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GFDL Events & Seminars

Visitors without GFDL affiliation attending seminars or other organized events must present government or university issued photo ID or two other forms of identification to gain access to the facility. If an acceptable ID cannot be provided, the Visitor will not be allowed access. If access is granted, the Visitor must sign in and be given a Visitor Badge. The Visitor Badge expires immediately after the seminar.

January 28, 2020

calendar_today Characterizing the Oceanic and Atmospheric Drivers of Spatially Widespread Droughts over the Contiguous United States

person Informal Seminar - Seung Hun Baek (Columbia University)

access_time 10:30 am - 11:30 am

place Location: Smagorinsky Seminar Room

Droughts that achieve extreme spatial extent over the contiguous United States (herein pan-CONUS droughts) pose unique challenges because of their potential to strain multiple water resources simultaneously. Understanding the causes of these extreme droughts is critical given the significant financial damages of these droughts: pan-CONUS droughts in 1988 and 2012, for instance, cost an estimated $40 and $30 billion, respectively. The canonical understanding of oceanic influences on North American hydroclimate would suggest that pan-CONUS droughts are forced by a contemporaneous cold tropical Pacific Ocean and warm tropical Atlantic Ocean. However, analyses using mechanism-denial climate model simulations, observations, and paleoclimate reconstructions demonstrate this not to be the case. The contributions of oceanic and atmospheric variability to pan-CONUS droughts are first investigated using three 16-member ensembles atmospheric models forced with observed sea surface temperatures (SST) from 1856 to 2012. The employed SST forcing fields are either (i) global or restricted to the (ii) tropical Pacific or (iii) tropical Atlantic to isolate the impacts of these two ocean regions on pan-CONUS droughts. Model results show that SST forcing of pan-CONUS droughts originates almost entirely from the tropical Pacific because of atmospheric highs from the northern Pacific to eastern North America established by La Niña conditions, with little contribution from the tropical Atlantic. Notably, in all three model configurations, internal atmospheric variability influences pan-CONUS drought occurrence by as much or more than the ocean forcing and can alone cause pan-CONUS droughts by establishing a dominant high centered over the US Montane West. Model results are compared to and reconciled with the observational record. A millennium-length (850 - 1850 C.E.) perspective on the causes of pan-CONUS droughts is also provided using a new paleo reconstruction product that merges climate model information with multiple climate proxies (including tree rings, ice cores, and corals). Composite analyses show robust association between pan-CONUS drought events and cold tropical Pacific conditions, but not with warm Atlantic conditions. Similarly, self-organizing map analyses shows that pan-CONUS drought years are most commonly associated with a global SST patterns displaying strong La Niña and cold Atlantic conditions. These results show that La Niña events in the tropical Pacific are the principal oceanic influence on pan-CONUS droughts, while variability in the Atlantic has not played a significant role; the oceanic drivers over the paleo record are thus consistent with the model-based findings over the observational record.

January 29, 2020

calendar_today An Introduction to the NOAA Model Diagnostics Task Force (MDTF) Analysis Package and Application to GFDL Model Output

person Lunchtime Seminar - Lunchtime Seminar Series - John Krasting, Wenhao Dong and Tom Jackson (GFDL, UCAR and SAIC respectively)

access_time 12:00 pm - 1:00 pm

place Location: Smagorinsky Seminar Room

Despite decades of research and significant advancements in resolution and complexity, global climate models (GCMs) still suffer from persistent and often common biases that contribute to uncertainty in their projections of weather and climate. The climate and weather forecasting communities have great interest in improving these biases and have sought to better understand the causes and consequences of these long-standing biases. Among these efforts are the development of process-oriented diagnostics (PODs). A POD characterizes a specific physical process or emergent behavior that is found to be closely related to the ability to simulate an observed phenomenon. Applying these designed PODs routinely on model output -- especially in the context of model development -- could lead to improvements aimed at alleviating these model biases. This talk will first describe outcomes of activities by the NOAA Modeling, Analysis, Prediction, and Projections Program (MAPP) Model Diagnostic Task Force (MDTF). The MDTF Diagnostics effort, currently led by the GFDL, builds on prior existing community efforts aimed at developing process-oriented diagnostics. It provides an open-source analysis package that is portable, extensible, and usable to aid the application of PODs to the model development process. Application of this package to three latest GFDL models (i.e. AM4, CM4, and ESM4) will be presented as examples on initial steps towards an evaluation of our model performance and a verification of the capacity and efficiency of the diagnostic package. In the second part, a hands-on training on the use and application of the package will be provided.

