Events (Upcoming & Past)

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).  

Thursday, 18 May 2017, 3:30 PMRefreshments 3:15 PMNCAR-Foothills Laboratory3450 Mitchell LaneBldg. 2, Main Auditorium, Room 1022 

Building:
Room Number: 
1022
Type of event:
Will this event be webcast to the public by NCAR|UCAR?: 
Calendar Timing: 
Friday, May 19, 2017 - 3:30am to 4:30am

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 PMRefreshments 1:15 PM NCAR-Foothills Laboratory 3450 Mitchell Lane Bldg. 2, Main Auditorium, Room 1022

Building:
Room Number: 
1022
Type of event:
Will this event be webcast to the public by NCAR|UCAR?: 
Calendar Timing: 
Wednesday, April 19, 2017 - 1:30am to 2:30am

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-ReeveClimate and The Bjerknes Centre for Climate ResearchBergen, 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 PMRefreshments 3:15 PMNCAR-Foothills Laboratory3450 Mitchell LaneBldg. 2, Main Auditorium, Room 1022

Building:
Room Number: 
1022
Type of event:
Will this event be webcast to the public by NCAR|UCAR?: 
Calendar Timing: 
Friday, April 7, 2017 - 3:30am to 4:30am

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 AdvancesWalter PeacockTexas A&M University, Hazard Reduction & Recovery CenterCollege 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 PMRefreshments 3:15 PMNCAR-Foothills Laboratory3450 Mitchell LaneBldg. 2, Main Auditorium, Room 1022

Building:
Room Number: 
1022
Type of event:
Will this event be webcast to the public by NCAR|UCAR?: 
Calendar Timing: 
Friday, March 24, 2017 - 3:30am to 4:30am

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

Mesoscale Aggregation of Shallow Cumulus ConvectionOver The Oceans

Christopher S. BrethertonDepartment of Atmospheric Sciences, University of WashingtonSeattle, 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 PMRefreshments 3:15 PMNCAR-Foothills Laboratory3450 Mitchell LaneBldg. 2, Main Auditorium, Room 1022

Building:
Room Number: 
1022
Type of event:
Will this event be webcast to the public by NCAR|UCAR?: 
Calendar Timing: 
Friday, March 10, 2017 - 5:30am to 7:00am

Pages