09 Mar - Weather observing explained
Date: Sunday 09 March 2002
Position @ 1200 (UTC -3): 56° 07'S 052° 30'W
Next destination: Stanley, Falkland Islands
ETA: 10 March 2003
Distance to go: 330.7 NM
Total Distance Sailed this Season: 19636.9 NM
Current Weather: Windy, overcast, cloudy, dull, raining and very blustery
Wind: WNW x 38 kts
Barometric pressure: 1008.8 mb
Sea state: Rough sea and moderate swell
Air temperature: 6.0°C.
Sea temperature: 4.7°C.
Click here for ships track
The Weather Window
Above: This week's view of our world at 12.00 noon on a Sunday. Click the image to enlarge it.
Today's weather - is rough. Not as rough as Saturday which laid everybody low, but still rough. However, having crossed the Antarctic convergence, the temperature is rising and the ice that festooned the decks has now completely disappeared. A sprinkling of rain has also helped !
"Set Your Course For Alderan"
That was the rumour started this week onboard RRS Ernest Shackleton. Rumour control started the rumour and within a short space of time we had FID's (scientist passengers) on the bridge asking 'Where is Alderan ?'...
'It's the proposed new base a few hundred kilometers away from the US McMurdo Base' was the answer. ' Oooohhh'. In point of fact, the rumours were just that and had no substance whatsoever. They were started by Murdo the A/B during one of those watches where he obviously had nothing better to do than fabricate rumours ? Those who were led to believe that the Ernest Shackleton was veering away from her next destination to the 'Star Wars' Rebel Base, could have been excused because it was indeed a disturbance in the Force!
In actual fact, from Halley we arrived at South Georgia's King Edward Point (KEP) on the Tuesday as intended. The only deviation to our course was the previously mentioned ADGPS Science task around the East side of the South Sandwich Chain. (see diary 23 from last week). This week we have indeed been 'Base - hopping' with King Edward Point, followed by Bird Island followed by Signy. Not bad. That's 4 British Antarctic Survey bases in the space of only 2 weeks ! To conclude we only need to complete our journey to Rothera station next week in order to have collected the 'full boxed set' !
Weather - yet again - was a prime factor in the duration of our visitations on route. All of Tuesday was spent alongside the wharf at KEP, thus allowing the odd 'walkabout' in green tussock grass for those Halley winter personnel who had not actually had mud on their boots for many a month. There would not have been enough daylight left had we departed KEP in the afternoon and taken the 6 or 7 hours to steam around to Bird Island in the North. So Capt Gatti agreed to stay alongside until evening meal and then take a 'slow steam' overnight to arrive at Bird Island at first light the following morning. The weather co-operated nicely and we had a day of sunshine for walks around the Grytviken area and calm conditions for the cargo work around at Jordan Cove, Bird Island early on Wednesday morning. All the work was completed in just five runs of the FRC (Fast Rescue Craft) between 0630-0930 hours (ship's time). Aside : I find it amusing that as we leave the ship at 0630 in the morning, it is already 0930 on the base who keep GMT throughout !
Weather again prompted us to move on. Looking at the Antarctic Weather Charts that we receive daily, we could see that a depression was developing that could hamper our operations in Signy. The workload there demanded the use of our cargo tender Tula and so good weather would be required.
Here we can clearly see that the depression over the peninsula moves towards Signy and threatens 30-40knt winds.
As it transpired, our timely departure meant that we covered the distance to Signy in two days under fair conditions and had the whole day on Friday to work the cargo in Borge Bay, Signy. Only with the very last run of the day around 1900 hours local time, did the sky darken, the snow start to fall thick and fast, and the winds pick up to gusts of 30 knots. All tasks at Signy were accomplished in the one short day which meant that by 2100 hours, the Tula was recovered to deck, secured for sea and the ship could make an early start on it's journey back to the Falklands.
As a passenger on the last Tula of the day, it was eerie to see the tender pick it's way past icebergs in Borge Bay that were as large as the Tula and to find our way through the fast-darkening storm to the welcome lights of the Ernest Shackleton out in the bay. It was a late dinner onboard that night for the workers in the cargo tender, but it was a job well done.
WAVEY DAVEY'S WITTY SPOT !
Wavey Davey dropped his watch from the 40th Floor of a skyscraper
when he was last in the United States.
Having watched his priceless Timex disappear over the rails, he made directly for the stairs and started vaulting
down two at a time. Around about the 2nd floor, and out of breath, Davey bumped into a friend and said,
'can't stop, I'm trying to catch my watch at the bottom'.
'You dropped it from the top floor, and now you expect to catch it at the bottom ??' inquired his friend ?
'It's okay', said Davey, 'the watch is running Ten Minutes late !!! '...
Back to normal standards there, Davey ! The Captain was wondering - do you just like to see time fly ???
The Onboard Social Life
Has been quiet. There are reports of some rather late nights (or should I say 'early mornings') in the Red Room, but these 'get togethers' were purely impromptu gatherings. There has been one Cheese and Wine evening onboard this week, and Richie, the Chef has been continuing to take us all on 'circuits' to fight the effects of his good grub. Post Bird Island, Nathan 'Small Productions' Keen, organized a 70/80's night in the red room however, it was very short notice for any real investment in costume-making to be attempted. Nice one Nathan ! However, as seen below, the 'Razzles' nightclub had an assembly of punters that saw midnight through with fun and frolicks and dancing.
Above: Nathan 'Small Productions' Keen with Mandy Willis and Paul Sharp. Click on image to make those wide lapels even wider!!!
