GFDL - Geophysical Fluid Dynamics Laboratory

GFDL Events & Seminars

Upcoming GFDL events & seminars

Events and seminars

  • August 15, 2018: Enhanced frequency of Sudden Stratospheric Warming events due to a stronger equatorial Madden-Julian Oscillation, and suppression of Arctic air formation, in warm climates
    Eli Tziperman (Harvard)
    First, it is proposed that in a warmer, higher CO2 world, the expected strengthening of the equatorial Madden-Julian Oscillation (MJO) can lead to more frequent sudden stratospheric warming (SSW) events. This may, in turn, affect tropospheric weather and extreme events. The proposed SSW enhancement mechanism involves an interaction of MJO-forced planetary waves with the mid-latitude tropospheric jet that amplifies its zonal asymmetry. This therefore amplifies the stationary waves generated at the mid-latitudes and propagating to the Arctic Stratosphere, triggering additional SSW events. Second, we consider the process of Arctic air formation currently occurring over northern North America during the winter season's polar night, and leading to extreme cold outbreaks further south. We propose that such Arctic air formation may be suppressed in a warmer climate by a low-cloud feedback. This may explain the existence of frost-intolerant animals and trees such as crocodiles and palm trees that thrived in northern North America 50 Million years ago (Eocene), where current temperatures could be as low as -40C. We further show that the proposed mechanism also explains recent climate observations and future climate projections, both showing an unexplained enhanced and surface-intensified warming over high-latitude continental areas.
    Time: 2:00 pm - 3:15 pm
    Location: Smagorinsky Seminar Room
  • August 15, 2018: AOS Workshop
    AOS Workshop
    AOS Workshop POC: Anna Valerio
    Time: 3:15 pm - 4:45 pm
    Location: Smagorinsky Seminar Room
  • August 16, 2018: Prediction of Extreme Precipitation Associated with Landfalling Tropical Cyclones using the Geophysical Fluid Dynamics Laboratory (GFDL) fvGFS Model
    Kalen Fisher (CICS Intern)
    The 2017 Atlantic hurricane season was very active, producing three major hurricanes that made landfall in the US, with Hurricane Harvey causing the most damage and producing the largest rainfall amounts. The focus of this project is to assess the forecasting skill of extreme precipitation associated with Hurricane Harvey and other 2017 Atlantic tropical cyclones using quantitative verification methods. The NOAA Geophysical Fluid Dynamics Laboratory (GFDL) has developed a Finite Volume Global Forecast System (fvGFS), an improved version of the operational GFS with an upgraded dynamical core and microphysics, and this project verifies the fvGFS forecasts of precipitation against the National Center for Environmental Prediction (NCEP) Stage IV data. The National Center for Atmospheric Research (NCAR) Meteorological Evaluation Tools (MET) verification package is used to quantitatively assess the forecast skill. Using MET, the 13-km fvGFS forecast skill is compared against the skill of two operational models, the 13-km GFS and 3-km NAM. The skill metrics considered include the Equitable Threat Score and Multiplicative Bias, which are assessed for different accumulated precipitation thresholds.
    Time: 12:15 pm - 12:30 pm
    Location: Smagorinsky Seminar Room
  • August 16, 2018: Survey and contextualization of various physiological effects of past, present and future pCO2 on fish
    Annika Barth (Intern)
    We reviewed over 40 studies to characterize the robustness of physiological responses to ocean acidification in marine organisms and explore appropriate methods for better representing fish physiological responses in ecosystem models. These responses included, but were not limited to increased otolith size, altered growth and survival, and impaired neurosensory function – the latter of which is attributed to acid base regulation and excitation of gamma-aminobutyric acid receptor. As most studies considered only a few levels of pCO2, we provide a more complete quantification of the anticipated emergence of these effects over past, present and projected future scenarios.
    Time: 12:30 pm - 1:00 pm
    Location: Smagorinsky Seminar Room
  • August 16, 2018: Bridging observations, theory and models of the El Nino/Southern Oscillation
    Pedro DiNezio (University of Texas)
    New ideas on the dynamics and predictability of the ENSO phenomenon focusing on its oscillatory behavior and asymmetries between El Niño and La Niña.
    Time: 10:00 am - 11:15 am
    Location: Smagorinsky Seminar Room
  • August 16, 2018: A spring view of El Nino Diversity
    Shang-Ping Xie (University of California, San Diego)
