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The availability of climatic data is a major consideration in selecting a model for calculating ET. Data input requirements for the different models vary, ranging in complexity from those that use only temperature data to those that require temperature, wind, humidity, and radiation data. Historical records of weather data have been available for the Upper Green River Basin primarily from the National Weather Service's Cooperative Network. The network consists mainly of stations recording maximum and minimum daily temperatures and precipitation. Depending upon the period of interest, approximately 12 of these stations exist in the Basin. In addition, the station at Rock Springs has data on wind, humidity, and solar radiation. Other historical weather data of interest includes records of evaporation rates from pans located at Green River and Farson, although the pan at Farson is no longer in operation. It is apparent that historical weather data for use in ET models are not widely available in the Basin for parameters other than temperature. Thus, one objective of this project was to acquire and analyze additional climatic data.
Weather Stations and Sites
Seven weather stations utilizing CR-21 microloggers manufactured by Campbell Scientific of Logan, Utah for recording weather data were installed in the Green River Basin (Figure 2). The stations were installed during April and May 1983. Sites were selected to provide as even a distribution of area as possible and included Rock Springs, Farson, Merna, Daniel, Big Piney, Seedskadee, and Mountain View. However, the Merna and Daniel sites were selected to provide stations at both the upper and lower portions of Horse Creek which was the area of intensive measurements of mountain meadow ET. Detailed descriptions of each site are given in Appendix A.
The installed weather stations recorded temperature, precipitation, wind, relative humidity, and solar radiation data. The stations' data loggers were programmed to provide values at the following specified time intervals:
Figure 2. Map of the Green River Basin Showing the Project Sites.
In addition to the automated weather stations, instrumentation at each site included a 4 inch plastic rain gauge. These gauges were monitored weekly and were used as a check on the precipitation recorded by the automated weather stations. Two additional 4-inch plastic rain gauges were operated near the mountain meadow lysimeters along Horse Creek. These were located along the road immediately below the Bridger-Teton National Forest Boundary near lysimeters 3A and 3B and below Merna between lysimeters 3C and 3D. These rain gauges were used to determine the amount of precipitation received by lysimeters 3A through 3F.
Evaporation pans provide one of the simplest, inexpensive, and most widely used methods of estimating evaporative losses and are often used as a reference for ET rates. Thus, three standard class A evaporation pans, with automated reservoirs, were installed and operated during 1984 and 1985. The pans were located adjacent to the weather stations at Merna, Daniel, and Seedskadee. The pans were monitored weekly.
Climatic Data Collection and Reduction
The CR-21 data loggers were programmed to allow a maximum of 15 days between visits. The data stored on the microloggers were transferred to a portable cassette tape through a recorder. The cassette tape was used to transport the data to Laramie where it was transferred to the University of Wyoming Cyber computer system for permanent storage, reduction, and analysis. During the 1985 season the Mountain View station was interrogated via phone.
Monthly summaries of the weather data are given in Tables 1 through 3 while weekly summaries are given in Appendix B. Since all ET measurements were made on a weekly schedule, climatic data for daily and shorter periods are not given in this report but are stored at the University of Wyoming.
Analysis of Climatic Data
Analyses of long-term records were done to compare climatic conditions during 1984 and 1985 with long-term averages and variations (Tables 4 and 5). Data for the long-term averages and variations were derived from the published records of the National Weather Service cooperative network (NOAA, 1965 ... ). The long-term averages used for these comparisons are not the published 30 year normals, which would include the years 1951-1980, but are based on the years 1965-1984.
In general, 1984 is shown to have been a relatively wet summer with the May through October accumulated precipitation at 5 of 6 stations being greater than the long-term average for each station while 1985 was a relatively dry summer with the May through October accumulated precipitation at all 6 of the stations being less than the long-term average for these stations (Table 5). Temperatures for individual months occasionally were considerably less than or greater than the long- term monthly values and are shown in Table 4. However, average temperatures for the entire May through Oct period during 1984 and 1985 were not greatly different than the long-term normal values, except for the 1985 temperature at Seedskadee. The seasonal temperature comparisons are extremely close considering that the sites of the project weather stations and the National Weather Service cooperative stations are not at the exact same locations (Appendix A gives information on specific locations).
