Heat Waves

Heat WavesHeat Waves

By: Kathryn BullingerBy: Kathryn BullingerBy: Kathryn BullingerBy: Kathryn Bullinger

Double Major: Geography and Earth Sciences

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The 1995 Heat Wave: How Likely is a Recurrence?

Contribution of Land-Atmosphere Coupling to Recent European Heat Waves

By: Thomas R. Karl & Richard W. Knight

By: Fischer, Seneviratne, Lüthi, & Schär

Kathryn BullingerGeography and Earth Sciences Double Major

Lets Start with the Basics:Lets Start with the Basics:

Defined: It is a prolonged period of Defined: It is a prolonged period of excessive heat, often accompanied by excessive heat, often accompanied by excessive humidity.excessive humidity.

Qualifications: Qualifications: The weather is noticeably The weather is noticeably warmerwarmer than normal than normal for the time of year and climate.for the time of year and climate.

The unusual weather continues for a The unusual weather continues for a prolongedprolonged period of period of timetime long enough to be considered a long enough to be considered a specific phase.specific phase.

The weather will most likely bring about some The weather will most likely bring about some sort of increased sort of increased riskrisk to humans and animals, to humans and animals, and may place an increased and may place an increased strainstrain on power on power supplies.supplies.

Defined: It is a prolonged period of Defined: It is a prolonged period of excessive heat, often accompanied by excessive heat, often accompanied by excessive humidity.excessive humidity.

Qualifications: Qualifications: The weather is noticeably The weather is noticeably warmerwarmer than normal than normal for the time of year and climate.for the time of year and climate.

The unusual weather continues for a The unusual weather continues for a prolongedprolonged period of period of timetime long enough to be considered a long enough to be considered a specific phase.specific phase.

The weather will most likely bring about some The weather will most likely bring about some sort of increased sort of increased riskrisk to humans and animals, to humans and animals, and may place an increased and may place an increased strainstrain on power on power supplies.supplies.

What are they? …(if the name alone isn’t enough of a clue…seriously.)

How Does This Happen?How Does This Happen?

When an air mass becomes quasi-When an air mass becomes quasi-static/stationary over a region static/stationary over a region (and it meets all those (and it meets all those qualifiers), it is labeled a qualifiers), it is labeled a heat heat wavewave..

When an air mass becomes quasi-When an air mass becomes quasi-static/stationary over a region static/stationary over a region (and it meets all those (and it meets all those qualifiers), it is labeled a qualifiers), it is labeled a heat heat wavewave..



Why they are Dangerous:Why they are Dangerous:

Heat Heat killskills by taxing by taxing the body beyond its’ the body beyond its’ normal abilities.normal abilities. On average, < 1000 On average, < 1000 Americans Americans diedie heat- heat-related deaths each related deaths each year (as reported by year (as reported by the American the American Meteorological Meteorological Society)Society)

Heat waves kill more Heat waves kill more Americans than any Americans than any other type of other type of natural disaster.natural disaster.

Heat Heat killskills by taxing by taxing the body beyond its’ the body beyond its’ normal abilities.normal abilities. On average, < 1000 On average, < 1000 Americans Americans diedie heat- heat-related deaths each related deaths each year (as reported by year (as reported by the American the American Meteorological Meteorological Society)Society)

Heat waves kill more Heat waves kill more Americans than any Americans than any other type of other type of natural disaster.natural disaster.



Why they are Dangerous: Cont’d.Why they are Dangerous: Cont’d. People who live in People who live in urbanurban areas are at a areas are at a greatergreater risk from risk from heat wave effects.heat wave effects. Stagnant atmospheric Stagnant atmospheric conditions conditions traptrap pollutants.pollutants.

Poor air quality Poor air quality aggravatesaggravates health health problems.problems.

Asphalt and concrete Asphalt and concrete store store heat longer, heat longer, which results in which results in higher nighttime higher nighttime temperatures.temperatures.

Known as the ‘Known as the ‘urban urban heat islandheat island effecteffect’.’.

People who live in People who live in urbanurban areas are at a areas are at a greatergreater risk from risk from heat wave effects.heat wave effects. Stagnant atmospheric Stagnant atmospheric conditions conditions traptrap pollutants.pollutants.

Poor air quality Poor air quality aggravatesaggravates health health problems.problems.