    The eastern tropical Pacific features strong climatic asymmetry across the equator, with the intertropical convergence zone (ITCZ) displaced north of the equator most of time. In February-April (FMA), the seasonal warming in the Southern and cooling in the Northern Hemisphere weaken the climatic asymmetry, and a double ITCZ appears with a zonal rain band on either side of the equator. The relative strength between the northern and southern ITCZ varies from one year to another and this meridional seesaw results from ocean-atmosphere coupling. Surprisingly this meridional seesaw is triggered by El Niño-Southern Oscillation (ENSO) of moderate amplitudes. Although ENSO is originally symmetric about the equator, the asymmetry in the mean climate in the preceding season introduces asymmetric perturbations, which are then preferentially amplified by coupled ocean-atmosphere feedback in FMA when deep convection is sensitive to small changes in cross-equatorial gradient of sea surface temperature. Moderate ENSO follows a distinct decay trajectory in FMA than extreme El Niño. Moderate El Niño dissipates rapidly as southerly cross-equatorial wind anomalies intensify ocean upwelling south of the equator. In contrast, extreme El Niño remains strong through FMA as enhanced deep convection causes westerly wind anomalies to intrude and suppress ocean upwelling in the eastern equatorial Pacific.
    Time: 2:00 pm - 3:15 pm
    Location: Smagorinsky Seminar Room
  • August 16, 2018: AOS Workshop
    AOS Workshop
    AOS Workshop POC: Anna Valerio
    Time: 11:15 am - 2:00 pm
    Location: Smagorinsky Seminar Room
  • August 16, 2018: AOS Workshop Panel Discussion
    Pedro DiNezio, Nat Johnson, George Philander, Eli Tziperman, Shang-Ping Xie
    1. What are the most important known unknowns about ENSO? 2. What lessons from our successes in learning about ENSO (especially in the last decade) can we apply to studying other modes of natural variability? 3. Is our ability to use paleorecords to study ENSO limited by data quality or by a gulf between paleoclimatologists and atmopsheric and oceanic scientists?
    Time: 3:30 pm - 4:45 pm
    Location: Smagorinsky Seminar Room
  • August 28, 2018: Carbon Cycling on the Great Baham Bank
    Emily Geyman (Hollings Intern)
    Much of our understanding of Earth history comes from shallow water carbonates because deep ocean archives tend to get metamorphosed or subducted at plate margins. However, little work has been done to calibrate how ocean chemistry is recorded in modern carbonates. As a result, interpretations of climate and environmental change from ancient stratigraphy have large and unquantified uncertainties. I integrate measurements of carbon and oxygen isotopes in the water column and modern carbonate sediments on the Great Bahama Bank with simple box model frameworks to understand how water and sediment chemistry evolve as water moves from the open ocean to the increasingly restricted shelfal waters. Ultimately, my study of the modern Bahamas serves as a calibration study to better assess whether the isotopic fluctuations in ancient stratigraphy represent global changes in ocean chemistry rather than natural intra-shelf variability.
    Time: 12:00 pm - 1:00 pm
    Location: Smagorinsky Seminar Room
  • August 29, 2018: Using PCA and storm tracking to characterize AM4 ensembles
    Lunchtime Seminar - Erixen Cruz (Engility Intern)
    Differences between ensembles of year long AM4 model runs are explored with metrics from principal component analysis and a simple hurricane tracker. They are strapped into pyCECT to see how they can help differentiate ensembles with statistical significance. These new metrics will help in determining whether different runs produce different climates, disregarding bit-for-bit reproducibility. POC is Chris Dupuis, ext. 5396
    Time: 12:30 pm - 1:00 pm
    Location: Smagorinsky Seminar Room
  • August 29, 2018: Analyzing climate data with parallelized empirical orthogonal functions
    Lunchtime Seminar - Curtis Bechtel (Engility Intern)
    Empirical orthogonal function (EOF) analysis is a statistical method that can be used to find the underlying patterns and relationships among variables while filtering out unwanted noise. However, the calculation of EOFs can be difficult and computationally expensive, so we developed a C++ toolset that simplifies this process for the end-user and allows for easy analysis of large climate datasets. Chris Dupuis, ext. 5396
    Time: 12:00 pm - 12:30 pm
    Location: Smagorinsky Seminar Room
  • September 13, 2018: A new look at Atlantic-European weather regimes: physical processes governing their life cycles and applications
    Formal seminar - Christian Grams (Institute for Meteorology and Climate Research, KIT, Karlsruhe, Germany)
    The large-scale midlatitude flow is dominated by Rossby wave activity along the upper-level midlatitude wave guide and jet stream. In the Atlantic-European region this activity occurs in preferred quasi-stationary, persistent, and recurrent states, so-called weather regimes. Weather regimes explain most of the atmospheric variability on sub-seasonal time scales. An extended definition of year-round Atlantic-European weather regimes based on 37 years of ERA-Interim reanalysis data helps to elucidate the physical processes governing their life cycles. A specific focus lays on the role of atmospheric blocking and of diabatic outflow driven by cloud-condensational processes at distinct weather regime life cycle stages. Weather regimes help to assess the potential for extreme weather as discussed exemplarily for atmospheric river occurrence in Europe. Also they help to understand multi-day volatility in continent-scale, near-surface wind speed with important implications for the planning of wind farm deployment across Europe. Finally, a recent forecast bust demonstrates the challenges in predictability imposed by the multi-scale interactions governing weather regime life cycles.
