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Transcript of + Land-atmosphere interaction: Heat island effect & heat waves Jenny Stubler, Mallory Buckley, &...
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Land-atmosphere interaction: Heat island effect & heat waves
Jenny Stubler, Mallory Buckley, & Rachel Dougherty
+The 1995 Chicago Heat WaveJenny Stubler – Atmospheric Science
Impacts and Responses to the 1995 Heat Wave: A Call to Action
The 1995 Chicago Heat Wave: How Likely is a Recurrence?
Stanley A.
Changnon
Atmosp
heric
Scientis
t @ Ill
inois
State
Wate
r Surv
ey
Kenneth E. K
unkel
Senior Scie
ntist @
CICS-N
C
Beth C
. Reinke
Webmaster @
Illinois
Thomas R
. Karl
Directo
r @ N
OAA-
NCDC Richard
W. K
night
Scientis
t @ N
OAA-
NCDC
+1st Paper
1995
Central United States/Midwest
5 days : July 12 – July 16
>800 deaths
525 in Chicago
“a citywide tragedy”
– Chicago Tribune
Introduction/Background
+
+
Impacts
Facts about weather related deaths in the US People don’t understand the danger of different events
Fail to recognize lightning & winter storms & heat Statistics of weather related deaths are unreliable Most deaths concentrated in a few events
Example 1061 IL tornado deaths since 1916 57% occurred in 1 hour in 1925
+
+Heat related deaths difficult to assess
No federal definition
“heat stroke”
Primary vs. secondary
+Apparent Temperature
High temp, high humidity, no air mvmt, radiation40% RH + 30°C DBT = Apparent Temp
30°C70% RH + 30°C DBT = Apparent Temp
35°C> 8m/s winds = 34°C
“heat stress index”=“heat index”
+
*Chicago 550
*Milwaukee 60
+July 13-16: apparent temps during daytime exceeded 40°C (104°F) and night time temps never dropped below 30°C (86°F), resulting in the most deaths in Chicago
+Comparison to 1936
July 8-15 1936 July 12-16 1995
38°C or higher every day
41°C average
24°C average minimum
297 heat related deaths
40°C or higher every day
35°C minimum never got below
525 heat related deaths
Why the nearly double in deaths???
Late June 1931
36.1°C apparent temperature over 4 days
Ranked as worst of this century due to apparent temp
169 heat related deaths
+Why so many deaths in 1995?
1. Change in social conditions
2. Increased population
3. Differences in record keeping
4. Age distribution
5. Social class
+
+
Impacts
Energy use increased – record high July 14 Many power outages and brownouts Increase in revenue, but sued by businesses
Highways and railroads damaged Heaving and buckling of roadway joints and rails
Insufficient number of ambulances in Chicago Fire trucks used as substitutes
Livestock affected
+Winners of 1995 Heat Wave!!
1. Wisconsin tourism
2. Air conditioner sales
3. Public swimming pools
+Who’s fault was it?
Failure of Chicago government to declare a heat emergency until July 15
Tried to blame NWS
“It’s hot. It’s very hot. We all have our little problems, but let’s not blow it out of proportion”- Mayor R. Daley on July 13th to USA Today
+Urban Heat Island Effect
+Federal Help
President Clinton provided $1000 million for emergency funds for the Low Income Home Energy Assistance Program.
+Summary
Heat waves have the highest death rates
Primary victims are elderly in urban heat island cities
Many cannot afford air conditioning and do not feel safe to open their windows at night due to high crime
+What should we do?
Define the heat island conditions during the day for all major cities to improve forecasts
Develop a national uniform means for classifying heat related deaths
Improve warning systems
Increase research on the meteorological and climatological aspects of heat stress and heat waves
Heat related deaths are PREVENTABLE!!!
+2nd paper
Introduction/Background Chicago heat wave had
over 500 deaths
Karl and Knight considered the apparent temperature
During heat wave, high dew points due to limited vertical mixing from a subsidence inversion, played a key role in the high values of apparent temperature.
