EOS 170 III Flashcards
when was Fort MacMurray 2016 fire extinguished
after 2017 snow melt
what is a fire hazard
a woodland fire directly impacts humans
examples of how fires impact human activity
- wildland-urban interference
- threaten economic activity
- forestry, mining, pipelines, communications
how does forestry impact fire hazard
Forestry invests in monoculture tree farms, primarily pine
-monoculture easy to burn
Physical fire hazard modelling
relies on understanding of physical processes
- must know fuels, terrain, weather
- use radiation, convection
empirical modelling of fire hazard
statistical relationship btw observed fire behaviour and input variables
- do not have to rely on physics
- relate behaviour to observed
physical modelling advantages
widespread applicability
empirical modelling advantages
-easy to implement
physical modelling disadvantage
-must have thorough understanding of physical processes
empirical modelling disadvantage
- model tied to calibration data/area
- not good widespread (highly variable env’ts)
fire behaviour modelling vectors
- terrain / topography
- weather
- fuel
Fire behaviour modelling, topography
- most stable
- slope gradient
- aspect
Fire behaviour modelling, weather
- standard meteorological conditions
- may add historic data
Fire behaviour modelling, fuel
- most complez
- species, forest structure, complexity
- coarse woody debris (forest floor)
slope gradient
first derivative of elevation
aspect
direction of maximum slope
SWI
soil wetness index
-complex metric combining upslope drainage area and gradient
fuel typing
- vegetation type (grassland, deciduous, etc)
- stand structure (height, density, leaf area, height, age)
Fire fuel mapping
- MODIS, optical sensor, 250m res
- LANDSAT, os, 30m res
- RADARSAT, microwave sensor, variable res
- Airborne Imaging RADAR, ms, variable res
- LiDAR
LiDAR
Light Detection and Ranging
- pulsed laser beam
- high frequency
- measures very detailed heights
Modelling caveats
- output detail = input detail
- output accuracy - product of input variable errors
weather
- meteorological conditions
- short-term processes
- localized
- temperature, precipitation, wind at a given time and place
climate
- meteorological conditions
- T, precip, wind that characteristically prevail in a region
- long-term processes
- regional
- statistics of weather
- weather averaged over t for a region
weather changes on short-long t scales due to
- meteorological conditions (moving air masses)
- daily T changes
- seasonal variation
- climate change
Natural climate change
- polar continents
- continents aligned N-S
- variations in solar heating/ sun spots (11-110 yr cycles)
- Milankovitch cycles
Natural climate change, polar continents
= increased albedo = lower global T
Natural climate change, N-S aligned continents
= ocean circulation bringing warm water to high lats = increased precip. – increased glaciation - lower global T
Milankovitch cycles
- variation in E’s orbital properties
- eccentricity
- tilt
- wobble
atmospheric circulation cells
- 3 cells per hemisphere
- driven by solar E, cold air sinking, weak horizontal P gradient at equator
circulation cell closest to equator
Hadley cell
Hadley cell
- warm air rises at eq.
- atmospheric instability – thunderstorms, latent heat released
- latent heat drives hadley cell
latent heat
- E release as water vapour changes to liquid water droplets
- surrounding air becomes warm and moist
Polar front
- typically 30º
- surface high P causes ground air to diverge
- air mass descends to replace diverging air
- clear skies, dry air
- warm moist vs cold dry = gradient = front at 45º
coriolis
- movement deflected to right in NH
- increases w/ objects horizontal speed
- zero at equator, increases towards poles
eccentricity
- changes in earths orbit
- 100,000 yr cycle
- more elliptical = larger variability in season length
large eccentricity coincides with
broad glacial cycles
orbital tilt
- change in inclination of earths spin axis
- 41,000 yr cycle
- 21.5 - 24.5
- currently 23.5
greater orbital tilt
- greater seasonal extremes
- colder winter, warmer summer
- decreased glaciation
orbital wobble
change in spin-axis direction
- 19-23,000 yr cycle
- precession of the equinoxes
- changes extremeness of seasons
current orbital wobble
E closest to sun during NH winter - milder winters and summers in N than S
greenhouse effect
- INSOLATION as shortwave radiation heats E
- longwave radiates back to space
- greenhouse gases capture longwave (IR, heat) preventing loss