Asphalt and concrete Asphalt and concrete store store heat longer, heat longer, which results in which results in higher nighttime higher nighttime temperatures.temperatures.

Known as the ‘Known as the ‘urban urban heat islandheat island effecteffect’.’.



The Chicago Heat Wave of ‘95:The Chicago Heat Wave of ‘95: July 12July 12thth - 16 - 16thth, 1995., 1995. Approximately Approximately 700700 people died in just 5 people died in just 5 days.days.

July 13July 13thth: : The temperature in the city hit The temperature in the city hit 106° F106° F.. Including the heat index, it felt hotter than Including the heat index, it felt hotter than 120° F120° F..

Chicago’s infrastructure had a meltdown Chicago’s infrastructure had a meltdown (almost literally).(almost literally). Communities lost water pressure.Communities lost water pressure. Train rails and roads buckled.Train rails and roads buckled. Paramedics, hospitals, and morgues overwhelmed.Paramedics, hospitals, and morgues overwhelmed.

Majority of deaths were elderly men who Majority of deaths were elderly men who lived alone.lived alone.

July 12July 12thth - 16 - 16thth, 1995., 1995. Approximately Approximately 700700 people died in just 5 people died in just 5 days.days.

July 13July 13thth: : The temperature in the city hit The temperature in the city hit 106° F106° F.. Including the heat index, it felt hotter than Including the heat index, it felt hotter than 120° F120° F..

Chicago’s infrastructure had a meltdown Chicago’s infrastructure had a meltdown (almost literally).(almost literally). Communities lost water pressure.Communities lost water pressure. Train rails and roads buckled.Train rails and roads buckled. Paramedics, hospitals, and morgues overwhelmed.Paramedics, hospitals, and morgues overwhelmed.

Majority of deaths were elderly men who Majority of deaths were elderly men who lived alone.lived alone.

On to the 1st Paper!On to the 1st Paper!

The analysis:The analysis: Considers the apparent Considers the apparent temperature, temperature, TTapap , which , which attempts to quantify the attempts to quantify the effects of temp. and effects of temp. and moisture on the human moisture on the human body.body.

““Focuses on the severity Focuses on the severity and duration of extreme and duration of extreme heat waves relative to heat waves relative to changes of mean T, changes of mean T, variance, day-to-day variance, day-to-day persistence of T, and the persistence of T, and the cross correlations of cross correlations of these quantities.”these quantities.”

Also created Also created future future scenariosscenarios for heat waves for heat waves of similar or greater of similar or greater intensity. intensity.

The analysis:The analysis: Considers the apparent Considers the apparent temperature, temperature, TTapap , which , which attempts to quantify the attempts to quantify the effects of temp. and effects of temp. and moisture on the human moisture on the human body.body.

““Focuses on the severity Focuses on the severity and duration of extreme and duration of extreme heat waves relative to heat waves relative to changes of mean T, changes of mean T, variance, day-to-day variance, day-to-day persistence of T, and the persistence of T, and the cross correlations of cross correlations of these quantities.”these quantities.”

Also created Also created future future scenariosscenarios for heat waves for heat waves of similar or greater of similar or greater intensity. intensity.



Notable Points that they Took into Account for their Analysis:

Notable Points that they Took into Account for their Analysis:

High High dewpointsdewpoints play a key role in play a key role in high Thigh Tapap values. values.

Minimum T may be especially Minimum T may be especially important.important.

Deaths due to heat are Deaths due to heat are greatestgreatest during the 1during the 1stst few days of a heat few days of a heat wave.wave.

Acclimatization factors also seem to Acclimatization factors also seem to be important.be important.

High High dewpointsdewpoints play a key role in play a key role in high Thigh Tapap values. values.

Minimum T may be especially Minimum T may be especially important.important.

Deaths due to heat are Deaths due to heat are greatestgreatest during the 1during the 1stst few days of a heat few days of a heat wave.wave.

Acclimatization factors also seem to Acclimatization factors also seem to be important.be important.

Assessing the Wave:Assessing the Wave:

Use the TUse the Tapap algorithm algorithm developed by developed by Steadman.Steadman.

TTapap values apply to values apply to shaded daytime shaded daytime conditions and night.conditions and night.

