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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.

February 25, 2020

calendar_today Couplings in the Pacific in a changing climate: Theories, Observations, and Models

person Informal Seminar - Informal Seminar - Youngji Joh (postdoc candidate) (Georgia Institute of Technology)

access_time 10:30 am - 11:30 am

place Location: Smagorinsky Seminar Room

Pacific climate and weather extremes including heatwaves, drought, and hydrological hazard, which drive significant impact on the U.S. community and thus have been paid great attention, are dynamically linked to not only local air-sea interactions, but also large-scale climate variability (e.g., Pacific decadal variability and El Niño Southern Oscillation). This study aims at improving the theories of climate coupling within the North Pacific and across to the central tropical Pacific with investigating their response to anthropogenic forcing. Using multiple observational reanalyses and global climate model ensembles, we first show that winter ocean temperature extremes over the Northeast Pacific significantly resemble the representations of the North Pacific decadal variability (e.g., North Pacific Gyre Oscillation, NPGO and Pacific Decadal Oscillation, PDO). We find that the multi-year warm anomalies in the Northeast Pacific are associated with the consecutive occurrences of NPGO-like and PDO-like ocean signatures via ENSO atmospheric teleconnections. The results suggest that the increasing coupling between NPGO and PDO leads to the prolonged North Pacific marine heatwaves, and those warm events are becoming stronger in amplitude with a larger area under anthropogenic forcing. Combining satellite data with several observation reanalysis products, we next offer observational evidence revealing that a preferred decadal timescale (~10yrs) in the North Pacific western boundary current system, the Kuroshio Extension (KE) region, may arise from an interaction with the central tropical Pacific (CP) (e.g., CP-ENSO). The results show that the KE decadal dynamic state can drive a persistent downstream wind stress curl that projects on atmospheric forcing of the CP-ENSO, which in turn excites westward oceanic Rossby waves in the central North Pacific that reach the western boundary back. Consistent with this hypothesis, the cross-correlation function between the KE and CP-ENSO indices exhibits a significant sinusoidal shape corresponding to a preferred spectral power at 10yrs. Using high-resolution coupled climate models, we finally show that the decadal KE dynamics are not independent of the central tropics and their coupling is becoming stronger under anthropogenic forcing. The results suggest that a higher amplitude quasi-decadal KE/CP-ENSO sequence under warmer climate may allow a stronger basis for decadal predictions of Pacific climate variability, further for societally relevant biogeochemical quantities (e.g., salinity, oxygen, and chlorophyll-A) and fisheries.

February 26, 2020

calendar_today Field-scale land surface modeling and remote sensing for hydrologic predictions at the decision-making scales

person Lunchtime Seminar - Lunchtime Seminar Series - Noemi Vergopolan (Civil and Environmental Engineering Department at Princeton University (postdoc )

access_time 12:00 pm - 1:00 pm

place Location: Smagorinsky Seminar Room

Accurate and detailed information on soil moisture is critical for estimating agricultural water demands, forecasting extreme drought and flood events, monitoring wildfires and landslides, understanding the spatiotemporal distribution of species, and providing initial conditions for climate models and numerical weather prediction. One of the challenges in monitoring and predicting soil moisture dynamics is the gap in spatial scales between observations, models, and applications. While in-situ observations are sparse and expensive, microwave satellite retrievals can cover the entire globe but are only available at coarse scales (36 km). A promising path forward to overcome this scale gap is to combine physical models and observations. However, most of the land surface models used for this purpose still operate at coarser scales (5-25 km) than what is required at the stakeholder's level decision-making (1-100 m). Also, these models often do not account for human activities that influence soil moisture dynamics, such as irrigation, groundwater pumping, reservoir operation, etc. To address this gap, I am continuing the development of HydroBlocks, a field-scale land surface model that takes advantage of big data, machine learning, and high-performance computing to model the land surface processes at an effective 30-m spatial resolution. HydroBlocks solves the field-scale spatial heterogeneity of the landscape through interacting Hydrologic Response Units (HRUs), also known as tiles or mosaics. In this presentation, I will demonstrate how HydroBlocks' HRUs can be leveraged to improve soil moisture predictions at relevant scales for water resources decision-making. More specifically, (i) I will show how this framework can be used for HRU-based assimilation and downscaling of coarse-scale microwave satellite soil moisture to 30-m spatial resolution. For this purpose, radiative transfer modeling and Bayesian merging are used to combine field-scale estimated and satellite observed brightness temperature, to subsequently retrieve updated soil moisture estimates. Also, (ii) I will present a water management module I developed for HydroBlocks to account for the influence of human activities on the simulation of soil moisture dynamics. This module quantifies at fine-spatial scales the impact of surface and groundwater withdraws to meet agricultural, livestock, domestic, and industrial water demands. In specific, I will show results that demonstrate the effects of irrigation from groundwater pumping on the land surface fluxes at agricultural regions in Nebraska. This work paves the way towards hydrologically consistent field-scale soil moisture estimates. It highlights the value of land surface modeling to bridge the gap between coarse-scale satellite retrievals and field-scale hydrological applications.