One of our readers noticed our 'weather station' in a photograph featured in the webpages earlier last month. Therefore, Alan Newman the Navigator takes the opportunity to elucidate and tell us of the mystical and cosmic world of Weather Reporting from the ship that is at sea...
ERNEST SHACKLETON – VOLUNTARY WEATHER OBSERVING SHIP!
Under the Met Offices programme, the ES’s Deck Officers compile weather reports every 6 hours, midnight, 6am, 12pm, 6pm GMT. These are standard observation times for weather reports and forecasts. Most nations and services co-operate with one another with forecasting and databases, so it helps if everyone’s singing from the same hymn sheet, so to speak! For example, if a Chilean forecaster needed information about an Antarctic or South Atlantic weather system it is helpful to know that observations were taken simultaneously.
Apart from the forecasting a database of all observations is kept. This is helpful when examining an area or for us on board ship. ‘Routing Charts’ are made which show average wind and current direction and strength for each month of the year. Since the ES is in the Antarctic, ice observations can also be made. This is an area where much more information is needed and ice patterns may be able to give a clearer indication of the effects of global warming.
The report is compiled using a laptop/windows programme. At the top of the screen each icon will display a standard form where the data is typed in. A normal report would have in it:
- Ships position, Heading (direction ship is pointing), Track
(direction ship is actually following)
- Estimated true wind speed and direction
- Wind waves and swell waves ( the latter are the larger ‘rollers’ you would see in an open area – created by wind blowing in the same direction for a couple of days)
- Air pressure (in Bar) and the ‘tendency’ of the barograph. This is the shape of the trace of the barograph – it shows whether or not a pressure system is almost past the ship for example.
- Air Temperatures – Dry: this is simply the reading of a thermometer hung to windward. Wet: as dry but this one has a piece of material called ‘muslin’ over the bulb which holds fresh water in it making the bulb damp. Obviously the more humid the atmosphere the closer the readings of wet and dry. The amount of moisture in the atmosphere is a factor affecting the creation of cyclones. (also known as Hurricanes) and indicates if you are approaching a fogbank.
- Sea temperature – taken from a seawater cooling intake (in the ships bottom plates) for the engines. You can also use a special bucket (made so that it quickly adjusts to the same temp as the sea and stays the same whilst you wheeze your way pulling it all the way back up to bridge level! Great fun in strong winds, even on the lee (sheltered) side of the ship!)
- Present weather – describes the kind of precipitation (rain,
snow, hail etc) you are seeing and how much etc.
- Past weather – for the past 6 hours
- Cloud types and quantity. To make it easier, it's described in octas or ‘eights’. If the sky was half covered in cloud you’d have 4 octas etc. Also the height of the base of the lowest couds – the lower the cloud is the more likely it is to give some kind of precipitation.
- Ice accretion – this describes the build up of ice on the ships hull. Quite rare except in extreme circumstances – we did have some in the storm Steve describes in the 23rd February Wepage No.22 - the first time I’ve seen any.
- Ice – numbers of icebergs and growlers (small, hard to see but still quite large pieces of ice. Area of sea covered by sea ice (frozen seawater). Also what difficulty the ship is having passing through it.
All the data is coded and sent off by Sat-C to Bracknell in the UK, each report takes about 15 minutes.
Above: Precision Aneroid Barometer Mk2 : The sensing element is a stack of 3 aneroid capsules inside the airtight silver case. To prevent the reading being affected by the rise and fall of the ship, there is only one hole in the casing which serves to dampen the reading. Vent can be seen on the front left. Click the image to enlarge it.
Above: Vaisala Digital Barometer: Our reference baro for checking the research station barometers. Its calibrated against a pressure balance traceable to the National Institute of Standards and Technology. Click the image to enlarge it.
Above: Marine Barograph Met 1191: Same principle as the Aneroid, but it records its readings by the movement of the pen over the chart. Chart changed and clock wound weekly. Click the image to enlarge it.
Above: Digitron 8754 Temperature indicator: Electrical Resistance thermometers are enclosed in a Marine Screen above deck. It is known how the resistance of a platinum wire varies with temperature. A platinum wire is enclosed in a highly conductive ceramic former, which is enclosed in a stainless steel sheath for protection. Readings are always taken from the windward side of the ship except the sea temperature – The sea temp probe shouldn’t be affected by the wind if all is going well! Muslin and wicks for the wet bulbs in the foreground, and sea and air thermometers. Sea thermometer has the smaller bulb.
Marine Screen : This is a wooden box with louvered vents to allow free circulation of air over the thermometers. Painted white and of wooden construction to protect it and the thermometer readings from sun radiation. Note there is also a pair of standard thermometers to check the readings of the Resistance thermometers.
Author : Alan 'Navs' Newman
We sailed from Signy in a gathering storm with snow blizzards and freshening winds. Our destination was Stanley, Falkland Islands and according to the charts, the wind would be backing around to blow us there all the way. Over the weekend, the expected change failed to materialize and so we find ourselves battling against head winds and seas all the way back. This impedes the progress of the ship through water and has had a resulting effect on our anticipated time of arrival.
Forthcoming events: Arrive at FIPASS, Stanley, Falkland Islands where we will discharge all waste and cargo collected, take on bunkers and offload all the ex-Halley FID's. There is an anticipated change-of-command in Stanley as Captain Antonio hands over to Captain Stuart Lawrence due to arrive on March 14th, and with just 1 extra passenger joining us in the Falklands, it is intended that we will leave for Rothera on the Peninsula around March 15th.
Contributors this week: Many thanks to Alan 'Navs' Newman for the Weather-spot and Wavey Davey as always.
Diary 25 will be written on 16th March 2003 for publication on the website by 17th March 2003.
'May the Force be with You, Always'