Focus on the the full Focus on the the full distribution of distribution of hourly T’s during hourly T’s during the 1the 1st st few days for few days for 26 stations in and 26 stations in and around the Chicago around the Chicago area.area.

Use the TUse the Tapap algorithm algorithm developed by developed by Steadman.Steadman.

TTapap values apply to values apply to shaded daytime shaded daytime conditions and night.conditions and night.

Focus on the the full Focus on the the full distribution of distribution of hourly T’s during hourly T’s during the 1the 1st st few days for few days for 26 stations in and 26 stations in and around the Chicago around the Chicago area.area.



Min, 25P, 50P, 75P, and Max T plotted for the warmest annual 1, 2, and 3-day events in Chicago history.

Calculated the average Tap for any 2-day period during the ‘95 heat wave to help delineate the aerial extent of the wave.

Calculating Trends of Tap

Calculating Trends of Tap

Used values from 1, Used values from 1, 2, and 3-day 2, and 3-day intervals between intervals between June 15June 15thth and August and August 1515thth (the period of (the period of mostmost intense intense summertime heat in summertime heat in the Midwest).the Midwest).

““The analysis was The analysis was performed for both performed for both observedobserved Tap and Tap and those those adjustedadjusted for for the effects of the the effects of the growth of the urban growth of the urban heat island.”heat island.”

Used values from 1, Used values from 1, 2, and 3-day 2, and 3-day intervals between intervals between June 15June 15thth and August and August 1515thth (the period of (the period of mostmost intense intense summertime heat in summertime heat in the Midwest).the Midwest).

““The analysis was The analysis was performed for both performed for both observedobserved Tap and Tap and those those adjustedadjusted for for the effects of the the effects of the growth of the urban growth of the urban heat island.”heat island.”

Heat island Heat island adjustments applied adjustments applied based on the based on the algorithm algorithm developed developed by Karl et al.by Karl et al.

““Used the algorithm Used the algorithm to help to help developdevelop an an interval that would interval that would bound the effects bound the effects of urbanization on of urbanization on T trends.”T trends.”

Heat island Heat island adjustments applied adjustments applied based on the based on the algorithm algorithm developed developed by Karl et al.by Karl et al.

““Used the algorithm Used the algorithm to help to help developdevelop an an interval that would interval that would bound the effects bound the effects of urbanization on of urbanization on T trends.”T trends.”

Applying the AlgorithmApplying the Algorithm

Assumed the hourly T’s Assumed the hourly T’s at at 1500 LT1500 LT were were associated with the associated with the maxmax and T’s at and T’s at 0600 LT0600 LT with the with the minmin..

Started with a Started with a population of 0 for population of 0 for each urban area, with each urban area, with the final population the final population estimate equal to the estimate equal to the 1990 city census (“to 1990 city census (“to provide an provide an upper boundupper bound for the effect of for the effect of urbanization on the urbanization on the trends of T.”trends of T.”

Assumed the hourly T’s Assumed the hourly T’s at at 1500 LT1500 LT were were associated with the associated with the maxmax and T’s at and T’s at 0600 LT0600 LT with the with the minmin..

Started with a Started with a population of 0 for population of 0 for each urban area, with each urban area, with the final population the final population estimate equal to the estimate equal to the 1990 city census (“to 1990 city census (“to provide an provide an upper boundupper bound for the effect of for the effect of urbanization on the urbanization on the trends of T.”trends of T.”



The Probability of RecurrenceThe Probability of Recurrence

10,000 sequences on 10,000 sequences on monthly July daily monthly July daily max and min values max and min values were simulated using were simulated using various values of a various values of a 4-parameter model4-parameter model.. Mean TMean Tapap SSa a - the variance of - the variance of monthly mean Tap monthly mean Tap calculated across yearscalculated across years

SSm m - the variance of T- the variance of Tapap calculated for a given calculated for a given month using daily month using daily valuesvalues

r - persistence r - persistence coefficient of the coefficient of the daily Tdaily Tapap

10,000 sequences on 10,000 sequences on monthly July daily monthly July daily max and min values max and min values were simulated using were simulated using various values of a various values of a 4-parameter model4-parameter model.. Mean TMean Tapap SSa a - the variance of - the variance of monthly mean Tap monthly mean Tap calculated across yearscalculated across years

SSm m - the variance of T- the variance of Tapap calculated for a given calculated for a given month using daily month using daily valuesvalues

r - persistence r - persistence coefficient of the coefficient of the daily Tdaily Tapap



““Using the Using the simulated July simulated July values of daily values of daily max and min Tmax and min Tapap, , the probability of the probability of exceeding specific exceeding specific thresholds of T thresholds of T can be can be easily easily calculatedcalculated relative to what relative to what actually occurred actually occurred during 1995.”during 1995.”