TABLE 1. MONTHLY SUMMARY OF CLIMATIC DATA - 1983
===================================================================================================
MAX MIN MAX MIN DEW SOLAR TOTAL WIND D/N
STATION MONTH TEMP TEMP RH RH PT RADTN PRECIP RUN WIND
(F) (F) (%) (%) (F) (LY/DY) (IN/MO) (MI/DY) RATIO
---------------------------------------------------------------------------------------------------
APR 55. 30. 98. 42. 32. 458. .16 178. 1.47
MAY 60. 32. 96. 34. 31.2 590. 1.34 202. 1.50
JUN 73. 41. 96. 28. 40.1 640. 1.34 153. 1.71
RCK SPR JUL 84. 46. 91. 18. 39.5 621. .87 150. 1.62
AUG 88. 51. 93. 17. 44.9 582. .59 136. 1.42
SEP 74. 40. 87. 21. 33.5 492. .35 175. 1.71
---------------------------------------------------------------------------------------------------
APR 53. 26. 100. 44. 31.4 316. .75 176. 1.79
MAY 59. 28. 97. 35. 30.7 361. .83 193. 1.86
JUN 72. 38. 97. 28. 40.7 430. 1.10 154. 1.98
FARSON JUL 80. 43. 94. 18. 38.9 428. .67 140. 1.75
AUG 84 47. 94. 15. 40.8 456. 2.05 113. 1.55
SEP 71. 32. 91. 18. 28.9 346. .91 141. 2.11
---------------------------------------------------------------------------------------------------
MAY 56. 25. 95. 33. -99.0 587. .98 -99. -.99
JUN 66. 34. 99. 36. 38.4 538. .87 117. 1.67
MERNA JUL 72. 37. 98. 36. 43.3 545. 1.65 105. 1.51
AUG 75. 43. 99. 39. 47.9 455. 2.36 86. 1.41
SEP 65. 31. 97. 32. 33.6 400. 1.46 98. 1.95
---------------------------------------------------------------------------------------------------
MAY 60. 27. 99. 31. 30.7 593. .39 122. 1.58
JUN 68. 36. 99. 32. 39.5 553. .91 109. 1.60
DANIEL JUL 75. 39. 100. 29. 43.4 535. 1.14 101. 1.61
AUG 79. 43. 100. 29. 47.6 462. 1.97 82. 1.34
SEP 67. 29. 99. 29. 34.6 389. 1.69 104. 1.70
---------------------------------------------------------------------------------------------------
MAY 61. 26. 99. 32. 30.9 713. 1.22 127. 1.77
JUN 71. 38. 99. 29. 40.1 700. .43 126. 1.76
B. PINEY JUL 78. 40. 100. 23. 42.4 705. .63 128. 1.70
AUG 82. 47. 100. 26. 48.5 605. 1.85 103. 1.61
SEP 70. 32. 95. 26. 34.7 493. 1.34 121. 1.92
---------------------------------------------------------------------------------------------------
APR 53. 28. 99. 41. 30.5 424. 1.57 168. 1.62
MAY 59. 31. 96. 33. 30.2 548. 1.34 179. 1.64
JUN 73. 41. 93. 26. 38.8 572. 1.26 132. 1.83
SEEDSK. JUL 84. 46. 87. 17. 37.8 575. .63 121. 1.68
AUG 88. 52. 89. 16. 43.8 521. .83 110. 1.44
SEP 73. 38. 90. 21. 33.2 437. 1.57 150. 1.97
---------------------------------------------------------------------------------------------------
APR 52. 27. 99. 53. 32.4 448. .43 124. 1.38
MAY 58. 30. 95. 42. 32.6 584. 1.81 170. 1.33
JUN 69. 39. 99. 41. 43.8 631. .98 151. 1.47
MTN VIEW JUL 77. 43. 97. 33. 47.1 600. .28 130. 1.33
AUG 81. 48. 99. 37. 53.7 534. 3.39 107. 1.09
SEP 72. 34. 95. 26. 37.2 498. 1.38 160. 1.57
===================================================================================================
