SANAE 50 newsletter 2011 06
Upcoming SlideShare
Loading in...5
×
 

SANAE 50 newsletter 2011 06

on

  • 630 views

 

Statistics

Views

Total Views
630
Slideshare-icon Views on SlideShare
630
Embed Views
0

Actions

Likes
0
Downloads
0
Comments
0

0 Embeds 0

No embeds

Accessibility

Upload Details

Uploaded via as Adobe PDF

Usage Rights

© All Rights Reserved

Report content

Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

Cancel
  • Full Name Full Name Comment goes here.
    Are you sure you want to
    Your message goes here
    Processing…
Post Comment
Edit your comment

    SANAE 50 newsletter 2011 06 SANAE 50 newsletter 2011 06 Document Transcript

    • Halfway Home & Happy Mid‐Winter!JUNE 2011 Mid‐Winter Weather Base Power Source And Heating Youve Got to Hand it to Us Page 1 June 2011
    • Half‐way home! And Happy Mid‐Winter!“In research stations throughout Antarctica, Midwinter is widely celebrated as a way to mark thefact that the people who winter-over just went through half their turn of duty. [T]he celebrations… are typically marked by parties, team games, redecoration of the premises and days [sic!] offwork”. (Guillaume Dargaud, 2005 team member on Concordia Base, paraphrased in Wikipedia).Preparations for the MidWinter Festival begin many days ahead of the event. It is a tradition thatGreetings Cards and Invitations are issued amongst the 40-odd Over-Winter Bases all over theContinent. We must admit that we would be severely startled if the Germans, say, did actuallypitch up on the day – but still, much effort is put into concocting amusing and cordial welcomes.We particularly enjoyed the small glimpses these cards afforded us of other Bases.21 June 2011, MidWinters Day, and the team slugs out of bed at a gentle hour (all except Paul,of course. The South African Weather Service doesnt believe in any of this Holiday nonsenseand there he was at 07h45, peering earnestly at the pitch-black sky and intuiting he could seesome cirrus cloud or whatever out there). The plan for the day? - a leisurely start, easing intothe Pull-Up Competition, Dozer-Runs followed by dips into the sauna for those who could handleit, then cooking a mighty meal, and lastly – the highlight – drinking the mighty meal. And eatingthe odd tidbit, as well. Although the term “Winter Solstice suggests a day of freezing darkness with blustering snow and icy winds, this was not the case. Our weather was good (see p.6), and although there was no direct sunlight, there were a few hours of bright twilight; enough for us to get outside prior to any scheduled activity. A little photo- shoot on the roof, just to show how dark it isnt. The perennial Smelly: work does go on, after all... Page 2 June 2011
    • The Pull-Up competition was the first major event of theday. Why a pull-up competition goodness only knows.This is something Renier and Paul cooked up betweenthem. The entire team assembled in the gym, bets andcounter-bets offered in interested undertones by thenon-contenders as each aspirant stripped his jacket offand showed his form. Chances were evaluated on theweight-strength ratio of each individual. Serious moneywas on Johan – slender but strong. Serious money got itwrong. Not that he didnt perform credibly, but Scelocame in from behind and showed us what real strengthis. 17 pull-ups straight, he acheived. Renier did well with16, Paul showed what climbers are capable of with 15,and Johan managed 14½. Those of us who were notmourning having betted away our entire nights wine andbeer then went for the dozer run. This involves – forSANAE 50 at least – scampering down BC link stairs,across the sastrugis, around the dozers, and backagain. Clad in costume, with footwear optional. Thenwarming up in the sauna, and repeating at will.Mid-Winters day is special not only because of in-base team activities, but also because allsorts of people phone us to wish us well – anybody from Radio Stations to previous team members. Paul was unanimously elected as spokesman when Heart FM phoned us, but the rest of the team took it in turns to answer the phone and chat to the various well- wishers. Our most valued call came from Marten du Preez. Marten was a member of SANAE 1 in 1960; the very first South African expedition to Antarctica. Marten was the radio technician. He returned to Antarctica in 1962 as Team Leader for SANAE 3, and was a honoured VIP in 1997, when he was invited to the opening of the SANAE IV Base. Page 3 June 2011
