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GFDL Events & Seminars

Poster Expos

Upcoming GFDL events & seminars

Events and seminars
  • September 9, 2015: The role of climate variability and large-scale transport on western US surface ozone means and extremes: Implications for seasonal prediction of air quality
    Meiyun Lin (NOAA/GFDL)
    I will give an overview of our recent publications on the key drivers of western US surface ozone means and extremes, with a particular focus on how climate variability (e.g. ENSO) modulates deep stratospheric ozone intrusions [Lin M. et al., Nature Communications, 2015] and long-range transport of Asian pollution [Lin M. et al., Nature Geoscience,2014]. Advancing this knowledge is directly relevant for an effective implementation of the lowered US ozone standard - A decision by the EPA Administrator is expected in October 2015. Recognizing the link between known modes of climate variability and regional air quality offers an opportunity to develop seasonal forecast, which could allow public education to reduce health effects.
    Time: 12:00 pm - 1:00 pm
    Location: Smagorinsky Seminar Room
  • September 10, 2015: Case Studies in Regional Scale Inverse Modeling: Surface fluxes of CH4 and CO2 from Arctic and Urban/Industrial Sources
    Steve Wofsy (Harvard University)
    We examine the current state-of-the-art for determining regional scale emissions of greenhouse gases and pollutants, using the "top down" approach that combines high resolution assimilated meteorology, spatial information on sources, and atmospheric measurements, using a Lagrangian model framework. We discuss regional to continental (100 -- 1000 km) scale inverse model results for CH4 emissions over North America, including the Northeast, major natural gas production areas, and Alaska, and also CO2 net fluxes over Alaska. Recent advances promise simulations of observed atmospheric concentrations with higher fidelity than possible hitherto. The emerging analytical framework shjould enable us to deliver strong constraints on the loss rates of natural gas to the atmosphere, emissions of greenhouse gases from the Arctic as climate warms, and a range of other scientific questions with strong societal interest.
    Time: 2:00 pm - 3:00 pm
    Location: Smagorinsky Seminar Room
  • September 16, 2015: How does the deep ocean manage to achieve upwelling, and on the thermodynamics of seawater and frazil ice
    Trevor McDougall (University of New South Wales, Sydney, AUS)
    TBD
    Time: 12:00 pm - 1:00 pm
    Location: Smagorinsky Seminar Room
  • September 17, 2015: Modeling the impact of current and future Artic sea ice loss on teh atmosphere
    Lantau Sun (NOAA CIRES Univeristy of Colorado/ESRL)
    Arctic sea ice extent is declining at an accelerating pace, and climate models project a seasonally ice-free Arctic by the middle of this century in response to increasing greenhouse gas (GHG) concentrations. The impact of Arctic sea ice loss on lower latitudes in a changing climate is a topic of current research and highly debated. First, we use a multi-model approach to explore the impact of recent sea ice loss on the winter atmosphere, and specifically, test the hypothesis that “warm Arctic, cold continents” is a symptomatic pattern of climate change. The atmospheric circulation response to the recent sea ice loss alone is found to be non-robust across models. Any surface cooling associated with sea ice loss is appreciably smaller than the warming caused by external radiative forcing. Therefore, the paradigm of climate change is better expressed as “warm Arctic, warm continents” for the Northern Hemisphere during winter. The observed recent cooling trend over Central Asia has likely been a low probability state of internal variability, not a fingerprint of forced response to Arctic sea ice loss. By contrast, the atmospheric response to late 21st century Arctic sea ice loss is larger, and robust across models. The mechanism of the stratospheric and tropospheric circulation response will be explored using NCAR’s “high-top” climate model, Whole Atmosphere Community Climate Model (WACCM). It is also shown that there is a tug of war in winter between the future Arctic sea ice loss and the GHG effect in causing tropospheric circulation changes, consistent with other modeling studies.
    Time: 11:00 am - 12:00 pm
    Location: Smagorinsky Seminar Room
  • September 17, 2015: Warming of Upper Circumpolar Deep Water and Climate Change Impact in West Antarctic Peninsula
    Doug Martinson (Columbia University)
    TBD
    Time: 2:00 pm - 3:00 pm
    Location: Smagorinsky Seminar Room
  • September 23, 2015: On the Process Controlling Antarctic Dense Shelf Warters Outflow
    Gustavo Marques (GFDL)
    Formation of intermediate and abyssal water masses as dense water flows off continental shelves contributes to the lower limb of the meridional overturning circulation. This talk will be focused on two previously unknown processes that may influence the volume flux and physical properties of dense shelf water outflows around Antarctica. First, idealized and realistic numerical simulations will be used to show that Antarctic outflows can excite topographic vorticity waves (TVWs). The modeled waves are sufficiently energetic to play an important role in cross-slope water mass exchanges and Antarctic Bottom Water production. The wave frequency depends on the amount of stretching in the ambient fluid over the outflow and on the background along-slope mean flow. Frequency is higher for steeper bottom slope, larger outflow density anomaly, and stronger westward mean flow. For weak stratification and weak