Earths T without greenhouse gases
-18º (average)
Earth’s T with GHGs
16º (average)
Mars T
-53º (no GHG)
Venus T
480º (excess GHG)
greenhouse gases
H2O CO2 CH4 N2O O3 CFCs
anthropogenic GHGs
- burning fossil fuels (CO2)
- decomp, cattle, rice (CH4)
- fertilizer, auto combustion (N2O)
- undustrial gases (O3, smog)
- coolents (CFCs)
Climate change in BC
- Pacific too warm for salmon
- increased wildfires and length of fire season
- more winter precip., more spring floods, landslides, avalanche
4/5 of most costly Canadian disasters 1900-2005
drought
top 3 deadliest Canadian disasters
- influenza, 1918-1925, 50,000 deaths
- halifax explosion, 1917, 1900 deaths
- heat wave, 1936, 1200 deaths
drought can cause
- economic loss: crops, pastures, livestock, water
- famine, death
common cause of drought
- entrenched high pressure ridge
- descending warm dry air mass desiccates land
- high P ridge block moist air flow
‘Dirty 30’s’
- severe drought during 1930s
- 40% less rainfall
- non-drought resistant crops died, did not protect erosion
- immense dust storms blew away top soil
- millions of acres of farmland ruined
- thousands of livestock died
- 1/4 million people abandoned farms
heat-related deaths in Canada
1940s - 50/yr
1970s - 7/yr
present- none
1936 Canada heat wave
- 1180 deaths
- 44º in Manitoba, Ontario, 50º in Kansas
- night-time min. >25º
- rail lines warped
- road surfaces melted in >65º sun
2003 European heat wave
- 35000 died
- worst heat wave in 150 yrs
- 10º hotter than 2001
- 14,800 deaths in France
- 7000 Germany
- 4000 Spain
- 4000 Italy
- 2000 UK
2003 European heat wave, France
- 14,800 deaths
- no AC, nights usually cool
- stone/concrete homes - radiate absorbed heat and cool at night
- high night min.s prevented cooling
- early Aug, many away on Vacation, left elderly home alone to parish
heat wave predictions
- more frequent, more severe
- exacerbated w/ urbanization
- AC reduces hazard
thunderstorms kill, injure, damage by
- lightning
- fires
- hail
- wind
- rain, flash floods
thunderstorm stages
cumulus
mature
dissipating
highest average number of days/yr w/ thunderstorms
southern interior of country
- 25 around Edmonton, regina, toronto
- least near coasts and in North
lightning worldwide
100 strikes/s
9 million strikes/day
lightning in Canada
3 mill flashes/yr 10 deaths/yr 125 injuries/yr 3 light. fire deaths/yr -male deaths 5X fm
lightning deaths
- more in CAD/US than any other natural hazard
- less publicized b/c smaller groups, damage
- death rate decreasing
lightning cause
- updraft/downdraft collisions btw super-cooled water and ice crystals cause electric charge separation
- collision transfer + charge to ice, - to water-ice mixture
- updraft drive ice up = + accumulation at top
- gravity pulls water-ice down = - accumulation at bottom
- induces opposite charge accumulation in ground
water-ice mixture in thundercloud
graupel
Lightning strike is
-electrical discharge btw opposite charge accumulations
lightning strikes occur
- btw cloud and ground
- btw clouds
- w/i cloud
lightning speed
> 10,000 km/s
creates T 30,000º
thunder
rapid thermal expansion of air from 30,000º T
lightning groundstroke
-connection of stepped leader and positive streamer establishes channel of ionized air = low resistance path
stepped leader
(-)electrons stream from cloud-Earth in 50m jumps (stepped leader)
postive streamer
-as near E, positive streamer initiated upward, connecting 50m above surface
lightning groundstroke, return stroke
high-current flow of +charge from E-cloud along ionized path = bright flash
what to do in case of lightning
- follow warnings
- avoid elevated, exposed location
- get into car, don’t touch sides
- crouch down on ground
- stay 5m away from others
lightning 30/30 rule
- if time btw lightning and thunder less than 30s, take shelter (30s = 10km)
- wait 30min after last lightning flash before leaving shelter
what not to do in lightning
- shelter under tree, near metal fence, in tent w/ poles, in cave
- walk under power lines, along rails, highway w/ guards
- go swimming
- stay near open window
- use electric devices
- wash dishes, take shower
- use land-lines
Hail
- layered ice ball formed in thunderstorms w/ large vertical T contrast
- cycle up/down through cloud until too heavy
- add most of mast
- hail clouds often dark w/ green tinge
hail distribution
- require cold air at elevation
- most common in prairies, central BC
- AB ‘hailstorm alley’ lee side of rockies - highest hail rates in world
hailstone sizes
- compared to common objects