-99.0 INDICATES MISSING DATA
TABLE 2. MONTHLY SUMMARY OF CLIMATIC DATA - 1984
===================================================================================================
MAX MIN MAX MIN DEW SOLAR TOTAL WIND D/N
STATION MONTH TEMP TEMP RH RH PT RADTN PRECIP RUN WIND
(F) (F) (%) (%) (F) (LY/DY) (IN/MO) (MI/DY) RATIO
---------------------------------------------------------------------------------------------------
APR 50. 24. 93. 42. 24.5 428. .55 200. 1.36
MAY 69. 36. 81. 23. 29.3 568. .43 233. 1.67
JUN 75. 41. 80. 21. 33.2 573. .83 172. 1.67
JUL 86. 50. 83. 17. 40.7 615. .79 153. 1.57
RCK SPR AUG 84. 50. 83. 18. 41.1 526. .94 139. 1.61
SEP 69. 37. 86. 24. 32.8 451. 1.57 169. 1.55
OCT 54. 26. 90. 28. 23.3 319. .24 163. 1.46
NOV 47. 23. 96. 38. 24.3 214. .24 203. 1.29
---------------------------------------------------------------------------------------------------
APR 48. 19. 84. 27. 17.3 421. .79 177. 1.63
MAY 68. 28. 77. 15. 19.0 549. .75 220. 2.16
JUN 72. 33. 77. 16. 22.8 573. .94 175. 1.73
JUL 82. 35. 87. 20. 36.6 605. 3.58 121. 1.66
FARSON AUG 81. 37. 93. 19. 39.8 530. .43 108. 1.82
SEP 68. 28. 94. 20. 28.0 433. 1.34 139. 1.72
OCT 56. 17. 91. 20. 16.7 321. .00 115. 1.73
NOV 42. 11. 96. 39. 16.1 197. .20 139. 1.56
---------------------------------------------------------------------------------------------------
APR 45. 16. 91. 44. 19.1 487. 1.30 109. 1.65
MAY 57. 28. 93. 37. 28.6 548. 1.18 130. 1.97
JUN 63. 32. 93. 35. 34.8 582. 2.17 116. 1.84
JUL 74. 41. 92. 35. 44.3 570. 2.99 92. 1.82
MERNA AUG 72. 40. 96. 39. 45.3 494. 2.44 88. 1.55
SEP 61. 29. 95. 35. 32.2 400. 2.28 101. 1.66
OCT 49. 19. 94. 35. 21.8 293. .63 102. 1.66
NOV 39. 10. 96. 51. 18.3 164. .71 99. 1.33
--------------------------------------------------------------------------------------------------
APR 44. 17. 95. 48. 22.0 494. .75 136. 1.53
MAY 59. 27. 96. 35. 30.7 549. 1.14 146. 2.18
JUN 66. 34. 94. 32. 36.8 599. .94 143. 1.61
JUL 77. 42. 95. 30. 45.6 590. 2.09 106. 1.44
DANIEL AUG 76. 39. 96. 29. 44.1 502. 1.57 104. 1.59
SEP 63. 26. 96. 29. 31.0 404. 2.09 121. 1.71
OCT 50. 19. 95. 31. 21.7 305. .28 126. 1.46
NOV 39. 11. 96. 48. 18.2 200. .31 112. 1.49
--------------------------------------------------------------------------------------------------
APR 47. 19. 95. 43. 23.0 452. .83 134. 1.81
MAY 64. 28. 93. 27. 29.5 546. .83 158. 2.09
JUN 71. 34. 93. 24. 34.5 570. .94 137. 1.77
JUL 83. 44. 94. 21. 42.9 563. 1.69 115. 1.65
B. PINEY AUG 81. 42. 95. 22. 43.1 476. .28 105. 1.66
SEP 67. 28. 96. 25. 31.5 403. 2.09 117. 1.66
OCT 53. 17. 94. 24. 19.9 304. .04 102. 1.83
NOV 42. 12. 96. 46. 18.7 197. .39 96. 1.51
--------------------------------------------------------------------------------------------------
APR 49. 24. 91. 44. 23.3 443. .83 168. 1.57
MAY 66. 30. 86. 28. 29.4 573. .55 208. 2.01
JUN 75. 35. 84. 22. 33.0 576. .75 167. 1.75