    • He is a keen radio ham with the call sign ZS6ZY, and as such is a friend of Gerard, our electrical engineer, himself a keen HF man. Although Mid-Winter is usually thought of as a Christmas celebration, we had neither turkey nor ham readily available on Base, so the food was an eclectic mixture of team specialities: Tikis garlic bread, Alans spiced rice, Pauls stir-fried vegetables, Beat and Kevins succulent roast lamb, and a very special hand-crafted (instant) cheesecake imported by Renier for the occasion – just a few of the dishes presented.So we have passed the half-way point. The Sun is returning, the ship is returning, we will soonbe returning Home again. But theres still seven months to go, and we still relish every day ofour life in the icy embrace of Antarctica. Author: Abi Page 4 June 2011
    • Page 5June 2011
    • Page 6June 2011
    • Mid Winter Weather at SANAE ‐ by Paul “Weather outlook for today. Maximum temperature expected 1 3 degrees below zero dropping to 20 below through the day. Winds: gale force, 50 kph expected. Overcast with blowing snow”.... this was my prediction for the Mid Winter solstice.The 21 st of June was the Winter solstice and marks the time on the calendar that we startreturning towards direct sunshine and the summer months. But although the Sun should start topeak along the Northern horizon in late July, the reality is that the Winter is not over and June isnot necessarily the coldest month in the Antarctica. So what significant weather phenomena dooccur in June? How cold is cold? The 21 st was not a particularly eventful day in terms of tem- perature extremes. The average for the day was -1 7.2 0C, fluctuating between a maximum of -1 3.8 0C and a minimum of -20.6 0C. However, the mercury had fallen to –31 .7 0C on the 8th of the month, marking the coldest temperature for June. The average temperature for the whole month was -20.9 0C. In the mid latitudes of South Africathe lowest temperatures of the year tend to occur after the solstice. A well defined Winterminimum is usually apparent toward August-September, towards the end of Winter. This is not thecase in the Antarctic, where heat loss occurs earlyand rapidly, and Winter temperatures tend to beeuqal throughout the period. Here there is also aclear asymmetry in the time span of Winter andSummer. The term “Coreless Winter” depicts astable non-fluctuating winter temperature that variesonly a few degrees between the onset and closure ofthe winter period, during which polar temperatures donot continue to fall during the long winter period. Thelatter is very short - between December and Johan does a weather station checkFebruary at SANAE. This short duration has earnedthe name “ Pointed Summer” as a descriptive title. Page 7June 2011
    • But there can be a large difference between actual (dry bulb) temperature and apparenttemperature. Our average dry bulb temperature in June was -20.90C. Actual or dry bulbtemperature is the temperature of the air without the effects of relative humidity or wind speed.However, these parameters are very important when it comes to measuring how quickly we loseheat. In the Antarctic with its continuous winds, the cooling effect of the wind (“wind chill”) issignificant, and the very low humidity also contributes to a rapid loss of heat by aidingevaporation. “Apparent temperature” is the term used for that measurement which factors in therelative humidity (called “heat index” in tropical countries) and the wind chill. Wind chill is theextra cooling effect felt on the skin due to wind, and is calculated using wind speed and dry bulbtemperature. There are intricate formulae used to derive the apparent temperature (e.g. Windchill temp. = 35.7 + 0.6215T - 35.75V0.16 + 0.4275TV0.16). At SANAE, we just take what thecomputer says on trust! Apparent temperature is highly significant to us, as this, and not dry bulbtemperature, determines the likelihood of cold injury and frostbite. So on Mid-Winters Day, thewind was on average 31 kph and the dry bulb temperature around -17.20C. In thesecircumstance the apparent temperature was -300C – very nearly double the dry bulb.How hard did it blow?Wind is our most severe environmental hazard at SANAE, in that even relatively low windspeeds increase the risk of cold injury. Our winds were particularly strong in June. While theaverage wind for the month was around 40 kph, which is the norm for SANAE, we reached ourhighest wind speed yet on the 24th, three days after Mid Winter. This blizzard produced windspeeds up to 61 ms-1 - thatis, 21 8 kph. Such speedsare very much theexception; in the monthspreceding this our maximumgusts typically peaked at1 30 kph. So 21 8 kph isclearly an outlier. TheMeteorological Officer andseveral team membersclosely scrutinised the datafrom the South AfricanWeather Services station toensure that this extra-ordinary reading was not just a computer glitch and concluded it was a reliable reflection of events. Our conclusions were aided by another anomaly occurring simultaneously - the breaking of the anemometer propeller. Page 8 June 2011