- CD 128mm
- softball 114mm
- Grapefruit 102mm
- baseball 70mm
- Egg 50mm
- golfball 44mm
- marble 13mm
- pea-size 6.4mm
Hail terminal velocity
- max speed
- balance of g acceleration vs air drag
- varies by diameter
- 1cm = 9m/s (32km/hr)
- 8cm = 48m/s (170km/hr)
largest documented hailstone
0.75kg
28cm diameter
hail damage
- rarely injures or kills
- one of most expensive natural hazards damages:
- cars, aircraft, skylights, glass grooves, kills livestock, destroys crops
Canada’s deadliest tornadoes
Regina, 1912, 28 deaths
Edmonton, 1987, 27d
Windsor, 1946, 17d
most tornadoes in the world
US - 1000/yr
Canada- 100/yr
Europe 250/yr
most canadian tornadoes
south end of province and BC interior
-very highest in S Ont
most tornadoes in US
E side of country
tornado classification
Fujita scale
-6-level scale
-according to storm damage, wind speed
F0 - F5
F0
light damage
- 65-115km/h wind
- 28% of all tornadoes
- width up to 15m
- damages grooves, signs, antennas
- break twigs, branches
F1
moderate damage
- 117-180km/hr
- 39% of all tornadoes
- width 16-50m
- length 1-5km
- damage weak structures
most intense atmospheric phenomena
Tornado
500km/hr wind
F2
considerable damage
- 181-253 km/h
- 5-16kmlong, 50-160m wide
- destroy mobile homes, tip vehicles, uproot large trees
F3
severe 254-332 km/h -6% -16-50km long, 160-500m wide -entire roofs, levels trees, lift heavy vehicles
F4
devastating 333-418km/hr -2% -160km long, 1500m wide -well-built building flattened, tossed cars, tree havens, trains flipped
70% of all tornado deaths
F4, F5
F5
incredible >419km/h wind -less than 1% -more than 160km long, 1500-5000m wide -few seconds but terrifying strength -buildings disintegrated, rubble carried far, steel damaged, heavy vehicles thrown up to 2km
tornado formation
3 air masses in different direction cause rotation w/i thunderstorm cloud
tornado forming air masses, NA
- low altitude N flow warm moist air (GoMex)
2.mid-alt. winds to SE of cool dry air - ## high alt., high -speed jet stream winds to E
tornado alley
- US great plains, btw rockies and appalachians
- cold dry rocky air meets warm moist GoMex air, hot dry Sonoran desert air
required to spawn tornado
super-cell thunderstorm
super-cell thunderstorm
wind shear title thcloud into anvil - warm updraft separated from cool downdraft - more intense thstorm, higher change of tornado
single-cell thunderstorm
-moisture condenses from rising hot moist air, falls through cloud = cool downdraft, suppresses updraft, reduces intensity of thunderstorm and chance of tornado
tornado damage
- buildings- blow off roofs, gutters, off foundation
- battering from airborne projectiles
- throw people
tornado safety
- listen for warnings
- cellar/ basement w/o windows
- safe room
- safer in a parked vehicle than mobile home
1947 super tornado outbreak
- > 16 hours
- 148 tornadoes in 13 states + Ontario
- 6 F5s on ground >50km
- 335 deaths
- 1200 injuries
- > 7500 destroyed homes
1987 Black Friday tornado, edmonton
Deadliest since 1912
- F4, max winds 330-415km/hr
- 40km long path, 1km wide, 1hr on ground
- 27 killed, 300 injured, 750 homeless
Changing climate in canada, Natural Resources
- new opportunities (North)
- awareness and action most important where clear direct relationship w/ climate (forestry, hydro)
Changing climate in canada, food
- increased invasives, diseases
- medium-term increase in production
- warmer-weather crops grown further north
- extended growing period, feeding season for livestock
Changing climate in canada, biodiversity
- species distr. shifts
- many species cannot adapt fast enough
- protected areas, migration corridors imperative
- ecological restoration/ mitigation provides resilience
Changing climate in canada, human health
- climate-sensitive disease (lyme), vectors
- hazards
- new tools: heat alert, projection of vector-borne illnesses, greening urban areas
long-lived, straight-line wind storm associated with fast-moving severe thunderstorms
Derechos
Derechos winds
- gust front/ outflow boundary
- sustained winds
- increased in strength behind front
Derechos occurrance
- US warm-weather phenomenon
- mostly in summer in NH
Derechos cause
hurricane-force winds, tornadoes, heavy rain, flash floods
Flood:
overflow or accumulation of water that submerges land
flooding causes
damage to buildings, roads, bridges, sewers, vehicles
- drowning (ppl, livestock)
- contamination of water
- spreads disease
- destroys crops
- kills trees
- famine
Canada floods
- few deaths (ca. 200 in 20th C), 10-15/decade