““Using the Using the simulated July simulated July values of daily values of daily max and min Tmax and min Tapap, , the probability of the probability of exceeding specific exceeding specific thresholds of T thresholds of T can be can be easily easily calculatedcalculated relative to what relative to what actually occurred actually occurred during 1995.”during 1995.”

Their ResultsTheir Results

The stationarity of The stationarity of TTapap:: The overall trends of The overall trends of TTapap in the Midwest are in the Midwest are more more moderatemoderate than the than the Chicago results.Chicago results.

However, the climate However, the climate in the Midwest appears in the Midwest appears to be to be stationarystationary..

Sensitivity of the Sensitivity of the probabilistic model:probabilistic model: Changes in mean TChanges in mean Tapap are are important, but other important, but other parametersparameters are also are also criticalcritical, such as , such as persistence and persistence and variance.variance.

The stationarity of The stationarity of TTapap:: The overall trends of The overall trends of TTapap in the Midwest are in the Midwest are more more moderatemoderate than the than the Chicago results.Chicago results.

However, the climate However, the climate in the Midwest appears in the Midwest appears to be to be stationarystationary..

Sensitivity of the Sensitivity of the probabilistic model:probabilistic model: Changes in mean TChanges in mean Tapap are are important, but other important, but other parametersparameters are also are also criticalcritical, such as , such as persistence and persistence and variance.variance.

Recurrence for the ‘95 Recurrence for the ‘95 heat wave in the present heat wave in the present climate:climate: The probability of The probability of maxmax T Tapap exceeding 48.9° C two exceeding 48.9° C two consecutive days in a row consecutive days in a row is is < 1< 1 %%, or 1 in 150 years. , or 1 in 150 years.

The probability of having The probability of having minmin T Tapap values above 31.6° C values above 31.6° C for two consecutive days is for two consecutive days is extremely extremely rarerare..

Recurrence for the ‘95 Recurrence for the ‘95 heat wave in a changed heat wave in a changed climate:climate: Projected increases in T are Projected increases in T are by by 3° C3° C by the end of the by the end of the next century due to next century due to greenhouse gases.greenhouse gases.

FasterFaster return return periods for periods for extreme T’s.extreme T’s.

Recurrence for the ‘95 Recurrence for the ‘95 heat wave in the present heat wave in the present climate:climate: The probability of The probability of maxmax T Tapap exceeding 48.9° C two exceeding 48.9° C two consecutive days in a row consecutive days in a row is is < 1< 1 %%, or 1 in 150 years. , or 1 in 150 years.

The probability of having The probability of having minmin T Tapap values above 31.6° C values above 31.6° C for two consecutive days is for two consecutive days is extremely extremely rarerare..

Recurrence for the ‘95 Recurrence for the ‘95 heat wave in a changed heat wave in a changed climate:climate: Projected increases in T are Projected increases in T are by by 3° C3° C by the end of the by the end of the next century due to next century due to greenhouse gases.greenhouse gases.

FasterFaster return return periods for periods for extreme T’s.extreme T’s.

Is there a looming doomsday in our future?

The Sensitivity of Multivariate and Univariate Changes

The Sensitivity of Multivariate and Univariate Changes

Daily max

Daily min

Their SummaryTheir Summary

An event like the Chicago heat wave of An event like the Chicago heat wave of ‘95 is quite ‘95 is quite rarerare, due to the elevated , due to the elevated 2-day nighttime (2-day nighttime (minmin) temperatures.) temperatures.

DurationDuration and and intensityintensity of heat waves of heat waves have been shown to be affected by 4 have been shown to be affected by 4 parametersparameters..

Min TMin Tapap probability results especially probability results especially rarerare and and unusualunusual..

In their opinion, and event like the In their opinion, and event like the Chicago heat wave will Chicago heat wave will notnot be repeated be repeated any time in the near future.any time in the near future.