February 27, 2020

calendar_today tratospheric polar vortex influence on sub-seasonal predictive skill of near-surface temperature

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

access_time 2:00 pm - 3:00 pm

place Location: Smagorinsky Seminar Room

Stratospheric variability is an important potential source of predictive skill of surface weather on sub-seasonal to seasonal (S2S) timescales. In particular, variations of the stratospheric polar vortex can perturb the large-scale extratropical circulation for weeks to months. In this seminar I will show the influence of initializing forecasts during weak and strong Northern Hemisphere polar vortex events, and during the springtime breakdown of the vortex (the so-called "final warming"), on weeks 3-4 predictive skill of near-surface temperature. In general, skill increases and root mean square error decreases across the Northern Hemisphere for forecasts initialized during weak and strong vortex events and early final warming events relative to control forecasts; but in some regions, skill decreases. I will also briefly discuss the most recent disruption of the Southern Hemisphere polar vortex and how it influenced the forecast for the anomalously hot and dry austral spring in 2019. These results come in part from international community efforts within WCRP/SPARC to analyze the S2S project database of historical forecasts in order to better understand how stratospheric information contributes to surface predictive skill. Speaker email: Amy.Butler@noaa.gov

February 28, 2020

calendar_today Surface and Boundary-Layer Interactions in Continental Convection: Improving convective-scale simulations through better representation of turbulence and land-surface heterogeneity

person Informal Seminar - Informal Seminar - MadhuLatha Akkisetti (Korean Institute of Atmospheric Prediction Systems)

access_time 11:00 am - 12:15 pm

place Location: Smagorinsky Seminar Room

Convective storms and especially organized deep convective systems are a crucial source of precipitation during what would otherwise be a hot, dry summer over continental regions. In some areas, particularly agricultural regions like the central US, convective systems are the principal source of rain during the warm season. However these systems also pose hazards to life and property as severe convective storms bring flooding, frequent cloud to ground lightning, high winds, large hail, and tornadoes to these regions. Despite their importance, continental convection has proven to be a significant challenge for global weather and climate models to represent realistically. The initiation, growth, and organization of convective storms are strongly governed by mesoscale and small-scale processes not resolved by large-scale global models, and typically the study and prediction of such storms is done by regional high-resolution models; however these regional models are only useful for simulations of at most a few days, before boundary errors and mean-state drift contaminate the interior solution. Further, both the pre-storm environment as well as the evolution of convective storms are strongly coupled to the planetary boundary layer and to the land surface, which are also difficult for many models to represent realistically. Both modeling and observational studies support that the differential heating of the atmosphere by a heterogeneous land surface can induce a secondary circulation that influences the turbulent transport in the planetary boundary layer (PBL) and development of clouds (Taylor et al., 2007). Convective initiation is affected by the distribution of soil moisture which partitions the surface available energy into latent heat and sensible heat fluxes and in turn affect the boundary layer evolution (Betts et al., 1996). Many different processes (Figure 1) over a wide range of space and time scales govern the interactions of the PBL and clouds with a heterogeneous land surface. A variable resolution global model with two-way global to regional interaction, (Madhulatha et al., 2018, Harris et al., 2019) can be a powerful tool for both examining the relevant interactions across temporal and spatial scales as well exploiting these processes to enable skillful prediction of continental convection across these scales. Join Hangouts Meet meet.google.com/tns-tqhm-fos

March 4, 2020

calendar_today What controls the hemispheric asymmetry in the seasonality of extratropical storm track intensity? - New insights from the moist static energy budget.

person Lunchtime Seminar - Lunchtime Seminar Series - Pragallva Barpanda (University of Chicago (postdoc candidate))

access_time 12:00 pm - 1:00 pm

place Location: Smagorinsky Seminar Room

Extratropical storm tracks are collective paths of synoptic scale (~1000 km) cyclones that exist in the midlatitudes of both hemispheres. The storm track seasonality is controlled by solar insolation gradient, yet they exhibit distinct hemispheric seasonality. In the Northern Hemisphere (NH) the zonal-mean storm track weakens by ~2.5 PW and shifts poleward by 10 degrees from winter to summer. In contrast, the Southern Hemisphere (SH) storm track shows much weaker seasonality ( dc) produce surface heat fluxes that are out of phase with atmospheric shortwave absorption resulting in small storm track seasonality and 2) small mixed layer depths (d < dc) produce surface heat fluxes that are in phase with atmospheric shortwave absorption resulting in large storm track seasonality. The aquaplanet simulations confirm the above hypotheses thus establishing that surface heat fluxes (dominated by surface turbulent fluxes) play a causal role in damping the seasonality of SH stormtrack.