January 30, 2020

calendar_today Energetic and heat-engine constraints on the spatial patterns of climate and climate change

person Formal Seminar (approved) - Formal Seminar - Gerard Roe (University of Washington)

access_time 2:00 pm - 3:00 pm

place Location: Smagorinsky Seminar Room

The climate system operates as a thermodynamic heat engine. A surplus of energy in the tropics and a deficit of energy in the high latitudes must be balanced with a poleward transport of energy by atmospheric and oceanic motions that ultimately do work against frictional dissipation. Sadi Carnot understood as much when formulating the laws of thermodynamics in the early nineteenth century. Atmospheric motions carry approximately eighty percent of the maximum poleward energy transport, and latent heat in the form of water vapor is a crucial component of this transport. Thus, the climatic patterns of temperature, evaporation, precipitation, the isotopic composition of water vapor, and even natural aerosols, are all linked through this transport. Recent research has demonstrated that atmospheric energy transport can be usefully approximated as a linear down-gradient transport of moist enthalpy. This single simple rule for transport explains many features of the mean climate, the predicted climate changes under global warming, and the spread of uncertainty among numerical climate models. Among these features are: polar amplification; the poleward migration of the subtropics, storm tracks, and jet stream under warming; uncertainty in model predictions maximizing in polar regions; hydrologic change as a function of climate state; and the sensitivity of the isotopic composition of precipitation to climate change. Speaker email: gerard@ess.washington.edu

January 31, 2020

calendar_today Centennial glacier retreat as categorical evidence of regional climate change

person Informal Seminar - Gerard Roe (University of Washington)

access_time 10:30 am - 11:30 am

place Location: Smagorinsky Seminar Room

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February 5, 2020

calendar_today Impact of Radio Occultation Data on the prediction of Tropical Cyclogenesis

person Lunchtime Seminar - Lunchtime Seminar Series - William Kuo (University Corporation for Atmospheric Research, Boulder, U.S.A. (UCAR))

access_time 12:00 pm - 1:00 pm

place Location: Smagorinsky Seminar Room

Tropical cyclones are one of the most devastating severe weather systems that are responsible for huge loss of lives and properties every year. Accurate prediction of tropical cyclogenesis by numerical models has been a significant challenge, largely because of the lack of observations over the tropical oceans. The atmospheric limb sounding technique, which makes use of radio signals transmitted by global navigation satellite systems (GNSS), has evolved as a robust global observing system. This technique, known as radio occultation (RO) can provide valuable water vapor and temperature observations for the analysis and prediction of tropical cyclogenesis. Using the WRF modeling and data assimilation system, we show that the assimilation of RO data can substantially improve the skills of the model in predicting the tropical cyclogenesis for ten typhoon cases that took place over the Western Pacific from 2008 to 2010. To gain insight on the impact of GPS RO data assimilation, we perform a detailed analysis of the formation process of Typhoon Nuri (2008), and examine how the assimilation of the GPS RO data enables the model to capture the cyclogenesis. The joint Taiwan-U.S. COSMIC-II mission was launched in June 2019. It is currently going through check-out phase, and will provide 5,000 GPS RO data per day over the tropics when it is fully operational. This will provide a great opportunity for research and operational prediction of tropical cyclogenesis. Host: Leo Donner

February 6, 2020

calendar_today Detecting climate change impacts on extreme weather

person Formal Seminar (approved) - Formal Seminar - Kevin Reed (Stony Brook University)

access_time 2:00 pm - 3:00 pm

place Location: Smagorinsky Seminar Room

The next century will see unprecedented changes to the climate system with direct consequences for society. As stated in the National Climate Assessment, "changes in extreme weather events are the primary way that most people experience climate change." In this sense, the characteristics of extreme weather are key indicators of climate change impacts, at both local and regional scales. Understanding potential changes in the location, intensity and structure of such extremes (e.g., tropical cyclones and flooding) is crucial in planning for future adaptation as these events have large economic and social costs. The goal of this work is to better understand climate impacts on extreme weather events in various high-resolution configurations of the Community Atmosphere Model (CAM) run at horizontal grid spacings of approximately 28 km and forced with prescribed sea-surface temperatures and greenhouse gas concentrations for past, present, and future climates. This analysis will include the evaluation of conventional (AMIP-style) decadal simulations typical of climate models, short 7-day ensemble hindcasts of recent devastating events (e.g., Hurricane Florence in 2018), and reduced complexity simulations of idealized states of the climate system. Through this hierarchical modeling approach the impact of climate change on the characteristics (frequency, intensity, rainfall, etc.) of extreme weather, including tropical cyclones, can be quantified. Speaker Email: kevin.a.reed@stonybrook.edu