+Assessing the 1995 Heat Wave
Apparent temperature used Temp Humidity Wind speed Solar radiation
+
+
+
+
+Inconsistency in Temperature
NWS HO-83 Increased all temperature readings
High temps in Chicago 1995 = HO-83 values Heat Island Effect
+Probability of Recurrence in Current Climate
Maximum Apparent temp exceeding 48.9°C for 1 day is 4.3% (1 in 23
years) Apparent temp exceeding 47.8°C for 2 consecutive days is
less than 1% (1 in 150 years)
Minimum Apparent temp remaining at or above 33.9°C is less than
0.1% Apparent temp remaining above 31.6°C for 2 consecutive
days is less than .01%
+Probability of Recurrence in a Changed Climate Increase of greenhouse=increase in summer temps by 3°C
at the end of next century
Uncertainties in these quantities produce even bigger uncertainties in the recurrence of the Chicago heat wave
Maximum Apparent temp exceeding 47.8°C for 1 day is 1 in 6 years, and for
2 consecutive days is 1 in 25 years
Minimum The 1&2 day events remaining above 33.9°C&31.6°C is still
unusual with probabilities less than 1%
+Summary
Chicago’s 1995 heat wave was very unusual, mostly due to the high night time temperatures that persisted for 2 consecutive days
Without global warming: not expected to happen anytime soon
With global warming: the frequency is elevated but it is still rare
+IntroductionMallory Buckley – Atmospheric Science
Martin Beniston Dr. Erich Markus Fischer
2003 heat wave in Europe: A shape of things to come?
Contribution of land-atmosphere coupling to recent European summer
heat waves
+Introduction
Heat waves Quasi-stationary circulation anomalies
Produce subsidence, clear skies, warm air advection, and prolonged hot conditions at the surface
Land-atmosphere coupling strength Degree to which anomalies in land surface state (soil
moisture) can affect rainfall generation and other atmospheric processes
+The 2003 heat wave in Europe: A shape of things to come?Martin Beniston
+Beniston – Background
2003 heat wave in Europe
Causes: High pressure system centered on English
Channel Prolonged drought and heat Rivers running dry and wilted crops
Expectations for summers in late 21st century Temperature increase by over 4˚C Enhanced content of greenhouse gases Increase in frequency of severe heat waves
+Beniston – Methods
Trends assessed since 1900 from Swiss climate observation network
Information on future shifts in means and extremes of summer temperatures are based on regional climate model simulations HIRHAM4
Reproduces past climates confidence in future predictions
Two simulations 1961-1990 2071-2100
+Beniston – Methods
Assumes a high level of emissions during 21st century resulting from low priorities on greenhouse gas abatement strategies and high population growth in the developing world. Leads to atmospheric CO2 levels of about 800 ppmv by
2100 (three times their pre-industrial values)
Fully-coupled ocean-atmosphere general circulation model HADCM3 Provides initial and boundary conditions for RCMs
Showed trends on daily summer maximum temperatures averaged over June, July, and August
+Beniston – Data & Results
Departures of summer maximum temperatures from the 1961–1990 means
+Beniston – Data & Results
Number of days during which temp exceeded the 30 degree C threshold in Basel (black) and persistence of threshold exceedance (white) from 1901-2003
+Beniston – Data & Results
Change in mean summer Tmax between 1961-1990 and 2071-2100
Number of days exceeding 30˚C threshold compared to 1961-1990
+Beniston – Conclusions
2003 heat wave mimics quite closely the predicted future events
Soil moisture depletion, positive feedback on summer temperatures, & lack of convective rainfall projected for future
+Contribution of land-atmosphere coupling to recent European summer heat wavesE. M. Fischer
+Fischer – Background
Heat waves preceded by pronounced spring precipitation deficit
Results Reduced latent heat cooling Amplify summer temperature extremes
Land-atmosphere interactions contribute to daily maximum temperatures Important for heat wave impacts
Increase in mortality due to number of consecutive days with extremely high temperatures
+Fischer – Methods
Regional climate simulations conducted with and without land coupling for heat waves 1976 1994 2003 2005
Coupled simulations Fully coupled land-surface model
Uncoupled simulations Mean seasonal cycle of soil moisture
+Fischer – Methods
Climate High-Resolution Model (CHRM) 46 year simulation covering 1960-2005 coupled
Repeated uncoupled for ‘76, ‘94, ‘03, and ‘05 uncoupled Comparison between CL and UCL allow the contribution
of land-atmosphere coupling to be isolated
Looked at severity of heat waves Number of hot days (NHD) Maximum heat wave duration (HWD)
+Fischer – Data & Results
1976
Northern France, Southern England
Mean summer temp exceeded by more than 2˚C
More than 35 hot days observed
Unprecedented 16-month period with strong precipitation deficits, less than 50% of long term mean
Coupling model Soil moisture Distinct drought conditions
+Fischer – Data & Results
1994
Central Europe and Mediterranean
Temp anomalies around 2˚C
15-30 Hot days
Precipitation low in June, the month before the heat wave
Coupling model Local drying 500 mb ridge enhanced over
Mediterranean
+Fischer – Data & Results
2003
Central Europe and Mediterranean
Temps exceeded average by more the 3˚C and over 5˚C regionally.
