Extreme weather events Flashcards
important research areas
improving observational capability, extending the record of observations, improve diagnostic process studies, develop models, conducting integrated impact assessments
reasons for increase in extreme events
climate change
whats a hazard
process, phenomenon or human activity that may cause loss of life, injury, property damage, social/economic disruption or envtl degradation
whats a risk
chance, high or low, that any hazard will actually cause somebody harm
whats weather
reflects the conditions of the atmosphere over a short period of time
whats climate
refers to the average weather/atmospheric patterns over an extended time period
whats happened to the intensity and deadliness of cyclones across the atlantic
they’ve increased alot
whats the palmer drought severity index (PDSI)
prominent index of drought and measures the cumulative deficit in surface land moisture by incorporating previous precipitation and estimates of moisture drawn into the atmosphere into a hydrological accounting system
whats the trend of precipitation in USA
increased - concentrated inn heavy events, particularly in the northeast and midwest
ACE index
accounts for combined strength and duration of tropical storms and hurricanes during a given season by computing theism of squares of the 6 hour maximum sustained surface winds in knots while the storm is above tropical storm intensity
-levinson 2005
have amount and length of storms increased?
those lasting 2 days have not increased
those lasting less than 2 days have increased a lot - maybe due to better observations
what else could wildfires be affected by
land management and regulatory decisions
people building homes at the wildland urban interface
costs of weather variability
9 weather and climate disaster events with losses exceeding $1 billion each in USA
overall impact
wet gets wetter, dry gets dryer
what does disproportionate warming of the poles do
reduce meridional temp gradient, impacting speed and waviness of jet stream.
jet stream moves further north
what happens to jet stream
moves further north
slows
becomes more wavy
more episodes of severe cold weather
whats the most pronounced mode of coupled atmosphere-ocean variability
el nino
- largest source f climate variability in the instrumental record
an atmosphere ocean coupling
Normally, the tropical Pacific Ocean features strong trade winds that blow from east to west - warm water piles up near Indonesia
These trade winds bring ocean water with them, which gets heated up by the sun. piles up in the western Pacific. The large warm pool of water near Indonesia causes the air above it to rise, creating rainfall. Meanwhile, back east along South America, frigid water deep down in the ocean gets pulled up closer to the surface — cooling the waters around Peru.
sea levels are about half a meter higher in Indonesia than they are in South America. Sea surface temperatures near Indonesia are also about 8°C (or 14.4°F) warmer than near Peru
- convective loop
el nino
what is it and effects
pacific trade winds disrupted every few years.
- warm water near Indonesia sloshes back E
- thermocline starts sinking
- waters near Peru start warming
- less rain in sahel region of Africa so less triggering of African easterly waves (seeds for cyclones)
This all causes sea surface temperatures in the east and central Pacific to start rising and the trade winds to weaken further - positive feedback
el Nino associated with drier weather in places like Australia and Indonesia
who is sir Gilbert walker
boomerang
pacific so vast - ENSO system is a major driving force in global climate
whats la nina
cold and dry in california
attribution
process f evaluating relative contributions of multiple causal factors to a change or event with assignment of statistical confidence
2 classes of attribution
- those that rely on observational record to determine change in probability and magnitude
- those that use model simulations to compare the manifestation of an event in a world of human caused climate change and one without
climate models can be ran several times with variations in:
- diff future warming scenarios
- diff models
- account for natural ‘random’ variability in earths system
solution to each simulation giving slightly diff answer
run it enough and get a mean
what do we look out for in events to see change
- frequency
- intensity
- duration
- timing
winter of 2013/14 storm in UK
record rain and flooding. thames river valley was damaged - £1billion
in the SE England whats the chance of exceeding the current rainfall record in at least one month in any winter
7%
confidence in attribution results is strongest for extreme events that
- have long term record
- simulated adequately in climate models
- purely meteorological in nature and we understand the driving physical mechanisms
are all the events purely meteorological?
no they have human components till
are the impacts always the same
no, depends what intervention and mitigation occurs
many cities located near coast
benefits of understanding links between cc and weather events
- prediction
- mitigation
- international corporation and investment
- insurance and risk transfer
why can temp rise effect weather
- increase in evapotranspiration
- atmosphere hods 4% more water vapour now than 40yrs ago
- disproportionate warming of poles compared to equator
- changes in sea surface temp
