[Eoas-seminar] Change in date and time of the seminar for the 4th MET faculty candidate

[eoas-seminar at lists.fsu.edu]

Colleagues,

The date and time of the seminar for the 4th EOAS MET faculty candidate 
has changed to Thursday March 9th at 3:15 in EOAS 1044. For those that 
can't be there in person, the zoom link is

https://fsu.zoom.us/j/95826615551?pwd=Tk1LQ0Q5UEN1MEVqbDRCc1BkVi9KUT09

Speaker: Troy Zaremba

Title: Precipitation Growth Processes in the Comma Head Region of the 7 
February 2020 Northeast Snowstorm: Results from IMPACTS


Abstract: On 7 February 2020, precipitation within the comma head region 
of an extratropical cyclone was sampled remotely and in-situ by two 
research aircraft during the Investigation of Microphysics and 
Precipitation for Atlantic Coast-Threatening Snowstorms (IMPACTS) field 
campaign, providing a vertical cross-section of microphysical 
observations and fine-scale radar measurements. The sampled region was 
stratified vertically by distinct temperature layers and horizontally 
into a stratiform region on the west side, and a region of elevated 
convection on the east side. In the stratiform region, precipitation 
formed near cloud top as polycrystalline crystals. No supercooled water 
was present. Polycrystalline habits occurred through the cloud depth, 
implying that the cloud top region was the primary source of particles. 
Total number concentration slightly decreased with depth, consistent 
with growth by vapor deposition and aggregation. In the convective 
region, new particle habits were observed within each 
temperature-defined layer along with detectable amounts of supercooled 
water, implying that ice particle formation occurred in several layers. 
Total number concentration decreased from cloud top to the -8°C level, 
consistent with particle aggregation. At temperatures >-8°C, ice 
particle concentrations in some regions increased to >100 L-1, 
suggesting secondary ice production occurred at lower altitudes. Recent 
work also shows that cloud top phase was predominantly liquid within the 
convective region and predominantly ice within the stratiform region. 
WSR-88D reflectivity composites during the sampling period showed a 
weak, loosely organized banded feature. The increase in reflectivity 
associated with the easternmost band was consistent with the melting ice 
particles.  A conceptual model of precipitation growth processes within 
the comma head will be presented.

Regards,
Mark
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