Form Approved
REPORT DOCUMENTATION PAGE
OMB No. 0704-0188
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1. AGENCY USE ONLY (Leave blank)
2. REPORT DATE
3. REPORT TYPE AND DATES COVERED
December 1998
4. TITLE AND SUBTITLE
5. FUNDING NUMBERS
Accounting for Clouds in Sea Ice Models
Contract nos.:
N0001496MP30005 (ONR)
OPP-90-24544 & OPP-93-12642
6. AUTHORS
Aleksandr P. Makshtas, Edgar L Andreas, Pavel N. Svyashchennikov, and
DA Project 4A161102AT24
Valery F. Timachev
Russian Fund Projects:
96-07-89159 & 97-05-65926
7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES)
8. PERFORMING ORGANIZATION
REPORT NUMBER
U.S. Army Cold Regions Research and Engineering Laboratory
72 Lyme Road
CRREL Report 98-9
Hanover, New Hampshire 03755-1290
9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES)
10. SPONSORING/MONITORING
AGENCY REPORT NUMBER
U.S. Office of Naval Research, Arlington, Virginia 22217-5660
U.S. National Science Foundation, Arlington, Virginia 22230
Office of the Chief of Engineers, Washington, D.C. 20314-1000
Russian Fund for Fundamental Investigations, Moscow
11. SUPPLEMENTARY NOTES
For conversion of SI units to non-SI units of measurement, consult ASTM Standard E380-93, Standard Practice for Use of the
International System of Units, published by the American Society for Testing and Materials, 100 Barr Harbor Drive., West
Conshohocken, Pennsylvania 19428-2959.
12a. DISTRIBUTION/AVAILABILITY STATEMENT
12b. DISTRIBUTION CODE
Approved for public release; distribution is unlimited.
Available from NTIS, Springfield, Virginia 22161
13. ABSTRACT (Maximum 200 words)
Over sea ice in winter, the clouds, the surface-layer air temperature, and the longwave radiation are closely
coupled. This report uses archived data from the Russian North Pole (NP) drifting stations and recent data from
Ice Station Weddell (ISW) to investigate this coupling. Both Arctic and Antarctic distributions of total cloud amount
are U-shaped: that is, observed cloud amounts are typically either 02 tenths or 810 tenths in the polar regions.
These data obey beta distributions; roughly 70 station-years of observations from the NP stations yielded fitting
parameters for each winter month. Although surface-layer air temperature and total cloud amount are corre-
lated, it is not straightforward to predict one from the other, because temperature is normally distributed while
cloud amount has a U-shaped distribution. Nevertheless, the report presents a statistical algorithm that can pre-
dict total cloud amount in winter from surface-layer temperature alone and, as required, produces a distribu-
tion of cloud amounts that is U-shaped. Because sea ice models usually need cloud data to estimate incoming
longwave radiation, this algorithm may be useful for estimating cloud amounts and, thus, for computing the
surface heat budget where no visual cloud observations are available but temperature is measured--from the
Arctic buoy network or from automatic weather stations, for example. The incoming longwave radiation in sea
ice models is generally highly parameterized. The report evaluates five common parameterizations using data
from NP-25 and ISW. The formula for estimating incoming longwave radiation that Knig-Langlo and Augstein
14. SUBJECT TERMS
15. NUMBER OF PAGES
39
Cloud cover
Modeling
Radiation balance
Surface heat budget
16. PRICE CODE
Longwave radiation
Polar regions
Sea ice
17. SECURITY CLASSIFICATION
18. SECURITY CLASSIFICATION
19. SECURITY CLASSIFICATION
20. LIMITATION OF ABSTRACT
OF REPORT
OF THIS PAGE
OF ABSTRACT
UNCLASSIFIED
UNCLASSIFIED
UNCLASSIFIED
UL
Standard Form 298 (Rev. 2-89)
NSN 7540-01-280-5500
Prescribed by ANSI Std. Z39-18
298-102
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