conditions, and the convective activity over tropical South China Sea (SCS) and West Pacific Ocean (WP), change the WNPSH. Boundary warming is more important than atmospheric warming and favors WNPSH extending westward, as does weaker convection over SCS and WP. Further numerical experiments confirm the importance of ocean surface warming and reduced SCS and WP convection.
Climate Dynamics Spring 2016
All seminars at 1:30pm on Wednesday unless otherwise noted.
20 Jan: Marat Khairoutdinov (Stony Brook University)
Application of cloud-resolving model to climate-change problem
Wed 2-3pm Research Hall 163
The talk will demonstrate some recent results of application of cloud-resolving model to better understand the role of clouds in climate system. In particular, the results of +4K and 4xCO2 perturbation experiments in so-called Near-Global CRM will be discussed. Also, the results of resolution and microphysics convergence tests and the effect of high-order closure scheme on climate sensitivity in radiative-convective equilibrium simulations will be shown. Finally, recent results of super-parameterized version of the IFS will be presented.
21 Jan: Tal Ezer (Old Dominion University)
Sea level rise and variability along the U.S. east coast and the impact from the Gulf Stream and AMOC
Thu 1:30-2:30pm Research Hall 163
The talk will review recent studies that show how variations in the Atlantic Meridional Overturning Circulation (AMOC) and the Gulf Stream (GS) impact sea level along the U.S. East coast. Data suggest that climate-related slowdown in the GS is already causing an increase in flooding in places like Norfolk, Va. These findings have implications for future sea level rise projections and for studies of past climate change. A way to reconstruct past variations in AMOC from tide gauge records is demonstrated.
4 Feb: Kim Cobb (Georgia Tech)
The 2015/2016 El Nino: climate change or natural variability?
Thu 1:30-2:30, Research Hall 163
9 Feb: Song Yang (Sun Yat-sen University)
Tue, 11:00-12:00, Exploratory Hall 3301
Changes in Climate over Southeast Asia: Response to and Feedback on Global Climate Change
El Niño-Southern Oscillation and the Asian monsoon have experienced significant long-term changes in the past decades. These changes and other factors have in turn led to large climate change signals over Southeast Asia. An attribution analysis of the feedback processes of these signals indicates the predominant importance of water vapor and cloud radiative feedbacks. Experiments with earth system models also show that these regional climate change signals exert significant influences on global climate. The increases in atmospheric heating over Southeast Asia and sea surface temperature in the adjacent oceans in the past decades have weakened the Indian and African monsoons and led to a drying effect over East Asia, explaining several prominent climate features in and outside Southeast Asia.
24 Feb: Kathy Pegion (GMU)
Extratropical Precursors of the El Niño Southern Oscillation: The Elephant of Long-Lead ENSO Prediction
Research Hall 163
We identify the combination of precursors that best fit eastern Pacific (EP) and central Pacific (CP) El Nino-Southern Oscillation (ENSO) indices. The extratropical precursors and their impact on the tropics can be seen a year in advance and therefore extratropically forced ENSO events have a higher potential for long lead predictability than events without an extratropical influence. Although a subset of precursors is selected for the models, evidence of all of the precursors is present when fields are regressed with the modeled CP index. This demonstrates that the precursors are highly interrelated and should be evaluated in a holistic manner rather than as separate mechanisms.
2 Mar: Hendrik Tolman (NOAA)
NWS operational modeling, past present and future
Research Hall 163
The NWS is unique in its prediction mission. Central to the NWS prediction enterprise is the NCEP Production Suite of weather and environmental models. These models are run by NCEP Central Operations (NCO), and are maintained and improved by the Environmental modeling Center (EMC). The presentationwill give some background information on the production suite. The business model is central to the production suite, and is often misunderstood by academia. Moreover, roles of EMC and its partners including academia are rapidly changing. Against this backdrop, external reviews have indicated that the NCEP production suite needs to be re-designed (simplfied). All these aspects of the production suite will be discussed duiring the presentation.
