Events (Upcoming & Past)

Upcoming MMM Events

Andy Wood
Martyn Clark
NCAR/RAL/HAP 

Ensemble hydrologic (streamflow) prediction provides critical inputs for water, energy and hazard management, particularly in the face of extremes such as floods and droughts.  Following steady advances in operational ensemble numerical weather prediction since the 1990s, US and international operational prediction groups have invested heavily in developing datasets, methods, and models to enable a seamless suite of probabilistic hydrologic predictions spanning timescales from hours to seasons.  Ensemble hydrologic forecasting systems are now operational in a number of countries (including the US), and are enhanced by an increasingly crowded field of operational continental and global ensemble hydrologic prediction services.  In this presentation, we provide background describing the evolution of ensemble hydrologic prediction systems, and highlight the role of the HEPEX (Hydrologic Ensemble Prediction Experiment; www.hepex.org) initiative since 2004 in defining and promoting an integrative, scientific view of the elements of a hydrologic ensemble prediction approach.  These include methods for the probabilistic downscaling and calibration of meteorological forecast ensembles, hydrologic model parameter estimation and uncertainty quantification, hydrologic model data assimilation, model output post-processing, and ensemble forecast verification and communication for use in risk-based decision-making.  We summarize the current state of practice in applying these methods to achieve reliable ensemble streamflow forecasts (locally and globally), and discuss long-standing and new challenges identified by the ensemble hydrologic prediction community.

Refreshments:  3:15 PM  

First Name: 
Bobbie
Last Name: 
Weaver
Phone Extension (4 digits): 
8946
Email: 
weaver@ucar.edu
Building:
Room Number: 
1022
Host lab/program/group:
Type of event:
Calendar Timing: 
Thursday, March 1, 2018 - 3:30pm to 4:30pm

Hugh Morrison
MMM/NCAR

The representation of cloud and precipitation microphysics is a critical element in atmospheric models of all scales. It affects the thermodynamics and dynamics from latent heating/cooling and condensate drag, strongly influences cloudy radiative transfer, and is a key component of the hydrological cycle through the generation and fallout of precipitation. An overview of the historical development of microphysics schemes in cloud and mesoscale models will be presented first. Advances over the last decade will be covered in more detail, particularly the recent development of a scheme called Predicted Particle Properties (P3) that predicts and smoothly evolves ice particle properties such as density and fall speed. This approach is a significant departure from traditional microphysics schemes that separate ice into categories with fixed properties corresponding to particular ice types (small ice, snow, graupel, hail, etc.). Simulations using P3 implemented in the Weather Research and Forecasting (WRF) model will be presented and contrasted with those using traditional schemes. Additional developments related to P3, including an improved numerical treatment of cloud and precipitation transport, will also be presented. Finally, more “outside of the box” ideas for parameterizing microphysics will be highlighted, including a Bayesian statistical-physical parameterization framework that facilitates observational constraint of process rates and a rigorous characterization of uncertainty. The talk with conclude with a broader outlook and commentary on future microphysics scheme developments over the next 5-10 years and beyond.

Refreshments: 3:15 PM

First Name: 
Bobbie
Last Name: 
Weaver
Phone Extension (4 digits): 
8946
Email: 
weaver@ucar.edu
Building:
Room Number: 
1022
Host lab/program/group:
Type of event:
Calendar Timing: 
Thursday, February 15, 2018 - 3:30pm to 4:30pm

Shane Keating
University of New South Wales
Australia  

The era of earth-observing satellites has revolutionised our understanding of our planet and the dynamical processes that shape it. In many real-world geophysical systems, however, estimates of turbulent mixing and transport are limited by the resolution of available observations. In this talk, I will describe a suite of stochastic filtering strategies for estimating mixing in turbulent
geophysical flows from “superresolved” satellite imagery obtained by combining coarse observations with an efficient stochastic parameterization for the unresolved scales.

The method enhances the effective resolution of satellite observations by exploiting the effect of spatial aliasing and generates an optimal estimate of small scales using standard Bayesian inference. The technique is tested in quasigeostrophic simulations driven by realistic climatological shear and stratification profiles. Two applications are considered: calculating poleward ocean eddy heat flux from satellite altimetry, and estimating the three-dimensional upper ocean velocity field from superresolved sea-surface temperature imagery. In each case, the superresolved satellite observations result in a considerable improvement in estimates of turbulent fluxes compared with the raw observations.