    • This piece of equipment is rated for extremes of wind and temperature, and it took somethingreally out of the norm to cause this failure. Clearly the wind was too high for our anemometerand it sheared the 5 mm stainless steel prop shaft. As shown on the graph this occurred, notduring the peak at 04h45, but a few hours later at 08h00 the same morning.Inversion windsOf course, Antarctica is notorious for its winds. As they say, “when the wind stops blowing, thepenguins fall over”. The question is why is the wind such a feature here. One reason istopography, causing “inversion winds” – winds that blow in line with the maximum slope of theterrain in a fixed direction. This is the main cause of wind at SANAE. The cold heavy air from thepolar-plateau shifts down slope from the South Pole in a northerly direction while simultaneously deflecting leftwards due to the Coriolis force - a rotationally induced force that deflects a moving object leftwards in the southern hemisphere. Because there is s a steady supply of cold air draining off the polar plateau towards the edges of the continent these winds tend to blow unabated.Looking at the wind rose we can see thisreflected in the dominant 1 30 0 direction: thewind blows mostly from the South-East to theNorth-West.Katabatic WindsWe have also a second and more drasticwind event, called “katabatic winds” (katabaise in Greek is “going down”). Katabatic winds tendto exhibit highly variable wind speeds, gusts and weaker winds alternating randomly, withinterspersed periods of complete calm. These occurat the edge escarpments, on very steep drop-offs.Because of the steeper slopes, the cold air drainsrapidly and the resultant katabatic wind is morespasmodic and violent than its inversion counterpart.Sudden wind speed jumps from calm to 40 knots canbe expected. The wind that broke our anemometer(our highest wind speed yet) is a good example ofkatabatic wind drainage coming off the bulk of theAhlmann mountain range to the South, which isabout 1 000 m higher than Vesleskarvet. Page 9 June 2011
    • Snow, drifting snow and blowing snow and what’s the difference anyway!Wind is a menace not only in its ability to freeze us, but also in its action on loosesnow. We had clear skies and no surface snow on Mid Winters Day, despite the stiff breeze of20 knots (40 kph), so we were lucky. Frequently wind is accompanied by blowing snow as theloose surface snow lifts and becomes entrained in the air flow. The endless days of wind-bornesnow curtail our outdoor activities, confining us to base and seriously interfering with theongoing outdoor work of cargo, transport, melting snow to make water and various other tasks.The amount of lifted snow varies with wind speed, increasing exponentially, but other factorsalso play a role, such as surface roughness, which increases turbulence, or surface freezing,which restricts lifting. When winds speed attains a moderate 5 ms-1 it will start to lift snowmarginally. If the lift is less than 2 m vertical height the term “drifting snow” is used. Once windsreach 20 ms-1 the situation is much more severe - even life threatening for anybody trappedoutside. Visibility reduces to less than a few metres at best and the term “blowing snow” is usedto describe snow lifted in excess of 2 m vertical height. Often it blows right over the Base. Insuch situations, the sky is obscured and it is not possible to see if there are clouds so itbecomes difficult to differentiate between blowing snow and actual falling snow. SANAE weather office recorded falling snow on nine days and drifting/blowing snow on 1 0 days this month. The question of how much snow falls at SANAE is a vexing one. We have no means of measuring precipitation here. The question is by no mean trivial as it addresses the whole issue of long term ice stability and accretion and is closely related to global climate change issues. Certainly we have seen through the Winter how the snow has built up around Piggen and other mountain slopes. Yet we cannot know to what extent this was from blowing snow or falling precipitation. It is said that the Antarctic plateau is a vast desert yet it is inarguable that accumulation balances loss since the ice sheet is not noticeably changing in the short term. We will await Summer to see if the accumulations decrease in height again. We were fortunate on Mid-Winters Day: the weather was really mild – by Antarctic standards. Dozer runs were an option which almost all of us took. At the same rat an! " ice Day fo time, we did not have to feel cheated by our tame Mid- R enier: "N Winter. Although we could not expect the South African Weather Service to share our sense of drama, thebreaking of the anemometer prop attested to our rugged Ice Pioneer experience of extremeconditions. Of course, fixing the wretched thing was another story... . Page 1 0June 2011
