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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.

November 14, 2019

calendar_today The Strength of Low Cloud Feedbacks and Tropical Climate

person Formal Seminar (approved) - Nathalie Burls (George Mason University)

access_time 2:00 pm - 3:00 pm

place Location: Smagorinsky Seminar Room

The spread in equilibrium climate sensitivity (ECS) across climate models is largely attributable to variability in the strength of their low cloud feedbacks. This raises the question: What are the regional implications for key features of tropical climate of globally weak versus strong low-cloud feedbacks in response to greenhouse gas-induced warming? To address this question, we perform a suite of idealized, fully-coupled and slab-ocean, climate simulations across which we systematically scale the strength of the low cloud cover (LCC) feedback under abrupt 2xCO2 forcing within a single model, thereby isolating the impact of this feedback. The unperturbed decrease in low cloud cover (LCC) under 2xCO2 is greatest in the mid- and high-latitude oceans, and the subtropical eastern Pacific and Atlantic, a pattern that is magnified as the feedback strength is scaled. Consequently, sea surface temperature (SST) increases more in these regions as well as the Pacific cold tongue. As the strength of the low-cloud feedback increases this results in not only increased ECS, but also an enhanced reduction of the large-scale zonal and meridional SST gradients, with implications for the atmospheric Hadley and Walker circulations, as well as the hydrological cycle. The centennial to millennial transient adjustment under the range of LCC feedback strengths imposed, as well as the relevance of our results to simulating both 20th century warming and past warm climates, will also be discussed. Speaker Email: nburls@gmu.edu

November 18, 2019

calendar_today Unravelling Arctic sea-ice impacts on extratropical cold winters

person Informal Seminar - Informal Seminar - Yeonsoo Jang (Pohang University of Science and Tech)

access_time 10:30 am - 11:30 am

place Location: 317 Seminar Room

In recent decades, midlatitude continents frequently experienced severe winters despite increasing greenhouse gas concentrations. Several observational and modelling studies have suggested that the Arctic-to-midlatitude connection might have played a central role in the cold winters. However, it is highly controversial whether the Arctic-to-midlatitude connection is indeed driven by the Arctic sea-ice variability or is simply the result of internal atmospheric processes. Here we unravel this issue by presenting a time-varying midlatitude temperature response to the Arctic sea-ice variability. The low sea-ice concentration over the Barents-Kara-Laptev Seas in autumn typically leads cold Eurasian winters, suggesting delayed impacts that cannot be explained by internal atmospheric processes. More importantly, it is shown that the Arctic-to-midlatitude connection depends on the state of autumn atmospheric circulation. When the autumn sea-ice reduction is accompanied by anticyclonic circulation over northern Eurasia, Eurasia becomes anomalously cold in the early winter via the intensified continent high and monsoon trough. However, when cyclonic circulation is dominant, distinctive Eurasian cold anomalies appear in the late winter. This seasonally-delayed response is further found to be related to the wind-driven sea-ice drift that causes warm anomalies over the Barents-Kara-Laptev Seas in the following winter. These results indicate that the recent Eurasian cold winters could be largely explained by their forced response to the low Arctic sea-ice concentration.

November 20, 2019

calendar_today On the logarithmic scaling and spatial variations of CO2 forcing

person Lunchtime Seminar - Lunchtime Seminar - Nadir Jeevanjee (Princeton AOS)

access_time 12:00 pm - 1:00 pm

place Location: Smagorinsky Seminar Room

The logarithmic scaling of CO2 forcing is well-known and well-tested, but not very well understood in the sense that multiple unrelated explanations for it exist in the literature. Less well-known is the spatial heterogeneity in CO2 forcing, which varies from negligible or even negative values near the poles to much larger values in the tropics. In this talk I present a first principles, analytical model for CO2 forcing which captures both the logarithmic scaling of the forcing as well as these spatial variations, and which provides basic insight into both.

November 21, 2019

calendar_today Examining Northern Hemisphere Autumnal Stratospheric Variability in Subseasonal-to-Seasonal (S2S) Prediction Models

person Formal Seminar (approved) - Andrea Lang (University of Albany)

access_time 2:00 pm - 3:00 pm

place Location: Smagorinsky Seminar Room

This talk will examine S2S prediction skill associated with tropical-extratropical interaction and the impacts of stratospheric variability on the troposphere. This talk will examine the occurrences of the extratropical-transition (ET) of tropical cyclones in producing early, weak stratospheric polar vortex events that extended the period of influence of an ET's impact on the extratropical waveguide. Using the S2S Prediction Project database, the analysis highlights 1996 and 2016, two seasons where sequential ET events, in the North Atlantic then North Pacific, resulted in large amplitude planetary wavenumber 2 patterns that influenced the stratospheric circulation. Both events produced anomalous upward wave activity flux into the stratosphere and a weak stratospheric vortex. The impacts were enhanced negative Arctic Oscillation (Northern Annular Mode) conditions, associated with cold air outbreaks and high impact weather, for approximately 4 weeks. Analysis of similar events from the 1996-2010 period, available in S2S Prediction Project hindcast data, reveals the implications of resolving the stratospheric variability and the horizon of forecast skill for this sequence of events. The second part of the talk explores these results and considers S2S tropical variability from the MJO, ENSO and the QBO to examine variability of the location, frequency, and duration of October and November ET events. The analysis shows that the sign of the QBO influences not only the frequency of ET events, but also the latitude of intense extratropical cyclones. The mechanisms of the QBO to influence weather systems are discussed in the context of these early season weak vortex events and S2S prediction. Speaker Email: alang@albany.edu

November 22, 2019

calendar_today Dr. Kikuro Miyakoda Symposium

person Special Event - Dr. Kikuro Miyakoda Symposium

access_time 12:00 pm - 5:00 pm

place Location: Smagorinsky Seminar Room

Dr. Kikuro Miyakoda Symposium will highlight Kikuro's life achievements in the world of Science. A memorial coordinated by his Daughter will be in the morning.