40-60 hot days
Persistent precipitation deficit between Feb and August 2003
Excess in total net radiation in late winter and spring 2003 led to soil moisture depletion
Coupling model Strengthening of 500 mb ridge Strong anticyclonic circulation anomaly
+Fischer – Data & Results
2005
Iberian Peninsula & southern France
1.5-2.5˚C above average
Low precipitation between November 2004 and September 2005
Coupling model Extremely dry conditions
+Fischer – Conclusions
Coupled simulation shows excess in surface net radiation leading to enhanced evaporation
Land-atmosphere interactions over drought regions account for 50-80% of NHD
Land-atmosphere coupling increases mean, maximum, and minimum temperatures averaged over warm summers Important because these extreme episodes of heat are critical
measures for the impact on ecosystems and public health
CHRM has notable accuracy
Lack of precipitation leading up to heat event leads to more severe heat
+Summary
Beniston Based off of the models, the 2003 heat wave is the best
indicator of the future heat wave events
Fischer Land-atmosphere coupling greatly contributes to heat wave Lack of precipitation intensifies heat wave
+Future Research
Limitations exist with the small computational domains
Global simulations would help further explore the effect of drought conditions on heat wave events
+New Directions: The growing urban heat and pollution “island” effectPaul Crutzen
Rachel Dougherty – Atmospheric Science
+Paul Crutzen
Amsterdam
Chemistry and physics
Many notable awards—Nobel Prize winner
+Effects of Human Energy Production
HEP is 1% of greenhouse gas forcing (GHG) of 2.7W/m2.
Leads to increased releases of CO2 and air pollution.
HEP alone is not much of a concern overall, regionally it can cause problems.
Increased energy production in urban areas can lead to urban heat islands.
+ UHI Local Problems
UHI’s main concern is overheating from solar radiation absorption and human energy release.
Positive feedback: A/C example
+ UHI Global Problems
Precipitation effects: aerosols lead to less precipitation in urban areas and more downwind.
Increase in lightning frequency downwind.
Strong convection + UHI could lead to cloud seeding.
+ Why is this important?
Doubling of population in 50 years.
Doubling of urbanization within 20 years.
80% of population expected to live in cities/mega-cities.
+
Solution?
Research and collaboration.
+Suppression of Rain and Snow by Urban and Industrial Air PollutionDaniel Rosenfeld
+Daniel Rosenfeld
Over 150 papers
Hebrew University of Jerusalem
Cloud and rain physics
+Formation of Precipitation
+ Cloud Condensation Nuclei
Small particles (.2μm) on which water vapor condenses
Air pollution in big cities is creating CCN and affecting precipitation.
+Is Pollution Affecting Precipitation Around Cities?
Proven that burning vegetation created small CCN and causes raindrops to form ineffectively near site and causes larger droplets to form downwind.
Is air pollution doing the same thing?
+Methods
Utilized TRMM satellite and NOAA’s AVHRR.
Study pollution tracks, monitor rainfall, measure cloud top temperatures.
+ Turkey
Yellow: areas with smaller dropletsRed: areas with larger droplets
+ Canada
+ Australia
+ Australia
+
T-reff
Relationship
Black: areas of pollutionRed: areas unaffected by pollutionGreen: 14 μm precipitation threshold
Long dash: 15th percentileSolid: 50th percentileShort dash: 85th percentile
+ Cloud Height vs. Reflectivity
• Line 6 (polluted) has the lowest reflectivity
• The 2/2.5km peak corresponds to the “bright band”.
+Conclusions and Further Research Air pollution from UHI produce more CCN, which lead to
small rain droplets in urban areas and less precipitation.
The areas downwind of UHIs are experiencing an increase in precipitation.
Conduct similar studies in more areas.
Look into the other theories mentioned in Crutzen’s paper.
Nothing is ever proven.
+
Questions?