16 Mar: Chris Selman (GMU)
Varying the Intensity of Irrigation and the Impact the Southeastern United States’ Climate
Research Hall 163
The impacts of irrigation on the Southeast United States (SEUS) diurnal climate are investigated using simulations from four regional climate model runs. We find a pronounced decrease in monthly averaged temperatures in irrigated regions, with the diurnal cycle intensifying. The daytime warming is due to diminished low cloud cover. Nighttime and daily-mean cooling are due to repartitioning of energy into latent heat flux over sensible heat flux, and of a higher net downward ground heat flux. Precipitation decreases over irrigated regions, with more dry days and fewer wet days. Despite an increase in moisture flux convergence, there is a large-scale stabilization of the atmosphere stemming from a cooled surface. This stabilization lowers the intensity of stationary precipitation patterns, but is also seen to impact transient frontal passages in the early and late growing season. Lastly, irrigation is implicated in mitigating the intensity of heat waves.
23 Mar: Graduate Student Presentations
Research Hall 163
24 Mar: Kuan-Man Xu (NASA Langley Research Cntr)
Turbulence Closure in Cloud Model and Climate Modeling An Upgraded Multi-scale Modeling Framework (MMF)
Thu, 1:30-2:30, Exploratory Hall 3301
I will provide an overview of an advanced turbulence closure scheme (IPHOC) used in cloud-resolving models (CRMs) and the multi-scale modeling framework (MMF) approach. In MMF, a CRM is embedded into each atmospheric column of a host climate model. CRMs replace the traditional subgrid-scale physical parameterizations in a conventional climate model. In this seminar, we will discuss the climatology simulated in the control simulation. Two sensitivity simulations with doubling of CO2 and an increase of sea surface temperature, respectively, are performed and compared to similar simulations without this advanced turbulence closure in CRMs. The goal of this research is to better understand the role of low-level clouds in climate sensitivity and cloud feedbacks.
30 Mar: Kent Moore (U. Toronto)
An assessment of the changing nature of the winter hydroclimate in eastern North America and its impacts on risk management
Exploratory Hall 3301
The winter hydroclimate of eastern North America has a spatially complex combination of snow and rain stemming in part from the presence of Great Lakes. The region’s winter has warmed by 1-2.5 C over the past 30 years and so its hydroclimate may be changing. Here we use reanalysis and high-resolution Athena model runs to investigate such changes. The model results show that a horizontal resolution below ~40 km is needed to resolve the observed spatial gradients. The mean and 95th percentile snowfall rates have decreased by as much as 20% in the southern part of the region and increased by a similar magnitude in the northwest. Rainfall has increased across the region, with increases exceeding 100% in the vicinity of Lake Superior. Future warming is expected to continue these hydroclimate trends. They impact a number of societal functions, including winter road maintenance, and influence the management of property risks such as flooding.
6 Apr: Steven Pawson (NASA)
Using NASA satellite observations to enhance Earth System Analyses and prediction
2:30-3:30 Research Hall 163
13 Apr: Ning Zeng (U Maryland)
Making SENSE of our environment: monitoring urban air pollution, weather and greenhouse gases with a smart sensor network
Exploratory Hall 3301
70-80% of the world’s fossil fuel CO2 emissions come from cities, where much of the human activities are concentrated. Yet, surprisingly, we know relatively little about the spatial-temporal distributions of CO2 and air pollution in the cities, in part limited by our ability to monitor the atmosphere at urban scales.
We describe an innovative approach using low-cost, moderate-precision, and smart sensor network to monitor urban environmental, based on a University of Maryland project, named SENSE (sense.umd.edu), with participation of a highly interdisciplinary body of students. Our goal is to eventually set up a dense network of approximately 200 sensors around the Baltimore-Washington Metropolitan Region that provides unprecedentedly high spatial-temporal information on weather, air pollution and greenhouse gases (GHGs) in near real time.