Refreshments: 3:15 PM

First Name: 
Bobbie
Last Name: 
Weaver
Phone Extension (4 digits): 
8946
Email: 
weaver@ucar.edu
Building:
Room Number: 
1022
Host lab/program/group:
Type of event:
Calendar Timing: 
Thursday, February 8, 2018 - 3:30pm to 4:30pm

Buo-Fu Chen
National Taiwan University
NCAR/MMM  

Although deep-layer (200−850 hPa) vertical wind shear (VWS) is generally an inhibiting factor for tropical cyclone (TC) intensification, there is still a considerable variability of TC intensification and structural evolution under similar VWS magnitudes. A hypothesis to address this variability is that the interaction between a vertically-sheared TC and the shear-relative low-level mean flow (LMF) modifies the convective structure and its azimuthal distribution, resulting in various pathways of TC structure evolution. This hypothesis was explored from three different perspectives: (1) a global, climatological statistical analysis of the correlations between the 24-hour intensity/size changes and the shear-relative LMF orientations, (2) examining the structural evolution of 180 western North Pacific TCs based on satellite composites, (3) a set of idealized numerical simulations produced with Weather Research and Forecasting (WRF) Model. Based on the best track data of 775 TCs from all basins during 2003−2016, statistical results suggest that a TC affected by an LMF orienting toward down-shear-left favors a relatively large intensification rate, while an LMF orienting toward up-shear-right is favorable for TC expansion. Also, in a storm-motion-relative and shear-relative framework, the analyses based on satellite observations and idealized WRF simulations reveal possible mesoscale processes in the boundary layer causing the distinct convective features associated with TCs affected by various shear-relative LMF. 

Refreshments:  3:15 PM

Note Special Location

First Name: 
Bobbie
Last Name: 
Weaver
Phone Extension (4 digits): 
8946
Email: 
weaver@ucar.edu
Building:
Room Number: 
1001 (Note Location)
Host lab/program/group:
Type of event:
Calendar Timing: 
Thursday, February 1, 2018 - 3:30pm to 4:30pm

2018 NORTH AMERICAN WORKSHOP ON HAIL & HAILSTORMS
AUGUST 14 - 16, 2018, BOULDER, COLORADO
NCAR CENTER GREEN CAMPUS

Across North America, hailstorms are responsible for over $10 billion dollars in annual property damage. The increase in the impact of hailstorms has outpaced advances in detection, forecasting, and mitigation. The National Science Foundation, the National Center for Atmospheric Research and the Insurance Institute for Business & Home Safety are organizing the first North American Workshop on hail, and hailstorms. The workshop will bring together public and private stakeholders to discuss the current state of the science regarding all facets of this peril and provide a look to the future. The workshop will be held at the NCAR Center Green 1 (CG1) campus, 3080 Center Green Drive, Boulder, Colorado.

Call For Abstracts: The deadline for abstract submissions is May 1, 2018.

For information: https://www.mmm.ucar.edu/north-american-hail-workshop 

First Name: 
Kris
Last Name: 
Marwitz
Phone Extension (4 digits): 
8198
Email: 
KMARWITZ@UCAR.EDU
Building:
Room Number: 
Auditorium
Host lab/program/group:
Type of event:
Calendar Timing: 
Repeats every day every Monday and every Tuesday and every Wednesday and every Thursday and every Friday until Thu Aug 16 2018.
Tuesday, August 14, 2018 - 9:00am to Thursday, August 16, 2018 - 5:00pm
Wednesday, August 15, 2018 - 9:00am to Friday, August 17, 2018 - 5:00pm
Thursday, August 16, 2018 - 9:00am to Saturday, August 18, 2018 - 5:00pm

