LTER

2009-10 Sub-ice Current Velocities Recorded with an Acoustic Doppler Current Profiler

Abstract: 

On 7 January 2010, a SonTek Argonaut-XR 1.5 MHz Acoustic Doppler Current Profiler (ADCP) was fixed at the bottom of the lake ice in the Lake Hoare Limno Hole inside the Polar Haven, looking downward through the water column. Every 10 seconds, the ADCP measured horizontal and vertical current velocities in ten, 30-cm-thick cells between 0.5 and 3.5 m below the lake ice. Over 32.5 hours, horizontal currents in the shallowest cell (0.5 to 0.8 m below lake ice) had a mean speed of 23.8 cm/sec. This speed was independently validated by lowering a SonTek handheld Acoustic Doppler Velocity (ADV) meter into the ice hole. Horizontal speeds oscillated between 10.1 and 37.5 cm/sec over the course of the ADCP dataset. Fast Fourier Transforms of x-direction velocity data from the shallowest cell identified oscillation periods of 11, 3.7, and 2.5 minutes consistent with the theoretical first-mode longitudinal surface seiche in Lake Hoare. Current direction oscillated between N 78 degrees E and N 289 degrees E along the east-west longitudinal axis of the lake, consistent with the behavior of a seiche.

Data set ID: 

74

Associated Personnel: 

5

Methods: 

  1. Location: Limno Sample Hole, Lake Hoare, Taylor Dry Valley
  2. GPS: S77°37.660’, E162°54.572’
  3. 7 January 2010, 10:50 p.m. to 9 January 2010, 7:24 a.m. (New Zealand Time).
  4. Duration: 32.5 hours
  5. Time correction: Add 18 hours to the raw data times to convert to the New Zealand Time Zone used in the McMurdo Dry Valleys and to synchronize sample times with other datasets provided on MCM-LTER web site.

7 - 9 January 2010 Methods and Settings

  • ADCP fixed to a metal pole to minimize motion
  • ADCP inverted and arrow aligned with North such that:
    1. +x is West, -x is East
    2. +y is North, -y is South
    3. +z is Down, -z is up