I will also spend 5-10 minutes in the beginning of the seminar to describe some work at UMD under the umbrella of Carbon Cycle, Climate and Ecosystem.
19 Apr: Patrick Staton (GMU MS Project presentation)
A shift in attitudes for a shift in climate.
Tue, 9:30-10:30am, Research Hall 256D/E (COLA Library)
This project investigates how an introductory climate science course affected student beliefs about climate change. The study analyzed six years of data from pre and post surveys given to students in George Mason University’s CLIM 101: Weather, Climate, and Society. Although the surveys show that students learned facts related to global warming and shifted their beliefs about climate change, many of the changes were small. This may be partially attributed to students already being aware of the issues of global warming as evidenced by the fact that students tended to overestimate global warming and U.S. CO2 emissions.
Apr 20: Xiaoqin Yan (GMU, Climate Dynamics PhD Defense)
A Systematic Framework for Improving Estimates of Anthropogenic Aerosol Cooling
Wed, 10:30am-12:00, Johnson Center Rm G 337 (note new room)
Advisor: Dr. Timothy DelSole
Committee members: Dr. Edwin K. Schneider, Dr. Barry A. Klinger, Dr. James Gentle
Uncertainty in the cooling effect of aerosols limits observation-based estimates of climate sensitivity to increases in greenhouse gas concentrations. A new measure called “potential detectability” is used to quantify the extent to which a response to climate forcing can be detected in a model. Global joint temperature-precipitation information provides a more accurate estimation of aerosol-forced responses than temperature, precipitation, or sea level pressure individually or in combination. Unfortunately, observational errors in precipitation are too large to permit estimation of aerosol-induced climate changes. Repeating this estimation using only land-data, where reliable rain gauge data are available, succeeds in estimating aerosol cooling, but is only modestly improved by including precipitation data. We show that the time evolution of the response to aerosol forcing can be estimated from observations. This conclusion goes beyond previous studies by using only the spatial structure of the forced response to detect aerosol forcing.
20 Apr: Earth Day Lightning Talks
Research Hall 163
27 Apr: Joe Santanello (NASA)
Research Hall 163
Land-atmosphere (L-A) interactions play a critical role in processes that lead to the persistence of hydrological extremes such as drought. Under the Global Energy and Water Exchanges project and Global Land-Atmosphere System Study (GEWEX-GLASS) panel, the GLACE project (Koster et al., 2004) led to the idea of “hotspots” of L-A coupling, where precipitation is sensitive to soil moisture variability. Subsequently, the local L-A coupling (‘LoCo’; Santanello et al., 2011) project has been examining the diurnal process-level of L-A interactions while focusing on a range of single-column, mesoscale, and climate models confronted with observations. LoCo has produced an array of L-A coupling diagnostics and involves a growing number of (particularly young) scientists from research and operational institutions around the world. This talk will summarize the LoCo effort, discuss the importance of satellite retrieval and model data fusion, and outline current plans for field campaigns and community model intercomparison projects.
3 May: Andrew Light (GMU)
The Path to the Paris Climate Agreement and a Way Forward
Tue, 1:30-2:30pm, Exploratory Hall 3301
In Paris last December over 190 countries succeeded in creating a new agreement at the United Nations Framework Convention on Climate Change. Many have heralded the outcome as a groundbreaking achievement. Others have argued that the commitments for emissions reductions are too weak to achieve the agreement’s lofty aspirations. To understand the significance of the Paris agreement we will review how this outcome evolved from earlier failed attempts in this process. A more important question may be what global climate cooperation is now required of us after Paris. To close the gap between the Paris pledges and what is needed to achieve climate stabilization, we need to look beyond the UN system to find new opportunities for enhanced climate action.
4 May: David DeWitt (NOAA CPC)
Charting a Path Forward at NOAA’s Climate Prediction Center
Research Hall 163
10 May: John McCormack (Naval Research Laboratory)
Can the Stratosphere Improve Extended Range Prediction Capabilities?