February 7, 2020

calendar_today TBD

person Informal Seminar - Informal Seminar - Pavel Berloff (Imperial College of London)

access_time 10:30 am - 11:30 am

place Location: Smagorinsky Seminar Room

To be provided

February 10, 2020

calendar_today Simulation of large-scale circulation and properties in the North Atlantic and Southern Ocean in coupled climate models

person Informal Seminar - Informal Seminar - Rebecca Beadling (U of Arizona)

access_time 10:30 am - 11:30 am

place Location: Smagorinsky Seminar Room

The global oceans act as a mediator of Earth's climate due to their role in the storage of heat and carbon. Presently, the oceans account for the storage of approximately 93% of the anthropogenic heat on our planet and ~27% of the anthropogenic CO2. Two regions in particular, the Southern and North Atlantic Ocean (SO,NA), act as gateways for the exchange of CO2 and heat between the atmosphere and the interior ocean, due to the unique deep and intermediate water formation processes that occur here. Large uncertainty exists with respect to understanding how the ocean circulation patterns and properties are projected to change in these regions throughout the 21st century. One avenue of reducing projection uncertainty is through improved representation of ocean circulation and properties in these regions in historical simulations relative to the observational record and through the interpretation of projected trends with knowledge of mean state biases. In the subtropical NA, a key region through which properties from the tropics are advected to the subpolar latitudes, the volume transports of the major flow regimes are reasonably represented in many CMIP5 models relative that observed by the RAPID array at 26oN. As the climate warms, the NA subtropical gyre is weakened in response to a reduced wind stress curl, which acts as a source of significant additional weakening to the northward western boundary current flow. In the SO, despite its dominant role in the oceanic uptake of anthropogenic carbon and heat relative to other basins, the large-scale circulation and properties have been poorly represented in climate models, resulting in low confidence ascribed to 21st century projections of the state of the SO. A comprehensive assessment performed across ensembles of models contributed to the past three CMIP generations (CMIP3 - CMIP6) show improved representation of key observable-metrics in this region including surface wind stress and wind stress curl, strength of the ACC, and density gradients in the region of the ACC. However, some persistent biases have carried over into CMIP6 including an upper ocean that remains too fresh and too warm, significant warm biases at depth in several simulations, and a poor representation of Antarctic sea ice extent. These biases in observable metrics need to be considered when interpreting projected trends or biogeochemical properties in this region.

February 12, 2020

calendar_today Changes in ocean water masses reveal the distribution of excess heat in the climate system

person Lunchtime Seminar - Lunchtime Seminar Series -Prof Jan Zika (University of New South Wales, Sydney, Australia)

access_time 12:00 pm - 1:00 pm

place Location: Smagorinsky Seminar Room

Over 90% of the excess heat trapped in the earth system is contained in the ocean and the consequent thermal expansion was the largest contributor to sea level rise in recent decades. Since 2006 ocean warming and hence sea level rise has been spatially heterogenous, with some regions such as the Southern Ocean showing intense warming and others such as the sub-polar North Atlantic showing intense cooling. This heterogeneity may be due to spatial variability in the rate at which heat added to the ocean at the sea surface propagates into the ocean interior or to changes in circulation which redistribute the existing heat reservoirs within the ocean. However, the importance of these two mechanisms at a regional scale is unclear. Here we show that the spatial variability in warming and sea level rise is dominated by changes in ocean circulation. In some regions the redistribution term is 10 times larger than the excess heat component which is distributed much more homogenously across the oceans. In the North Atlantic, substantial excess heat uptake is balanced by cooling due to redistribution associated with a slowdown in the Atlantic Meridional Overturning Circulation. Both circulation change and heat uptake drive intense warming in the Southern Ocean with an anomalous poleward heat transport of 118 ±50 PW the largest effect. Our results suggest near term projections of sea level change will hinge on understanding and predicting changes in ocean circulation.

February 13, 2020

calendar_today Formal Seminar - Ron Kwok

person Formal Seminar (approved) - Formal Seminar - Ron Kwok (NASA JPL)

access_time 2:00 pm - 3:00 pm

place Location: Smagorinsky Seminar Room

Speakers email: ronald.kwok@jpl.nasa.gov

February 20, 2020

calendar_today Formal Seminar - Pamela Heinselman

person Formal Seminar (approved) - Formal Seminar - Pamela Heinselman (NOAA/NSSL)

access_time 2:00 pm - 3:00 pm

place Location: Smagorinsky Seminar Room

Speaker email: pam.heinselman@noaa.gov

February 27, 2020

calendar_today Formal Seminar - Amy Butler

person Formal Seminar (approved) - Formal Seminar - Amy Butler (NOAA/ESRL)

access_time 2:00 pm - 3:00 pm

place Location: Smagorinsky Seminar Room

Speaker email: Amy.Butler@noaa.gov

March 5, 2020

calendar_today Formal Seminar - Yoshimitsu Chikamoto

person Formal Seminar (approved) - Formal Seminar - Yoshimitsu Chikamoto (Utah State)

access_time 2:00 pm - 3:00 pm

place Location: Smagorinsky Seminar Room

Speaker email: yoshi.chikamoto@usu.edu

March 12, 2020

calendar_today Formal Seminar - Benjamin Poulter

person Formal Seminar (approved) - Formal Seminar - Benjamin Poulter (NASA/GSFC)

access_time 2:00 pm - 3:00 pm

place Location: Smagorinsky Seminar Room

Speaker Email: Benjamin Poulter Benjamin.Poulter@nasa.gov NASA/GSFC Greenbelt/MD/USA Elena.Shevliakova@noaa.gov

