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

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Station Information 3 The Change: – Station 1: May 1980 – Station 2: June 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 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 6 Temperature Range

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Daily Temperature Range 8 Given as the greatest single day range per month Since change, 1980, range has increased for all seasons Greatest increase is during summer and least is during winter Greatest variability during 30’s and 40’s Possible 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 10 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.

Average Maximum Annual Temperature Trends Based on Station Relocation 11 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 12 Minimum Temperature

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Minimum Temperature 17 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 temperatures Variations in the land and roughness around Boone Change of the Station in elevation and location

Austin Milt 18 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) 19

Evidence of station change effect on freezing days

Freezing days summary Pre-80’ Largest trend and least variability in Avg Little overall trend Post-80’ Largest trend and least variability in Min Strong trend in Min Combined Largest trend and least variability in Avg Little overall trend Time Period Temperature Measure Rate of Change (days/yr) Data Variability (R 2 ) Pre-80'Min Avg Max Post-80'Min Avg Max CombinedMin Avg Max 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) 21