Tue 11:00-12:00 Research Hall 163
Abstract: An emerging requirement for numerical weather prediction (NWP) is to extend current capabilities beyond short-range (i.e. 5-day) forecasts out to extended range or seasonal (30-90 days) time scales. One potential source of seasonal predictability is the region of the atmosphere between 10-85 km altitude that includes the stratosphere and mesosphere. This presentation will discuss current research at the Naval Research Laboratory that focuses on first improving the representation of the stratosphere and mesosphere in current NWP forecast models, and then assessing the impact of this improvement on extended range forecast skill using the coupled atmosphere-ocean system being developed under the Earth System Prediction Capability initiative.
Giovanni Conti (CMCC-Italy)
Path Integral, Fokker-Planck Equation and Transitional Matrices in Climate Dynamics
Mon 23 May 1pm Research Hall 163
The Stochastic Ordinary and Partial Differential Equations turn out to be a very important tool in the understanding and modeling the Climate System. The resolution of this kind of problems is far from trivial. The only meaningful quantities are those derived by ensemble mean over the noise using the probability density function of the studied problem. In order to address these issues, three different methods of investigation are presented. The first one is inspired by the Statistical Mechanics and Quantum Field Theory. Its power resides in the fact that it introduces a generating functional, from whom, using functional differentiation, all the n-points functions of the problem can be found. This technique has been used to study three different configurations of the Stochastic Barotropic Vorticity Equation, obtained adding or neglecting damping and mean flow. This technique is applicable but with many technical difficulties. For this reason I have preferred to use a simple ENSO model to test the other two techniques and to study in depth ENSO itself. The second method is based on the resolution of the Fokker-Planck equation, related to the stochastic system, via eigenfunctions expansion. It is suggested a new way to consider ENSO, as a system that can jump between two states, one positive and one negative, represented by a double potential wells which arise by the non-linearity that damps the system. The jumps are possible thanks to the stochastic fluctuations.The investigation prompted the idea that ENSO could be a system described by a sequence of state, rather than a simple oscillation. To check this idea, the third method has been introduced. It is shown how the transition probability matrices can be used to deal climatic phenomena. Temperature anomalies are divided into four blocks, states, and the probability to move from one state to another has been calculated both for observations and General Circulation Model. In particular, these matrices have been used to define a predictability index of ENSO using their entropy.
Spring 2016 Geology Seminar Series
Thursdays, 4:30-5:30 pm, Exploratory Hall 3301
Linda Hinnov, Coordinator, lhinnov@gmu.edu
Jan. 28
Kirby Runyon (Johns Hopkins University)
Crater ejecta emplacement experiments
Feb. 11
Emmy Smith (Smithsonian)
Co-evolution of life, climate, and tectonics
Feb. 25
Jules Goldspeil (Planetary Science Institute)
Mars surface systems
Mar. 17
Matt Carrano (Smithsonian)
Patterns of dinosaur evolution
Mar. 31
Jean Self-Trail (USGS)
The Early Eocene hothouse
Apr. 14
Peter Driscoll (Carnegie Institute)
Evolution of the Earth’s core
Apr. 28
Student presentations
Climate Dynamics Fall 2015
All seminars at 1:30pm on Wednesday unless otherwise noted.
03 Sep: Ahmed Tawfik (NCAR)
Lessons from Seasonal Droughts: How Local Surface-Atmosphere Feedbacks and Global Patterns Work Together
Exploratory Hall 3301
Note seminar is on a Thursday.
09 Sep: Phil Pegion (NOAA/ESRL/PSD and CIRES/U Colorado)
Global Ensemble Forecasting Development at NOAAs Earth System Research Lab
Exploratory Hall 3301
Observations typically lie outside the range of possibilities predicted by numerical weather and climate models. Two approaches to improve reliability: reduce forecast error (hard); produce an ensemble forecast that better represents model uncertainty (less hard). This talk will focus on the improvements to Global Forecast System (GFS) data assimilation system and newly implemented methods for addressing model error during the forecast.
