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

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Clock corrections were applied routinely to the data and were effective in correcting for large nonstandard initial values. An attempt to make the correction algorithm responsive to diurnal clock variations incorporated featzres which caused random pressure errors of 0.15 mb and a significant Loss cf o%hem-Lse good ~ressurs xeasuremmts. The precision of buoy pressures is significantly better when the buoy clocks are assumed to be constact with time (Figs. 3 and 4). A more efficient aljprithm incorporating better resolution and some averaging could. be used easily, OH simpler checks of clock behavior could be done periodically by hand. The use of clocks with smaller temperature coefficients, insulation of the buoy, and relaxation of pressure accuracy requirements would reduce the need for frequent clock corrections. Selection of barometers with decreased pressure sensitivity per unit change in frequency output would increase the need for frequent clock correction. Wind-Induced Dynamic Pressures The Parge tails in the pressure difference histograms (Figs. 3 and 4) and thz ano?iaiy in thc pressure difference time series at day 140 (Fig. 1) are due to dynamic pressures associated with high winds. The pressure orifice of buoy 1663 faced northeast into the strongest prevailing winds occurring in the first half of the test period, while buoy 1671 faced the opposite direc- tno~. ligure 8 ~RQWS the distribution of winds for the test period: Figure 9 S~QWS that the pressure errors depend on the component of wind on the pressure orifice. The effect is most pronounced during the first half of the test, when the highest on-axis winds occurred. The suggestion of lower buoy pressures during high on-axis winds for buoy 1671 may be due to sensitivity of the raWS reference pressures to southwest winds, or to a protective shroud covering the orifice of that buoy. The effect of wind gusts on the pressure sample is reduced by the combination of a teflon filter in the pressure orifice and a one-minute integration period which produces a two-minute response time to pressure change, However, the horizontal orientation of the port makes the pressure measurement susceptible to the dynamic pressures of the average wind. occurrence of these errors is frequent enough to affect the sample variances The 72
Nr3RTH I SC'JTH BRR40W KIN3 ORTE June - July - 8 0 . 9 2 M/S PER 3i'J Fig. 8. Wind roses at Barrow for first and second halves of test period. Pressure orifice of buoy 1663 pointed to the northeast and was exposed to strong on-axis winds during the first half of the test period. in the first half of the test, but not the sample means. Smaller variances during the second half of the test reflect smaller on-axis winds during that period. Since these errors occur only during times of high winds, which are generally driven by large pressure gradients, they do not seriously degrade the usefulness of the barometric pressure measurements. AIR TEMPERATURE MEASUREMENTS The measurement of air temperature requires a sensor on the exterior of the buoy hull, freely exposed to the atmosphere. The sensor must be rugged enough to withstand a severe direct impact with ice and snow when the buoy bounces during a parachute landing. Radiation effects must also be minimized. In the test, radiation effects were to be minimized by using a small (14 mil) thermistor with low thermal mass-to-surface-area ratio to enhance self-cooling. The thermistor was protected by a permanent plastic arch and a temporary plastic cup. The cup was designed to remain over the sensor for 12 seconds after initial impact, but in fact when one of the buoys was dropped in a test deployment the cup disengaged prematurely; on a second attempt the cup, the arch, and the sensor itself all broke cleanly away from the buoy hull, 73
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DATA BUOYS AIDJEX BULLETIN No. 40 J
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NOTE TO FRIENDS, AND BYSTANDERS . .
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SUMMARY OF TECHNICAL DEVELOPMENTS I
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milestones, kept the vendor working
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The scene during deployment of HF-N
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The initial AIDJEX scientific plan
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poizr-orbiting satellite, which is
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t@ the spacecraft during each orbit
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BUOY NAHE COMMUN. COMMANDS FIXES TA
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L( 0 I 2 3 4 3 Radial error, kilome
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The buoy will be subjected to tempe
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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 42 and 43: Sensor samples were taken every thr
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
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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 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
Page 92 and 93: The translocation principle removes
Page 94 and 95: POSITION ACCURACY To evaluate the q
Page 96 and 97: TABLE 1 STAND-ALONE ACCURACY 68th P
Page 98 and 99: Az i mu t h s When both receivers a
Page 100 and 101: DATA PROCESSING Following the field
Page 102 and 103: model ice motion in the statistical
Page 104 and 105: FREC 1 INCY / DOPPLER / FREQUENCY /
Page 106 and 107: 35 30 25 v) > 0 2 20 LL 0 r= E m 15
Page 108 and 109: An example of a large-scale buoy ar
Page 110 and 111: observations are needed in remote a
Page 112 and 113: useful for determining how various
Page 114 and 115: as well as velocity fields, we must
Page 116 and 117: Since small changes in the yield su
Page 118 and 119: The transformation of the system of
Page 120 and 121: e able to judge how well such a mod
Page 122 and 123: then the flow rule becomes Q = +A -
Page 124 and 125: [-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
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B Cards (continued) 201
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AIDJEX Bulletin #40 - Polar Science Center - University of Washington

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