U.S, Ross SEA AND MCMURDO SOUND NAVY-NOAA JOINT ICE CENTER SEASONAL OUTLOOK APPENDIX X-B X-B-1

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1 APPENDIX X-B U.S, NAVY-NOAA JOINT ICE CENTER SEASONAL OUTLOOK Ross SEA AND MCMURDO SOUND PREPARED BY COMMANDING OFFICER NAVAL POLAR OCEANOGRAPHY CENTER NAVY DEPARTMENT 4301 SUITLAND RD WASHINGTON, DC PREPARED FOR COMMANDER NAVAL OCEANOGRAPHY COMMAND NSTL STATION, BAY ST. LOUIS, MS X-B-1

2 This appendix reproduces pp 1-8 from the original publication X-B-2

3 I. Introduction This outlook forecasts the positions of the northern and southern ice pack edges in the Western Ross Sea and the rate of recession of the fast ice in McMurdo Sound along a typical shipping resupply route to McMurdo Station. The initial analysis of innerpack and fast ice conditions are interpreted from NOAA-7 and NIMBUS-7 satellite imagery. The positions of the ice pack and fast ice edges are predicted from the initial data through an analogue approach using historical data provided in NAVOCEANO Special Publication 265 (Perchal, 1975) and locally archived Ross Sea satellite imagery and satellite derived ice analyses. II. Initial Ice Conditions Ross Sea (Fijure 1.) The 28 October 1982 ice edge position the analyzed 1980 and 1981 location for similar extends north of time frames. With the exception of inner pack weaknesses in the vicinity of the Balleny Islands (67S, 163E), Cape Adare (72S, 170E), Drygalski Ice Tounge (76S, 167E) and a narrow shore lead adjacent the Ross Ice Shelf the ice pack is very close (9-10 tenths). The sea ice currently year ice which is observed consists primarily of first thinner and weaker than old ice. The position of the ice edge north of the Ross Sea is 15 nautical miles north of the historical average position (Perchal, 1975). X-B-3

4 Figure I. Initial ice conditions in the Ross Sea, 28 October 1982 X-B-4

5 McMurdo Sound (Figure 2.) From NOAA-7 satellite imagery of 28 October 1982, the fast ice has been analyzed as extending 32 nautical miles from Hut Point. As depicted the fast ice extent is normal. In McMurdo Sound north of the fast ice, compact ice conditions consist of 6 tenths of old ice and 4 tenths of first year medium and thick ice. X-B-5

6 16 16 Arq Er ROSS SEA BEAUFORT ISLAND R 0ii CAPE SPIK5 do d XAkMPLES S -. h....l de,.*.s ;. d. * a vp"* 1 empise u.s... - I.. *.s...uy vl*s elip *.t.)i,,..6. C - -.fln' hi tosi ta',t - C.itflm.1 t 4]. )d ckt l)..d tt u'kjai lcl t 'AW"c 1ta. u.u..ita tytmfl 0 J. :- ktt ISt,. - 2ut t.c.a4 11J k -c * c-rn-'.. - -r'- wj *%-'9C* * * 'tnra 30 flti..i - $,,,t,,.u f,,n gm) * t., yu... dui I'D in *fl 4i2'3* Figure 2. Initial ice conditions in McMurdo Sound, 28 October 1982 and fast ice extent along a typical shipping route. X-B-6

7 III. Outlook Ross Sea The compactness of the overall sea ice conditions in the Ross Sea and the more northerly extent of the northern ice edge indicate less favorable Ross Sea ice conditions for DEEP FREEZE 83. The northern ice edge is expected to recede southward at a rate week through the first of approximately 15 nautical miles per of December and then recede more rapidly. An ice free channel through the ice pack is expected near the twenty-first of January as the southern and northern ice edge positions converge (Figures 3. and 4.). McMurdo Sound Due to the normal extent of fast ice in McMurdo Sound (Figure 2.), it is expected that the total breakup to Hut Point will not occur without icebreaker assistance prior to 15 February. The fast ice (Table 1) will recede at normal rates through out the melt season. By mid-january the fast ice extent is expected to be 12 nautical miles decreasing to 5 nautical miles by early February. X-B-7

8 0 0 DO X Figure 3. Expected recession pattern in the Ross seo X-B-8

9 I LATITUDE os UU 1 Nov 15 Nov 1 Dec 15 Dec 1 Jan 15 Jan DATE Figure 4. Expected positions of the northern and southern ice pack edges along 175E. X-B-9

10 Table 1. Estimated schedule of fast ice recession in McMurdo Sound. Date Extent of fast ice from Hut Point** (nautical miles) 01 Nov Nov Dec Dec Jan Jan Feb Feb 83 0 **The extent of fast ice is determined along a line from the souithernmost latitude of the fast ice edge observed between 'E and 'E thence due south to a true bearing of 1420 extending to Hut Point. X-8-10