07 Oct: Gabrielle De Lannoy (NASA)
Global Soil Moisture Estimation through Assimilation of Remotely Sensed Microwave Observations from SMOS and SMAP
Exploratory Hall 3301
Improving the estimation of soil moisture at the global scale helps to better monitor floods, droughts and agricultural yield, and to improve weather and climate predictions. Direct global measurements of soil moisture are not available, but two recent satellite missions, SMOS and SMAP, are exploiting the high sensitivity of passive L-band microwave observations to soil moisture. The seminar will discuss the concept of microwave data assimilation for global soil moisture estimation, show results from the multi-year assimilation of SMOS data, and present some initial results of the operational SMAP Level 4 data assimilation product, generated at NASA/GMAO.
14 Oct: Erik Swenson (GMU/COLA)
Simulation of Rossby Wave Breaking and its Dependence on Circulation Regimes: What Horizontal Resolution is Necessary?
Research Hall 163
Rossby Wave Breaking (RWB) is a fundamental process linking sub-seasonal to seasonal climate variability and extreme weather at mid-latitudes. At what horizontal resolution can a model resolve RWB and its circulation dependence? To address this, RWB is examined in multiple sets of re- run at different horizontal resolutions (roughly 0.560, 0.280 and 0.140). Interestingly, results are found to be fairly insensitive to resolution, and robust circulation regimes are well simulated in all re-forecasts. However, RWB is simulated to occur about half as much as observed. A potential explanation for this may be that the model is overly diffusive at the resolutions considered here.
28 Oct: Gregory Jenkins (Penn State University)
The Titans of Climate Change in West Africa: Weather Hazards
Research Hall 163
Global and regional climate models show a trend towards a warmer, drier climate in West Africa with increased radiative forcing in the late 21st century – but what about weather hazards? Weather hazards such as mesoscale convective systems (MCSs), dust storms, tropical disturbances in coastal areas, and coastal flooding exist today and are often responsible for damage, displacement and fatalities. What do we know about the prediction of weather hazards and will these hazards change in the future. I address the various aspects of weather hazards in West Africa and suggest some ideas for protecting vulnerable populations during the coming century.
04 Nov: Emily Becker (NOAA)
Predictability and forecast skill in multi-model ensembles
Exploratory Hall 3301
The North American Multi-Model Ensemble (NMME), a collaboration between several modeling centers from the US and Canada, has been producing real-time monthly-mean and seasonal anomaly forecasts regularly since August, 2011. The NMME system has included between six and eight state-of-the-art coupled climate models for real-time forecasting, and features a database of approximately 30-year retrospective forecasts from eleven models in total. This talk will cover some background on multi-model ensembles, as well as bias correction, model characteristics, deterministic and probabilistic forecasting, and developments in the NMME real-time forecasting system. The results of research studies into forecast skill and potential predictability of 2 m temperature, precipitation rate, and sea-surface temperature using the NMME database of retrospective forecasts will be discussed.
11 Nov: Ben Zaitchik (John Hopkins University)
Causes and Consequences of Climate Variability in the Nile Basin
Research Hall 163
The two headwaters regions of the Nile River – the western Ethiopian Highlands and the Equatorial Lakes of East Africa – lie at the intersection of powerful and competing atmospheric circulations. The Nile basin is prone to significant hydro-political tensions that are fed both by climate variability and by unilateral development of hydrological resources that has set upstream and downstream nations against each other. I will review the drivers of climatic and hydrologic variability affecting the Nile basin. I will then introduce several ongoing studies that target topics of scientific uncertainty and social relevance in the Nile, including drivers of subseasonal precipitation variability, the distributed water balance, tradeoffs in water resource utilization, local climate vulnerability profiles, and the reliability of 21st century climate projections.
