Transcript Slide 1

Simple methods for do-it-yourself monitoring of
temperature inversions and atmospheric stability
Steven J. Thomson, Daniel K. Fisher, Bradley K. Fritz1
Yanbo Huang, Reginald Fletcher
USDA ARS CPRSU, Stoneville MS
1USDA ARS APMRU, College Station, TX
7/16/2015
Steven J. Thomson USDA ARS Stoneville MS
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Spraying must not occur where a
temperature inversion prevents the
spray cloud settling within the treated
area.
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Temperature inversions are associated
with STABLE atmospheric conditions.
7/16/2015
Steven J. Thomson USDA ARS Stoneville MS
105’ 33°F
64’
32’
16’
8’
NOT OK to SPRAY!
32°F
31°F
29°F
27°F
Surface Inversion - STABLE CONDITIONS
Source:
Ramsey (2001)
7/16/2015
http://www.cdpr.ca.gov/docs/enforce
/drftinit/confs/2001/ramsey.ppt
Steven J. Thomson USDA ARS Stoneville MS
Stability Ratio
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Is a function of temperature at two heights and
wind speed.
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When temperature increases with height and
this is combined with low enough wind speed,
the stability ratio may indicate STABLE
atmosphere.
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Application should not be made under these
conditions.
7/16/2015
Steven J. Thomson USDA ARS Stoneville MS
Use 8 and 30 feet for temperature sensors; 15 feet for
wind sensor
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Steven J. Thomson USDA ARS Stoneville MS
Atmospheric Stability
Category
Unstable
OK to spray
Neutral
Stable
Very Stable
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SR Result
-1.7 to -0.1
-0.1 to 0.1
0.1 to 1.2
1.2 to 4.9
Steven J. Thomson USDA ARS Stoneville MS
Typical response from instruments on a tall tower
40
350
35
300
30
250
25
20
200
15
150
Temperature at 30 ft (C)
10
Wind speed at 15 ft (miles/h)
Stability ratio
Wind direction (degree)
100
5
50
0:00
1:00
2:00
3:00
4:00
5:00
6:00
7:00
8:00
9:00
10:00
11:00
12:00
13:00
14:00
15:00
16:00
17:00
18:00
19:00
20:00
21:00
22:00
23:00
0
-5
8 ft (C)
Temperature at 15
Time of Day
0
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We wanted portability since field surface conditions
influence the rate of ground heating.
We used a portable tower at first.
These were OK, but they were not as easy to set up
and move as first thought.
Steven J. Thomson USDA ARS Stoneville MS
Soil texture also affects
rapidity of soil warming.
7/16/2015
Steven J. Thomson USDA ARS Stoneville MS
New System
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Steven J. Thomson USDA ARS Stoneville MS
Large Helium Balloon.
Precision temperature sensors at 8 and 30 ft
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Kestrel 4500 Bluetooth wind logger
at eye level.
Some temperature sensing systems
Bluetooth
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Radio
Steven J. Thomson USDA ARS Stoneville MS
Recommendations to applicators
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We are still defining how much faster bare soil surface warms
compared with a crop canopy.
Final form of recommendations will be referenced to sunrise and
sunset.
What about conditions early in the season?
 Data shows that we lose up to one hour in the morning and one
hour at night when it is acceptable to spray, shortening the time
window.
 Cloud cover appears to have the same effect.
Wind effects are being considered in recommendations.
7/16/2015
Steven J. Thomson USDA ARS Stoneville MS
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Data can be obtained at the field level using a Windowsbased tablet (via Bluetooth).
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Web-based or Android/Iphone app for pilot and farm
manager using easily obtainable measurements (like use
of temperature differences – recommendations from
Arkansas Plant Board):
http://170.94.200.136/weather/Inversion.aspx.
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Steven J. Thomson USDA ARS Stoneville MS
7/16/2015
Steven J. Thomson USDA ARS Stoneville MS
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We are working on a web interface to
monitor sensors remotely and present
recommendations
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Steven J. Thomson USDA ARS Stoneville MS
Thank You!
Work partially funded by a grant from the Mississippi
Soybean Promotion Board (MSPB)
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Contact:
7/16/2015
[email protected]
Steven J. Thomson USDA ARS Stoneville MS