Events (Upcoming & Past)

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Past MMM Events

Piotr SmolarkiewiczEuropean Center for Medium Range Weather Forecasts (ECMWF)United Kingdom 

The talk highlights the development of the Finite-Volume Module (FVM) of the Integrated Forecasting System (IFS) at ECMWF. FVM represents an alternative dynamical core that enhances the spectral dynamical core of the IFS with new capabilities, such as a compact-stencil finite-volume discretisation, flexible meshes, conservative non-oscillatory PDATA transport, and all-scale nonhydrostatic governing equations. As a default, FVM solves the compressible Euler equations in a geospherical framework, using a centred two-time-level time-stepping scheme with 3D implicit treatment of acoustic, buoyant and rotational modes. A hybrid computational mesh, fully unstructured in the horizontal and structured in the vertical, enables efficient global atmospheric modelling. Theoretical considerations are illustrated with results of benchmark simulations of intermediate complexity, and comparison to the operational spectral dynamical core of the IFS.

Refreshments: 3:15 PM

Building:
Room Number: 
1022
Type of event:
Will this event be webcast to the public by NCAR|UCAR?: 
Calendar Timing: 
Friday, October 27, 2017 - 3:30am to 4:30am

Piotr Smolarkiewicz
European Center for Medium Range Weather Forecasts (ECMWF)
United Kingdom 

The talk highlights the development of the Finite-Volume Module (FVM) of the Integrated Forecasting System (IFS) at ECMWF. FVM represents an alternative dynamical core that enhances the spectral dynamical core of the IFS with new capabilities, such as a compact-stencil finite-volume discretisation, flexible meshes, conservative non-oscillatory PDATA transport, and all-scale nonhydrostatic governing equations. As a default, FVM solves the compressible Euler equations in a geospherical framework, using a centred two-time-level time-stepping scheme with 3D implicit treatment of acoustic, buoyant and rotational modes. A hybrid computational mesh, fully unstructured in the horizontal and structured in the vertical, enables efficient global atmospheric modelling. Theoretical considerations are illustrated with results of benchmark simulations of intermediate complexity, and comparison to the operational spectral dynamical core of the IFS.

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, October 26, 2017 - 3:30pm to 4:30pm

Paul Field UK Met OfficeExeter, United Kingdom

We use convection permitting global aquaplanet simulations to explore the interaction between aerosol and mid-latitude cyclones. Based on model simulations we propose a hypothesis about how midlatitude cyclones will respond to increases in aerosol loading.  In this talk, I will introduce the model results and describe how we tested it with a decade of satellite observations and a more focused period coinciding with the Icelandic volcanic eruption in 2014.

Refreshments: 3:15 PM

Building:
Room Number: 
1022
Type of event:
Will this event be webcast to the public by NCAR|UCAR?: 
Calendar Timing: 
Friday, September 29, 2017 - 3:30am to 4:30am

Paul Field
UK Met Office
Exeter, United Kingdom

We use convection permitting global aquaplanet simulations to explore the interaction between aerosol and mid-latitude cyclones. Based on model simulations we propose a hypothesis about how midlatitude cyclones will respond to increases in aerosol loading.  In this talk, I will introduce the model results and describe how we tested it with a decade of satellite observations and a more focused period coinciding with the Icelandic volcanic eruption in 2014.

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, September 28, 2017 - 3:30pm to 4:30pm

Xiaolei ZouEarth System Science Interdisciplinary Center (ESSIC)University of Maryland

Abstract: The Advanced Technology Microwave Sounder (ATMS) onboard Suomi National Polar orbiter Partnership (S-NPP) satellite combines Advanced Microwave Sounding Unit-A (AMSU-A) and Microwave Humidity Sounder (MHS) onboard NOAA and Meteorological Operational Satellite Program of Europe (MetOP) satellites to simultaneously provide collocated radiance measurements of the atmospheric temperature and moisture profiles under almost all weather conditions except for heavy precipitation. The two lowest frequency ATMS window channels 1-2 (23.8GHz and 31.4 GHz) are the same as AMSU-A channels 1-2 and the other two high-frequency ATMS window channels 17-18 (88.2GHz and 165.5GHz) are similar to MHS window channels 1-2. These four ATMS window channels can be used together for identifying both liquid and ice cloudy radiances. This important feature of ATMS proved to be important for improving the forecast skill of severe weathers populated with clouds (e.g., hurricanes) through satellite microwave radiance assimilation (Zou et al., 2013). Assimilation of microwave radiance data in numerical weather prediction (NWP) models has traditionally been carried out with AMSU-A and MHS data in two separate data streams since the launch of NOAA-15 in 1998. Inspired by the ATMS data assimilation success, a new approach was proposed to combine AMSU-A and MHS radiances into one data stream for their assimilation. It was shown that the spatial collocation between AMSU-A and MHS field of views (FOVs) allows for an improved quality control of MHS data, especially over the conditions where the liquid-phase clouds are dominate. It was found that the quantitative precipitation forecast (QPF) skill associated with landfall hurricanes was significantly improved by the one data stream approach, resulting from a closer fit of analyses to AMSU-A and MHS observations is obtained, especially for AMSU-A surface-sensitive channels (Zou et al., 2017). A shortcoming was also found for S-NPP ATMS whose radiance observations displayed a clear across-track striping noise, which was not found in AMSU-A radiances. Three algorithms were subsequently developed for mitigating the ATMS striping noise for the upper-level sounding channels (Qin et al., 2013), for an operational implementation (Ma and Zou, 2015) and for surface sensitive channels (Zou et al., 2017). Impacts of striping noise mitigation on observation error variances were also quantified for assimilation of destriped ATMS radiance observations.

