Survey Campaign - Ross Sea
by Greg Cox, DML Surveys, Deputy Surveyor In Charge, Neville Ching, NIWA, Project Manager
Tangaroa from Possession Island, Ross Sea
During February and March 2001, Land Information New Zealand (LINZ) contracted a survey of Cape Hallett and the Possession Islands in the Western Ross Sea. The Antarctic environment brought some unique problems, but also brought the reward of vastly improving the existing nautical charts of the area. LINZ (New Zealands national hydrographic organisation) is responsible for all charting and hydrographic survey work.
Favreaux Pillar A sheer monolith that rises vertically from depths of over 70m.
The National Institute of Water and Atmospheric Research (NIWA) was awarded the Contract by Land Information NZ LINZ.to undertake a hydrographic survey of coastal areas within the western Ross Sea, Antarctica. As prime contractor, NIWA pooled together resources and personnel with a variety of skills, including MBES specialists from USA, surveyors and data processors from Terra Remote Surveys, Canada and DML Surveys, Auckland and geodetic surveyors from Thales, Australia.
Many of the previous ship borne surveys undertaken in the area have been completed by a variety of nations, mainly the US, UK and Russia. Most existing charts, which are compilations of various ships tracks dating back to the 1800s, are really just crude reconnaissance charts.
The aim of the survey was to prove a safe shipping route and anchorages from Cape Adare to Cape Hallett for the various commercial cruise ventures that are visiting the region in ever-increasing numbers, in particular the historic and wildlife sites dotted along the coast. Scientific research was also undertaken for fisheries, aquatic biodiversity, oceanographic and other marine science studies. Having only short operating seasons to work with, the surveys are expected to be completed over the next few years.
An extensive amount of research and planning took place during some ten months prior to departure. Climate and ice studies along with an environmental evaluation were completed. A risk assessment was also undertaken to ensure that all anticipated issues were foreseen and managed. This resulted in among other things; medicals for all personnel, doctor and hospital faculties facilities on board, food/fuel caches for Cape Adare and Hallett, warm survival cells on the vessels, personnel and group survival kits and an emergency response plan.
Some sites within the survey area share some very poignant moments in history. At Cape Adare, historic expedition huts still exist dating back to the 1898-1900 British Antarctic Expedition led by Carsten Borchgrevink.Borchgrevink and nine of his team spent a gruelling winter in these two huts. They were later repaired and re-used in 1911 by the British Northern Party led by Commander Victor Campbell.
Possession Islands, aptly named by James Clark Ross, who as leader of the 1839-43 British Antarctic Expedition landed on the island on 12 January 1841 and took possession in the name of Queen Victoria. Cape Hallett was the site of a joint NZ and US scientific station erected in 1957 and manned until 1973, but now used only a refuge hut.
The voyage by the 70m NIWA vessel RV TANGAROA was planned from 4 February 18 March with the actual survey period being confined to a pressure four-week period when ice concentrations were expected to be at the minimum. The survey area included the coastal route from Cape Adare (710 18 S, 1700 15 E) south past the Possession Islands and onto Cape Hallett (720 19S, 1700 16 S) along the eastern seaboard of Victoria Land.
The TANGAROA was fitted with the SIMRAD EM300 medium depth multibeam echo sounder (MBES) in November last year. Being a 1C ice rated ship, she was an ideal platform from which to commence New Zealands ambitious inaugural Antarctic survey programme.
From 29 January 3 February 2001 a mobilisation period was completed which involved the rigorous testing and calibrations of all survey systems and the MBES. MBES patch testing and target detection trials were undertaken in the Cook Strait. The ship departed Wellington on 4 February and after an uneventful 6-day passage south, a smooth transit was made through the northern ice barrier, a band of 3-5 tenths thick ice that spreads in an arc across the northern approach to Ross Sea.
The ship arrived off the Possession Islands on 11 February to commence survey operations. A tidal station consisting of two automatic gauges and tide pole was established on Possession Island, amongst near one of the regions largest Adelie Penguin colonies. A team of four hardy souls endured a two-day period ashore here, camped in tents in the snow amongst near hundreds of very noisy onlookers.
Most survey effort was concentrated on ship sounding the main coastal route, although a small amount of inshore sounding and coastlining was achieved in the Possession Islands group using the survey motorboat PELORUS a former RNZN survey boat specially modified by NIWA for Antarctic conditions. Weather and sea conditions were relatively mild throughout the period in Ross Sea. Average day temperatures hovered around -50 C and sea conditions were usually calm thanks largely to the dampening effect of the ice sheets further to seaward. Frequent snow showers and associated poor visibility had the largest impact on survey operations, making iceberg avoidance a delicate manoeuvring procedure at times.
The survey progressed until 22 February with a large amount of the survey area from Possession Islands to Cape Hallett completed, by the time the ship departed the area. Unfortunately, ice coverage in vicinity of Cape Adare meant that the ship could not work in this area.
Cape Hallett Seafloor
The Ross Sea survey was halted prematurely on the 22 February due to the rapid influx of large concentrations of ice making it difficult to run economical and safe sounding lines. The exit route through the northern ice barrier was also closing in by an increasing amount of pack-ice which had been held back by large icebergs some 40nm wide and 100nm long.
Over a two-day period, the ship made a cautious transit north through the increasing pack ice. The departure from Ross Sea was timed well. Without much wind and -1.80 seawater, pancake ice, resembling small frozen discs, began to form on the surface around the ship. These continue to increase in size until they knit firmly together. The speed at which this can occur is frightening.
On reaching the open ocean TANGAROA sailed for the backup survey area at the Balleny Islands. The Balleny Islands (67 S, 163 E) are a group of five main islands of volcanic origin extending over a distance of 105 miles. Situated some 300 miles to the NW of Cape Adare, and in the path of depressions that continually sweep around the Pole, this environment was not the most pleasant to work in. Winds in excess of 80 knots were recorded on several occasions.
TANGAROA arrived off the Balleny Islands on 24 February and commenced a 2-week survey period around these rugged and remote islands. First discovered in 1839 by John Balleny onboard the Eliza Scott, Ministry of Foreign Affairs and Trade (MFAT) records show that only 19 landings have been made, mainly by helicopter during the 1950s and 60s. Several attempts were made at establishing tidal and geodetic marks ashore, but the steep cliffs and constant swell action prevented this. A difficult and brief landing was made at Eliza Cone on the W coast of Buckle Island, this being a significant achievement, as there have never been any landings made on this part of the island group. A landing was also made on Sabrina Islet, which is home to a large Adelie and Chinstrap penguin rookery.
The Balleny Islands survey consisted of using the MBES swathe to maximum potential by sounding all coastal areas within 5 miles of the coast. This was achieved without too much difficulty, although as with the Ross Sea survey, the timeframe did not allow for full completion of all areas and will have to wait until the next phase of the survey. However, a significant amount of work has been achieved and will be used for the production of the first NZ chart of the islands.
The 24-hour daylight period meant that survey operations proceeded without fail throughout the entire voyage. The ship steamed a total of over 8000 miles and over 7500 km2 of MBES sounding was completed. The survey, although incomplete at this stage, was very successful, with many significant differences to existing charted information being discovered. Several shoals were identified and of note, the charted coastline in most areas (in particular Balleny Islands) was on average 2 miles out of true position. Noting the age of the previous surveys, this is not at all surprising.
It was a memorable experience to work in such a striking environment. Massive tabular icebergs and startling coastline features provided a magnificent backdrop to a very historic occasion.