Past MMM Events

Hugh Morrison
MMM/NCAR

The representation of cloud and precipitation microphysics is a critical element in atmospheric models of all scales. It affects the thermodynamics and dynamics from latent heating/cooling and condensate drag, strongly influences cloudy radiative transfer, and is a key component of the hydrological cycle through the generation and fallout of precipitation. An overview of the historical development of microphysics schemes in cloud and mesoscale models will be presented first. Advances over the last decade will be covered in more detail, particularly the recent development of a scheme called Predicted Particle Properties (P3) that predicts and smoothly evolves ice particle properties such as density and fall speed. This approach is a significant departure from traditional microphysics schemes that separate ice into categories with fixed properties corresponding to particular ice types (small ice, snow, graupel, hail, etc.). Simulations using P3 implemented in the Weather Research and Forecasting (WRF) model will be presented and contrasted with those using traditional schemes. Additional developments related to P3, including an improved numerical treatment of cloud and precipitation transport, will also be presented. Finally, more “outside of the box” ideas for parameterizing microphysics will be highlighted, including a Bayesian statistical-physical parameterization framework that facilitates observational constraint of process rates and a rigorous characterization of uncertainty. The talk with conclude with a broader outlook and commentary on future microphysics scheme developments over the next 5-10 years and beyond.

Refreshments: 3:15 PM

First Name: 
Bobbie
Last Name: 
Weaver
Phone Extension (4 digits): 
8946
Email: 
weaver@ucar.edu
Building:
Room Number: 
1022
Host lab/program/group:
Type of event:
Calendar Timing: 
Thursday, February 15, 2018 - 3:30pm to 4:30pm

Shane Keating
University of New South Wales
Australia  

The era of earth-observing satellites has revolutionised our understanding of our planet and the dynamical processes that shape it. In many real-world geophysical systems, however, estimates of turbulent mixing and transport are limited by the resolution of available observations. In this talk, I will describe a suite of stochastic filtering strategies for estimating mixing in turbulent
geophysical flows from “superresolved” satellite imagery obtained by combining coarse observations with an efficient stochastic parameterization for the unresolved scales.

The method enhances the effective resolution of satellite observations by exploiting the effect of spatial aliasing and generates an optimal estimate of small scales using standard Bayesian inference. The technique is tested in quasigeostrophic simulations driven by realistic climatological shear and stratification profiles. Two applications are considered: calculating poleward ocean eddy heat flux from satellite altimetry, and estimating the three-dimensional upper ocean velocity field from superresolved sea-surface temperature imagery. In each case, the superresolved satellite observations result in a considerable improvement in estimates of turbulent fluxes compared with the raw observations.

Refreshments: 3:15 PM

First Name: 
Bobbie
Last Name: 
Weaver
Phone Extension (4 digits): 
8946
Email: 
weaver@ucar.edu
Building:
Room Number: 
1022
Host lab/program/group:
Type of event:
Calendar Timing: 
Thursday, February 8, 2018 - 3:30pm to 4:30pm

Buo-Fu Chen
National Taiwan University
NCAR/MMM  

Although deep-layer (200−850 hPa) vertical wind shear (VWS) is generally an inhibiting factor for tropical cyclone (TC) intensification, there is still a considerable variability of TC intensification and structural evolution under similar VWS magnitudes. A hypothesis to address this variability is that the interaction between a vertically-sheared TC and the shear-relative low-level mean flow (LMF) modifies the convective structure and its azimuthal distribution, resulting in various pathways of TC structure evolution. This hypothesis was explored from three different perspectives: (1) a global, climatological statistical analysis of the correlations between the 24-hour intensity/size changes and the shear-relative LMF orientations, (2) examining the structural evolution of 180 western North Pacific TCs based on satellite composites, (3) a set of idealized numerical simulations produced with Weather Research and Forecasting (WRF) Model. Based on the best track data of 775 TCs from all basins during 2003−2016, statistical results suggest that a TC affected by an LMF orienting toward down-shear-left favors a relatively large intensification rate, while an LMF orienting toward up-shear-right is favorable for TC expansion. Also, in a storm-motion-relative and shear-relative framework, the analyses based on satellite observations and idealized WRF simulations reveal possible mesoscale processes in the boundary layer causing the distinct convective features associated with TCs affected by various shear-relative LMF. 

