Events (Upcoming & Past)

Upcoming MMM Events

Stipo Sentic
New Mexico Tech

Tropical convective organization is the process in which disorganized convection organizes into regions of intense convective activity surrounded by dry, convectively inactive regions. Well known examples are tropical cyclones and the Madden-Julian Oscillation (MJO)—they affect atmospheric energetics, and the MJO affects virtually all weather on our planet. Recent advances in idealized modelling of tropical convection, namely the weak temperature gradient (WTG) approximation, enable us to study convective organization in idealized settings. The WTG approximation parameterizes the effects of the large-scale on local convection, and can be used in idealized sensitivity studies of convection to changes in large-scale convective environment. To model organized convection in the context of the MJO, we used observations from the Dynamics of the Madden-Julian Oscillation (DYNAMO) field campaign to force WTG simulations in a cloud resolving model, and test how well the WTG approximation reproduces variations in convective diagnostics: precipitation rate, stability, moisture content, and large-scale transport (gross moist stability). We find that the WTG approximation reproduces variations in these diagnostics, and relationships between them.  The ability of WTG approximation to reproduce important observed diagnostics provides confidence that this is a good strategy for exploring tropical phenomena.  An example that I'll talk about is the behavior of convective organization at different SSTs.

(Special Date) Tuesday, 30 May 2017, 3:30 PM
Refreshments: 3:15 PM 
NCAR-Foothills Laboratory 
3450 Mitchell Lane
Bldg. 2, Small Seminar Room 1001 (Note Location)


First Name: 
Bobbie
Last Name: 
Weaver
Phone Extension (4 digits): 
8946
Email: 
weaver@ucar.edu
Building:
Room Number: 
1001 (Please note location)
Host lab/program/group:
Type of event:
Calendar Timing: 
Tuesday, May 30, 2017 - 3:30pm to 4:30pm

Michael Tjernström
Department of Meteorology & Bolin Centre for Climate Research
Stockholm University, Sweden

Arctic climate is ultimately determined by a balance between meridional heat transport into the area, and radiation heat loss at the top of the atmosphere over the same area. Since the net radiation loss is due to small-scale processes parameterized in models, and the meridional heat flux is due to larger scale atmospheric dynamics resolved by the models, the two has usually been studied separately. In this seminar this concept will be called into question.

In an episode during the Arctic Clouds in Summer Experiment (ACSE) in the summer of 2014, warm air from the Siberian mainland flowed in over melting sea-ice in the East-Siberian Sea for over a week. As the ~25 °C warm air flowed over the melting surface, maintained at the melting point, a strong surface inversion formed in which dense fog also formed. This resulted in a positive net longwave radiation while the sensible heat flux was downward. Although solar radiation was attenuated by the fog, this led to an additional 10-20 Wm-2 energy to the surface. This led us to hypothesize a zone from the ice edge where the surface will receive enhanced energy when the atmospheric flow is northward onto the ice. 

To test this hypothesis, we analyzed the observation from the entire ACSE expedition. All temperature profiles taken over sea ice were categorized into cases with or without a surface inversion; the inversion cases where further divided into two categories using the humidity profiles. When projecting other observations onto these three classes, many are systematically different. Surface inversion with increasing moisture with height systematically added 10-20 Wm-2 energy to the surface energy budget, indicating that meridional heat flux must be considered together with the small-scale processes caused by the air mass transformation.

Please note the location change.

Thursday, 1 June 2017, 3:30 PM
Refreshments:  3:15 PM
NCAR-Foothills Laboratory
3450 Mitchell Lane
Bldg. 2, Small Seminar Room 1001 

First Name: 
Bobbie
Last Name: 
Weaver
Phone Extension (4 digits): 
8946
Email: 
weaver@ucar.edu
Building:
Room Number: 
1001 (Please note location change)
Host lab/program/group:
Type of event:
Calendar Timing: 
Thursday, June 1, 2017 - 3:30pm to 4:30pm

Anders Sivle
Norwegian Meteorological Institute
Oslo, Norway 

Different people in different occupations depend on weather forecasts to plan their work and recreational schedules. People with no expertise in meteorology frequently interpret weather forecasts and uncertainty information. These non-experts apply their prior knowledge and experiences in a variety of fields to synthesize different types of information to interpret forecasts. In this PhD study, situations of typical users were simulated when examining how different user groups interpret, integrate, and use information from an online weather report (www.Yr.no) in their everyday decision-making. First, qualitative interviews of twenty-one Norwegians (farmers, exterior painters, tour guides, teachers and students) were conducted. Second, sixteen students participated in an eye-tracking study.

