AIDJEX Bulletin #40 - Polar Science Center - University of Washington

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Sensor samples were taken every three hours, initially on the synoptic weather observation schedule. An inappropriate simplifying assumption in the electrical design caused the sample times to drift at the rate of three hours in one year. Since the same clock was used to control the 10-minute interval for frequency measurement of the barometric pressure sensor, the offset of 4 parts in lo-" caused apparent errors of about 4 millibars. Both of these effects were discovered by careful examination of the data after the buoys were deployed, and the appropriate corrections were applied The current speed was also sampled over the same 10-minute interval, but the direct relationship of sample counts to current speed renders the time errors insignificant (0.03%). Samples of compass bearing, air temperature, and current direction were instantaneous--in the case of the latter, to avoid errors caused by averaging the 0'-360" crossover. The buoy memory holds eight synoptic sets of sensor samples, the oldest being replaced after a new sample period, so that the last 24 hours of data are continuously stored in memory and available for transmission. The normal format for transmission to the Nimbus spacecraft is a one-second burst every minute. It was considered desirable to transmit the entire contents of buoy memory within 8 minutes to insure reception of a full day's data within one 15-minute satellite pass. Since the quantity of data in each synoptic sample set was twice the capacityofasjngleRllMS transmission, transmissions were made every 30 seconds. To avoid confusion in the organization and processing of data by NASA, two different identification codes were used alternately so that the" appearance was that of two independent buoys whose one-minute bursts happened to be 30 seconds apart. The data were easily recombined in processing at AIDJEX. When the spacecraft was within view (12-14 times each day at high latitudes) these data were received and recorded, together with measurements of the Doppler-shifted frequency of the received transmission, and played back to a NASA tracking station, usually to Gilmore Creek near Fairbanks. NASA performed basic processing of the raw data, computed geographic positions from the Doppler data, and furnished the results to our office on magnetic tapes. The position data wer.e corrected, edited, and smoothed by processing developed at AIDJEX [Martin and Gillespie, 1976; Thorndike and Cheung, 19771. 37
. J BUOY PERFON4ANCE A brief summary of M/O buoy performance is listed in Table 1. In conformance with AIDJEX notation we have listed time in days from the beginning of calendar 1975; e.g., day 366 is 1 January 1976. Good environmental data were collected from M/O 1 for 145 days and from M/O 4 for 332 days as shown. M/O 1, M/O 2, and M/O 4 each produced good position data for more than 300 days and are believed to have exhausted their power supplies. The premature environmental data failures are believed to be due to integrated circuit failures. M/O 3 was mishandled during installation and produced only very sparse data for the next four months. Figures 1 through 4 (adapted from Thqrndike and Cheung, 1977) show drift tracks for the buoys. M/O 1 left the air on day 452, but began transmitting again about two months later. Environmental data after that time are garbled, which is unfortunate since the buoy drift in the vicinity of the Barrow Canyon is often anomalously swift, and it would have been particularly useful to have surface current measurements there. A sample of the barometric pressure record is shown in Figure 5. Experience with these sensors (Hamilton Standard ''Vibrasense") has shown them to be very stable with time. The coarse resolution, about 1.4 millibar, is due to an erroneous simplifying assumption in the electrical design. It should have been 0.1 millibar. The data have been enhanced by smoothing and used in pressure analyses. It has not been possible to decode any coherent air temperature data, and a shortcoming in design is suspected. All current directions are referenced to the buoy hull, and the azimuth of the buoy hull is measured with a magnetic compass (Digicourse Mode1 215). Figures 6 and 7 show the magnetic azimuth data obtained from the M/O buoys. Early work on the use of magnetic compasses for data buoys in the Arctic Ocean suggested that weak horizontal components of the magnetic field and magnetic disturbances would be expected to cause errors of 5"-1.0" [Haugen and Dozier, 19751. The raw data shown in the figures require a correction, unique to each compass and dependent on the compass direction and the local horizontal field strength, to get the actual magnetic azimuth used to define true current directions. Calibration curves taken in Seattle and checked in Barrow, where field 38
Page 2 and 3: DATA BUOYS AIDJEX BULLETIN No. 40 J
Page 4 and 5: NOTE TO FRIENDS, AND BYSTANDERS . .