- increase since 1960s
Floods in canada, occurrence
- every month
- max: Spring, early summ
- min: fall, early winter
- every province
Most floods in Canada
- ON, QB, NB
- few in North
Eliminate flood risk
- move away from water
- live near water for food, water, travel, transport, trading, irrigation, recreation, aesthetics
- perceived value exceeds risk
Flood types
- Hydrometeorological floods
- Natural dams
- rainfall flood
Hydrometeorological floods
- caused by specific weather
- rainfall
- snowmelt
- rain-on-snow
- icejam
Natural dam flood
-obstructed water flow floods land
catastrophic failure of natural dam
outburst flood
worldwide, affects more people than any other natural disaster
flooding
rainfall flood
-precip > infiltration + carrying capacity of streams/ rivers
slow rainfall flood
- sustained heavy rain over large are for 1+ days
- exceed runoff capacity
flash flood
- torrential rainfall over short t period (less than 6hr) and small area
- saturate ground w/ runoff
VI slow flood
2009
- 300 homes evacuated
- schools close
- high tides flood Duncan
- high tides stopped rainwater from draining
VI 2009 flood cause
Pineapple express
- several days of heavy rain
- 250 mm in 24hrs on N island
- 8 rivers flooded including cowichan, animo
Pineapple express
warm, moist, sub-tropical P air from Hawaii = heavy rains
canadian record flash flood
Buffalo gap, SK, 1961 -254mm in less than 1hr Toronto, 2005 -153mm + hail -$500M damage
flash flood fatalities
1/2 - driving
driving flood fatalities
- water 0.3 m deep can move vehicle laterally
- water 0.6m can float car, roll or flip
- road surface can be washed out
snowmelt flood
- most common flooding in Canada
- generally in spring
- water unable to penetrate frozen ground - runs over surface
- affects large areas
rain-on-snow flood
- combines rainfall w/ snowmelt flood
- heavy rain on snow at ca 0º
- rain+snow cannot penetrate frozen ground
- heavy water-saturated snow damages buildings, roofs, and cause avalanche hazard
Icejam flood
- major problem in CAD rivers
- accumulation of ice, obstructs river flow
- at freeze-up or break-up, worst flooding at break-up
common icejqm sites
- river bend
- change in slope
- bridges, piers
rivers particularly vulnerable to icejam
S-> N flowing
- S break-up sends ice N where still frozen
- ex. St Lawrence, McKenzie, Red River
Natural dams formed by
- glaciers
- mass movement
- lava/ pyroclastic flow
catastrophic failure of natural dam
outburst flood
outburst flood of glacial origin
Jökulhlaups
-icelandic for ‘glacier-burst’
Vatnajökull Jökulhlaup
-icelandic volcanism beneath Vat. icecaps maintain sub-glacial lake
Vatnajökull Jökulhlaup, 1996
13day eruption filled lake w/ 4km3 of water
- lake failed, 3.6km3 discharged in 20hrs
- peak 55,000 m3/s (20X rate of Niagra)
- 1000 tonne iceblocks
- 9m of sediment
Vatnajökull Jökulhlaup lake
Grimsvötn
Vatnajökull Jökulhlaup damages
- 6km of highway
- power, phone lines
- 2 concrete and steel bridges
Flood frequency plot
- of historical data
- to estimate return period for given size flood
- river discharge vs return period (yrs)
- use for designing roads, bridges, buildings
100-yr flod
1% probability of occurring in any year
flood safety, before
- build flood resistant
- listen for warnings
- if time permits, move valuables above ground level, turn off furnace, gas
- if imminent, turn off power, plug sewer drains
make your home flood resistant
seal ground-floor/basement windows, doors
- install drains
- install sump pump, one-way valves in drains
flood safety, during
- listen to radio
- do not cross flooded area
flood safety, after
- wear boots
- beware of electrical shock
- dispose of food/water exposed to flood (contaminated)
- do not move back in until dried, disinfected
Flood structural mitigation
- contain waters: dams, levees, floodways
- increase river carrying capacity: deepen, widen channel, remove debris/ obstructions
Flood non-structural mitigation
- zoning, land-use policies
- education and evacuation planning
- improved flood forecasting (satellites, river gauges, etc)
Red River
- flows N
- drains N/S Dakota, Minnesota, Manitoba
- Slowly meanders
- broad floodplain
- frequently floods
Red River flooding causes
- geologically young (less than 9000yrs) – not carved deep
- valley underlain by impermeable red clay
- low riverbed slope (8cm/km)
- prone to icejams (S->N flow)
1950 Winnipeg flood
- snowy winter
- late thaw
- dike collapse
- flooding of 1600 km2
- largest CAD evac., over 100,000 ppl, 1/3 of Winnipeg pop.