JUL 85. 48. 87. 22. 43.8 592. 2.13 125. 1.70
SEEDSK. AUG 84. 48. 86. 22. 42.6 506. .63 121. 1.67
SEP 69. 36. 89. 26. 34.1 427. 1.85 136. 1.84
OCT 55. 24. 90. 27. 22.7 310. .08 133. 1.61
NOV 43. 19. 94. 56. 23.3 211. .43 171. 1.33
--------------------------------------------------------------------------------------------------
APR 48. 21. 92. 48. 24.5 456. .63 191. 1.22
MAY 64. 32. 88. 33. 33.1 568. .55 224. 1.76
JUN 69. 37. 93. 30. 38.9 577. .67 174. 1.33
JUL 80. 46. 90. 29. 46.5 561. 1.34 127. 1.22
MTN VIEW AUG 78. 46. 89. 30. 46.6 471. 1.02 123. 1.10
SEP 68. 34. 90. 30. 35.0 427. 1.50 157. 1.29
OCT 52. 25. 91. 33. 25.2 321. .28 158. 1.16
NOV 45. 17. 92. 47. 22.4 208. .24 165. 1.38
=================================================================================================
TABLE 3. MONTHLY SUMMARY OF CLIMATIC DATA - 1985
================================================================================================
MAX MIN MAX MIN DEW SOLAR TOTAL WIND D/N
STATION MONTH TEMP TEMP RH RH PT RADTN PRECIP RUN WIND
(F) (F) (%) (%) (F) (LY/DY) (IN/MO) (MI/DY) RATIO
-----------------------------------------------------------------------------------------------
APR 60. 28. 80. 20. 18.9 546. .12 196. 1.74
MAY 72. 36. 78. 15. 24.2 615. .43 164. 1.74
JUN 81. 45. 56. 16. 24.0 687. .63 170. 1.60
RCK SPR JUL 89. 52. 73. 11. 34.3 617. .39 131. 1.78
AUG 85. 45. 43. 11. 20.0 628. .04 115. 1.81
SEP 68. 35. 82. 18. 24.3 439. .91 139. 1.26
OCT 59. 27. 86. 25. 21.0 355. .47 148. 1.76
-----------------------------------------------------------------------------------------------
APR 61. 20. 90. 18. 17.3 534. .16 175. 2.02
MAY 70. 27. 96. 17. 25.3 605. .91 174. 1.79
JUN 77. 34. 85. 18. 27.8 646. 1.77 163. 1.91
FARSON JUL 86. 40. 93. 12. 36.2 574. .39 119. 1.67
AUG 82. 37. 75. 11. 22.7 607. .08 163. 2.16
SEP 66. 25. 95. 18. 23.2 446. 1.26 162. 1.97
OCT 58. 18. 92. 21. 16.4 342. .43 151. 1.65
-----------------------------------------------------------------------------------------------
APR 53. 21. 92. 23. 17.1 565. .16 116. 1.73
MAY 60. 27. 91. 25. 25.5 541. .67 121. 1.77
JUN 68. 33. 90. 23. 30.5 640. .83 117. 1.76
MERNA JUL 77. 41. 87. 22. 38.7 591. 1.97 100. 1.57
AUG 72. 34. 80. 17. 27.3 582. .12 115. 1.72
SEP 58. 25. 93. 28. 26.0 389. 2.44 110. 1.91
OCT 51. 20. 90. 28. 19.8 333. .79 109. 1.67
----------------------------------------------------------------------------------------------
APR 56. 20. 96. 22. 20.0 530. .20 147. 1.94
MAY 64. 26. 95. 23. 27.8 534. .67 142. 1.87
JUN 69. 34. 92. 29. 37.3 622. .94 138. 1.74
DANIEL JUL 79. 43. 97. 33. 47.4 583. 1.57 110. 1.45
AUG 76. 31. 97. 20. 33.5 564. .16 131. 1.78
SEP 60. 25. 98. 31. 29.6 398. 2.09 134. 2.06
OCT 54. 17. 97. 30. 21.9 321. .28 130. 1.65
----------------------------------------------------------------------------------------------
APR 59. 21. 95. 18. 18.6 536. .00 131. 2.19