The study found that nuances such as color and the number of drops were important in the interpretations of the weather symbols and forecast uncertainty, which were sometimes interpreted differently than intended by the forecast provider. Prior knowledge and the integration of information from different representations affected the participants’ interpretations. The decision-making process influenced the selections of representations in different situations; their selection was dependent on the importance of the envisaged activity and the weather conditions for the day. Additionally, in situations in which the participants had a lack of experiences, this lack provides a possible explanation for why part of the information was occasionally not understood and used.

Some implications of the findings for communication and future research will be discussed in the presentation. For example, it appears that some users should be supported to facilitate the interpretation and use of information in situations where they lack experiences. One possibility to support persons that lack experiences and have low situation awareness might be to provide consequences and impacts of forecast weather. 

Thursday, 8 June 2017, 3:30 PM
Refreshments 3:15 PM
NCAR-Foothills Laboratory
3450 Mitchell Lane
(Location Change) Bldg. 2, Room 1001

First Name: 
Bobbie
Last Name: 
Weaver
Phone Extension (4 digits): 
8946
Email: 
weaver@ucar.edu
Building:
Room Number: 
1001 (Please note location change)
Host lab/program/group:
Type of event:
Calendar Timing: 
Thursday, June 8, 2017 - 3:30pm to 4:30pm

The triennial IUFRO conference on the effect of wind and trees will take place at the National Center for Atmospheric Research’s (NCAR) Mesa Laboratory in Boulder, Colorado, from 17 July to 21 July 2017 

Call for Abstracts 

This conference encourages scientists from all backgrounds with an interest in the interaction between wind and trees to present a paper. The broad theme of the conference targets understanding the interaction of the wind on trees at scales ranging from the leaf to entire forests and forested landscapes. We are interested in how trees adapt to wind, how they acclimate during their lives, and the physical mechanisms of wind damage. Presentations discussing the atmospheric processes producing damaging near-surface winds and climatological controls on their likelihood are also encouraged.  We are keenly interested in the impact of forest disturbance on carbon budgets and ecosystem functioning in forests and management strategies to mitigate the impact of damage in all types of forestry.   

The deadline for submitting an abstract is 17 February 2017. 

https://www.regonline.com/IUFROWT

First Name: 
Kris
Last Name: 
Marwitz
Phone Extension (4 digits): 
8198
Email: 
kmarwitz@ucar.edu
Building:
Room Number: 
132 - Main Seminar Room
Host lab/program/group:
Type of event:
Calendar Timing: 
Repeats every day 5 times.
Monday, July 17, 2017 - 8:00am to 5:00pm
Tuesday, July 18, 2017 - 8:00am to 5:00pm
Wednesday, July 19, 2017 - 8:00am to 5:00pm
Thursday, July 20, 2017 - 8:00am to 5:00pm
Friday, July 21, 2017 - 8:00am to 5:00pm

Past MMM Events

Sharon Sessions
Department of Physics, New Mexico Tech
Socorro, New Mexico

Tropical convection is difficult to understand and even more difficult to predict, in part because of the interplay between the convection itself and the large scale circulations.  Predictability is possible, however, if the  scales of convective disturbances are large enough that they are influenced by voriticity anomalies in the environment.  Ooyama, in 1982, discussed this idea in the context of mature tropical cyclones, in a process he refered to as "cooperative intensification".  Recently, Raymond et al. (2015) revisted Ooyama's ideas and addressed the question of whether other less extreme types of tropical disturbances could be a response to a nonlinear form of "balanced dynamics".  If so, they argued that these types of disturbances would have potential for predictability (and therefore would also be parameterizable).  In terms of time scales, disturbances which occur on scales longer than the time to establish balance, are candidates for predictability based on the potential for moist convection to evolve as a balanced response to large scale vorticity anomalies.  

In this talk, I'll revisit some of Ooyama's and Raymond's ideas regarding balance dynamics, and discuss how we would look for signatures of balanced dynamics in convective systems.  I'll also discuss the mechanism by which a vorticity anomaly can modulate and strengthen a developing convective system, and address the question of whether the Madden-Julian Oscillation is a candidate for a convective disturbance under the influence of balanced dynamics.  Finally, I discuss how these concepts can potentially be used to evaluate and diagnose global models that have varying degrees of skill in simulating tropical disturbances (and the MJO in particular).  