- 51 day flood
- 10,000 bldgs damaged
- RR floodway built in response
RR Floodway
48km long, 140m wide artificial flood-control waterway around Winnipeg
- normally empty
- in flood, gates open to divert water around city
- built for 1-in-225 yr flood
- typically required every 2-3 yrs
1997 RR flood
- ‘96 fall rainfall 4X normal
- early cold, froze soil
- record winter snow pack
- spring blizzard
- rapid thaw
- N Dakota: 60,000 evacuated, 120,000 cattle drowned, $1B damage
- Manitoba: saved by dike, diverted water at (peak) 1400m3/s, nearly overwhelmed dykes
Alberta flood, 2013
$5B damages (costliest CAD disaster)
- S and central AB
- Bow, Elbow, Highwood, Red Deer, Sheep, :little Bow, S Sak. rivers
- calgary directly hit
- 2200 CAD forces deployed
cause of 2013 AB flood
- heavy spring rainfall
- low-pressyre system blocked S of AB
- resulting air from E pumped moist warm air across semi-arid slopes
- heavy rains particularly over Calgary, >300mm
- saturated ground, steep watershed, heavy snow load
- rivers up to 10X normal flow rate
2013 AB flood, impact
- largest evacuation in cities history, 75,000 ppl
- days before power restored
- central business district off-limits for nearly a weak (very important business hum in CAD)
- bonnybrook bridge collapse
- 150 ppl stranded on rooftops in High River
Boonybrook Bridge Collapse
- under weight of CPR freight train
- pilings scoured by floater, undermined strength
- train was carrying hazardous petrochemicals
what went well in AB flood
- modern construction and codes
- good forecasting and governance
- social trust
- low loss of life despite huge level of destruction
- rapid rebuild
snowpack on slopes can fail due to gravity as
creep
fall
slide
flow
avalanche path
- similar to landslide
- A starting zone (steepest, 30-45º)
- B Track, guided by topography (20-30º)
- C Run-out zone (less than 20º)
Avalanche types
Size 1 -5
- relatively harmless, 10tonnes, 10m, 1kpa
- could injure or kill, 100t, 100m, 10kpa
- damage buildings/vehicles, 1000tonnes, 1000m, 100kpa
- destroy large vehicles, forests, railways, 10,000tonnes, 2000m, 500kpa
- 100,000 tonnes, 3000m, 1000kpa
snowpack
- deposited by multiple storms
- layers w/ diff. properties
- powder and wet
- denser near bottom, with age
- hoar frost crystals can grow btw layers
snowpack, powder
- 95% void
- does not pack
- dry, not sticky
- doesnt stick together
snowpack, wet snow
water between ice
-packs well
snowpack layer boundaries
planes of weakness
loose powder avalanche
- acts like flow
- high speed (65-100km/hr)
- light snow
- buries victims
- largely unharmed, but can smother, disorient
slab avalanche
- slab of heavy cohesive mass detaches at layer boundary
- acts like translational slide evolving into flow
- speed 30-65km/hr
- death, destruction
- most dangerous
avalanche safety -before
- consult avalanche bulletins
- carry avalanche kit
avalanche safety - during, after
- escape to side, can’t outrun
- if caught, ditch backpack, skis, poles
- use swimming motion to stay near surface
- maintain air pocket in front of face
- stay calm
avalanche survival rate
- 50% if buried 30min.
- 15% for 2hr burial
Extraterrestrial impacts
- asteroids
- comets
- fragments of asteroid and comets
fragments of asteroids and comets
- meteoroid
- meteor
- meteorite
before impacting Earth
meteoroid
most impacts
- asteroid fragment
- meteoroid
asteroid
- stony, metallic body
- orbiting sun in inner solar system
- medium sized
- smaller than a planet, larger than meteoroid
- 1-1000km
- sometimes called planetoid, minor planet
comet
- small (.1 - 40km diameter)
- highly elliptical orbit
- nuclei of rock, dust, water ice, frozen gases (CO, CO2, CH4, NH3)
meteorite
after impact with Earth
Asteroid ‘belt’
- 1-2 million asteroids between MVEM (terrestrial) and JSUN (gas giants)
- likely ‘failed planet’
why would asteroid belt be a failed planet
- Jupiter’s gravity prevented coalescence
- large gap btw MVEM and JSUN
smaller asteroid orbits
3 small groups that intersect E/M orbit
- Apollos group (>1000 asteroids)
- Aten group
- Amors group
meteor
while passing through atmosphere
Multiple impacts
2+ asteroids can be gravitationally bound
asteroid/comet fragment before it impacts Earth
meteoroid
Comets in inner SolarSystem SS
- solar radiation vaporizes volatiles in nucleus = tail
- tail points away from sun
- tail up to 1 AU
AU
astronomical unit
- distance from sun to E
- 150M km
Meteorite types
- stony
- Fe-rich
Most meteoroids are
chondritic
-burn or break up in atmosphere)
meteoroid influx
- 100B meteoroids/day
- add 100-1000t to E
- number of impacts decrease w/ size
angle of impact
important to whether it will burn up
of 1mm diameter meteoroids
1/30seconds
cosmic dust
less than 1mm diameter
-drifts down gently
shooting star
ca. 1mm
- melt about 100km above E
- glow for about 1s
meteorite influx
- 1mm -100m
- reach E surface
- up to 3000º
- slowed by atmos.
- 320-640km/hr
1m diameter meteoroids
1/yr
impacts >350t
pass through atmos. largely unaffected
Craters
simple or complex
simple crater
- smaller meteorite
- raised rim
- concave bottom
- no uplift
Complex crater
- larger meteorite, asteroid, comets
- melt/vaporize rock
- central uplift from rebound
- collapsed outer rim leaves crater 20X larger than impacting body
- new mineral formation from high T/P
Earth impact craters
- erased by erosion, subduction, cont. collision, infilling of sed.