An event like the Chicago heat wave of An event like the Chicago heat wave of ‘95 is quite ‘95 is quite rarerare, due to the elevated , due to the elevated 2-day nighttime (2-day nighttime (minmin) temperatures.) temperatures.

DurationDuration and and intensityintensity of heat waves of heat waves have been shown to be affected by 4 have been shown to be affected by 4 parametersparameters..

Min TMin Tapap probability results especially probability results especially rarerare and and unusualunusual..

In their opinion, and event like the In their opinion, and event like the Chicago heat wave will Chicago heat wave will notnot be repeated be repeated any time in the near future.any time in the near future.

Guess What!? I’m Not Done Yet!Guess What!? I’m Not Done Yet!

Most of the recent Most of the recent European heat waves European heat waves have been have been preceded preceded by a spring by a spring precipitation precipitation deficitdeficit..

Regional climate Regional climate simulations simulations conducted conducted withwith and and w/ow/o land/atmosphere land/atmosphere coupling for 4 major coupling for 4 major European heat waves; European heat waves; 1976, 1994, 2003, 1976, 1994, 2003, and 2005. and 2005.

Most of the recent Most of the recent European heat waves European heat waves have been have been preceded preceded by a spring by a spring precipitation precipitation deficitdeficit..

Regional climate Regional climate simulations simulations conducted conducted withwith and and w/ow/o land/atmosphere land/atmosphere coupling for 4 major coupling for 4 major European heat waves; European heat waves; 1976, 1994, 2003, 1976, 1994, 2003, and 2005. and 2005.

Paper Number Two…omg



An Intro to European Heat WavesAn Intro to European Heat Waves 2003 heat wave 2003 heat wave record-breaking; record-breaking; over over 40,00040,000 deaths.deaths.

Crop shortages.Crop shortages. Forest fires.Forest fires. These highlight These highlight the importance of the importance of understanding understanding what what causescauses these these extreme events.extreme events.

2003 heat wave 2003 heat wave record-breaking; record-breaking; over over 40,00040,000 deaths.deaths.

Crop shortages.Crop shortages. Forest fires.Forest fires. These highlight These highlight the importance of the importance of understanding understanding what what causescauses these these extreme events.extreme events.



The Experiment:The Experiment:

Focuses on Europe and Focuses on Europe and the north-eastern the north-eastern Atlantic.Atlantic.

Performs a 46-year Performs a 46-year simulation (1960-2005) simulation (1960-2005) with a with a coupledcoupled land- land-surface scheme (surface scheme (CLCL simulation).simulation).

Repeat the simulations Repeat the simulations for ‘76, ‘94, ‘03, and for ‘76, ‘94, ‘03, and ‘05, but with soil ‘05, but with soil moisture moisture uncoupleduncoupled from from atmospheric evolution atmospheric evolution ((UCL UCL simulation).simulation).

NHDNHD and and HWD HWD

Focuses on Europe and Focuses on Europe and the north-eastern the north-eastern Atlantic.Atlantic.

Performs a 46-year Performs a 46-year simulation (1960-2005) simulation (1960-2005) with a with a coupledcoupled land- land-surface scheme (surface scheme (CLCL simulation).simulation).

Repeat the simulations Repeat the simulations for ‘76, ‘94, ‘03, and for ‘76, ‘94, ‘03, and ‘05, but with soil ‘05, but with soil moisture moisture uncoupleduncoupled from from atmospheric evolution atmospheric evolution ((UCL UCL simulation).simulation).

NHDNHD and and HWD HWD



The 4 Major WavesThe 4 Major Waves

1976: 1976: Confined to Confined to northern France and northern France and southern Englandsouthern England

> 35 hot days > 35 hot days observed.observed.

16-month period of 16-month period of precip. deficits precip. deficits prior.prior.

1994:1994: Affected central Affected central Europe and parts of Europe and parts of the Mediterranean.the Mediterranean.

Somewhat weaker on Somewhat weaker on the seasonal scale.the seasonal scale.

1976: 1976: Confined to Confined to northern France and northern France and southern Englandsouthern England

> 35 hot days > 35 hot days observed.observed.

16-month period of 16-month period of precip. deficits precip. deficits prior.prior.

1994:1994: Affected central Affected central Europe and parts of Europe and parts of the Mediterranean.the Mediterranean.