    True current direction (degrees from N) = 360 – observed direction

  • ADCP lowered to the bottom of the limno ice hole top of ADCP near the ice-water interface.
  • ADCP diagnostics test performed
  • Tarp placed over sample hole during deployment
    1. Averaging Interval: 10 seconds
    2. Sampling Interval: 10 seconds
    3. Quality of data: Good.
    4. ADCP resolution = plus/minus 0.1 cm/sec.
    5. ADCP accuracy = plus/minus 0.5 cm/sec. Files for standard deviations and signal-to-noise ratios provided
    6. Total ice thickness: 3.3 m
    7. Distance from piezometric surface to base of ice: 2.8 m
    8. Date ice thickness measured: 7 January 2010
    9. "Automatic Boundary Adjustment" used
    10. Coordinant system "XYZ" Averaging Interval: 10 seconds
    11. Sampling Interval: 10 seconds
    12. Quality of data: Good.
    13. ADCP resolution = plus/minus 0.1 cm/sec.
    14. ADCP accuracy = plus/minus 0.5 cm/sec. Files for standard deviations and signal-to-noise ratios provided
    15. Total ice thickness: 3.3 m
    16. Distance from piezometric surface to base of ice: 2.8 m
    17. Date ice thickness measured: 7 January 2010
    18. "Automatic Boundary Adjustment" used
    19. Coordinant system "XYZ"
    20. Averaging Interval: 10 seconds
    21. Sampling Interval: 10 seconds
    22. Quality of data: Good.
    23. ADCP resolution = plus/minus 0.1 cm/sec.
    24. ADCP accuracy = plus/minus 0.5 cm/sec. Files for standard deviations and signal-to-noise ratios provided.
    25. Total ice thickness: 3.3 m
    26. Distance from piezometric surface to base of ice: 2.8 m
    27. Date ice thickness measured: 7 January 2010
    28. "Automatic Boundary Adjustment" used
    29. Coordinant system "XYZ"
    30. "Profile Mode" used
    31. : Averaging Interval: 10 seconds
    32. Sampling Interval: 10 seconds
    33. Quality of data: Good.
    34. ADCP resolution = plus/minus 0.1 cm/sec.
    35. ADCP accuracy = plus/minus 0.5 cm/sec. Files for standard deviations and signal-to-noise ratios provided.
    36. Total ice thickness: 3.3 m
    37. Distance from piezometric surface to base of ice: 2.8 m
    38. Date ice thickness measured: 7 January 2010
    39. "Automatic Boundary Adjustment" used
    40. Coordinant system "XYZ"
    41. "Profile Mode" used
    42. : Averaging Interval: 10 seconds
    43. Sampling Interval: 10 seconds
    44. Quality of data: Good.
    45. ADCP resolution = plus/minus 0.1 cm/sec.
    46. ADCP accuracy = plus/minus 0.5 cm/sec. Files for standard deviations and signal-to-noise ratios provided.
    47. Total ice thickness: 3.3 m
    48. Distance from piezometric surface to base of ice: 2.8 m
    49. Date ice thickness measured: 7 January 2010
    50. "Automatic Boundary Adjustment" used
    51. Coordinant system "XYZ"
    52. "Profile Mode" used
    53. Cell thickness: 0.3 m; Averaging Interval: 10 seconds
    54. Sampling Interval: 10 seconds
    55. Quality of data: Good.
    56. ADCP resolution = plus/minus 0.1 cm/sec.
    57. ADCP accuracy = plus/minus 0.5 cm/sec. Files for standard deviations and signal-to-noise ratios provided.
    58. Total ice thickness: 3.3 m
    59. Distance from piezometric surface to base of ice: 2.8 m
    60. Date ice thickness measured: 7 January 2010
    61. "Automatic Boundary Adjustment" used
    62. Coordinant system "XYZ"
    63. "Profile Mode" used
    64. Cell thickness: 0.3 m
    65. Averaging Interval: 10 seconds
    66. Sampling Interval: 10 seconds
    67. Quality of data: Good.
    68. ADCP resolution = plus/minus 0.1 cm/sec.
    69. ADCP accuracy = plus/minus 0.5 cm/sec. Files for standard deviations and signal-to-noise ratios provided.
    70. Total ice thickness: 3.3 m
    71. Distance from piezometric surface to base of ice: 2.8 m
    72. Date ice thickness measured: 7 January 2010
    73. "Automatic Boundary Adjustment" used
    74. Coordinant system "XYZ"
    75. "Profile Mode" used
    76. Cell thickness: 0.3 m
    77. : Averaging Interval: 10 seconds
    78. Sampling Interval: 10 seconds
    79. Quality of data: Good.
    80. ADCP resolution = plus/minus 0.1 cm/sec.
    81. ADCP accuracy = plus/minus 0.5 cm/sec. Files for standard deviations and signal-to-noise ratios provided.
    82. Total ice thickness: 3.3 m
    83. Distance from piezometric surface to base of ice: 2.8 m
    84. Date ice thickness measured: 7 January 2010
    85. "Automatic Boundary Adjustment" used
    86. Coordinant system "XYZ"
    87. "Profile Mode" used
    88. Cell thickness: 0.3 m
