A Comparison of Extreme Climate Linkages To Heat Related Emergency (911) Calls

in Chicago, Illinois and Phoenix, Arizona 2003 - 2006

Donna A. Hartz

School of Geographical Sciences and Urban Planning

Arizona State University; Tempe, Arizona

Climate Data:

• Phoenix: Sky Harbor NWS ASOS station

• Chicago: Midway Airport (FAA ASOS station)

• Heat Index calculated hourly for both data sets:

HI = -42.379 + 2.04901523T + 10.14333127R - 0.22475541TR - 6.83783x10-3T2

- 5.481717x10-2R2 + 1.22874x10-3T2R + 8.5282x10-4TR2 - 1.99x10-6T2R2

Heat Related Emergency Dispatch

(911 call) Data:

• Chicago:

• City of Chicago Department of Environment

• From City of Chicago only: Population 2.8 Million

• Phoenix:

• Phoenix Fire Department’s 911 call dispatch center

• From multiple cities: population 2.7 Million

Chicago versus Phoenix

(Climate)

Chicago Phoenix

Climate Humid Continental

Hot, humid summer

Cool to cold winter

Arid, semi-tropical

Extremely hot summer

Mild winter

Mean rainfall 36.27” 8.29”

July Means:

Maximum Temp

Minimum Temp

83.5°F (28.6°C)

63.2°F (17.3°C)

105.9°F(41.1°C)

82.2°F (27.9°C)

Can reach 103°F (39.4°C) 120°F (48.9°C)

Chicago versus Phoenix

(HRD)

Chicago Phoenix

HRD (2003 – 2006) 1118 4206

Most Occur During May through Sept (2 exceptions: Jan 04 & Oct 05)

March through Oct

(many exceptions)

% Days with HRD

(May – Sept) 32% 92%

% Days w/ 1 or 2 HRD 49% 37%

Highest HRD Count 87 35

Chicago: Days with HRD

with Maximum Temperature and

Maximum Heat Index

2003 - 2006

Phoenix: Days with HRD

with Maximum Temperature and

Maximum Heat Index 2003 - 2006

Phoenix vs Chicago Days with HRD with

Maximum Temperature

2003 - 2006

Phoenix vs Chicago Days with HRD with

Maximum Heat Index

2003 - 2006

HRD

Range

HRD

count

Mean

HRD

Mean

Max T

C

Mean

HI C

Max T

diff

from

Norm

Max T

Max HI

diff

from

Norm

Max T

Chicago HRD

1 to 4 134 1.7 29.2 29.3 1.3 1.4

5 to 9 34 6.5 31.9 32.4 3.8 4.3

10 to 20 17 13.2 33.8 34.9 5.5 6.7

20+ 9 48.3 35.4 39.0 6.3 9.9

Phoenix HRD

1 to 4 418 2.0 34.4 32.5 1.9 0.0

5 to 9 209 7.4 40.1 38.6 2.0 0.2

10 to 20 103 13.0 42.4 40.7 3.3 1.6

20+ 22 26.5 44.3 42.7 4.5 2.9

HRD

Range

HRD

count

Mean

HRD

Mean

Max T

C

Mean

HI C

Max T

diff

from

Norm

Max T

Max HI

diff

from

Norm

Max T

Chicago HRD

1 to 4 134 1.7 29.2 29.3 1.3 1.4

5 to 9 34 6.5 31.9 32.4 3.8 4.3

10 to 20 17 13.2 33.8 34.9 5.5 6.7

20+ 9 48.3 35.4 39.0 6.3 9.9

Phoenix HRD

1 to 4 418 2.0 34.4 32.5 1.9 0.0

5 to 9 209 7.4 40.1 38.6 2.0 0.2

10 to 20 103 13.0 42.4 40.7 3.3 1.6

20+ 22 26.5 44.3 42.7 4.5 2.9

Higher than normal

MaxT and MaxHI does

not play as large a role

in HRD in Phoenix

HRD

Range

HRD

count

Mean

HRD

Mean

MaxT

C

Mean

HI C

Max T

diff

from

Norm

Max T

Max HI

diff

from

Norm

Max T

Chicago HRD

1 to 4 134 1.7 29.2 29.3 1.3 1.4

5 to 9 34 6.5 31.9 32.4 3.8 4.3

10 to 20 17 13.2 33.8 34.9 5.5 6.7

20+ 9 48.3 35.4 39.0 6.3 9.9

Phoenix HRD

1 to 4 418 2.0 34.4 32.5 1.9 0.0

5 to 9 209 7.4 40.1 38.6 2.0 0.2

10 to 20 103 13.0 42.4 40.7 3.3 1.6

20+ 22 26.5 44.3 42.7 4.5 2.9

For 20+ HRD –

Chicago has a much

higher mean number of

HRD than Phoenix

BUT… also a higher than normal

maximum temperature, and much

higher heat index

Heat Wave(s) of 2006 –

Chicago July13 to Aug 3

16 days at or above normal maximum temperatures:

Mean HRD 25.9 Range HRD 1 to 87 Median: 13.5

Mean Max T = 33.4 C (92F) … 4.1 C (7.4F) > normal Mean Heat Index = 36.3 C (97.3F) …7.0 C (12.5F) > normal

Heat Wave of 2006 – Phoenix

July 11 to 26

Mean Max T = 44.4 C (112F) … 4.4 C (8F) > normal Max T)

Mean Heat Index = 42.8C (109F) ... 2.8 C (5F) > normal Max T)

15 days with higher than normal Maximum Temperature

Mean HRD 20.6 Range: 7 to 34 Median: 22

Heat Waves of 2006:

Maximum Temperature

Chicago vs Phoenix

Mean HRD 25.9

Median HRD: 13.5

Range HRD 1 to 87

Mean Max T = 33.4 C (94F)

[4.1 C (7.4F)> normal]

Mean HRD 20.6

Median HRD: 22

Range HRD: 7 to 34

Mean Max T = 44.4 C (112F)

[4.4 C (8F) > normal)

Heat Waves of 2006:

Maximum Heat Index

Chicago vs Phoenix

Mean Heat Index = 42.8C (109F)

[2.8C (5F) > norm]

Mean Heat Index = 36.3 C

(97F) [7.0 C (12.6F) > normal]

Conclusions:

• Phoenix has many more days of HRD each year:

• Begin earlier

• End later in the year

• Chicago has a many fold increase in HRD after about 4 to 5 days of maximum temperature and heat index much higher than the normal maximum temperature

• Phoenix does not experience these huge spikes in HRD

Conclusions:

• Phoenix’s HRD thresholds for rapidly

rising HRD

• Very similar for maximum temperature and heat index

• around 35C to 38C

• Chicago’s HRD thresholds for rapidly

rising HRD:

• Considerable differences between thresholds for Max T and Max Heat Index

• About 28C to 30C for maximum temperature

• About 32C to 35C for maximum heat index

Conclusions:

• Maximum temperature and heat index

experienced during Phoenix’s 2006 heat

wave was much less above the normal

maximum temperature than measured

during Chicago’s heat wave.

• Phoenix, during its heat wave experienced relatively moderate increases in HRD

• Chicago had a many fold increase in HRD

when the maximum temperature, and

especially heat index, rose more than 5C

higher than the normal MaxT

Many thanks to my co-authors:

Wen-Ching Chuang, Chona Sister, Anthony Brazel and

Jay Golden, Arizona State University

And:

Nancy Selover, Arizona State Climatologist

City of Chicago

Phoenix Fire Department

Thank you.

Questions?