Sunday, 16 February 2014

Fieldwork you say??

Last night I watched the full film of Chasing Ice for the first time, not sure why it has taken me so long though.  Putting my feelings about James Balog and his over-emphasis on his old mans knee aside... it demonstrates amazingly the wonder of our world.  However you want to argue the future of our climate and the impact of human induced change, the film shows some stunning footage with some pretty music (I'm a sucker for some background piano motif) not just reminding me that the world of ice is super dynamic and (in many cases) rapidly changing, but also that it exists in the first place... Seeing pictures of a friend's recent trip to Antarctica and the Chasing Ice's footage from the Greenland Ice Sheet just amazes me.  It makes me happy to have a decent fieldwork component to my PhD research.

At least 4 times this year, starting in April, I will be journeying out to the Alps in order to study the variations in temperature across my study glacier.  The glacier in question is the well studied debris-covered Miage Glacier, which lies at the flank of Mont Blanc, on the Italian side (see below).

The clearly, very carefully placed red square shows very approximately where the Mont Blanc Massif, and my study glacier is.  Looking at local area maps, it is always easy to find this glacier because of its very distinct shape....

Above is the local area digital elevation model (DEM) processed in ArcMap GIS, showing the shape outline of the Miage Glacier (black line).  The 10 metre resolution of the DEM has been shown here processed into the slope angle, whereby the reds and oranges show a steeper slopes and the greens, less so.  As you can see, the glacier itself is quite gently sloping, making fieldwork a little easier (though it is ~10km long in total!).
The way the tongue of glacier bends around into the valley, makes it easily distinguishable in areal maps etc.. I'm not nearly clever enough to come up with some shape description for it, but happy for funny suggestions.

I will be spending time this year setting up tripods with temperature collecting equipment over as much of the glacier as possible, to best capture the variability in temperature as the elevation and site characteristics change.  For most of the glacier, until the tributaries nearer the top, the glacier has thick debris cover of rocks and dirt.

  These have accumulated over time from various avalanches and rockfalls onto the glacier, which have actually protected the ice below from melting as fast where the debris is very thick.  Glaciers like this are therefore very interesting to monitor in respect to changing climate.

Further up glacier, as the ice branches out into its sourcing tributaries, the ice surface becomes visible.  However, the presence of ice falls and crevasses makes life a bit more hazardous.. and fun!

Hopefully, it will be possible to establish some temperature stations further up here on the glacier, to better understand the variations temperature lapse rate.  However, at the time of year when the stations will be placed, snow cover may obscure the presence of crevasses (of varying sizes), which equipment can be affected by when the snow melts further on in the year.  The above image shows a zoomed in slope map of the area in question.  Below, the picture extracted from a shiny new Google maps shows part of this region in summer time.  Crevasses are hiding... but not very well....

Some discussions with the supervisory team are in order.

I'm looking forward to this April, when we drive all the of the needed equipment to the alps (not looking forward to the drive as much mind) and spending time with ice and snow!  My pictures will be unlikely to rival that of that guy with the dodgy knee, but I don't have several weeks and a calving front of the Greenland Ice Sheet, or expensive camera equipment... I'll try my best.
However, the part I look forward to most of all is just finding a spot to sit and taking it all in before I ski on to the next site......That reminds me......

I should really learn how to ski! :)

Monday, 10 February 2014

What's the temperature like outside???

Considering the obliteration of the South-West by ridiculous amounts of rainfall (and wind) and a general wet and windy country for all... the question of climate change often gets put into peoples heads (mainly because people expect to get Mediterranean style heat and clear skies).  Freezing my hands off up in Scotland over the weekend hiking because of constant wind and rain (and often blizzards) during winter made me think plenty about how mild the winter has been this year (so far) [see image].  Though to be honest, mostly I was thinking... my feet are wet and I'm actually a bit miserable.  I love the outdoors and the adverse weather... but this was a bit stupid!  

Anyway... I digress...... Temperature!!  important! unpredictable??  Nevertheless... with respect to glaciers.. it is hoped we can better predict their response in the future by understanding how exactly they react to variations in temperature .  The important thing to note with predicting anything is that it is based on some very general assumptions and simplifications.  For example knowing the exact temperature across a landscape at any one time isn't going to happen because we don't have a thermometer waving around in the air every few meters.
It is a common issue upon glaciers that we don't know how the air temperature varies.  Even if we had 10 million sensors across your average glacier and all the time in the world to set them up, there are often areas that we cannot really access because they are too dangerous: either they are too high up or likely to be highly crevassed.  It is typical for a glaciology study that looks at the accuracy of predictions to be operating with just a couple of detailed weather stations on a glacier.