MAY 67. 28. 95. 20. 26.5 560. .67 134. 2.11
JUN 77. 36. 90. 17. 30.3 625. .55 126. 2.06
B. PINEY JUL 86. 44. 97. 13. 39.1 566. .98 96. 1.78
AUG 81. 34. 86. 12. 26.1 583. .04 124. 2.18
SEP 63. 27. 98. 22. 27.4 419. 1.50 126. 2.36
OCT 57. 18. 97. 21. 19.3 329. .12 110. 2.04
-----------------------------------------------------------------------------------------------
APR 61. 25. 76. 17. 16.6 540. .04 188. 1.92
MAY 71. 36. 78. 16. 24.2 591. .83 176. 1.64
JUN 80. 43. 63. 14. 25.8 650. .59 161. 1.87
SEEDSK. JUL 89. 52. 67. 11. 33.0 590. .55 132. 1.57
AUG 84. 44. 49. 11. 21.1 608. .12 168. 2.05
SEP 67. 34. 82. 18. 24.4 433. .98 161. 1.77
OCT 60. 24. 82. 19. 17.0 345. .08 160. 1.48
----------------------------------------------------------------------------------------------
APR 54. 24. 89. 28. 21.6 484. .31 193. 1.68
MAY 69. 32. 92. 17. 29.2 642. .00 178. 1.50
JUN 75. 38. 90. 20. 33.8 652. 1.38 154. 1.36
MTN VIEW JUL 82. 48. 88. 21. 43.4 566. 1.57 125. 1.13
AUG 79. 40. 76. 12. 27.2 612. .05 171. 1.44
SEP 66. 29. 90. 21. 27.6 432. .59 160. 1.48
OCT 58. 24. 89. 26. 22.7 342. .98 158. 1.29
===============================================================================================
TABLE 4. LONG-TERM NORMAL VS MEAN 1984 AND 1985 TEMPERATURES*
=============================================================================================
AVERAGE
STATION YEAR APR MAY JUNE JULY AUG SEPT OCT MAY-OCT
---------------------------------------------------------------------------------------------
1985 44.0 54.0 63.0 70.5 65.0 51.5 43.0 57.8
RCK SPR 1984 37.0 52.5 58.0 68.0 67.0 53.0 40.0 56.4
NORMAL 39.9 50.1 59.7 67.9 65.6 55.5 43.6 57.1
S. DEV. 3.28 2.70 3.05 1.23 2.69 3.40 3.58
--------------------------------------------------------------------------------------------
1985 40.5 48.5 55.5 63.0 59.5 45.5 38.0 51.7
FARSON 1984 33.5 48.0 52.5 58.5 59.0 48.0 36.5 50.4
NORMAL 36.9 47.0 56.0 63.2 61.0 51.0 39.4 52.9
S. DEV. 3.36 2.35 2.69 1.65 2.21 2.95 3.60
-------------------------------------------------------------------------------------------
1985 37.0 43.5 50.5 59.0 53.0 41.5 35.5 47.2
MERNA 1984 30.5 42.5 47.5 57.5 56.0 45.0 34.0 47.1
NORMAL 30.1 41.1 49.1 56.2 55.1 46.9 37.1 47.6
S. DEV. 3.39 2.14 2.10 1.28 2.24 2.98 3.21
--------------------------------------------------------------------------------------------
1985 38.0 45.0 51.5 61.0 53.5 42.5 35.5 48.2
DANIEL 1984 30.5 43.0 50.0 59.5 57.5 44.5 34.5 48.2
--------------------------------------------------------------------------------------------
1985 40.0 47.5 56.5 65.0 57.5 45.0 37.5 51.5
B. PINEY 1984 33.0 46.0 52.5 63.5 61.5 47.5 35.0 51.0
NORMAL 33.8 44.7 53.7 60.1 57.0 47.3 37.0 50.0
S. DEV. 2.80 2.39 2.49 1.23 1.96 2.97 3.02
-------------------------------------------------------------------------------------------
1985 43.0 53.5 61.5 70.5 64.0 50.5 42.0 57.0
