DTIC ADA249871: Upper Tropospheric Jet Streams Over North America During Summer 1988

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by  Defense Technical Information Center

AD-A249 871
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1. AGENCY USE ONLY (Leave oiank) 2. REPORT DATE POR TYPE AND DATES COVERED
4. TITLE AND SUBTITLE 5. FUNDING NUMBERS
Upper Tropospheric Jet Streams Over North America
During Summer 1988
6. AUTHOR(S)
David E. Landers, Capt
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REPORT NUMBER
AFIT Student Attending: Texas A & M University AFIT/CI/CIA- 91-115
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Approved for Public Release lAW 190-1
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ERNEST A. HAYGOOD, Captain, USAF
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DTIC
114
11. SECUR TY CLASSIF2:'TION 5ECJFTY CLASSIF!CATION 1.S-CU;YTy S: IAON 2 MT.:O
OF REPORT OF THI*S PAGE OF AESTR4CC , .
UPPER TROPOSPHERIC JET STREAMS OVER NORTH AMERICA DURING
SUMMER 1988
A Thesis
by
DAVID EDWARD LANDERS
Submitted to the Office of Graduate Studies of
Texas A&M University
in partial fulfuillment of the requirements
for the degree of
MASTER OF SCIENCE
August 1991
Major Subject: Meteorology
92-11987
!t! ! Ifl tII ti
~
iv
DEDICATION
I dedicate this thesis to Mr. Hyo-Sang Chung for his
endless patience and assistance during its preparation.
v
ACKNOWLEDGEMENTS
I acknowledge the excellent support provided by the
instructors of the Department of Meteorology at Texas A&M
University, specifically Dr. Dusan Djuric, Dr. James
McGuirk, Dr. Joe McFarland, and Dr. Lee Panetta. Without
their patience and guidance this work would not have been
completed.
I thank The United States Air Force, Air Force In-
stitute of Technology for allowing me the opportunity to
obtain my M.S. in Meteorology.
Finally, I thank my wife Lee who put up with me during
the lengthy and rocky course of my research.
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ABSTRACT
Upper Tropospheric Jet Streams over North America during
Summer 1988. (August 1991)
David Edward Landers, A.S., Broward Community College;
B.S., Florida International University
Co-Chairs of Advisory Committee: Dr. Dusan Djuric
Dr. James McGuirk
Much has been written describing the jet stream. Most
previous works dwell on the characteristics of the winter
jet stream, when jets are faster and more easily discerned.
This paper will instead focus on the jet streams over North
America during the summer of 1988.
During July 1988 the predominant jet regime over North
America (70% of the observations at 250 mb) was that of a
single jet along the United States/Canada border. During
August 1988, however, the single jet regime was only present
26% of the time, with a two jet regime occurring 53% of the
time.
The southern jet during August appeared in a location
similar to the winter season subtropical jet, but generally
had the characteristics of a polar front jet stream.
