Precipitation types and atmospheric conditions in complex terrain

Transcription

1 Precipitation types and atmospheric conditions in complex terrain Julie M. Thériault Université du Québec à Montréal and CCRN Third Annual General Meeting Tuesday 3 November 2015 theriault.julie@uqam.ca CCRN Third Annual General Meeting UQAM 1

2 Summary of my activities in CCRN 1 Finished on going projects : On the impact of snowflake types on the precipitation reaching the surface Housseyni Sankare, MSc Thesis, July 2015 On the precipitation occurrences during the Alberta flooding event Submission of 3 journal articles : Liu et al (2015), Kochtubajda et al (2015) and Li et al (2015) 2 Co-organized and conducted a mountain precipitation field experiment in the Kananaskis area [Ronald Stewart and John Pomeroy] Characterized precipitation types, rain-snow transitions and atmospheric conditions 3 Investigated the microphysical processes associated with the rain-snow transition during the Alberta flooding event theriault.julie@uqam.ca CCRN Third Annual General Meeting UQAM 2

3 Overview of the field project Objectives To better document and understand precipitation and associated atmospheric conditions in the Kananaskis area during the spring season (March-April 2015). What are the types of precipitation observed? What are the associated weather conditions aloft and at the surface? Approach To deploy instruments and collect detailed observations of precipitation types and weather conditions in the Kananaskis Valley To analyze data collected in the field and to conduct numerical simulations of selected case studies. CCRN Third Annual General Meeting UQAM 3

4 Field project in the Kananaskis Valley 122&3(%)'4"+&5& 6'7%#&8('$& 8(0(%&.#9$0'$*& ):)-";&!"#$#%&'$&(&)'$*+"&,+-"%&./'"+0& <(;"%(&)"-9=&=+(7"0&'$&(& >)/'$*&-"$-& CCRN Third Annual General Meeting UQAM 4

5 Data collected at Fortress Mountain!"#$#%&$'()*&'$&$")& +#,*$'-*&$#.& CCRN Third Annual General Meeting UQAM 5

6 Temporal evolution of weather conditions at the surface Type of events [# events] : Rain [4] Mixed precipitation [4] Snow [10] Temperature varied around 0 C Relative humidity varied from 20% to 95% during precipitation events Temporal evolution of precipitation type varied during the project theriault.julie@uqam.ca CCRN Third Annual General Meeting UQAM 6

7 Link among precipitation types, temperature and relative humidity!"#$%& +,"(& '()*& =/$1">"(,/4&/$06150& Legend: Rain Mixed Snow -./$0.)1%0&%$2($%&34&!,506)&$5&,17&89:;9<& Precipitation associated with dry conditions Most of the solid particles were rimed particles [Poster from Ida Hung] Mixed precipitation often reported Questions What is the relationship among the precipitation characteristics, atmospheric conditions at KES and the large-scale flow field? [See poster from Paul Vaquer] CCRN Third Annual General Meeting UQAM 7

8 Mixed phase precipitation event - 31 March 2015 Combinations of rain and wet snow have been recorded at the surface (KES) =">"?-@* 5066*89:*/0*123$4*5607*!"#"$%&'()*+",-*.*/0*123$4*5607* 9-***************9;*******9* 9'<"* The 0 C-isotherm is approximately 700 m higher than Z bright band The radar bright-band is slightly below the height of T w =0 C Questions What are the impacts of sublimation/accretion on the types of precipitation reaching the surface and on rain-snow transitions? [See poster from Émilie Poirier] theriault.julie@uqam.ca CCRN Third Annual General Meeting UQAM 8

9 Precipitation types at the surface Particle characteristics from 2200 to 2220 UTC!!""#$#!!%"#&'(#)#* +,-. #!!%"#$#!!!"#&'()#*!# OBS /-01## 2134# /-01#7:3+9## 506,7#+8-9,#+-:;<=,9# 5-01=>#:-01#7:3+9# Particle types changed and mean diameter decreased Estimated fraction of liquid drops 55% to 95% CCRN Third Annual General Meeting UQAM 9

10 Summary 18 weather events were documented during March-April 2015 in the Kananaskis area Temperatures were mainly near 0 C and dry conditions occurred during the events documented Combinations of precipitation types were often observed and varied during a single weather event Solid precipitation reached the surface at T>8 C The role of accretion is often critical and acts to increase amount of precipitation reaching the surface in dry near-surface conditions Overall, the preliminary analysis highlighted the importance to improve our understanding of the precipitation processes and associated atmospheric conditions in the Kananaskis area. theriault.julie@uqam.ca CCRN Third Annual General Meeting UQAM 10

11 Thank you to all the participants! Ron Stewart, John Pomeroy, Ida Hung, Juris Almonte, Émilie Poirier, Paul Vaquer, Stephen Berg, Émilie Bresson, Mélissa Cholette, Dominic Matte, Housseyni Sankare, Lucia Scaff, May Guan, Angus Duncan, Craig Smith, Bruce Cole, Scott Landolt, Al Jachick, the Biogeoscience Institute, the firefighters at KES, Nakiska ski area, Fortress Mountain people. CCRN Third Annual General Meeting UQAM 11