    • SANAE IV Base Power Source And Heating Systems ‐ by AlanSANAE IV Base is located in Antarctica with no Eskom around or the electricity hikes affectingus now; we rely solely on Diesel Engine Generators (Gensets) with electronic systems to keepall the equipment running and keep us cosy during our over-wintering experience. Diesel Generators (Gensets) There are three ADE Diesel Engines. Each of these is capable of pushing out an average of 1 50 kW at 1 500 r/min, with a maximum of 260 kW at 21 00 r/min. As a comparison: the average motor vehicle such as a Toyota Tazz (1 .3 litre) produces 55 kW at 6200 r/min. The S.A. Agulhas produces 4476 kW. Our generator engines have an electronic governor that controls the fuel supply to either increase or decrease the engines’power output, depending on the load required. Each engine is coupled to its respectivealternator that will convert this mechanical energy to electrical energy. The output of eachalternator is controlled with an AVR (Automatic Voltage Regulator) that receives informationfrom the PLC (Programmable Logic Controller). The PLC controls the voltages at 240 V singlephase or 400 V three phase, preventing the voltage from going above or below specificationwithin the circuits. The engines are fitted with a management system called Gencon Pro II. Itsbasic function is to monitor engine temperature, speed, oil pressure and water levels, whichinformation is sent to the PLC monitoring system.Now lets have a look at where the Gensets get their fuel from. The Base has six diesel bladderscontaining a 100  000 l each. The fuel is called Polar Diesel because of the components thatwere added or removed to lower the freezing temperature (cloud point) so that it is still usable invery cold conditions - minus 500C or even below this. The polar diesel gets pumped from thediesel bunkers to the Base on a daily basis into the day storage tank, to be available as aconstant supply to the respective gensets. Page 11 June 2011
    • Cooling the engines – and heating the base: one elegant solution We do not have radiators for cooling down the engines: we use heat exchangers instead, which perform the same function, but just in a different way. By a multistep process of heat exchangers we are able to use all the “waste” engine heat to warm up our domestic water: an elegant example of recycling. Each engine is equipped with a water/engine heat exchanger. A closed loop system of water is pumped through the engine to cool it down. This heated water then circulates through an engine- water/water heat exchanger, so that the heated water transfers its heat to a secondary closed loop system and returns to the engine as cool water again. The heat collected in this secondary water circuit is still not warm enough for Base use. It now passes through a water/exhaust-gas heat exchanger, drawing off yet more heat.The exhaust heat recovery process is veryimportant to the Base and for our survival inthis harsh environment. Instead of justexhausting the hot gas to the atmosphere, andlosing all the potential heat contained therein,we first remove the heat from it and this extraheat is now available to supplement ourheating require-ments. The exhaust-gas heatexchanger heats the water to about 85 0C.Finally, this very hot water passes through twoplate heat exchanger systems, one exchanger warming up our domestic water, the otherexchanger warming up water for the Fan Coil units. The Fan Coil Unit systems supply and Page 1 2 June 2011
    • regulate the air-conditioning in the basethat keeps us cosy in the freezing wintermonths.Although the secondary closed loopsystem has now lost heat to the domesticand fan coil unit water systems, it is still too warm to be circulated back directly to the heat exchanger drawing heat off the engine water. Before it is returned to the engine-water/water heat exchanger, therefore, it passes through a heat dump fan in the hangar, where cold air is fanned over the water and the excess heat dumped in the hangar. The water in the secondary loop, by giving up its heat, becomes cool enough to be returned to the engine-water/water exchanger. The cooling process is in this way repeated continuously. Average consumption p/m. Diesel 24000 l Electricity Energy 60 000 (kWh) Water 62 000 l Page 1 3 June 2011