Special Wednesday Date--Rescheduled from 18 May 2017 Due to Weather

Wednesday, 24 May 2017, 3:30 PM
Refreshments 3:15 PM
NCAR--Foothills Laboratory
3450 Mitchell Lane
Bldg. 2, Main Auditorium, Room 1022 

 

 

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: 
Wednesday, May 24, 2017 - 3:30pm to 4:30pm

Sharon Sessions
Department of Physics, New Mexico Tech
Socorro, New Mexico 

Tropical convection is difficult to understand and even more difficult to predict, in part because of the interplay between the convection itself and the large scale circulations.  Predictability is possible, however, if the  scales of convective disturbances are large enough that they are influenced by voriticity anomalies in the environment.  Ooyama, in 1982, discussed this idea in the context of mature tropical cyclones, in a process he refered to as "cooperative intensification".  Recently, Raymond et al. (2015) revisted Ooyama's ideas and addressed the question of whether other less extreme types of tropical disturbances could be a response to a nonlinear form of "balanced dynamics".  If so, they argued that these types of disturbances would have potential for predictability (and therefore would also be parameterizable).  In terms of time scales, disturbances which occur on scales longer than the time to establish balance, are candidates for predictability based on the potential for moist convection to evolve as a balanced response to large scale vorticity anomalies.  

In this talk, I'll revisit some of Ooyama's and Raymond's ideas regarding balance dynamics, and discuss how we would look for signatures of balanced dynamics in convective systems.  I'll also discuss the mechanism by which a vorticity anomaly can modulate and strengthen a developing convective system, and address the question of whether the Madden-Julian Oscillation is a candidate for a convective disturbance under the influence of balanced dynamics.  Finally, I discuss how these concepts can potentially be used to evaluate and diagnose global models that have varying degrees of skill in simulating tropical disturbances (and the MJO in particular).  

Thursday, 18 May 2017, 3:30 PM
Refreshments 3:15 PM
NCAR-Foothills Laboratory
3450 Mitchell Lane
Bldg. 2, Main Auditorium, Room 1022 

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, May 18, 2017 - 3:30pm to 4:30pm

Joseph Sedlar
Swedish Meteorological and Hydrological Institute
Norrkoping, Sweden 

Over the Arctic, persistent cloudiness and variable boundary layer structure pose serious problems for accurate numerical simulation of these phenomena. The issue is generally compounded by insufficient observational data, which are necessary for understanding processes and improvement of physical parameterizations.

In this presentation, observations spanning a broad range of spatial and temporal scales, including cloud-turbulence scales and up to pan-Arctic scales, are explored. Statistics and decomposition techniques are applied to understand the role of cloud-driven dynamics versus larger meso- and synoptic-scale forcings during the Arctic summer, to quantify their relative importance on the lower tropospheric structure. A particular focus of this presentation is devoted to highlighting the mechanisms supporting the decoupled nature between near-surface turbulence and mixed-phase cloud-driven mixing. The impact of poleward advection on components of the atmospheric energy budget is also analyzed.

Special Day and Time:

Tuesday, 18 April 2017, 1:30 PM
Refreshments 1:15 PM
NCAR-Foothills Laboratory
3450 Mitchell Lane
Bldg. 2, Main Auditorium, Room 1022

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: 
Tuesday, April 18, 2017 -
1:30pm to 2:30pm

Mathew Stiller-Reeve
Climate and The Bjerknes Centre for Climate Research
Bergen, Norway

If we want climate services to produce useable information for users, then the way scientists and users define events need to be comparable. In this talk, I will present some novel yet simple methods to compare beliefs of timing of recurrent climatic events with empirical evidence from multiple historical time series. We test the methods by applying them to the onset date of the monsoon in Bangladesh, where several scientific monsoon definitions can be applied. Time series from eight different scientific monsoon definitions in six regions are compared with respondent beliefs from a previously completed survey concerning the monsoon onset.

Beliefs about the timing of the monsoon onset are represented probabilistically for each respondent by constructing a probability mass function from elicited responses about the earliest, normal, and latest dates for the event. We use these dates to construct a circular modified triangular distribution (CMTD). These CMTD distributions are then compared to the historical time series using two approaches: likelihood scores, and the mean and standard deviation of time series of dates simulated from each belief distribution.

This work has developed from my previous PhD research and the more recent TRACKS project (Transforming Climate Knowledge with and for Society) funded by the Norwegian Research Council. The methods are initially based on the monsoon onset, but I would like to discuss the possibility of applying them to other meteorological or climatological events.

