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

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.5 .4 .3 0 A R 2 R 0 W J - 0 B U - .I 0 Y I4 B - .2 +- 3 + 8 - .4 -.5 82 102 122 142 162 182 2 02 222 DAY, 1977 Fig. 5. Twenty-day averages of pressure differences between NWS ("Barrowtt) data and the two buoys (NWS - buoy). The figure shows that the barometers were free from drift for the four-month test period. Sensor Temperature Coefficients Knowing how sensitive a barometric pressure sensor is to temperature is critical to achieving good pressure measurements from ADRAMS. The temperature dependence of sensors used in this test (Paroscientific Digiquartz Model 215A) is a complex function of temperature effects on several of the sensor components, principally the bellows and quartz beam. Coefficients are generally within a factor of 3 of 0.04 mb per degree Celsius, as measured at the factory over a wide range of temperatures and pressures. Barometer calibration coefficients were calculated at (and temperature corrections therefore normalized about) -26OC, or -15'F, to minimize pressure-dependent 68
temperature effects in the primary operating temperature range (Fig. 6). single temperature correction curve taken at the standard pressure will thus have pressure-dependent errors of less than 0.1 mb throughout the temperature and pressure ranges of interest. There were no significant temperature-related errors when buoy pressures were corrected according to the laboratory calibrations and compared with NWS pressures over the test period (Fig. 7). This suggests not only that the laboratory calibrations were appropriate to the field application, but also that the temperature sensitivity of the pressure sensors was stable with time The latter point has been verified by repeating laboratory calibrations after field use. An important part of compensation for temperature effects is the accuracy and stability of the internal temperature sensors. Field checks of laboratory calibrations of the thermistors have agreed within l0C, which is sufficient. The lack of temperature-related errors throughout the test period further suggests that the temperature sensors are stable with time. Since temperature dependence is a function of full-scale sensor range, it is possible to reduce temperature sensitivity per unit pressure at the expense of decreased pressure accuracy by selecting a sensor with increased full-scale range. For example, a sensor with two bars full-scale rating would be expected to have half the temperature sensitivity per n%ZZibar of a one-bar sensor, but twice the aging and sensitivity to clock errors. 1 A C1 ock Correction To measure barometric pressure using a sensor with a frequency output requires an accurate time base from which to reference the counting of sensor output. Time base errors of one part in lo5 contribute 0.1 mb pressure errors for the sensors used here. Nonstandard initial values, long-term aging, and seasonal and diurnal temperature effects can easily combine to produce clockrelated pressure errors of the order of 1 mb. It is possible to observe the behavior of the clock through the transmissions to the satellite and correct the pressure measurements accordingly (see Appendix A). 69
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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
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 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
Page 68 and 69: :
Page 70 and 71: I 25 23 t h--:!li[ NCI PiHCEl4l 22
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
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
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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
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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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