    • Youve got to hand it to us... ‐ by AbiThe view from the Base windows, even at this time of night and twilight, is magnificant. Darkskies arch vastly overhead, while shadowy ice-plains stretch forever into the wind-blowndistance. Trickles and tendrils of drifting snow curve across the rocks below us. Dusk and coldare the predominant themes, best appreciated with a cup of coffee snugly in hand, peering outhappily from the comfort of the Base. But occasionally this detached admiration is shattered bythe rude necessities of the job. We have to go outside. The snow smelter needs filling, theanemometer needs fixing, the dozer needs starting, the vehicle lift needs to be cursed andglared at... . Outside. Minus 25 and falling. Wind and snow and misery and cold. So, we kit up,take a deep breath (if we can breathe at all through those balaclavas), and venture forth. Under working conditions, the hands take the What do you do with brunt of the weather, and we have to plan accordingly.5 sets of The obvious start to keeping ones upper extremities warm is gloves. Backgloves? in Cape Town we were issued with five different sorts of glove. If any of us, at that innocent and inexperienced time, thought that this was a bewildering overkill, we have since had cause to learn. Inners, pigskins, mitts... . Each of them has a different and necessary function. The pigskins are thin leather working gloves. As such they soonacquire a useful patina of Wabasto-smoke, diesel, various oils, and rustyvarnish from a million spade handles. All this helps cut down thewindchill factor, but even so, more effective measures are needed when one is not generating a couple Pig‐ of thousand joules-worth of finger-warming energy by hoicking large quantities of snow skin from one spot to another with a hand-held implement. Thus the s mitten, which allows one to curl the Mitt fingers into a fist and reduce heat-loss through the palm. Cant work with them, of course, but at least the fingers dont frost ens up. This is very useful when driving skidoos where dextrous finger-work is not needed but protection against wind-chill is essential. Page 1 4 June 2011
    • Then theres something called a “North Polar” which we Southerners find useful as analternative to the pigskins. Again an outside leather working glove, with a nice tight ribbed cuff tostop icy breezes creeping past the wrists. And inners. Inners are self-explanatory: we have avariety of these for adding that extra layer of warmth while using any of the others, or, inmoments of fine-grip work, by themselves. “Moments” is about all one can manage under usualconditions here – the fingers start twinging and threaten to fall off if left in only inners for anylength of time.It becomes evident that there will be occasions when one needsboth warmth and a precision grip. For such occasions, there isanother answer, and that is chemical heating pads or sachets,made to slip into a glove. Most of us have gone this standardroute and bought commercial sachets, made, we are assured,with “natural, environmentally-friendly” ingredients. The Grabbercontains iron, water, salt, cellulose, activated carbon and iron; theHotties and the HotHands-2 substitutes vermiculite for cellulose. Ina real emergency we could probably shove in some nitrogen andturn them into tiny bombs, or even flares. They come in nifty littlepackets which are easy to carry in ones pocket or back-pack, anddo not self-activate. According to the package blurb, they provideat least seven hours of heat between 57 and 79 degrees. Thesealso come in a Toe-warmer form – very useful in those long, stillhours spent driving the dozers about their lawful occasions.There are a variety of other options. Ruan sourced a heat storage gel-pack which can be easily activated in the field. These come in engaging colours, also, so are especially welcome in the Tea bags vs Handwarmers long Winter dusk. Paul was caught warming a stash of teabags in the microwave just prior to one outdoor expedition. The rest of us are mightily intrigued: does he have a special tip for us Easy mistake?...hmm? in the way of tea-leaf hand warmers? The doctor wants to do a controlled study to see ifRooibos or Five Roses teabags are the more effective, but Paul justdoesnt see himself in guinea-pig mode.But whatever our personal favourites are regarding frostbite preventionof the extremities, there is an answer which all of us are agreed upon.The only answer, the one common factor. Nothing, NOTHING, beats ahot cup of coffee. Freshly ground. At the dining room table. Page 1 5June 2011
    • Page 1 6June 2011
    • Climate Stats: June 2011 SANAE 50 team members Abigail Paton -Doctor Pressure Alan Daniels -Diesel Mech (Generators)Maximum - hPa Beatrice van Eden -Scientist ( Spaceweather) eAverage MaximumAverage Offl i n - hPa - hPa Gerard de Jong -Electrical EngineerMinimum te m - hPaAverage Minimum Sy - hPa Johan Hoffman - Radio Tech ( Dep. Teamleader) Kevin Van Eden -Scientist ( Spaceeather) Temperature Paul Lee - Meteorologist (Teamleader) Renier Fuchs - Scientist ( Particle Physics)Maximum -1 0.0 ºCAverage Maximum -1 7.7 ºC Ruan Nel - Scientist (HF Radar)Average -20.9 ºCMinimum -24.2 ºC Scelo Ndwalane - Diesel Mech ( Vehicles)Average Minimum -31 .7 ºC Tiki Jordaan - Mechanical Engineer HumidityMaximum 99 %Average 74 %Minimum 28 % WindMaximum Gust 60.7 m/s Sunshine Average Day Length 0:00 hrs (21 9 km/h) Page 1 7June 2011