westward along-slope flows typical of the Antarctic slope, wave energy propagates eastward, in the opposite direction from phase velocity. These findings are consistent with recent observations of TVWs in the southern Weddell Sea and with a realistic simulation of the Ross Sea. Second, high-resolution numerical simulations that reveal the formation of a double plume pattern in oceanic outflows will be presented. Double plumes, previously observed in laboratory studies, carry water properties from the shelf into the deep ocean at two distinct depths. An important characteristic of the double plume regime is the flow transition from a supercritical condition, where the Froude number (Fr) is greater than one, to a slower and more uniform subcritical condition (Fr < 1). This transition is associated with an internal hydraulic jump and consequent mixing enhancement. The parameters needed to identify this flow regime will be discussed. These results are the first evidence that the double plume pattern may occur in oceanic environments, such as the Antarctic outflows.
    Time: 12:00 pm - 1:00 pm
    Location: Smagorinsky Seminar Room
  • September 24, 2015: What Has Caused the Global Warming Hiatus Since Year 2000?
    Aiguo Dai ( University at Albany)
    Despite a steady increase in atmospheric greenhouse gases (GHGs), global-mean surface temperature (T) has shown no discernible warming since about 2000, in sharp contrast to model simulations, which on average project strong warming. The recent slowdown in observed surface warming has been attributed to decadal cooling in the tropical Pacific, intensifying trade winds, changes in El Niño activity, increasing volcanic activity and decreasing solar irradiance. Earlier periods of arrested warming have been observed but received much less attention than the recent period, and their causes are poorly understood. Here we analyze observed and model-simulated global T fields to quantify the contributions of internal climate variability (ICV) to decadal changes in global-mean T since 1920. We show that the Interdecadal Pacific Oscillation (IPO) has been associated with large T anomalies over both ocean and land. Combined with another leading mode of ICV, the IPO explains most of the difference between observed and model-simulated rates of decadal change in global-mean T since 1920, and particularly over the so-called ‘hiatus’ period since about2000. We conclude that ICV, mainly through the IPO, was largely responsible for the recent slowdown, as well as for earlier slowdowns and accelerations in global-mean T since 1920, with preferred spatial patterns different from those associated with GHG-induced warming or aerosol-induced cooling. Recent history suggests that the IPO could reverse course and lead to accelerated global warming in the coming decades.
    Time: 2:00 pm - 3:00 pm
    Location: Smagorinsky Seminar Room
  • October 1, 2015: TBD
    Yi Deng (Georgia Institute of Technology)
    TBD
    Time: 2:00 pm - 3:00 pm
    Location: Smagorinsky Seminar Room
  • October 7, 2015: Analytical solution of PBL
    Ben-Jei Tsuang (NOAA)
    TBD
    Time: 12:00 pm - 1:00 pm
    Location: Smagorinsky Seminar Room
  • October 8, 2015: TBD
    Amy Clement (RSMAS - Miami)
    TBD
    Time: 2:00 pm - 3:00 pm
    Location: Smagorinsky Seminar Room
  • October 14, 2015: TBD
    Yohan Ruprich-Robert
    TBD
    Time: 12:00 pm - 1:00 pm
    Location: Smagorinsky Seminar Room
  • October 14, 2015: Impact of bio-geophysical feedback on present climate variability and future climate projection
    Jong-yeon Park (Max Plank Institute for Meteorology)
    TBD
    Time: 11:00 am - 12:00 pm
    Location: Smagorinsky Seminar Room
  • October 22, 2015: TBD
    Mary-Louise Timmermans (Yale University)
    TBD
    Time: 2:00 pm - 3:00 pm
    Location: Smagorinsky Seminar Room
  • November 4, 2015: TBD
    Sarah Purkey
    TBD
    Time: 12:00 pm - 1:00 pm
    Location: Smagorinsky Seminar Room
  • November 13, 2015: TBD
    Tim Plamer (Oxford University)
    TBD
    Time: 10:30 am - 11:30 am
    Location: Smagorinsky Seminar Room
  • November 19, 2015: TBD
    Marty Singh (Harvard University)
    TBD
    Time: 2:00 pm - 3:00 pm
    Location: Smagorinsky Seminar Room
  • December 2, 2015: TBD
    Lorenzo Polvani (Columbia University)
    TBD
    Time: 12:00 pm - 1:00 pm
    Location: Smagorinsky Seminar Room
  • December 3, 2015: TBD
    Jadwig Richter (NCAR, Boulder CO)
    TBD
    Time: 2:00 pm - 3:00 pm
    Location: Smagorinsky Seminar Room
  • December 9, 2015: TBD
    Laura Wilcox (University of Reading, UK)
    TBD
    Time: 12:00 pm - 1:00 pm
    Location: Smagorinsky Seminar Room
  • December 10, 2015: TBD
    Leif Thomas (Standford University)
    TBD
    Time: 2:00 pm - 3:00 pm
    Location: Smagorinsky Seminar Room
  • January 7, 2016: TBD
    Larissa Back (University of Wisconsin-Madison)
    TBD
    Time: 2:00 pm - 3:00 pm
    Location: Smagorinsky Seminar Room
  • January 14, 2016: TBD
    Elizabeth Barnes (Colorado State Univeristy)
    TBD
    Time: 2:00 pm - 3:00 pm
    Location: Smagorinsky Seminar Room
  • January 21, 2016: TBD
    Ed Gerber (NYU)
    TBD
    Time: 2:00 pm - 3:30 pm
    Location: Smagorinsky Seminar Room
  • February 11, 2016: TBD
    Jeff Arnold (U.S. Army Corps of Engineers)
    TBD
    Time: 2:00 pm - 3:00 pm
    Location: Smagorinsky Seminar Room
  • February 18, 2016: TBD
    Colette Heald (MIT)
    TBD
    Time: 2:00 pm - 3:30 pm
    Location: Smagorinsky Seminar Room
  • February 25, 2016: TBD
    Dennis Lettenmaier (UCLA)
    TBD
    Time: 2:00 pm - 3:30 pm
    Location: Smagorinsky Seminar Room

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