SEEDSK. 1984 36.5 48.0 55.0 66.5 66.0 52.5 39.5 54.6
NORMAL 37.5 47.3 56.8 64.4 62.7 51.9 40.0 53.9
S. DEV. 3.06 2.44 2.34 1.54 2.60 2.66 3.04
-------------------------------------------------------------------------------------------
1985 39.0 50.5 56.5 65.0 59.5 47.5 41.0 53.3
MTN VIEW 1984 34.5 48.0 53.0 63.0 62.0 51.0 38.5 52.6
NORMAL 37.5 47.9 56.1 63.2 61.8 53.5 42.6 54.2
S. DEV. 3.57 2.27 2.42 1.15 2.28 2.55 3.57
==========================================================================================
ALL TEMPERATURES ARE IN DEGREES F. NORMAL INCLUDES YEARS 1965 - 1984
TABLE 5. LONG-TERM NORMAL VS 1984 AND 1985 ACCUMULATED PRECIPITATION*
============================================================================
STATION YEAR MAY JUNE JULY AUG SEPT OCT
----------------------------------------------------------------------------
1985 0.43 1.24** 1.63 1.67 2.58 3.05
RCK SPR 1984 0.43 1.26 2.05 2.99 4.56 4.90**
NORMAL 1.31 2.28 3.33 4.06 4.95 5.78
--------------------------------------------------------------------------
1985 0.91 2.68 3.07 3.15 4.41 4.84
FARSON 1984 0.75 1.69 5.27 5.70 7.04 7.04**
NORMAL 1.24 2.40 3.37 4.18 4.94 5.80
--------------------------------------------------------------------------
1985 0.67 1.50 3.47 3.59 6.03 6.82
MERNA 1984 1.18 3.35 6.34 8.78 11.06 11.95**
NORMAL 1.25 2.85 4.19 5.55 6.94 8.05
--------------------------------------------------------------------------
1985 0.67 1.61 3.18 3.34 5.43 5.71
DANIEL 1984 1.14 2.08 4.17 5.74 7.83 9.35**
-------------------------------------------------------------------------
1985 0.67 1.22 2.20 2.24 3.74 3.86
B. PINEY 1984 0.83 1.77 3.46 3.74 5.83 5.89**
NORMAL 0.99 2.19 3.05 3.98 5.07 5.59
-------------------------------------------------------------------------
1985 0.83 1.42 1.97 2.09 3.07 3.15
SEEDSK. 1984 0.55 1.30 3.43 4.06 5.91 6.02**
NORMAL 0.96 2.06 2.85 3.50 4.51 5.12
------------------------------------------------------------------------
1985 1.38 2.95 3.00 3.59 4.57
MTN VIEW 1984 0.67 2.01 3.03 4.53 5.07**
NORMAL 1.14 2.05 2.95 3.95 4.86
========================================================================
* ALL PRECIPITATION IS IN INCHES. NORMAL INCLUDES YEARS 1965 - 1984
** DATA EXTRAPOLATED TO INCLUDE ENTIRE MONTH
In general, irrigation requirements of agricultural crops might be expected to be greater during hot dry years as compared to average years. Low precipitation leads not only to greater irrigation applications but tends to cause lower humidity conditions which usually increase water use rates. Increased consumptive use rates also are usually associated with higher temperatures. Thus, 1984 might be expected to be a year of lower than normal irrigation requirements while 1985 would be expected to be a year of greater than normal irrigation requirements.
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