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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

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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

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+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”

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*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

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+

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

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+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.

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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

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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.

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Questions?