Page 6 and 7: SUMMARY OF TECHNICAL DEVELOPMENTS I
Page 8 and 9: milestones, kept the vendor working
Page 10 and 11: The scene during deployment of HF-N
Page 12 and 13: The initial AIDJEX scientific plan
Page 14 and 15: poizr-orbiting satellite, which is
Page 16 and 17: t@ the spacecraft during each orbit
Page 18 and 19: BUOY NAHE COMMUN. COMMANDS FIXES TA
Page 20 and 21: L( 0 I 2 3 4 3 Radial error, kilome
Page 22 and 23: The buoy will be subjected to tempe
Page 24 and 25: nics occupy about 12 feet of the 17
Page 26 and 27: Ill -- - KEY AIUJEX WIN WW AEBa 0 4
Page 28 and 29: event that a melt pond should form
Page 30 and 31: chute supplied by Paranetics Inc. i
Page 32 and 33: 6'" IqORGANIC LITHIUM BP.TTEI?Y IMP
Page 34 and 35: OM (AD RAMS) UREMEN~ \ AIRDROP N m
Page 36 and 37: provides a grid from which geostrop
Page 38 and 39: words; a four-bit air temperature w
Page 40 and 41: PERFORMANCE OF MET/OCEAN BUOYS IN A
Page 44 and 45: strengths are known, were used with
Page 46 and 47: the ice (causing reduced shear). An
Page 48 and 49: (McPhee, Mangum, and Martin) , TABL
Page 50 and 51: 70°N 75'N n 3 P 17OOW (D Y 170°W
Page 52 and 53: 12OOW * U Station 25. Xeasurements
Page 54 and 55: (McPhee , Mangum, and Martin) 2701
Page 56 and 57: (McPhee, Mangum, and Martin) a 0 a
Page 58 and 59: "i BUOY 4 I 43 360- 309- 257 206 15
Page 60 and 61: a30gl 251 I 60 511 r 43 BUOY 4 I
Page 62 and 63: n 4, (McPhee, Mangum, and Martin) 8
Page 64 and 65: (McPhee, Mangum, and Martin) 33 W c
Page 66 and 67: . '-,..I.. . B A R R O W W I N D S
Page 68 and 69: :
Page 70 and 71: I 25 23 t h--:!li[ NCI PiHCEl4l 22
Page 72 and 73: .5 .4 .3 0 A R 2 R 0 W J - 0 B U -
Page 74 and 75: 9 1.5 1.0 c 8 w .5 R 930 $ 565 1000
Page 76 and 77: Clock corrections were applied rout
Page 78 and 79: Q) u o z z i 4- 4- Z + + z f n 9 Ef
Page 80 and 81: TABLE 1 DIFFERENCES IN DAILY TEMPER
Page 82 and 83: Laboratory calibration of the ADRAM
Page 84 and 85: 3.20- - 1 t W o? 2 3.051 ...:-.;..
Page 86 and 87: POSITION MEASUREMENTS OF AIDJEX MAN
Page 88 and 89: some redundancy. Four points were u
Page 90 and 91: 75.5 75.: - E75.1 LLI % y75.c - 1 1
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The translocation principle removes
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POSITION ACCURACY To evaluate the q
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TABLE 1 STAND-ALONE ACCURACY 68th P
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Az i mu t h s When both receivers a
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DATA PROCESSING Following the field
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model ice motion in the statistical
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FREC 1 INCY / DOPPLER / FREQUENCY /
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35 30 25 v) > 0 2 20 LL 0 r= E m 15
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An example of a large-scale buoy ar
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observations are needed in remote a
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useful for determining how various
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as well as velocity fields, we must
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Since small changes in the yield su
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The transformation of the system of
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e able to judge how well such a mod
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then the flow rule becomes Q = +A -
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[-B' -F Finally, we eliminate Carte
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differential equation. 2. Discontin
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Substituting (36) and (37) into (34
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arbitrarily assign the values of 1
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The special case when advection can
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TABLE 1 STRETCHING, STRESS, ASP CHA
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ate of deformation, we have normali
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CHARACTERISTIC EQUATIONS The ordina
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One way to circumvent the problems
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The equations governing solutions a
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It is readily seen that when body f
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which may be substituted into equat
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a the stress derivative dCldS remai
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Although we have not studied in thi
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Courant, R., and D. Hilbert. 1962.
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A RESEARCH PLAN TO TEST THE AIDJEX
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the barges managed to reach their d
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APPROACH A baseline simulation 0-f
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SENSITIVITY OF ICE RESPONSE TO DIFF
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Since free drift of ice is computed
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and what is observed becomes less i
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stresses appear to be relatively un
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ehavior is directly related to accu
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TABLE 1 COMPARISON OF ESTIMATED ERR
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a) Base line b) 24-hour prediction
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\ / a) Base line b) 24- hour predi
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a) Base line b) 24- hour predi ct i
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\ / a) Base line b) 24-hour predict
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.. a) Base line b) 24- hour predict
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J2 a) Base line b) 24-hour predicti
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) 24-hour prediction c) 36-hour pre
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8 Figure 17. AIDJEX surface pressur
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APPENDIX 1 AIDJEX DATA FILES 1. Pos
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9A. Surface-1 eve1 ai r pressure (d
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19. Surface pressure (Val i dated)
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APPENDIX 2 AIDJEX DATA TRANSFERRED
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I -7-71327GEO A Cards (continued) 7
Page 202:
B Cards (continued) 201
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AIDJEX Bulletin #40 - Polar Science Center - University of Washington

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