    Time: 2:00 pm - 3:00 pm
    Location: Smagorinsky Seminar Room
  • September 19, 2018: Does the Southern Ocean have sleep apnea?
    Lunchtime Seminar Series - Paul Spence (University of New South Wales, Sydney Australia)
    Satellite microwave observations of Antarctic sea ice started in 1973, just in time to capture a massive open water area enclosed in winter sea ice, known as a polynya, within the Weddell Sea. This polynya was roughly the size of the United Kingdom and it lasted thru the winters of 1974-1976 with mixed layer depths >3000m observed in its vicinity. A similar Weddell Sea polynya hasn’t been seen since. However, September 2017 satellite observations indicate that a new Weddell Sea polynya may be starting to form. This first aim of this research is to determine the impact (magnitude and duration) of the 1970s polynya on ocean carbon, biology, temperature, and volume transports. Secondly, how will the formation of a new large polynya in 2018 impact 21st century climate projections? We address these questions with a coupled ocean (MOM5), sea-ice (SIS), biogeochemistry (WOMBAT) model at ¼° resolution with 50 vertical levels. In the model, we create a polynyas of similar size and duration as observed in the 1970s with a small wind perturbation localised over Maude Rise in 1973 and 2017. We find that most of the observed warming trend of AABW and the slowdown of the lower cell of the Southern Ocean overturning since the 1980s can be attributed to the multi-decadal recovery from the 1970s Weddell Sea polynya event. The polynya also increases oxygen concentrations by 50% and the ocean-to-atmosphere carbon flux by >200% in the Atlantic sector of the Southern Ocean. In essence, the Southern Ocean breathed deeply from 1974-1976, and has been holding its breath since. If the Southern Ocean starts breathing deeply again in the winter of 2018, the climate impacts will be pronounced and last for decades to come.
    Time: 12:00 pm - 1:00 pm
    Location: Smagorinsky Seminar Room
  • October 29, 2018: Understanding and Modeling the Earth's Climate: A symposium in honor of Isaac Held
    Isaac Held Symposium
    This three-day symposium will foster scientific exchange at the interface of atmospheric and climate dynamics, celebrating Isaac Held's seminal contributions in advancing our understanding of the Earth's climate. A set of invited talks will provide the broad context for panel discussions and poster sessions that will address Isaac's core interests which include atmospheric general circulation, teleconnections, dynamical insights on climate change, geophysical turbulence, and tropical dynamics. Registration required. The symposium will be held in the Frick Chemistry Lab/Taylor Auditorium, Princeton, New Jersey. Program and additional information at splash.princeton.edu/heldfest
    Time: 8:00 am - 6:00 pm
    Location: Other (see event description)
  • October 30, 2018: Understanding and Modeling the Earth's Climate: A symposium in honor of Isaac Held
    Isaac Held Symposium
    This three-day symposium will foster scientific exchange at the interface of atmospheric and climate dynamics, celebrating Isaac Held's seminal contributions in advancing our understanding of the Earth's climate. A set of invited talks will provide the broad context for panel discussions and poster sessions that will address Isaac's core interests which include atmospheric general circulation, teleconnections, dynamical insights on climate change, geophysical turbulence, and tropical dynamics. Registration required. The symposium will be held in the Frick Chemistry Lab/Taylor Auditorium, Princeton, New Jersey. Program and additional information at splash.princeton.edu/heldfest
    Time: 8:00 am - 6:00 pm
    Location: Other (see event description)
  • October 31, 2018: Understanding and Modeling the Earth's Climate: A symposium in honor of Isaac Held
    Isaac Held Symposium
    This three-day symposium will foster scientific exchange at the interface of atmospheric and climate dynamics, celebrating Isaac Held's seminal contributions in advancing our understanding of the Earth's climate. A set of invited talks will provide the broad context for panel discussions and poster sessions that will address Isaac's core interests which include atmospheric general circulation, teleconnections, dynamical insights on climate change, geophysical turbulence, and tropical dynamics. Registration required. The symposium will be held in the Frick Chemistry Lab/Taylor Auditorium, Princeton, New Jersey. Program and additional information at splash.princeton.edu/heldfest
    Time: 8:00 am - 6:00 pm
    Location: Other (see event description)
  • February 14, 2019: TBD
    Formal Seminar
    TBD
    Time: 2:00 pm - 3:00 pm
    Location: Smagorinsky Seminar Room

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