April 23, 2009

Geography 414

Group 3

1

Boone, NC

•Laura Beth Adams- Average Temperature•Alec Hoffman – Daily Temperature Range•Jill Simmerman- Maximum Temperature•Knox Coleman– Minimum Temperature•Austin Milt- Freezing Days

2

Station Information

3

• The Change: – Station 1: 1929- May 1980– Station 2: June 1980- current

• Effects of the Change: – Change in observation of valley winds which tend to

keep temperatures depressed. – Change in local surroundings of the station effects

amount of daily shade and full sun time which effects latent heat and ground heat flow.

Laura Beth Adams

4

Average Temperature

5

1929

1939

1949

1959

1969

1979

1989

1999

2009

15

20

25

30

35

40

45

50

January Monthly Ave.

January Monthly AveragesLinear (January Monthly Averages)Pre-1980Linear (Pre-1980)Post-1980Linear (Post-1980)

19291939194919591969197919891999200945

50

55

60

65

70

May Monthly Ave.

MayLinear (May)Linear (May)Pre-1980Linear (Pre-1980)Post-1980Linear (Post-1980)

• What is Changing?-Slight changes after the station move-Changes are not consistent month to month

• Why the Change (or the lack thereof)?

-Station change- Pre-1980 highs and lows getting closer together- Post-1980 highs and lows getting further apart

Alec Hoffman

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Temperature Range

7

19291931

19331935

19371939

19411943

19451947

19491951

19531955

19571959

19611963

19651967

19691971

19731975

19771979

0

5

10

15

20

25

30

35

40

45

50

f(x) = − 0.125594069267765 x + 40.2737556561086R² = 0.298917086918552

Average Pre-1980

AverageLinear (Average)

19811982

19831984

19851986

19871988

19891990

19911992

19931994

19951996

19971998

19992000

20012002

20032004

20052006

20072008

20090

510

152025

3035

404550

f(x) = 0.281791643860608 x + 30.0925925925926R² = 0.38894711730611

Average post 1980

AverageLinear (Average)

Daily Temperature Range

8

Given as the greatest single day range per monthSince change, 1980, range has increased for all

seasonsGreatest increase is during summer and least is

during winterGreatest variability during 30’s and 40’sPossible Reasons:• Change in land cover• Changing station location (elevation and

surrounding environment • Change in cloud cover• Different moisture levels• Change in solar intensity

Jill Simmerman

9

Maximum Temperature

Average Maximum Annual Temperature Overall Trends

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• What is changing?– Overall there is a decrease in annual temperature of -0.03°F/year– Investigated using 5 year moving average results in distinctive nearly

20 year cycles of heating then cooling.

• Why the change?– This change could be due to a cycling of increased and decreased

cloud cover. But that is highly unlikely (See Alec’s data). – Change in the maturity of the surrounding area of the station could

result in a pattern such as this one.

1928 1938 1948 1958 1968 1978 1988 1998 200855

57

59

61

63

65

67Annual Av-erage Tempera-tureLinear (Annual Average Tempera-ture)29-40Linear (29-40)41-60Linear (41-60)61-80Linear (61-80)81-94

YEAR

Tem

oera

ture

(deg F

)

Average Maximum Annual Temperature Trends Based on Station Relocation

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1928 1938 1948 1958 1968 1978 1988 1998 200852

54

56

58

60

62

64

66

68

f(x) = 0.038472906403941 x − 15.9218719211825R² = 0.0299937648318817

f(x) = − 0.0603348416289593 x + 179.72761387632R² = 0.296879838471958

Old Sta-tionLinear (Old Sta-tion)New Sta-tion

Year

Tem

pera

ture

(deg F

)

• What is changing?– Before the 1980 move we were noticing a temperature reduction of -

0.06°F/year. – Since the move there is an increase in temperature of 0.04°F/year.

• Why the change?– The station moved from the interior of a valley to the top of a mountain. – Valley winds tend to move cool air from the top of the mountain to the

valley, therefore keeping the valley at a generally cooler temperature.

Knox Coleman

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Minimum Temperature

Minimum Temperature

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1929 1939 1949 1959 1969 1979 1989 1999 200934

36

38

40

42

44

46

f(x) = 0.00333333333333374 x + 32.9533333333325R² = 0.000130208333332993

f(x) = − 0.466363636363637 x + 971.131818181818R² = 0.53877287802482

f(x) = 0.223030303030303 x − 400.666666666667R² = 0.279091238830088

f(x) = 0.0409090909090908 x − 39.7272727272725R² = 0.0152876340027182

f(x) = − 0.12 x + 276.225454545455R² = 0.163851796125641

f(x) = 0.0518181818181821 x − 61.1800000000006R² = 0.0173724735322446

f(x) = − 0.0254545454545454 x + 90.9563636363635R² = 0.00195365063543462

f(x) = 0.326363636363636 x − 589.769090909091R² = 0.287616603436725

Average Annual Minimum Temperature 1920-2009

1929-1939Linear (1929-1939)1939-1949Linear (1939-1949)1949-1959Linear (1949-1959)1959-1969Linear (1959-1969)1969-1980Linear (1969-1980)1980-1990Linear (1980-1990)Linear (1980-1990)1990-2000Linear (1990-2000)2000-2009