- 164 known, 58 in NA
why so many craters in NA
large landmass
some Canadian impact craters
- Manicouagan, Quebec, 75km
- Lake Wanapitei, Ontario
- Pingualuit crater, Quebec
Tunguska event
1908, Siberia
- massive fireball
- heard 1000km away
- not inhabited
- reindeer killed
- man 60km away burnt
- people 480km away knocked off feet
- 80M trees damaged
- no impact crater
what happened in Tunguska event
- stony meteorite or comet frag.
- 30-50m diameter
- exploded at 8km elevation
- blast equivalent to 10-15Mt of TNT , 1000X more powerful than atomic bomb
KTB
- 65MYa
- 1cm clay layer between KT
- K rocks have abundant fossils, T do not
Chelyabinsk meteor
Russia, 2013
- 20m near-E asteroid, miss
- 19km/s
- light brighter than sun
- visible 100km away
- exploded in air –> hot dust and gas cloud
- blast yield 20X Hiroshima a-bomb
why did Chelyabinsk explode
high V
shallow entrance angle
KT extinction
- 85% of species disappeared
- dinos, marine reptiles, many plants
- many severely reduced numbersL fish, plankton, molluscs
- mammals (small), birds, suffered few extinctions
KT asteroid evidence
- Ir layer around world, 300X normal
- clay quartz grains ‘shocked’
- spherules
- radioactive ratios
- tsunami deposits in Yucatan peninsula
- buried impact crater (Chicxulub)
How Chicxulub was found
- petroleum well encountered 90m thick zone shattered rock, shocked quartz, globules, dated 65Mya
- radar topography indicates 180km ring (trough)
likely effects of KT impact
- M11 eq
- 300m tsunami
- worldwide fires
- dust, soot clouds block sun for weeks-months
- water vapour, CO2 in atmos. cause GH warming
- high death rate for many except carrion feeders
Impact hazards
- rare
- no confirmed fatalities
- 1 documented injury, Lethbridge 1954
- very small probability of catastrophic (KT size) and large (Tunguska size) impacts
- NEOs monitored
NEOs
- near Earth objects
- could be deflected by NASA
Space weather
- suns behaviour changes (sunspots, solar winds, magnetic storm)
- causes disturbances in E’s magnetic field - magnetic storm
solar cycle
- 11-yr change in suns activity (sunspots, flares, etc)
- causes effects in space, atmosphere, and E’s surface
Magnetic storms
- strong aurora borealis - indicate hazardous charged particles in atmos.
- severe storm could disrupt power grids
Carrington Event
1859
- sunspots observed
- southern aurorae observed far N on Australia
- solar flares observed
- flare associated w/ major coronal mass ejection (CME) that hit E w/i 18hrs
- geomagnetic storm next day on E
Carrington Event, geomagnetic storm
- largest recorded
- aurorae around the world, could read by them in US
- telegraphs failed, shocked operators
SWORM
Space Weather Operations, Research, and Mitigation
- US task force against space weather
- give 0.5 -2 day warning
Most deadly/destructive weather hazard
Hurricane
Hurricane effects
- huge areas, up to 4000km2
- high winds, up to 240km/hr
- storm surges raising sea level, 6+m
- heavy rains
Tropical cyclone
- powerful rotating low-P system
- warm core
- form between 5-20º of eq.
tropical cyclone with 1+ minutes sustained winds > 119km/hr are:
Hurricanes in Atlantic
Typhoons in Pacific
Cyclones in Indian
Deadliest worldwide disasters 1970-2011
- Cyclone, Bangladesh, 1970, 400,000d
- Eq., China, 1976, 255,000d
- Eq+tsunami, Indonesia, 2004, 245,000d
- Eq., Haiti, 2010, 230,000d
- Cyclone, Myanmar, 2008, 140,000
- Cyclone, Bangladesh, 1991, 140,000
Costliest disasters worldwide, 1970-2010
- Hurricane Katrina, USA, 2005, $50,850 millions of 2010 US dollars
- Hurricane Andrew, USA, 1992, $25,170 MUS
- Terrorist attack, US, 2001, $23,409
- Eq, USA, 1994, $,849
- Hurricane Ike
- Hurricane Ivan
- Hurricane Rita
- Hurricane Wilman
- Hurricane Charley
Canadian deadly Hurricanes, 1900-2011
- Galveston, Atl., 1900, 80-100d
- The August Gale, Atl., 1927, 56d
- Hazel, Atl., 1954, 81d
Pacific only has 2 in top 15
N Atlantic hurricanes
- hurricane season June 1- Nov 30
- peak mid-August- late October
- storm diameter 200-1300km
- lifespan 1-30 days
- direction - W then N
- surface winds counter-clockwise
Hurricanes require
- warm SST (>27ºC in upper 60m)
- warm, humid, unstable air
- weak upper level wind
- coriolis
forces balanced to produce cyclonic flow
-P gradient - force towards low P eye
-Coriolis - perpendicular to motion
-Centrifugal - radially outward
-Friction - opposes motion
NET motion - spiral in
Hurricane formation stages
- Tropic disturbance
- Tropical depression
- tropical storm
- Hurricane
Tropic disturbance
low P zone, draws in thdrstorms
- weak winds, 36km/hr
- not named
Tropical depression
- strengthening wind, 27-63km/hr
- coriolis causes cyclonic wind flow about low P core
- converging winds flow upwards near core, moisture condenses, releasing latent heat, intensified updraft
- not named
- identified by number
cyclone direction in SH
clockwise
Tropical storm
winds 64-118km/hr
-identified by name
Hurricane
winds >119km/hr
- now winds reach core, forms eye
- identified by name
Hurricane eye
- generally circular, 30-65km
- calm, clear, low P
- surrounded by eyewall
eyewall
- cylindrical area of upward spiralling winds
- strongest wind of hurricane
Hurricane decline
when cut off from water water E source
- landfall
- moving over cold water (Canada)
Hurricane paths
generally, in NH:
- start at 10-20ºN
- trades winds push to west at low lats.