December 3, 2019

calendar_today To be provided

person Informal Seminar - Informal Seminar Schedule - Laura Wilcox (University of Reading, UK)

access_time 10:30 am - 11:30 am

place Location: Smagorinsky Seminar Room

To be provided

December 4, 2019

calendar_today The role of Cloud physics in the TC intensity prediction

person Lunchtime Seminar - Lunchtime Seminar Series -Alexander Khain (Hebrew University - Isreal)

access_time 12:00 pm - 1:00 pm

place Location: Smagorinsky Seminar Room

In the presentation I'll discuss the role of clouds in formation of convective heating in the TC central zone, to present an overview of the methods of cloud description focusing on the explicit bulk and bin schemes, with stressing advantages and disadvantages of the methods. I will present comparison of different microphysical schemes in simulation of TC intensity and, finally, I'll speak (as an example of importance and ability of bin-microphysics) about the role of aerosols and sea spray on TC evolution and intensity. We will see how these factors affect the structure and intensity of TC at different stages of Tc evolution. POC: Morris Bender.

December 5, 2019

calendar_today Formal Seminar - Brian Tang

person Formal Seminar (approved) - Formal Seminar - Brian Tang (University of Albany )

access_time 2:00 pm - 3:00 pm

place Location: Smagorinsky Seminar Room

Speaker Email: btang@albany.edu

December 5, 2019

calendar_today Eddy Saturation

person Informal Seminar - Navid Constantinou (Australian National University)

access_time 10:30 am - 11:30 am

place Location: 317 Seminar Room

Eddy Saturation

December 19, 2019

calendar_today Formal Seminar - Wei-Jun Cai

person Formal Seminar (approved) - Formal Seminar - Wei-Jun Cai (University of Delaware)

access_time 2:00 pm - 3:00 pm

place Location: Smagorinsky Seminar Room

Speaker Email: wcai@udel.edu

January 8, 2020

calendar_today Progress in quantifying the effective radiative forcing due to aerosol-cloud interactions

person Lunchtime Seminar - Lunchtime Seminar Series - Johannes Quaas (Universität Leipzig, Institute for Meteorology, Leipzig University, Germany)

access_time 12:00 pm - 1:00 pm

place Location: Smagorinsky Seminar Room

The effective radiative forcing due to aerosol-cloud interaction, ERFaci, is composed of the radiative forcing due to aerosol-cloud interactions, RFaci (Twomey effect) that is the immediate response of cloud albedo to an increase in droplet number concentration, Nd. Previous satellite-based quantifications of this effect were hampered by deficiencies in the retrieval of aerosol and also Nd. The talk will firstly discuss progress in this regard, which leads to a stronger estimated RFaci than previous satellite-based approaches. The other component of ERFaci is in the cloud adjustments. These can be split into adjustments of cloud fraction, f, and liquid water path, L. In terms of the latter, statistical relationships between L and Nd show on average negative adjustments of L (a positive forcing component). In turn, the analysis of ship-, volcano- and industry tracks leads to an estimated small overall effect on L; these results are trustworthy since a cause-effect relation is assured. In terms of the f adjustment, the current results point to an increase in cloud fraction at larger Nd. It is unclear which processes lead to this result. The talk will also briefly discuss how cloud-resolving simulations may help to better understand the remaining uncertainties. In the last part, a brief discussion will be presented on initial steps towards an estimate of the response of cirrus to anthropogenic aerosols.

January 9, 2020

calendar_today Formal Seminar - Bob Kopp

person Formal Seminar (approved) - Formal Seminar - Bob Kopp (Rutgers University)

access_time 2:00 pm - 3:00 pm

place Location: Smagorinsky Seminar Room

Speakers Email: robert.kopp@rutgers.edu

January 22, 2020

calendar_today TBD

person Lunchtime Seminar - David Lindo-Atichati (College of Staten Island, CUNY)

access_time 12:00 pm - 1:00 pm

place Location: Smagorinsky Seminar Room

To Be Announced. POC: Sonya Legg

January 23, 2020

calendar_today Formal Seminar - Kyle Armour

person Formal Seminar (approved) - Formal Seminar - Kyle Armour (University of Washington )

access_time 2:00 pm - 3:00 pm

place Location: Smagorinsky Seminar Room

Speakers Email: karmour@uw.edu

January 30, 2020

calendar_today Formal Seminar - Gerard Roe

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

access_time 2:00 pm - 3:00 pm

place Location: Smagorinsky Seminar Room

Speaker email: gerard@ess.washington.edu

February 5, 2020

calendar_today TBD

person Lunchtime Seminar - Lunchtime Seminar Series - Pavel Berloff (Imperial College of London)

access_time 12:00 pm - 1:00 pm

place Location: Smagorinsky Seminar Room

To be provided

February 6, 2020

calendar_today Formal Seminar - Kevin Reed

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

access_time 2:00 pm - 3:00 pm

place Location: Smagorinsky Seminar Room

Speaker Email: kevin.a.reed@stonybrook.edu

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