17 March, 2000

The Great "Ice Thickness" Challenge!

WANTED: Students to parcticipate in our LAKE "ICE THICKNESS" COMPETITION! Well, everyone, this will be my final trip to Alaska for the

winter season. Once again, Dr. Jeffries and I will be going out

to Poker Flat (see earlier journal entries) to collect snow and

ice data.

How has the growth of the ice progressed? How thick will it be?

We are inviting students to send in their predictions, based

on data that was already collected from November through February.

WHAT TO DO: Study the following data tables for "MST" Lake. Notice that the right-hand column is labeled "thickness." Your mission, should you choose to accept it, is to use these numbers to predict what the mean thickness of MST Lake will be this week. There

are several possible ways to do this, but one simple approach

might be to graph either the average or the median thickness

as it changed over time, and to use your graph to help you to project what the thickness is now.

THERE WILL BE PRIZES FOR THOSE WHOSE PREDICTIONS ARE CLOSEST

TO THE ACTUAL VALUES THAT WE MEASURE THIS WEEK!!!

Explanation of the data table:

"distance" refers to the point along the transect, in meters,

from which the data was taken

"snow depth" is in centimeters

"S/I temp" is the temperature, in degrees Celsius, at the interface between the snow & ice

"density" (of the snow) is measured in grams per cubic centimeter "thickness" (of the ice) is in centimeters

Sample Data: MST LAKE (November 1, 1999-January 10, 2000)

11/01/99	Mean Surface Temperature = -13.33 C

distance snow depth	S/I  t 	density		thickness

0	17.50		-4.30	88.62		21.50

10	17.50		-3.00	103.87		22.50

20	17.50		-2.50	90.72		22.00

30	18.00		-2.80	88.97		21.50

40	18.50		-2.20	90.30		20.00

50	19.00		-2.60	88.16		19.00

60	18.50		-2.50	83.33		21.00

70	18.50		-2.90	89.05		21.00

80	21.50		-0.20	  --		16.50

11/15/99	Mean Surface Temperature =  -15.06 C

dist	snow depth	S/I  t	density		thickness

0	13.50		-4.00	143.85		27.00

10	9.00		-6.20	187.14		28.50

20	8.50		-5.60	177.04		28.50

30	9.00		-5.60	151.86		27.50

40	8.50		-5.40	164.59		28.50

50	7.00		-5.70	149.89		28.00

12/07/99	Mean Surface Temperature =  -30.95 C

dist	snow depth	S/I t	density		thickness

0	16.50		-6.60	177.10		37.50

10	15.00		-6.90	218.13		41.00

20	13.50		-6.50	250.55		42.00

30	13.00		-7.40	175.58		42.50

40	14.50		-6.50	154.88		39.00

50	15.00		-7.00	209.85		42.50

60	13.00		-8.20	258.06		45.00

70	10.50		-11.20	194.60		44.00

80	10.50		-11.50	122.28		48.00

12/15/99	Mean Surface Temperature = -25.70 C

dist 	snow depth	S/I  t	density		thickness

0	14.00		-8.00	171.91		45.00

10	14.00		-6.80	154.82		43.50

20	12.00		-8.60	155.70		44.00

30	11.50		-11.60	161.27		45.50

40	12.00		-8.40	255.41		47.50

50	11.00		-9.20	242.65		47.00

60	14.00		-8.80	184.41		43.50

70	14.00		-8.10	208.07		49.00

80	10.00		-9.80	159.69		51.50

01/04/00	Mean Surface Temperature = -40.70 C

dist	snow depth	S/I  t	density		thickness

0	26.00		-5.90	226.20		56.00

10	27.00		-5.30	289.60		53.50

20	25.00		-6.30	224.90		59.00

30	27.50		-5.20	265.40		59.00

40	21.00		-8.90	297.80		59.50

50	28.00		-5.80	160.70		54.50

60	26.00		-5.60	190.30		59.00

70	26.00		-6.70	151.70		59.50

80	24.00		-6.70	162.20		61.50

01/10/00	Mean Surface Temperature = -43.40 C

dist	snow depth	S/I  t	density		thickness

0	28.00		-6.60	166.98		55.00

10	7.50		-7.40	193.90		66.00

20	18.00		-2.70	185.61		65.50

30	20.00		-0.20	237.69		65.65

40	24.50		-0.30	166.80		63.00

50	20.00		-8.30	238.15		60.00

60	26.50		-6.80	227.68		61.50

70	24.00		-6.80	257.52		59.50

80	24.50		-7.60	172.24		61.50

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