18 Nov: Shineng Hu (Yale University)
Exploratory Hall 3301
An Exceptionally Strong Easterly Wind Burst Stalling El Nino of 2014: Links to Decadal Climate Change
The occurrence of two strong westerly wind bursts (WWBs) in early 2014 pushed the ocean-atmosphere system towards El Niño, which remained much weaker than predicted by climate models. Here we find that the occurrence of an unusually strong basin-wide easterly wind burst (EWB) in June was a key factor that impeded the El Niño development. Model experiments with superimposed wind bursts support this conclusion, pointing to inherent limits in El Niño predictability. Further, we show that the spatial structure of the easterly burst matches that of the recently observed decadal trend in wind stress in the tropical Pacific, suggesting potential links between intraseasonal wind bursts and decadal climate variations. Finally, I will talk about the implications for the strong El Niño of 2015, which is still developing and has a good possibility of reaching the magnitude of the 1997 extreme event.
20 Nov: Oluwayemi Garuba (GMU/AOES)
Fri., 11:00am, 281 Research Hall
Dissertation Defense: Mechanisms of Ocean Heat Uptake
Ocean heat uptake of global warming occurs through passive advection/diffusion and through the redistribution of existing temperature gradients due to circulation changes such as weakening of the Atlantic meridional overturning circulation (AMOC). Ocean general circulation model experiments are used to investigate the spatial pattern and mechanisms of passive advection and redistribution of surface warming. The Southern Ocean dominates passive heat uptake, largely through vertical and horizontal diffusion. Advection is more important in the subtropical cells and in the Atlantic high latitudes, both with a short time scale of about 20 years. Redistribution nearly doubles the surface heat input into the Atlantic but makes smaller increases in the Indian and Pacific. The Atlantic and Pacific gain similar amounts of heat though surface heat input, but transport from the other basins doubles the magnitude of heat storage in the Pacific.
02 Dec: Linda Hinnov (GMU/AOES)
Exploratory Hall 3301
Dust on Earth acts as an agent of climate change, directly by radiative forcing of the atmosphere, and indirectly by stimulating primary productivity of the oceans, biosphere and carbon cycle. Dust deposition is associated with the glacial phases of the Late Cenozoic Icehouse and Late Paleozoic Icehouse. Modeling enables identification of regions of dust sourcing, and impacts of dust on radiative balance and biogeochemistry. Climate modeling of the Late Paleozoic indicates dust sources in subtropical Pangaea, with sources increasing during colder climates. The modeled carbon cycle suggests that glacial-phase dust stimulated extreme productivity, potentially increasing algal activity and perturbing ecosystem composition. Recognition of dust preservation in Earth’s remote history opens new avenues for research into the drivers and recorders of climate through time, and into the emerging evidence for complex climatic-biotic interactions. (An NSF Earth-Life-Time collaborative project with Lynn Soreghan, University of Oklahoma; Sarah Aciego, University of Michigan; Nick Heavens, Hampton University; and Carl Simpson, Smithsonian.)
03 Dec: Suphadeep Halder (GMU/COLA)
Showcase, 1:30pm
Impact of land surface initialization and land-atmosphere feedbacks in the NCEP CFSv2 global model on the variability of the Indian summer monsoon
Accurate prediction of the Indian summer monsoon rainfall is not only critical for agriculture but is also challenging. We investigate the impact of land surface initialization strategies and coupled land-atmosphere feedbacks through a suite of seasonal ensemble retrospective forecasts. Results suggest that accurate initialization of soil moisture and snow cover/depth as well as proper representation of snow-atmosphere coupling are important for the sub-seasonal and seasonal forecast. It is also shown that soil moisture memory, variability and land-atmosphere coupling are all crucial in determining the strength of land-atmosphere feedbacks in the model and the variability and predictability of temperature and precipitation. However, biases which appear to be driven by parameterization of atmospheric and land surface processes can affect the coupled feedbacks and land state driven predictability.