Refreshments:  3:15 PM

Note Special Location

First Name: 
Bobbie
Last Name: 
Weaver
Phone Extension (4 digits): 
8946
Email: 
weaver@ucar.edu
Building:
Room Number: 
1001 (Note Location)
Host lab/program/group:
Type of event:
Calendar Timing: 
Thursday, February 1, 2018 - 3:30pm to 4:30pm

Julia Slingo
Chief Scientist, UK Met Office, Emeritus
United Kingdom

Today, we live in a global economy, relying on global trade, efficient transport systems and resilient and reliable provision. As we see time and time again, all these systems are vulnerable to adverse weather and climate conditions. The additional pressure of climate change creates a new set of circumstances and poses new challenges about how secure we will be in the future. More than ever, the weather and climate of food, energy and water have considerable direct and indirect impacts on us – our livelihoods, property, health, well-being and prosperity. In this talk I will describe recent advances in understanding, simulating and predicting our weather and climate and how these developments can be deployed to help us manage our risks, now and in the future.

Refreshments: 3:15 PM

First Name: 
Bobbie
Last Name: 
Weaver
Phone Extension (4 digits): 
8946
Email: 
weaver@ucar.edu
Building:
Room Number: 
1022
Host lab/program/group:
Type of event:
Calendar Timing: 
Thursday, January 25, 2018 - 3:30pm to 4:30pm
WRF TUTORIAL OVERVIEW

The Weather Research and Forecasting (WRF) model Tutorial will be held at the NCAR Foothills Laboratory (FL2) located at 3450 Mitchell Lane, Boulder, Colorado from 22 January - 2 February 2018.

The Basic tutorial will consist of lectures on various components of the WRF modeling system along with hands-on practice sessions.  (22 - 26 January 2018)

The WRF-Chem tutorial will provide lectures on main components of the model and associated tools along with hands-on practice sessions.  (29 - 30 January 2018)

The MET tutorial and the associated database and display system (METViewer) is a suite of state-of-the-art verification tools that can be used to read post-processed WRF output and match it to observed data to compute both traditional and non-traditional statistics.  MET and METViewer are being wrapped with python to extend the MET capability and make it easier to set-up a verification system.  This tutorial will provide lectures on main tools along with hands-on practice sessions.

https://www.mmm.ucar.edu/wrf-tutorial-0

First Name: 
Kris
Last Name: 
Marwitz
Phone Extension (4 digits): 
8198
Email: 
kmarwitz@ucar.edu
Building:
Room Number: 
Large Auditorium
Host lab/program/group:
Type of event:
Calendar Timing: 
Monday, January 22, 2018 - 8:30am to 5:00pm
Tuesday, January 23, 2018 - 8:30am to 5:00pm
Wednesday, January 24, 2018 - 8:30am to 5:00pm
Thursday, January 25, 2018 - 8:30am to 5:00pm
Friday, January 26, 2018 - 8:30am to 5:00pm
Monday, January 29, 2018 - 8:30am to 5:00pm
Tuesday, January 30, 2018 - 8:30am to 5:00pm
Wednesday, January 31, 2018 - 8:30am to 5:00pm
Thursday, February 1, 2018 - 8:30am to 5:00pm
Friday, February 2, 2018 - 8:30am to 5:00pm

Kevin Ash
NCAR/MMM/ASP 

Extreme weather and climate events continue to plague the United States in tandem with increased societal exposure and susceptibility stemming from higher population densities in hazardous locations and the exacerbated frequency and intensity of some hazards in association with anthropogenic climate change.  In this presentation I will focus on severe thunderstorm hazards, and specifically on risk perception, vulnerability, & communication in the tornado context.  Despite advances in forecasting and detection of severe thunderstorms over the past several decades, the calendar year 2011 saw over 500 deaths from tornadoes in the United States for the first time since 1953.  These events renewed interest in social science research related to severe thunderstorm hazards in order to better understand how people perceive danger from tornadoes and act (or fail to act) to protect themselves and their families when tornadoes threaten.