Aooession For
TTS
RA&I
DTTO !AB
Un f ) )m i ce d
BAyv~aIIsatbr~ll tirtv Codes
>--JAvall and/or
Diat special
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TABLE OF CONTENTS
CHAPTER Page
I INTRODUCTION. . ... .. .. .. .. .. . .. .~o....... 1~o
II BACKGRORID.o.o ...... o..o. ... o..... o.o. ... 4
III THE NUMBER OF JETS OVER NORTH AMERICA
DURING SUMMKER 1988...........o....oo..o.....16
A. Data....o..... o...... o.-o... o......16
B. Jet Count.......
.. .... .o......16
IV DESCRIPTION OF THE SUMMER 1988 JET
STREAM....... .... ... o........ ... o.o23
A. Maximum Speed. ......... .... .. . 23
Bo. Average Speed... ... .................. .26
C. Persistence..................o o......o.39
Do Height Fields. .. o. .. .. o.... o ..... 50
E. Vertical Sections. ....o ................61
F. Zonally Averaged Wind Components ......o65
V JET REGIME SIGNATURES..o....o....o..76
A. Q-vectors.... o..................o......o76
B. Potential Vorticity.. ....o.....o.........85
C. Satellite Images.. ......o..... .........o90
VI SUMMER 1988 WEATHER DESCRIPTION ......o..... 93
VII SUM'MA.RY .............................. ...... 98
REFERENCESo....... .......... oo.... oo.................99
VITA.... ....... .......... ...........o......... ........ 102
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LIST OF TABLES
Table Page
1. Summary of the number of upper tropos-
pheric jet streams observed over North
America during July 1988 ................... 19
2. Summary of the number of upper tropos-
pheric jet streams observed over North
America during August 1988 ................. 20
3. Summary of the number of upper tropos-
pheric jet streams observed over North
America during summer 1988 ................. 21
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LIST OF FIGURES
Figure Page
1. The Palmen mean winter meridional circul-
ation model, showing principal tropopauses
and jet streams ...............................5
2. Average Northern Hemisphere 200 mb winds
during: (a) July; (b) August .................. 7
3. Average Northern Hemisphere wind speed at
250 mb for June-July-August (m s"I) ........... 8
4. Hemispheric zonally averaged u (m s-1) and
potential temperature (K) between 90°N and
300S during (a) December-January-February;
(b) March-April-May; (c) June-July-August;
(d) September-October-November ................ 9
5. Hemispheric zonally averaged meridional
circulation between 90ON and 300S during
(a) December-January-February; (b) March-
April-May; (c) June-July-August (d) Sep-
tember-October-November ...................... 10
6. Five-year stream-function of summer circu-
lation ....................................... 11
7. Average zonal wind during July (m s-1) in:
(a) the Southern Hemisphere. (After Mecho-
so et al., 1985); (b) both hemispheres.
(After Mintz, 1948) .......................... 13
8. Maximum analyzed wind speed at 250 mb at
each grid point during July 1988 (m s-) ..... 24
9. Maximum analyzed wind speed at 200 mb at
each grid point during August 1988 (m s')...25
10. Average wind speed at 250 mb during July
1988 (m s-1), with average direction denot-
ed by vectors ................................ 27
11. Average wind speed at 200 mb during July
1988 (m s-1), with average direction denot-
ed by vectors ................................ 28
ix
Figure Page
12. Average wind speed at 150 mb during July
1988 (m s-1), with average direction denot-
ed by vectors ................................ 29
13. Average wind speed at 250 mb during August
1988 (m s-1), with average direction denot-
ed by vectors ................................ 31
14. Average wind speed at 200 mb during August
1988 (m s'1), with average direction denot-
ed by vectors ................................ 32
15. Average wind speed at 150 mb during August
1988 (m s-1), with average direction denot-
ed by vectors ................................ 33
16. Average wind speed at 250 mb during summer
1988 (m s-1), with average direction denot-
ed by vectors ............................... 36
17. Average wind speed at 200 mb during summer
1988 (m s 1), with average direction denot-
ed by vectors ............................... 37
18. Average wind speed at 150 mb during summer
1988 (m s 1), with average direction denot-
ed by vectors ............................... 38
19. Frequency of occurrence of wind greater
than 25 m s-1 (of 62 possible) at 250 mb
during July 1988 ............................. 40
20. Frequency of occurrence of wind greater
than 25 m s"I (of 62 possible) at 200 mb
during July 1988 ............................. 41
21. Frequency of occurrence of wind greater
than 25 m s"1 (of 62 possible) at 150 mb
during July 1988 ............................. 42
22. Frequency of occurrence of wind greater
than 25 m s"1 (of 62 possible) at 250 mb
during August 1988 ........................... 43
23. Frequency of occurrence of wind greater
than 25 m s-1 (of 62 possible) at 200 mb
during August 1988 ........................... 45
x
Figure Page
24. Frequency of occurrence of wind greater
than 25 m s"I (of 62 possible) at 150 mb
during August 1988 ........................... 46
25. Frequency of occurrence of wind greater
than 25 m s-1 (of 62 possible) at 250 mb
during summer 1988 ........................... 47
26. Frequency of occurrence of wind greater
than 25 m s-1 (of 62 possible) at 200 mb
during summer 1988 ........................... 48
27. Frequency of occurrence of wind greater
than 25 m s-1 (of 62 possible) at 150 mb
during summer 1988 ........................... 49
28. Average 250 mb height field (gpm) during
July 1988 .................................... 51
29. Average 200 mb height field (gpm) during
July 1988 .................................... 52
30. Average 150 mb height field (gpm) during
July 1988 .................................... 53
31. Average 250 mb height field (gpm) during
August 1988 .................................. 54
32. Average 200 mb height field (gpm) during
August 1988 .................................. 55
33. Average 150 mb height field (gpm) during
August 1988 .................................. 56
34. Average 250 mb height field (gpm) during
summer 1988 .................................. 57
35. Average 200 mb height field (gpm) during
summer 1988 .................................. 58
36. Average 150 mb height field (gpm) during
summer 1988 ................................. 59
37. Average Northern Hemisphere 250 mb height
field during June-July-August ................ 60
38. Orientation of pressure centers of the
same sign during multiple jet occurrences .... 61