March 19, 2020

calendar_today Formal Seminar - Anthony Didlake

person Formal Seminar (approved) - Formal Seminar - Anthony Didlake (Penn State University)

access_time 2:00 pm - 3:00 pm

place Location: Smagorinsky Seminar Room

Speaker email: didlake@psu.edu

March 26, 2020

calendar_today Formal Seminar - Wei Liu

person Formal Seminar (approved) - Formal Seminar - Wei Liu (University of California - Riverside)

access_time 2:00 pm - 3:00 pm

place Location: Smagorinsky Seminar Room

Speaker email: wei.liu@ucr.edu

April 2, 2020

calendar_today Formal Seminar - John Dabiri

person Formal Seminar (approved) - Formal Seminar - John Dabiri (Civil and Engineering Department of Stanford University)

access_time 2:00 pm - 3:00 pm

place Location: Smagorinsky Seminar Room

Speaker email: jodabiri@stanford.edu

April 9, 2020

calendar_today Formal Seminar - Susan van den Heever

person Formal Seminar (approved) - Formal Seminar - Susan van den Heever (Colorado State University)

access_time 2:00 pm - 3:00 pm

place Location: Smagorinsky Seminar Room

speaker email: sue@atmos.colostate.edu

April 16, 2020

calendar_today Formal Seminar - Christian Jakob

person Formal Seminar (approved) - Formal Seminar - Christian Jakob (Monash University)

access_time 2:00 pm - 3:00 pm

place Location: Smagorinsky Seminar Room

speaker email: christian.jakob@monash.edu

April 23, 2020

calendar_today Formal Seminar - Alberto Arribas

person Formal Seminar (approved) - Formal Seminar - Alberto Arribas (MET Office, Exeter UK)

access_time 2:00 pm - 3:00 pm

place Location: Smagorinsky Seminar Room

speaker email: alberto.arribas@informaticslab.co.uk

April 30, 2020

calendar_today Formal Seminar - Gabriele Pfister

person Formal Seminar (approved) - Formal Seminar - Gabriele Pfister (NCAR)

access_time 2:00 pm - 3:00 pm

place Location: Smagorinsky Seminar Room

speaker email: pfister@ucar.edu

May 7, 2020

calendar_today Formal Seminar - Kimberly Prather

person Formal Seminar (approved) - Formal Seminar - Kimberly Prather (UC San Diego)

access_time 2:00 pm - 3:00 pm

place Location: Smagorinsky Seminar Room

speaker email: kprather@ucsd.edu

May 14, 2020

calendar_today Formal Seminar - Sonia Senevirante

person Formal Seminar (approved) - Formal Seminar - Sonia Senevirante (ETH, Zurich Switzerland)

access_time 2:00 pm - 3:00 pm

place Location: Smagorinsky Seminar Room

speaker email: sonia.seneviratne@ethz.ch

May 21, 2020

calendar_today Formal Seminar - William Boos

person Formal Seminar (approved) - Formal Seminar - William Boos (University of California - Berkeley)

access_time 2:00 pm - 3:00 pm

place Location: Smagorinsky Seminar Room

speaker email: william.boos@berkeley.edu

June 4, 2020

calendar_today Formal Seminar - Susan Wijffels

person Formal Seminar (approved) - Formal Seminar - Susan Wijffels (Woods Hole)

access_time 2:00 pm - 3:00 pm

place Location: Smagorinsky Seminar Room

speaker email: swijffels@whoi.edu

June 18, 2020

calendar_today Formal Seminar - I-I Lin

person Formal Seminar (approved) - Formal Seminar - I-I Lin (National Tiawan university)

access_time 2:00 pm - 3:00 pm

place Location: Smagorinsky Seminar Room

speaker email: iilin@as.ntu.edu.tw

June 25, 2020

calendar_today Formal Seminar - Trude Storelvmo

person Formal Seminar (approved) - Formal Seminar - Trude Storelvmo (University of Oslo)

access_time 2:00 pm - 3:00 pm

place Location: Smagorinsky Seminar Room

speaker email: trude.storelvmo@geo.uio.no