09 Dec: Wanqui Wang (NOAA)
256D Research Hall (note new room)
Predictions and predictability of Arctic sea ice on different time scales have received increasing attention, partly because Arctic sea ice has decreased during recent decades and may be linked to weather and climate in lower latitudes. While modelling studies have shown that Arctic sea ice extent is potentially predictable out to eight months or longer, current dynamical operational climate models lose useful prediction skill for interannual sea ice anomalies beyond the first 2-3 months. Understanding the causes of the forecast errors, and the discrepancy between the potential predictability and actual skill, is highly desirable.
We analyze seasonal sea ice prediction in the current NCEP operational Climate Forecast System version 2 (CFSv2), based on retrospective and real-time forecasts from the CFSv2. We will assess the model’s sea ice extent climatology, long-term trend, and interannual anomalies and analyze impacts of the sea ice initialization and model configurations that affect atmosphere/ice and water/ice heat fluxes. Our analysis indicates that improvements in both the initialization system and forecast model are required for more reliable CFS sea ice predictions.
10 Dec: Emma Robinson
CHESS: Trends in evaporative demand in Great Britain
HUB Meeting Rm 1, Thu, 1:30
One challenge for land surface and hydrological modelling is the availability of high-resolution driving data. Motivated by this, we have created a 1km resolution meteorological dataset over Great Britain for the years 1961-2012, primarily intended as a dataset for offline runs of land-surface and hydrological models. It has also provided us with an insight into the changing climate of GB, particularly allowing us to explore changing evaporative demand. In this talk I will present the dataset and the methods used to create it, by interpolating from coarser resolution data. I will also discuss the climate trends in GB, and how these have lead to changing evaporative demand over the past decades.
Fall 2015 Geology Seminar Series
Thursdays, 4:30-5:30 pm, Exploratory Hall 3301
Linda Hinnov, Coordinator, lhinnov@gmu.edu
GEOL Seminar 1: Sep 10
Nora Noffke, Old Dominion University:
Microbial induced sedimentary structures
GEOL Seminar 2: Sep 24
Jay Kaufman, University of Maryland-College Park
Early Earth paleoclimatology
GEOL Special Seminar: Wed Sep 30 1:30-2:30
Mark Uhen, GMU/AOES
Weaving Whales into Cenozoic Earth History
GEOL Seminar 3: Oct 8
Mingsong Li, China University of Geosciences (Wuhan)
General aspects of Chinese geology
GEOL Seminar 4: Oct 22
Ken Livi, Johns Hopkins University
Biomineralization
GEOL Seminar 5: Nov 5
Sarah Penniston-Dorland, University of Maryland-College Park
The subduction zone factory
GEOL Seminar 6: NOTE: FRI. NOV. 20, 12:00
Naomi Levin, Johns Hopkins University
Early human evolution and climate
1309 Exploratory Hall
GEOL Seminar 7: Dec 3
Mike Meyer, Carnegie Institute of Science
The Ediacaran biota
Climate Dynamics Summer 2015
Thu 6 Aug: Erool Palipane
2-3pm, Research Hall rm 163
Atmospheric General Circulation Changes under Global Warming
Advisor: Dr. Edwin K. Schneider
Annular modes describe the change in speed and latitude of atmospheric jet streams. This thesis uses atmospheric general circulation model (AGCM) experiments to investigate the modes’ internal variability and response to global warming. High resolution experiments show that resolving small-scale processes (sub-synoptic and mesoscale) not resolved by CMIP-type climate models improves the realism of the modes. High resolution also increases the previously-described shift in summer southern-hemisphere surface westerly winds. Global warming effects are simulated by forcing large ensembles of AGCM runs with an abrupt change in sea surface temperature. The resulting poleward shift of the zonal wind is strongly influenced by nonlinear interactions between eddies and the mean flow. A budget analysis investigates how eddy wave-breaking, diabatic potential vorticity sources, and other processes affect the wind shift. The change in neffective diffusivity plays the dominant role in the poleward shift of the zonal wind.