Thursday, 6 April 2017, 3:30 PM
Refreshments 3:15 PM
NCAR-Foothills Laboratory
3450 Mitchell Lane
Bldg. 2, Main Auditorium, Room 1022

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, April 6, 2017 -
3:30pm to 4:30pm

Social Vulnerability Mapping: Approaches, Problems, and Recent Advances
Walter Peacock
Texas A&M University, Hazard Reduction & Recovery Center
College Station, Texas

Traditionally vulnerability analysis combined information on the potential physical properties and extent of various hazards, such as extreme wind, flooding, and surge, with the data on the spatial distribution and nature of the built environment and population to assess a community’s vulnerability to various natural disasters. The emergence of social vulnerability perspectives in hazard science has resulted in an increasing call for the inclusion of social as well as physical vulnerability assessments when undertaking community vulnerability analysis. Social vulnerability mapping is a critical element in these types of analysis. This presentation will review the basic logic and approaches to social vulnerability mapping. Problems and issues related to unit of analysis, data quality, and spatial resolution will be addressed. Recent advances and approaches for addressing data quality and spatial resolution will also be discussed. 

Thursday, 23 March 2017, 3:30 PM
Refreshments 3:15 PM
NCAR-Foothills Laboratory
3450 Mitchell Lane
Bldg. 2, Main Auditorium, Room 1022

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 23, 2017 -
3:30pm to 4:30pm

Mesoscale Aggregation of Shallow Cumulus Convection
Over The Oceans

Christopher S. Bretherton
Department of Atmospheric Sciences, University of Washington
Seattle, WA

 Over the oceans, shallow cumulus convection, often mixed with patchy stratocumulus, is a common cloud type.  It is usually 'aggregated' into mesoscale patches or polygons of deeper cumuli, with possible consequences for the mean vertical structure of cloud cover and cloud-precipitation-aerosol interaction.  Large-eddy simulations (LES) covering domains 50 km or more across also exhibit mesoscale aggregation of shallow cumulus convection, but it is not fundamentally well understood.   To further that understanding, we analyze the development of convective aggregation in multiday LES of a 108x108 km doubly periodic domain simulating mean summertime conditions at a location east of Hawaii.  The simulated convection aggregates within 12 hours.  Vertically resolved heat and moisture budgets on mesoscale subdomains elucidate this process.  Shallow cumulus deepen preferentially in more humid regions of the boundary layer, stimulating net moisture convergence into those regions.  Sensitivity studies show that the aggregation does not require precipitation.  Aggregation is weakened but not prevented if radiative cooling and surface fluxes are horizontally homogenized.  A unifying conceptual model explains these findings.

Thursday, 9 March 2017, 3:30 PM
Refreshments 3:15 PM
NCAR-Foothills Laboratory
3450 Mitchell Lane
Bldg. 2, Main Auditorium, Room 1022

First Name: 
Caroline
Last Name: 
Haws
Phone Extension (4 digits): 
8189
Email: 
haws@ucar.edu
Building:
Room Number: 
1022
Host lab/program/group:
Type of event:
Calendar Timing: 
Thursday, March 9, 2017 -
3:30pm to 5:00pm

Energy Conservations
Jielun Sun
NCAR/MMM

Energy conservations in the stratified atmosphere are revisited. Because the atmospheric thermal structure is strongly connected with air motions particularly turbulent mixing, the traditional thermal energy conservation is challenged in explaining observed atmospheric thermodynamic structures. The kinetic energy conservation based on the momentum conservation only explains how kinetic energy is generated but not where the non-hydrostatic energy for generating the vertical component of kinetic energy comes from. Total energy conservation including atmospheric kinetic and internal energies allows interactions between thermal and kinetic energies through non-hydrostatic pressure work, which explains the atmospheric thermodynamic structure as a result of the so-called stability effect on atmospheric motions. The traditional thermal energy conservation is only valid when both thermal energy to non-hydrostatic pressure work and thermal heating associated with viscous stress work are negligibly small. Based on total energy conservation, a new thermal energy conservation is introduced with consideration of the thermal energy transfer to non-hydrostatic energy work for changing kinetic energy and reduced thermal energy available for changing internal energy. Observed close relationships between surface heating to the atmosphere,  the energy transfer  associated with non-hydrostatic pressure work, and  turbulent kinetic energy  support the interpretation of the thermal energy transfer to the non-hydrostatic energy work in the new thermal energy conservation based on the total energy conservation.