- coriolis forces push to right
- westerlies push to East at higher lats.
- path influenced by bermuda high
why no hurricanes at 0-10ºN?
no coriolis!
Bermuda high
high P zone over mid Atlantic
Hurricane winds
add/subtract wind speed
- Hurricane w/ internal wind speed 160km/hr moving NW and 30km/hr
- 190km/hr wind speed on ground to the NE
- 130km/hr ground speed to SW
storm surge
rise in sea level due to:
- strong onshore winds pileing up water
- low atmos. P beneath eye carrying mound of water
- very dangerous if coincide w/ high tide
Maximum storm surge in NH
- 15-30km to right of eye path
- strongest winds
Cat5 storm surge
> 5.5m
record storm surge
13m, Australia, 1899
major cause of property damage in NA and death in low-lying countries like Bangladesh
storm surge
Bangladesh storm surge
7/9 of most deadly weather events in 20th C
- deltas 30cm above sea level
- 35% of country less than 6m above sea
- 5 cyclones/yr
- increasing population
- increasing sea level
Hurricane scale
Saffir-Simpson Scale
Cat 1-5
Hurricane Category 1
Minimal
- winds damage trees
- 119-154km/h wind
- 1.2-1.5m storm surge
Cat2 Hurricane
moderate
- blow down trees
- major damage to mobile homes
- 155-178km/h wind
- 1.8-2.4m SS
Cat3 Hurricane
extensive
- blow down large tress
- small buildings destroyed
- ca 200km/h wind
- 2.7-3.7m SS
Cat4 Hurricane
Extreme -signs blown down -heavy damage to windows, doors, roofs -flooding kms inland -211-250km/hr wind 4-5.5 m SS
Cat5 Hurricane
catastrophic
-severe damages, buildings overturned
->250km/hr wind
>5.5m SS
Hurricane Camille
Florida, 1969
- Cat5, >320km/hr wind, 7.3mSS
- 256deaths
Hurricane names
1953-1979 only female names
- since 1979 WMO uses preselected list of alternating fm/m names, recycled every 6yrs
- names of extreme storms retired (Katrina replaced by Katia, Juan replaced by Joaquin)
Hurricane safety, before
- listen to warnings
- evacuate from coastal area
- park in safe place, not under trees
- take cover
- close/shutter/ board windows
- secure items (lawn furniture, bikes)
- stock food/water, batteries
Hurricane safety during
- keep informed
- stay in secure room w/o windows
- use phone only for emergencies.
- stay inside during passage of eye
hurricane safety, after
- inspect property
- report downed lines
- take photos of damage
hurricane mitigation
- Land-use planning: avoid pop. centres in low-lying coastal land
- building codes: stronger codes for mobile homes, strengthen rook
key requirements to prevent hazards from becoming disasters
- good governance allows
- affluence to afford
- science to inform regulation
- and respond
- democracies
- high trust societies
2017 Atlantic hurricanes
- hyper active season
- 7 named storms, tied for 5th most active season
- ACE + number major hurricanes highest since 2005
- costliest year on record
- 2nd yr on record w/ 2 Cat5’s making landfall
- Irma strongest ever outside of GoMex and Caribbean
- only yr that 3 hurricanes had ACE >40 (Irma, Jose, Maria)
ACE
accumulated cyclone energy
2017 Atl Hurricane cost
US$316.51B
-mostly all due to Harvey, Irma, Maria
Katrina
2005, New Orleans
- costliest natural disaster (pre-2012), $50+B
- 6th strongest recorded
- 1/5 deadliest storms in IS history
- 1800d, 700missing
2005 hurricane season
one of most active ever
- most named storms (28)
- most hurricanes (15)
- most major hurricanes to hit US (4)
- costliest US hurr (Katrina)
- costliest Mexican hurr (Wilma)
New Orleans and Katrina
- 1.2M people
- much of city below sea level, estuary, and Mississippi river
- protected from lake and river by levees
Katrina time line
Aug 25: hurricane status 2hr before reaching Florida, surprised, killed 14
Aug 26: 17% chance of hitting NO (by computer models) w/ 8.5m SS
Aug 28: reaches Cat5 over GoM (unusually warm waters 28-32º), NO begins evac.