I will highlight two of my recent research projects and connect these to my current research.  The first seeks to understand how people interpret and potentially act upon spatially explicit visual depictions of tornado warnings.  Survey participants viewed and responded to hypothetical warning maps with varying representations of risk at locations distributed evenly across the maps.  The results suggest several key concepts for spatially explicit risk communication to elicit appropriate and timely protective action.  The second research project focuses on manufactured housing residents, an especially vulnerable sub-population which comprises nearly half of tornado fatalities.  The project used a mixed method research design to better understand why very few manufactured housing residents follow the recommendation to evacuate to a tornado shelter or other sturdy building during a tornado warning.  Based on interviews and survey data, many residents do not believe their manufactured home to be an unsafe sheltering location, while others who would like to evacuate are often very uncertain about appropriate timing and destinations for evacuation.  I will conclude by discussing how future work will incorporate risk perception, vulnerability, and communication within a single geospatial modeling framework.  

Refreshments: 3:15 PM

First Name: 
Bobbie
Last Name: 
Weaver
Phone Extension (4 digits): 
8946
Email: 
weaver@ucar.edu
Building:
Room Number: 
1022
Host lab/program/group:
Type of event:
Calendar Timing: 
Thursday, January 18, 2018 - 3:30pm to 4:30pm

Joseph Olson
Global Systems Division
NOAA--Earth System Research Laboratory 

The Rapid Refresh (RAP) and High-Resolution Rapid Refresh (HRRR) are NOAA real-time operational hourly updating forecast systems run at 13- and 3-km grid spacing, respectively. Both systems use the Advanced Research version of the Weather Research and Forecasting (WRF-ARW) as the model component of the forecast system. During the second installment of the Wind Forecast Improvement Project (WFIP 2), the RAP/HRRR have been targeted for the improvement of low-level wind forecasts in the complex terrain within the Columbia River Basin (CRB), which requires much finer grid spacing to resolve important topographic features in/near the CRB. Therefore, this project provides a unique opportunity to test and develop the RAP/HRRR physics suite within a very high-resolution nest (∆x = 750 m) over the northwestern US. Special effort is made to incorporate scale-adaptive flexibility into the RAP/HRRR physics suite, with emphasis on the representation of subgrid-scale boundary layer and orographic drag processes.

Many wind profiling and scanning instruments have been deployed in the CRB in support the WFIP 2 field project, which spanned 01 October 2015 to 31 March 2017. During the project, several forecast error modes were identified, such as: (1) too-shallow cold pools during the cool season, which can mix-out more frequently than observed and (2) the low wind speed bias in thermal trough-induced gap flows during the warm season. Development has been focused on improving these common forecast failure modes with the criteria of achieving at least neutral impacts in all other operational forecast objectives. This presentation will highlight the testing and development of various model components, showing the improvements over original RAP/HRRR physics. Examples of case studies and retrospective periods will be presented to illustrate the improvements.  Ongoing and future challenges in RAP/HRRR physics development will be touched upon.

Refreshments: 3:15 pm

First Name: 
Bobbie
Last Name: 
Weaver
Phone Extension (4 digits): 
8946
Email: 
weaver@ucar.edu
Building:
Room Number: 
1022
Host lab/program/group:
Type of event:
Calendar Timing: 
Thursday, November 30, 2017 - 3:30pm to 4:30pm

William Skamarock
NCAR/MMM 

One of the unsolved questions in atmospheric dynamics concerns the energetics responsible for the horizontal wavenumber k^(-5/3) scaling observed in the mesoscale portion of the atmospheric kinetic energy (KE) spectrum.  Model spectra qualitatively reproduce the observations-based spectrum in both the synoptic-scale k^(-3) and mesoscale k^(-5/3) regions, and given the limitations of the observations, modeling-based studies have become the primary approach for examining the mesoscale dynamics of the spectrum.  We are computing atmospheric spectra for global NWP forecasts using the atmospheric component of the Model for Prediction Across Scales (MPAS) to study these dynamics.  As in past studies, we find a mesoscale region in the model spectrum when resolution is sufficiently fine.  The first part of the present study examines the accuracy of model solutions, where we find that typical model configurations produce solutions that are significantly under-resolved vertically as revealed in convergence test results for KE spectra and examination of inertia gravity wave structure.  The second part of this study examines KE dissipation and its associated dynamics.  The mesoscale region is thought to be characterized as possessing a net downscale energy cascade, and the dynamics in the regions of energy dissipation should play a role in the downscale cascade.   Understanding these dynamics should help test existing theories for the mesoscale KE spectrum.  We will present results illustrating these points,  and we will discuss the implications of these results for current theories for the mesoscale KE spectrum.  We will also discuss the implications for atmospheric modeling applications in weather and climate given that current operational weather and climate model configurations do not resolve well the mesoscale KE, particularly in the upper troposphere and lower stratosphere.