Friday, March 3, 2017, 11:00 AM
Refreshments 10:45 AM
NCAR-Foothills Laboratory
3450 Mitchell Lane
Bldg. 2, Main Auditorium, Room 1022 

                                 

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: 
Friday, March 3, 2017 -
11:00am to 12:00pm

Society as a Complex System Seeking a Safe and Just Operating Space for Humanity

 John Finnigan
CSIRO Oceans and Atmosphere
Australia

The concept of planetary boundaries around a safe operating space for humanity in the coming century has proved a useful framing of the problems of global sustainability.  Originally defined in terms of the biophysical state of the planet, where a safe operating space is taken as the late Holocene climate, the concept has been extended to a safe and just operating space by defining some essential social attributes and freedoms that bound an acceptable society, for example through the UN’s sustainable development goals.  The problem we face is that the processes that define biophysical and societal ‘safety’ are deeply interconnected and should be understood as attributes of a single complex system.

In this talk we first discuss the key attributes of complex systems-emergence and self organisation-as they apply to simple systems and then to the human-earth system, defined as the intersection of the biophysical world and human society.  We contrast the pre- and post-industrial world and show how a strong attractor controlled the relationship between population and per-capita wealth until the industrial revolution but that this changed fundamentally 200 years ago.  We go on to construct a conceptual dynamical systems model of the post-industrial world, highlighting the links and feedbacks between population, economy, societal state and our impact on the biosphere.  This model highlights the key role played by urbanisation and inequality in societal transformation. Finally, we ask what this model can tell us about the current trajectory of the human-earth system and whether a safe and just operating space is an attractor for the system. 

Thursday, 23 February, 2017, 3:30 PM

Refreshments 3:15 PM
NCAR-Foothills Laboratory
3450 Mitchell Lanem Bldg. 2, Main Auditorium, Room 1022

 

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 23, 2017 -
3:30pm to 5:00pm

The 5th annual workshop of Rising Voices: Collaborative Science with Indigenous Knowledge for Climate Solutions will be held at the National Center for Atmospheric Research in Boulder, Colorado from 13-15 April, 2017. The workshop will be convened in partnership with Cultural Survival (https://www.culturalsurvival.org/) and the International Indian Treaty Council.

The theme of the 5th Rising Voices workshop is “Pathways from Science to Action.” Through collaborative research presentations and group discussions we will develop specific pathways to move from science to action for climate adaptation at local, national, and international levels. Rising Voices seeks to diversify scientific research and inform culturally appropriate solutions to weather and climate extremes with a focus on Indigenous science. The fifth workshop will be an opportunity to address the climate change issues and solutions impacting Indigenous communities globally and to reflect on lessons learned and best practices gleaned from the first five years of Rising Voices. Workshop participants will address the key question: What are the collaborative pathways to create more diverse science and to move from science to action? Through new partnerships, Rising Voices 5 will contribute to the 16th meeting of the United Nations Permanent Forum on Indigenous Issues.

This event is by invitation only. You can view the workshop by webcast.

First Name: 
Kris
Last Name: 
Marwitz
Phone Extension (4 digits): 
8198
Email: 
kmarwitz@ucar.edu
Building:
Room Number: 
1022
Host lab/program/group:
Type of event:
Calendar Timing: 
Thursday, April 13, 2017 -
8:30am to 5:00pm
Friday, April 14, 2017 -
8:30am to 5:00pm
Saturday, April 15, 2017 -
8:30am to 5:00pm

Observations and Large-Eddy Simulations of Wind Gusts in Hurricanes

George H. Bryan
National Center for Atmospheric Research

Measurements of wind speed in strong hurricanes are rare.  Hurricanes are infrequent, they typically occur far from land, and (of course) they are hazardous, making high-quality data collection quite difficult.  Some observations have shown that near-surface wind speeds can exceed 100 m/s, but these measurements are often dismissed as “suspect.”  More certain measurements of maximum wind speed in hurricanes would be useful for a variety of applications, such as the design of wind turbines that are planned for the east coast of the United States.  To help address this gap in knowledge, we have been using large-eddy simulations of idealized hurricanes with grid spacing as small as 31 m.  Our simulations feature near-surface wind gusts exceeding 110 m/s, and values of gust factor (the ratio of peak wind to average wind) exceeding 1.7.  We have identified a coherent structure that is associated with these gusts, which exists in the strongly sheared region between the eye and eyewall of the simulated hurricanes.  These simulations are also being used to assess the ability of observing platforms to measure peak wind gusts, including new technologies such as unmanned aerial vehicles.

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

NCAR-Foothills Laboratory
3450 Mitchell Lane
Bldg. 2, Main Auditorium, Room 1022

First Name: 
Caroline
Last Name: 
Haws
Phone Extension (4 digits): 
8189
Email: 
haws@ucar.edu
Building:
Room Number: 
1022
Host lab/program/group:
Type of event:
Calendar Timing: 
Thursday, February 16, 2017 -
3:30pm to 5:00pm

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