Events (Upcoming & Past)

Upcoming MMM Events

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

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

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

High-resolution climate simulations using a regional climate model

Dominic Matte
ESCER/UQAM
Montreal, Quebec, Canada

Although practitioners of dynamical downscaling are well aware that the jump of resolution between the driving data and the nested regional climate model impacts the simulated climate, the issue has never been properly studied. Larger is the jump of resolution, larger is the distance from the lateral inflow to fully develop the small-scale features permitted by the increased resolution. This latter point has repercussions on the computational cost, and becomes an issue for large jump of resolution.

My research has focused on those methodological issues for high-resolution climate simulation purposes. Using the idealized “perfect model” framework so-called the Big-Brother experiment, we have shown that the multiple nesting approach is not only appropriate for a large jump of resolution between the GCM and the RCM, but also reduces the computational cost. This is explained by a substantial reduction of the spatial spin-up, reducing, then, the minimal required domain size. Those results have led to a new study design to deepen our understanding about spatial spin-up. Using a similar Big-Brother experiment but with different jumps of resolution between the lateral boundary conditions and the grid mesh of the nested model, we have shown that the spatial spin-up is intimately linked to the jump of resolution and the weather regime. Thus, explaining the reduction of spatial spin-up observed in our previous study using the multiple nesting approach. In other world, since the multiple nesting reduces the jump of resolution, it also reduces the spatial spin-up distance. As a paramount result of our study, an empirical equation to estimate the spatial spin-up lateral distance has been developed. A complementary part of my research consists in an application of these findings for simulating the freezing and frozen precipitation occurrences in a climate-change context using various precipitation-type diagnostic algorithms.

In the last decade, several efforts have been made to foster high-resolution climate-change information through coordinated experiments such as CORDEX in which a strict simulation framework is imposed, including domain size and location. Ours findings have shed light on some of the methodological issues associated to dynamical downscaling which might help to elaborate such frameworks. 

Thursday, 9 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 9, 2017 -
3:30pm to 5:00pm

Cloud-Atmospheric Boundary Layer-Surface Interactions on the Greenland Ice Sheet

Amy Solomon
University of Colorado and NOAA/ESRL
Boulder, Colorado

The fate of the Greenland Ice Sheet (GIS) in a warming world will impact climate globally. For example, if the entire GIS melts, sea level is predicted to rise by up to 7 meters, thereby increasing flooding of coastal land, causing saltwater intrusion into groundwater, and potentially impacting ocean circulations through increased freshwater fluxes. 

Over the past two decades there has been a trend towards increasing GIS melt and mass loss, leading to a number of record melt years and providing increasing contributions to sea-level rise. This presentation is focused on the recent extreme melt event of July 2012, where over 90% of the GIS surface experienced melt, even at Summit Station (hereafter Summit, 3216 meters above sea level), which previously experienced melt 126 years before in 1889. 

Surface energy balance models have been used to demonstrate that melt at the top of the GIS would not have occurred in July 2012 without the warming effect of low-level thin mixed-phase clouds. We present results of the impact of clouds at Summit from measurements taken during The Integrated Characterization of Energy, Clouds, Atmospheric State and Precipitation at Summit (ICECAPS) campaign. We then explore the July 2012 extreme melt event in detail with limited-area model simulations that allow us to go beyond cloud radiative effect estimates and to investigate the coupled feedbacks related to these low-level clouds that influence surface energy fluxes, and therefore the energy available for melt, at Summit and across the GIS.

Thursday, 19 January 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, January 19, 2017 -
3:30pm to 5:00pm

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