Somewhat weaker on Somewhat weaker on the seasonal scale.the seasonal scale.

2003: 2003: Record-breaking.Record-breaking. Affected central Affected central Europe and the Europe and the Mediterranean.Mediterranean.

40-60 hot days 40-60 hot days observed.observed.

2005:2005: Confined to the Confined to the Iberian Peninsula Iberian Peninsula and southern France.and southern France.

Heat wave most Heat wave most pronounced in June.pronounced in June.

2003: 2003: Record-breaking.Record-breaking. Affected central Affected central Europe and the Europe and the Mediterranean.Mediterranean.

40-60 hot days 40-60 hot days observed.observed.

2005:2005: Confined to the Confined to the Iberian Peninsula Iberian Peninsula and southern France.and southern France.

Heat wave most Heat wave most pronounced in June.pronounced in June.

SimulationsSimulations

What the Figures Show Us:What the Figures Show Us:““Based on these simulations, it can Based on these simulations, it can be seen that the NHD as well as the be seen that the NHD as well as the HWD is substantially HWD is substantially reducedreduced if the if the soil moisture is prescribed (or soil moisture is prescribed (or dictated) by climatological mean dictated) by climatological mean conditions (conditions (UCLUCL simulations).” simulations).”

T amplification through CL is T amplification through CL is strongerstronger for daily max T’s than for for daily max T’s than for min and mean T’s.min and mean T’s.

““CL interactions contribute to an CL interactions contribute to an enhanced enhanced diurnal T range.”diurnal T range.”

““Based on these simulations, it can Based on these simulations, it can be seen that the NHD as well as the be seen that the NHD as well as the HWD is substantially HWD is substantially reducedreduced if the if the soil moisture is prescribed (or soil moisture is prescribed (or dictated) by climatological mean dictated) by climatological mean conditions (conditions (UCLUCL simulations).” simulations).”

T amplification through CL is T amplification through CL is strongerstronger for daily max T’s than for for daily max T’s than for min and mean T’s.min and mean T’s.

““CL interactions contribute to an CL interactions contribute to an enhanced enhanced diurnal T range.”diurnal T range.”

So Basically…So Basically…

Each of the 4 waves Each of the 4 waves was was precededpreceded by a by a mean precip. deficit mean precip. deficit of at least 4 of at least 4 months.months.

CL simulations show CL simulations show excess in surface excess in surface net rad. leading to net rad. leading to an an increaseincrease in in evaporation.evaporation.

CL is found to CL is found to increaseincrease mean max mean max and min T’s over and min T’s over unusually warm unusually warm summers.summers.

Each of the 4 waves Each of the 4 waves was was precededpreceded by a by a mean precip. deficit mean precip. deficit of at least 4 of at least 4 months.months.

CL simulations show CL simulations show excess in surface excess in surface net rad. leading to net rad. leading to an an increaseincrease in in evaporation.evaporation.

CL is found to CL is found to increaseincrease mean max mean max and min T’s over and min T’s over unusually warm unusually warm summers.summers.



My Thoughts…My Thoughts…

There is no There is no eminenteminent danger of us being danger of us being fried by a drastic fried by a drastic spike in summer spike in summer temperatures.temperatures.

Heat waves do Heat waves do happen, but they are happen, but they are very very infrequentinfrequent..

LackLack of of precipitation plays precipitation plays a role in hotter a role in hotter temperatures for the temperatures for the approaching summer.approaching summer.

There is no There is no eminenteminent danger of us being danger of us being fried by a drastic fried by a drastic spike in summer spike in summer temperatures.temperatures.

Heat waves do Heat waves do happen, but they are happen, but they are very very infrequentinfrequent..

LackLack of of precipitation plays precipitation plays a role in hotter a role in hotter temperatures for the temperatures for the approaching summer.approaching summer.

Future Study:Future Study: I would be I would be curious to see if curious to see if there is a there is a connection to connection to heat waves on heat waves on different different continents during continents during the same year. I the same year. I think some think some investigation investigation into that could into that could be interesting…be interesting…

Future Study:Future Study: I would be I would be curious to see if curious to see if there is a there is a connection to connection to heat waves on heat waves on different different continents during continents during the same year. I the same year. I think some think some investigation investigation into that could into that could be interesting…be interesting…

Questions?Questions?



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Heat Waves