Aug 29: landfall 55kmE of NO as Cat3, 195km/hr wind on Miss./Alabama coasts, 8m storm surge screeched levee in 53 places, flooding of 80% of NO
Was Katrina foreseen
yes
- years in advance
- by reports, studies, journals, weather forecasts
Katrina, rain
- extremely heavy local rains as far north as CAD
- up to 10cm rain in ON
- flooding in ON, QB
- 16” in FL 40cm
- 15”, 28cm in LA
New Orleans failures
- levee failures forecast, nothing done
- weather forecast good, evacuation delayed
- failure of leadership at all levels
- low trust, corruption
how could Katrina have been worse
- maintaining CAT4 or 5
- speeding up, earlier landfall
- earlier break of levee
- faster flooding
Hurricane Juan
2003, near Halifax
- Cat2, 160km/hr at landfall
- extensive wind damage to NS, PEI
- 8killed
- $300M damage
- 2m SS
- worst storm to hit Halifax in >100yr
Hurricane Juan damage
- 31% of homes in Halifax damaged
- millions of trees damaged or downed
- downed power lines
- 300,000 w/o power
- grounded boats
Juan retirement
name Juan retired after its effects in Canada in 2004
-first time CAD requested a name be retired
Hurricane Juan governance
- well forecast, action taken at all levels
- high trust society
- ready to respond quickly after event
- coherent response at all levels
- not perfect, but good
when did wildfire begin
appears in geo records after land plants evolve
- Ordovician
- 450Mya
fire influences
- vegetation distribution, structure
- carbon cycle
- climate
Canadian forests
- 10% of worlds forests
- Boreal forests 60% of CAD surface area
- BC dominated by temperate coniferous
- ON, PQ, maritimes are temperate broadleaf
boreal forest
mixed coniferous and deciduous trees
Canadian wildfire
- average 2.5million ha /yr
- huge inter annual variability
1 ha
2.471 acres
10,000m2
100x100m
fires, chemical reaction
-C-H bonds broken in plants, generating CO2 and H2O
C6H12O6 + 6O2 -> 6CO2 + 6H2O + energy heat
fire triangle
- 3 elements required for a forest fire to burn
- heat, oxygen, fuel
- if 1 side of triangle is broken fire will die
stage of combustion
- Ignition
- Preheating
- Flaming combustion
- Glowing or smouldering combustion
Combustion, Ignition
- human or natural
- cigaretes, campfires, power-lines, equipment
- lightning
Combustion, preheating
water is expelled from plants by nearby flames and heat
Flaming combustion
- flames present
- charcoal can be formed in absence of sufficient O2
- greatest E release of fire
glowing combustion
- late stage
- slower combustion
- blue flame
- smoke but no flame
- rarely self-sustained
forest fire classification by what part of forest they are in
- Ground fire
- Surface fire
- crown fire
ground fire
0ften bellow leaves
surface fires
up to 1m high
crown fire
tops of trees
ladder fuels
- tall grasses, small shrubs
- enable ground fires to carry upward into tall trees and form major fires
- multiple types of fire at once
factors that control wildfire starts and spreads
- climate, weather
- chemical constituents
- insects
- topography
- people
climate and weather, fires
- temperature
- humidity
- wind
- lighting
- soil moisture
- rainfall
chemical constituents, fires
- some plants have high oil content - easy ignition
- eg. eucalyptus
- some species more/less resistant to beetle kill
- monocultures spread fire more rapidly
insects, fires
-species such as mountain pine beetle destroy forests = easily combustible dead wood
Fort McMurray wildfire, 2016
- first time >60,000ppl so remote evacuate for fire in NA
- ignited May 1
- burned 600,000ha
- $3.6B in insured losses
- > 2400 buildings destroyed
- no deaths from blaze (at least one vehicle crash on evac.)
- 33º weather hard for firefighting
- humidity 7%, winds 45mph
- controlled July 5
- extinguished Aug. 2
Why the fire in Fort Mc.
- months ahead of typical fire season
- low P center brought hot SW winds across FM
- record daily highs of 33º
- uncommon bad timing - light winter snow, no summer greening yet
Fire suppression
- remove 1 wall of the triangle
- water to remove heat
- fire retardant to block oxygen
- bulldoze forest to remove fuel