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 5, 2020

calendar_today Understanding the Signal-to-noise Paradox in Climate Predictions

person Informal Seminar - Wei Zhang - Postdoc Candidate (Visiting Scientist Program (Univ of Maimi))

access_time 10:00 am - 11:00 am

place Location: Smagorinsky Seminar Room

Increasing evidence has been documented in recent years for the existence of the signal-to-noise paradox, where in the ensemble-based climate prediction, model ensemble mean forecast generally shows higher correlations with observations than with individual ensemble members. This seems to lead to a paradox referred to as the signal-to-noise paradox that the model makes better predictions for the reality than predicting itself. The signal-to-noise paradox highlights a potentially serious problem with climate model predictions as previous seasonal-to-decadal model predictions may be underestimated due to the existence of the paradox. Here we introduce a simple Markov model framework to represent the ensemble forecasts and aim to explain why the paradox exists. With the Markov model framework, one can easily reproduce the signal-to-noise paradox, the existence of which is dependent on the relative amplitude of the persistence and noise variance in models and observations. The North Atlantic Oscillation indices based on uninitialized historical simulations of 40 CMIP5 models have been analyzed, suggesting that the signal‐to‐noise paradox is common in currently available coupled models, and the paradox is not due to problems with initialization processes used in the seasonal‐to‐decadal predictions in previous studies and is instead a general model problem. We also identify the widespread existence of the signal-to-noise paradox in SST and SLP fields in CMIP5 models and the results suggest that the regions with the signal-to-noise paradox are very likely to underestimate the predictability. Increased ocean or atmospheric model resolution may have the potential to eliminate the signal-to-noise issue.

March 11, 2020

calendar_today SPEAR seasonal predictions: data assimilation, initialization and bias prevention

person Lunchtime Seminar - Lunchtime Seminar Series - Feiyu Lu (Princeton University/GFDL)

access_time 12:00 pm - 1:00 pm

place Location: Smagorinsky Seminar Room

To Be Announced.

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 Future change of the Atlantic meridional overturning circulation: causes and climate impacts

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

Future change of the Atlantic meridional overturning circulation (AMOC) results from both the response of AMOC system to external climate forcing and the feedback processes within the AMOC system. We first focus on the salt-advection feedback in AMOC system that is tied to AMOC stability. We notice that AMOC changes are moderate in most climate model projections under increasing greenhouse gas forcing. This inter-model consensus may be an artifact of common model biases that favor a stable AMOC, since observationally based freshwater budget analyses suggest that the AMOC is in an unstable regime susceptible for large changes in response to perturbations. To investigate the impact of AMOC stability bias on future climate projection, we use the NCAR CCSM3 and correct model AMOC stability bias by means of flux adjustment. We find that, via a positive salt-advection feedback, the AMOC in the corrected model collapses 300 years after the atmospheric CO2 concentration is abruptly doubled from the 1990-level. Compared to uncorrected model, the AMOC collapse brings about large, dramatically different climate response such as a prominent cooling over the northern North Atlantic and neighboring areas. We further find that, besides anthropogenic warming, precipitation change and Greenland ice sheet melting, the ongoing decline of Arctic sea ice can also induce a remarkable weakening of the AMOC on multi-decadal and longer timescales. Due to sea ice loss, anomalous warm water accumulates in the Arctic and spreads to the North Atlantic. At the same time, freshwater that accumulates from seasonal sea ice melting over most of the upper Arctic Ocean also spreads southward, reaching as far as south of Iceland. These warm and fresh anomalies reduce upper ocean density and suppress oceanic deep convection, and therefore lead to a slowdown of the AMOC. Such AMOC change can greatly mediate the global impacts of Arctic sea ice decline. During the first two decades when atmospheric processes dominate, sea ice decline induces a "bipolar seesaw" pattern in surface temperature with warming in the Northern and cooling in the Southern Hemisphere, leading to a northward displacement of the Intertropical Convergence Zone (ITCZ) and an expansion of Antarctic sea ice. In contrast, on multi-decadal and longer timescales, the AMOC slowdown mediates direct sea ice impacts and nearly reverses the original response pattern outside the Arctic. The Southern Hemisphere warms, a Warming Hole emerges in the North Atlantic, the ITCZ shifts southward, and Antarctic sea ice contracts. 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 22, 2020

calendar_today TBD

person Lunchtime Seminar - Lunchtime Seminar Series - Yuan Yu Xie (Princeton/GFDL)

access_time 12:00 pm - 1:00 pm

place Location: Smagorinsky Seminar Room

To Be Announced.