Year

Tem

pera

ture

(F)

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1929 1934 1939 1944 1949 1954 1959 1964 1969 1974 197934

36

38

40

42

44

46

f(x) = − 0.00655203619909503 x + 53.6105218702866R² = 0.00440956734292031

Average Annual Minimum Temperature 1920-1980

Series1Linear (Series1)

Year

Tem

pera

ture

(F)

1980 1985 1990 1995 2000 2005 201035

37

39

41

43

45

47

49

f(x) = − 0.15192118226601 x + 343.972216748768R² = 0.432656232514851

Average Annual Minimum Temperature 1980 - 2009

Series1

Linear (Series1)

Year

Tem

pera

ture

(F)

15

1920 1930 1940 1950 1960 1970 1980 199060

70

80

90

100

110

120

130

140

150

f(x) = 0.125067873303167 x − 129.73556561086R² = 0.0153126510781411

Days Below 32 (1929 - 1980)

Series1Linear (Series1)

Year

Num

ber

of

Days

1975 1980 1985 1990 1995 2000 2005 2010 201560708090

100110120130140150160

f(x) = 1.30103995621237 x − 2476.92419266557R² = 0.374222165527206

Days Below 32 (1980 - 2009)

Series1Linear (Series1)

Year

Num

ber

of

Days

16

1920 1930 1940 1950 1960 1970 1980 19900

1

2

3

4

5

6

7

f(x) = 0.0171945701357466 x − 32.1276018099548R² = 0.0246181123840697

Days below 0 (1929 - 1980)

Series1Linear (Series1)

Year

Num

ber

of

Days

1975 1980 1985 1990 1995 2000 2005 2010 20150

1

2

3

4

5

6

7

8

f(x) = − 0.0911330049261084 x + 183.374384236453R² = 0.161256125141349

Days below 0 (1980 - 2009)

Series1Linear (Series1)

Year

Num

ber

of

Days

Minimum Temperature

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The average annual minimum temperature has been decreasing in Boone. This occurs at both the pre 1980 site and post 1980 site.

Periods of incline and decline of average minimum temperature

There has been an increase in number of days below freezing

But there has been a decrease in the number of days below 0

Possible Causes:Change in snow cover due to the lower temperaturesVariations in the land and roughness around Boone Change of the Station in elevation and location

Austin Milt

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Days Below Freezing

• What is changing?• From 1997 – 2008, more days with freezing temperatures• Lack of change in Avg and Max temps indicates a move towards colder

nights instead of an overall temperature drop

• Why the change?• Less heat retention at night due to daytime H + LE ↑; cloud cover ↓; soil

moisture ↓• Station change

Days with temperatures below freezing (<32°F) (5 yr moving average)

1929

1935

1941

1947

1953

1959

1965

1971

1977

1984

1990

1996

2002

2008

0

20

40

60

80

100

120

140

160

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Evidence of station change effect on freezing days

1928 1938 1948 1958 1968 1978 1988 1998 20080

20

40

60

80

100

120

140

160

f(x) = 0.101532567049808 x − 154.8995621237R² = 0.00474812638548505

f(x) = 0.283891402714932 x − 510.13556561086R² = 0.106091242119244

f(x) = − 0.147235905856596 x + 311.66201423098R² = 0.0269431691669547

f(x) = 0.109592760180995 x − 199.222684766214R² = 0.0518083864912693

f(x) = NaN x + NaNR² = 0f(x) = NaN x + NaNR² = 0

Min Linear (Min)Max Linear (Max)

Freezing days summary

Pre-80’Largest trend and least variability in

Avg Little overall trend

Post-80’Largest trend and least variability in

MinStrong trend in Min

CombinedLargest trend and least variability in

AvgLittle overall trend

Time Period

Temperature Measure

Rate of Change (days/yr)

Data Variability (R2)

Pre-80' Min +0.0172 0.0005 Avg +0.2839 0.1061 Max +0.1096 0.0518

Post-80' Min +1.3478 0.4127 Avg +0.1015 0.0047 Max -0.1472 0.0269

Combined Min +0.0943 0.0255 Avg +0.1301 0.0575 Max +0.0751 0.0571

• Conclusions• Pre-80’ Boone

• high variability in number of freezing days, but little change in mean

• valley location may mask long-term variability

• Post-80’ Boone• colder nights, more

frosts, general unpleasantness

• Shorter growing season• Record at new station too

short to conclude if trends are due to station move or actual climate changes (other data supports station move as cause)

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