    89. Number of cells: 10; Averaging Interval: 10 seconds
    90. Sampling Interval: 10 seconds
    91. Quality of data: Good.
    92. ADCP resolution = plus/minus 0.1 cm/sec.
    93. ADCP accuracy = plus/minus 0.5 cm/sec. Files for standard deviations and signal-to-noise ratios provided.
    94. Total ice thickness: 3.3 m
    95. Distance from piezometric surface to base of ice: 2.8 m
    96. Date ice thickness measured: 7 January 2010
    97. "Automatic Boundary Adjustment" used
    98. Coordinant system "XYZ"
    99. "Profile Mode" used
    100. Cell thickness: 0.3 m
    101. Number of cells: 10; Averaging Interval: 10 seconds
    102. Sampling Interval: 10 seconds
    103. Quality of data: Good.
    104. ADCP resolution = plus/minus 0.1 cm/sec.
    105. ADCP accuracy = plus/minus 0.5 cm/sec. Files for standard deviations and signal-to-noise ratios provided.
    106. Total ice thickness: 3.3 m
    107. Distance from piezometric surface to base of ice: 2.8 m
    108. Date ice thickness measured: 7 January 2010
    109. "Automatic Boundary Adjustment" used
    110. Coordinant system "XYZ"
    111. "Profile Mode" used
    112. Cell thickness: 0.3 m
    113. Number of cells: 10; Averaging Interval: 10 seconds
    114. Sampling Interval: 10 seconds
    115. Quality of data: Good.
    116. ADCP resolution = plus/minus 0.1 cm/sec.
    117. ADCP accuracy = plus/minus 0.5 cm/sec. Files for standard deviations and signal-to-noise ratios provided.
    118. Total ice thickness: 3.3 m
    119. Distance from piezometric surface to base of ice: 2.8 m
    120. Date ice thickness measured: 7 January 2010
    121. "Automatic Boundary Adjustment" used
    122. Coordinant system "XYZ"
    123. "Profile Mode" used
    124. Cell thickness: 0.3 m
    125. Number of cells: 10; Averaging Interval: 10 seconds
    126. Sampling Interval: 10 seconds
    127. Quality of data: Good.
    128. ADCP resolution = plus/minus 0.1 cm/sec.
    129. ADCP accuracy = plus/minus 0.5 cm/sec. Files for standard deviations and signal-to-noise ratios provided.
    130. Total ice thickness: 3.3 m
    131. Distance from piezometric surface to base of ice: 2.8 m
    132. Date ice thickness measured: 7 January 2010
    133. "Automatic Boundary Adjustment" used
    134. Coordinant system "XYZ"
    135. "Profile Mode" used
    136. Cell thickness: 0.3 m
    137. Number of cells: 10
    138. Approximate depth range of ADCP cells: Averaging Interval: 10 seconds
    139. Sampling Interval: 10 seconds
    140. Quality of data: Good.
    141. ADCP resolution = plus/minus 0.1 cm/sec.
    142. ADCP accuracy = plus/minus 0.5 cm/sec. Files for standard deviations and signal-to-noise ratios provided.
    143. Total ice thickness: 3.3 m
    144. Distance from piezometric surface to base of ice: 2.8 m
    145. Date ice thickness measured: 7 January 2010
    146. "Automatic Boundary Adjustment" used
    147. Coordinant system "XYZ"
    148. "Profile Mode" used
    149. Cell thickness: 0.3 m
    150. Number of cells: 10
    151. Approximate depth range of ADCP cells:
      1. Rel. to bottom of the lake : Rel. to piezometric surface
      2. Cell 1: 0.5 to 0.8 3.6 to 3.9
      3. Cell 2: 0.8 to 1.1 3.9 to 4.2
      4. Cell 3: 1.1 to 1.4 4.2 to 4.5
      5. Cell 4: 1.4 to 1.7 4.5 to 4.8
      6. Cell 5: 1.7 to 2.0 4.8 to 5.1
      7. Cell 6: 2.0 to 2.3 5.1 to 5.4
      8. Cell 7: 2.3 to 2.6 5.4 to 5.7
      9. Cell 8: 2.6 to 2.9 5.7 to 6.0
      10. Cell 9: 2.9 to 3.2 6.0 to 6.3
      11. Cell 10: 3.2 to 3.5 6.3 to 6.6

Supporting file links (Standard Deviations, etc)

  1. "ADCP set up 7- 9 January 2010 This text file lists more details about how data were recorded. Link here
  2. "ADCP signal to noise ratio 26-30 Dec 2012" This file provides diagnostic data on the instrument which someone might find useful. Link here
  3. "ADCP standard deviation 26-30 Dec 2012" This text file provides information on sampling error.Link Here

Data sources: 

LIMNO_ANCILLARY_ADCP

Additional information: 

Data contained in these files has been subjected to quality control standards imposed by the investigator. The user of this data should be aware that, while efforts have been taken to ensure that these data are of the highest quality, there is no guarantee of perfection for the data contained herein and the possibility of errors exists. If you encounter questionable data, please contact the MCM LTER data manager corrected or qualified. Thus, these data may be modified and future data will be appended.

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