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 6, 2020

calendar_today GFDL Poster Expo

person Special Event - GFDL Poster Expo

access_time 1:00 pm - 4:00 pm

place Location: Smagorinsky Seminar Room

GFDL Poster Expo. For more information, please visit: https://www.gfdl.noaa.gov/poster-expo/

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 Weather & Forecasting Research Programs at the National Severe Storms Laboratory

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

access_time 2:00 pm - 3:00 pm

place Location: Smagorinsky Seminar Room

The National Severe Storms Laboratory (NSSL) serves to enhance NOAA's capabilities to provide accurate and timely forecasts and warnings of hazardous weather events. NSSL accomplishes this mission through: 1) research to advance the understanding of weather processes, 2) research to improve forecasting and warning techniques, and 3) development and transition of operational applications. NSSL transfers new scientific understanding, techniques, and applications to the National Weather Service (NWS). This presentation overviews the four divisions and primary programs at NSSL conducting basic and applied research in support of this mission. NSSL is NOAA's primary weather radar laboratory with strong scientific and engineering leadership in dual-polarization and phased array weather radar. Scientists and engineers within the Radar Research and Development Division (RRDD) are the primary research to operations (R2O) entity for the NEXRAD radar network. RRDD developed the dual-polarization weather radar prototype and used it to demonstrate improvements to quantitative precipitation estimation that led to the upgrade the NEXRAD network. This group is leading NOAA's research and development activities for a future operational radar network based on phased array radar technology. Weather radar data collected by the NEXRAD network, and other operational observation platforms, are the basis for severe weather applications developed by the Warning Research and Development Division (WRDD). A primary example is their development of the Multi-Radar Multi-Sensor (MRMS) algorithm. Transitioned recently to National Weather Service (NWS) operations, this algorithm is foundational to the development of forecast tools, such as quantitative precipitation estimation and flash flood forecasting via FLASH (Flooded Locations and Simulated Hydrographs). Additionally, WRDD is leading the Forecasting a Continuum of Environmental Threats Program at NSSL through the development and testing of observational-driven 0-1-hour probabilistic hazard information in the Hazardous Weather Testbed, and social science research to ensure usability of probabilistic information by users, partners, and publics. While WRDD focuses on the warning spatiotemporal scale, the Forecast Research and Development Division (FRDD) focuses on a broader spatiotemporal continuum, from 1-hr to sub-seasonal forecasting. Primary research activities in FRDD include process studies of convective storms and environments, ground-based instrument development and observational strategies, and the development of severe weather climatology and long-term forecasting methods. FRDD also contains two programs key to NOAA's convective- and storm-scale modeling research, development, and evaluation: the Hazardous Weather Testbed Experimental Forecast Program (co-led with the NWS Storm Prediction Center) and the Warn-on-Forecast Program. The presentation will focus primarily on research and development conducted by FRDD scientists. In support of these three divisions, the Field Observing Facilities and Support team develops, maintains, and supports unique mobile instrumentation like Collaborative Lower Atmosphere Mobile Profiling System (CLAMPS), Mobile Laboratories, Electric Field Meters, Particle-size Image and Velocity Probe (PASIV), and mobile weather radars. NSSL scientists and engineers use this instrumentation to conduct in-house research and collaborative field programs, like VORTEX SE and Targeting Observations by Radars and UAS of Supercells (TORUS), to improve the understanding of severe storm processes. Speaker email: pam.heinselman@noaa.gov

June 22, 2020

calendar_today Diathermal ocean heat transport and numerical mixing in MOM5 and ACCESS-OM2

person Informal Seminar - Dr. Ryan Holmes (New South Wales, Sydney Australia)

access_time 10:30 am - 11:30 am

place Location: Smagorinsky Seminar Room

The ocean transports vast amounts of heat around the planet, helping to regulate regional climate. In this talk I will discuss a framework that relates the ocean's meridional heat transport to the diabatic processes of air-sea heat fluxes and mixing that move heat across temperature classes (i.e. the ocean's diathermal heat transport). Applied to global MOM5 and ACCESS-OM2 simulations the framework emphasizes the role of surface heat gain and mixing in the eastern tropical Pacific and the exchange of heat between the Indo-Pacific and Atlantic basins. Turbulent mixing (both explicitly parameterized and numerical) plays a key role by moving heat from the warm, shallow Indo-Pacific circulation to the deeper-reaching Atlantic circulation and to the cold isotherms that outcrop in the North Atlantic. I will also discuss the use of the framework for estimating numerical mixing in realistic global model simulations as well as its sensitivity to resolution and explicit physics parameterizations.

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