Refreshments:  10:45 AM

Building:
Room Number: 
1022
Type of event:
Will this event be webcast to the public by NCAR|UCAR?: 
Calendar Timing: 
Wednesday, August 23, 2017 - 11:00pm to Thursday, August 24, 2017 - 12:00am

Xiaolei Zou
Earth System Science Interdisciplinary Center (ESSIC)
University of Maryland

Abstract: The Advanced Technology Microwave Sounder (ATMS) onboard Suomi National Polar orbiter Partnership (S-NPP) satellite combines Advanced Microwave Sounding Unit-A (AMSU-A) and Microwave Humidity Sounder (MHS) onboard NOAA and Meteorological Operational Satellite Program of Europe (MetOP) satellites to simultaneously provide collocated radiance measurements of the atmospheric temperature and moisture profiles under almost all weather conditions except for heavy precipitation. The two lowest frequency ATMS window channels 1-2 (23.8GHz and 31.4 GHz) are the same as AMSU-A channels 1-2 and the other two high-frequency ATMS window channels 17-18 (88.2GHz and 165.5GHz) are similar to MHS window channels 1-2. These four ATMS window channels can be used together for identifying both liquid and ice cloudy radiances. This important feature of ATMS proved to be important for improving the forecast skill of severe weathers populated with clouds (e.g., hurricanes) through satellite microwave radiance assimilation (Zou et al., 2013). Assimilation of microwave radiance data in numerical weather prediction (NWP) models has traditionally been carried out with AMSU-A and MHS data in two separate data streams since the launch of NOAA-15 in 1998. Inspired by the ATMS data assimilation success, a new approach was proposed to combine AMSU-A and MHS radiances into one data stream for their assimilation. It was shown that the spatial collocation between AMSU-A and MHS field of views (FOVs) allows for an improved quality control of MHS data, especially over the conditions where the liquid-phase clouds are dominate. It was found that the quantitative precipitation forecast (QPF) skill associated with landfall hurricanes was significantly improved by the one data stream approach, resulting from a closer fit of analyses to AMSU-A and MHS observations is obtained, especially for AMSU-A surface-sensitive channels (Zou et al., 2017). A shortcoming was also found for S-NPP ATMS whose radiance observations displayed a clear across-track striping noise, which was not found in AMSU-A radiances. Three algorithms were subsequently developed for mitigating the ATMS striping noise for the upper-level sounding channels (Qin et al., 2013), for an operational implementation (Ma and Zou, 2015) and for surface sensitive channels (Zou et al., 2017). Impacts of striping noise mitigation on observation error variances were also quantified for assimilation of destriped ATMS radiance observations.

Refreshments:  10:45 AM

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, August 23, 2017 - 11:00am to 12:00pm

Sisi ChenDepartment of Atmospheric and Oceanic Sciences, McGill UniversityMontreal, Quebec, Canada

Shallow convective clouds are ubiquitous, and warm rain largely contributes to the total annual rainfall, particularly in the tropics. Therefore, understanding the microphysical processes inside these cloud systems becomes important. Classical parcel models often produce narrow droplet size distributions (DSDs) which disagree with observations in cumulus clouds. Since the last century, turbulence have been postulated to explain the effective DSD broadening in early cloud stage.

This work studies the very fundamental process involving droplet condensational and collisional growth to explore the fast warm-rain initiation using the direct numerical simulation (DNS). DNS model can accurately resolve small-scale turbulence and simulates the turbulence impacts on droplets that are tracked in the Lagrangian framework, which is infeasible in other models.

This is the first modeling study that incorporates both droplet condensational process and collisional process into the DNS model and investigates the full droplet growth history in the turbulent environment. 

Model results show that condensational growth by itself produces narrow DSD under small-scale turbulence, which is similar to the parcel model results. Results from the simulations that consider pure collision-coalescence process show that small-scale turbulence significantly increases the collision rate between small droplets and thus accelerates the formation of large droplets. In particular, the enhancement is the strongest between similar-sized droplets, which indicates that turbulence effectively broadens the narrow DSD formed by condensational growth. On the other hand, condensational growth considerably brings tiny droplets to 5-10 microns, dynamically shifting the collision rates of those droplets in turbulence. To study how collisional process and condensational process interact under the effect of turbulence, simulation results that consider both condensational and collisional processes will be compared to pure collision-coalescence case. It is shown that the inclusion of condensation significantly changes the behavior of droplet collisions in the turbulence and thus has strong feedback on the DSD broadening. Detailed results and comparison will be presented in the talk.