Refreshments: 3:15 pm

First Name: 
Bobbie
Last Name: 
Weaver
Phone Extension (4 digits): 
8946
Email: 
weaver@ucar.edu
Building:
Room Number: 
1022
Host lab/program/group:
Type of event:
Calendar Timing: 
Thursday, December 7, 2017 - 3:30pm to 4:30pm

Raymond A. Shaw
Atmospheric Sciences Program
Michigan Technological University 

Aerosol particles, such as sea salt, dust and anthropogenic pollution, influence the optical properties of clouds and the tendency of a cloud to form precipitation through droplet collisions. We have investigated cloud droplet growth in a turbulent environment under varying levels of aerosol concentration. The results reveal a surprising role of turbulence in cloud droplet growth that leads to two regimes: a polluted cloud regime in which thermodynamic conditions are rather uniform and cloud droplet sizes are similar, and a clean cloud regime in which thermodynamic conditions are highly variable and cloud droplet sizes are very diverse. The narrowing of droplet size range under polluted conditions introduces a new stabilizing factor by which increased aerosol concentration can suppress precipitation and enhance cloud brightness. 

Cloud droplet growth in a turbulent environment is studied by creating turbulent moist Rayleigh-Benard convection in a laboratory chamber (the Pi Chamber). Cloud formation is achieved by injecting aerosols into the water-supersaturated environment created by the isobaric mixing of saturated air at different temperatures. In steady state, the injection and activation of aerosol particles to form cloud droplets is balanced by cloud droplet growth through vapor condensation and loss by gravitational settling. A range of steady-state cloud droplet number concentrations is achieved by supplying aerosols at different rates. As steady-state droplet number concentration is decreased the mean droplet size increases as expected, but also the width of the size distribution increases. This increase in the width is associated with larger supersaturation fluctuations due to the slow droplet microphysical response (sink of the water vapor) compared to the fast turbulent mixing (source of the water vapor). The boundary between the two regimes can be identified with a cloud Damkoehler number of order unity.

Thursday, 16 November 2017, 3:30 PM
Refreshments:  3:15 PM

First Name: 
Bobbie
Last Name: 
Weaver
Phone Extension (4 digits): 
8946
Email: 
weaver@ucar.edu
Building:
Room Number: 
1022
Host lab/program/group:
Type of event:
Calendar Timing: 
Thursday, November 16, 2017 - 3:30pm to 4:30pm

Richard Rotunno
NCAR/MMM 

From the point of view of the shallow-water equations (SWE), the hydraulic jump is a discontinuity in fluid-layer depth and velocity at which kinetic energy is dissipated. To provide an understanding of the origin and internal dynamics of the hydraulic jump, three-dimensional numerical solutions of the Navier-Stokes Equations (NSE) are carried out alongside SWE solutions for nearly identical physical initial-value problems. Analysis of the solutions to the initial-value problem shows that the tendency to form either the lee-side height/velocity discontinuity in the SWE, or the overturning density interface in the NSE, is a feature of inviscid, nonturbulent fluid dynamics. Dissipative turbulent processes associated with the lee-side hydraulic jump are a consequence of the inviscid fluid dynamics that initiate and maintain the locally unstable conditions. Implications for the modeling of atmospheric mountain waves and lee vortices are discussed.

Refreshments:  3:15 PM

First Name: 
Bobbie
Last Name: 
Weaver
Phone Extension (4 digits): 
8946
Email: 
weaver@ucar.edu
Building:
Room Number: 
1022
Host lab/program/group:
Type of event:
Calendar Timing: 
Thursday, November 9, 2017 - 3:30pm to 4:30pm

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