Refreshments: 3:15 PM

Building:
Room Number: 
1022
Type of event:
Will this event be webcast to the public by NCAR|UCAR?: 
Calendar Timing: 
Friday, August 18, 2017 - 3:30am to 4:30am

Sisi Chen
Department of Atmospheric and Oceanic Sciences, McGill University
Montreal, Quebec, Canada

Shallow convective clouds are ubiquitous, and warm rain largely contributes to the total annual rainfall, particularly in the tropics. Therefore, understanding the microphysical processes inside these cloud systems becomes important. Classical parcel models often produce narrow droplet size distributions (DSDs) which disagree with observations in cumulus clouds. Since the last century, turbulence have been postulated to explain the effective DSD broadening in early cloud stage.

This work studies the very fundamental process involving droplet condensational and collisional growth to explore the fast warm-rain initiation using the direct numerical simulation (DNS). DNS model can accurately resolve small-scale turbulence and simulates the turbulence impacts on droplets that are tracked in the Lagrangian framework, which is infeasible in other models.

This is the first modeling study that incorporates both droplet condensational process and collisional process into the DNS model and investigates the full droplet growth history in the turbulent environment. 

Model results show that condensational growth by itself produces narrow DSD under small-scale turbulence, which is similar to the parcel model results. Results from the simulations that consider pure collision-coalescence process show that small-scale turbulence significantly increases the collision rate between small droplets and thus accelerates the formation of large droplets. In particular, the enhancement is the strongest between similar-sized droplets, which indicates that turbulence effectively broadens the narrow DSD formed by condensational growth. On the other hand, condensational growth considerably brings tiny droplets to 5-10 microns, dynamically shifting the collision rates of those droplets in turbulence. To study how collisional process and condensational process interact under the effect of turbulence, simulation results that consider both condensational and collisional processes will be compared to pure collision-coalescence case. It is shown that the inclusion of condensation significantly changes the behavior of droplet collisions in the turbulence and thus has strong feedback on the DSD broadening. Detailed results and comparison will be presented in the talk.

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, August 17, 2017 - 3:30pm to 4:30pm

Dale Barker UK Met Office

The Met Office global and regional NWP applications are centered around the use of the Unified Model (UM) to provide short-range forecasts out to 5-7 days of global and local significant weather. This talk will describe some of the major upgrades implemented or planned during the timeframe of the new Cray XC40 supercomputer (2015 - 2020) beginning with a brief description of the basic NWP configurations and a summary or recent major upgrades e.g. variational bias correction, additional satellite data, etc.

In July 2017, the resolution of the global NWP system at the Met Office was increased to ~10km, with an associated increase to 20km for the global (MOGREPS-G) ensemble. A more significant change is the introduction of hourly-cycling four dimensional variational (4DVar) data assimilation for the km-scale UK model. The relative contributions to forecast skill improvements of hourly-cycling, the use of the 4DVar technique, and improved driving global model will be assessed in this talk.

Looking forward, additional major upgrades are planned in the next 1-2 years including weakly coupled ocean-atmosphere data assimilation, extension of the km-scale MOGREPS-UK ensemble to T+5 days (plus resolution increase from 2.2km to 1.5km), replacement of the current ETKF ensemble system with an ‘Ensemble of 4D Ensemble Vars’. Details of these promising scientific developments will be provided. Finally, a brief summary of plans for the post-UM ‘Exascale Era’ beginning in ~2023 will be outlined.

Note special date and time. 

Refreshments: 10:45 AM 

Building:
Room Number: 
1022
Type of event:
Will this event be webcast to the public by NCAR|UCAR?: 
Calendar Timing: 
Tuesday, August 8, 2017 - 11:00pm to Wednesday, August 9, 2017 - 12:00am

Dale Barker
UK Met Office

The Met Office global and regional NWP applications are centered around the use of the Unified Model (UM) to provide short-range forecasts out to 5-7 days of global and local significant weather. This talk will describe some of the major upgrades implemented or planned during the timeframe of the new Cray XC40 supercomputer (2015 - 2020) beginning with a brief description of the basic NWP configurations and a summary or recent major upgrades e.g. variational bias correction, additional satellite data, etc.

In July 2017, the resolution of the global NWP system at the Met Office was increased to ~10km, with an associated increase to 20km for the global (MOGREPS-G) ensemble. A more significant change is the introduction of hourly-cycling four dimensional variational (4DVar) data assimilation for the km-scale UK model. The relative contributions to forecast skill improvements of hourly-cycling, the use of the 4DVar technique, and improved driving global model will be assessed in this talk.

Looking forward, additional major upgrades are planned in the next 1-2 years including weakly coupled ocean-atmosphere data assimilation, extension of the km-scale MOGREPS-UK ensemble to T+5 days (plus resolution increase from 2.2km to 1.5km), replacement of the current ETKF ensemble system with an ‘Ensemble of 4D Ensemble Vars’. Details of these promising scientific developments will be provided. Finally, a brief summary of plans for the post-UM ‘Exascale Era’ beginning in ~2023 will be outlined.

Note special date and time. 

Refreshments: 10:45 AM 

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, August 8, 2017 - 11:00am to 12:00pm

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