I should mention that I've decided to produce awfully sketched up paint diagrams (or something edited in paint) to demonstrate my point(s), if indeed I have any.


Let's assume this looks anything like the outline of Storglaciaren in Northern Sweden and that lower elevations of the glacier are to the right of the diagram.... If the stars marked 1 and 2 represent automatic weather stations (AWSs) monitoring temperature, we would calculate the difference in temperature between them as a result of change in elevation.  We call this the lapse rate.  Because the atmosphere is warmed by convection from the Earth's surface... there is a decrease in this temperature the higher you get.  Hence why high altitude regions are not warmer because they are closer to the sun etc.

Because, in the above example, the AWSs are lower on the glacier, the difference in temperature between 1 and 2 would be used to estimate the rate of temperature change further up the glacier where there are no measurements.  If the AWS 2 was exactly 200 meters higher than AWS 1 and the temperature difference was 1 degree... we would assume a further 200 meters of elevation increase would be another 1 degree drop in temperature.  This is just a hypothetical temperature for Storglaciaren, but that is often how temperatures are estimated.

Also, these lapse rates are often constant in time and space in many studies that predict melt.  A good study on this glacier by Regine Hock and Bjorn Holmgren (2005) (1) investigates the energy balance variation by assuming a constant decrease in temperature of 5.5degrees (C) per kilometer of elevation increase (only after finding little difference in changing the lapse rates).  They find that the simulations agree well with observed melting from the glacier.

However...... It has been found by many studies that assuming that temperature changes evenly and consistently as a function of elevation is often incorrect and that predicting melt from glaciers using these assumptions can be inaccurate.  A fantastic study by Lene Petersen and Francesca Pellicciotti (2011) (2) shows variations in the way we can estimate temperatures across a glacier by studying the Juncal Norte Glacier in Chile.  The below diagram from this study shows the differences in changing the lapse rate we use to estimate temperatures.

Where the black outline is the glacier and the star (added) is the AWS as the point from which the temperature is derived, the left image shows the estimation if we assume a lapse rate of 15 degrees per kilometer decrease and the right image shows a lapse rate of 6.5 degrees per kilometer decrease.  It's clear what a big difference this can create, but accurately estimating this is very difficult... and ultimately, every glacier is different.

On top of all this difficulty, weather (such as rain and wind) can also impact the rate of decrease with elevation.  For example, wind alters the way in which the free air exchanges energy with the glacier surface (known as the sensible heat flux) and this can be a major factor in determining the temperature we are interested in.  But if wind is a common thing on the lower part of the glacier but not on the upper part, estimating lapse rates from the temperature impacted by localised weather is riddled with potential inaccuracies.

Welcome to my world of research!

It's very simple on the whole... but there is a lot to think about.

I have been summarising the variations in lapse rates across studies for the last decade or so and found that ultimately; the unique nature of each glacier means that assuming anything is the same can be a problem.  Nevertheless... for some glaciers (i.e. Storglaciaren) changes to the lapse rate can be very negligible.

My research aims to get a really widespread set up of temperature stations across a glacier and find exactly how temperature varies while a glacier is melting in the spring/summer, what causes it to change vary and how this can affect the way we predict melting.

More to follow......

(below are the papers I've referred to... interesting and worth a read)

(1) Hock, R., & Holmgren, B. (2005). A distributed surface energy-balance model for complex, Sweden topography and its application to Storglaciaren. Journal of Glaciology, 51(172), 25–36.

(2) Petersen, L., & Pellicciotti, F. (2011). Spatial and temporal variability of air temperature on a melting glacier: Atmospheric controls, extrapolation methods and their effect on melt modeling, Juncal Norte Glacier, Chile. Journal of Geophysical Research, 116(D23), D23109. doi:10.1029/2011JD015842

Saturday, 1 February 2014

Some like the cold... then there's me :)

When I tell people what I do, it's generally met with a interesting mixture of "that's cool" or "did you say gynecologist??".  While the latter is obviously a very closely related subject, most of the time I have to repeat it and say that I hang around on large masses of ice that can vary in size from a small housing estate to the size of small countries.  And I really enjoy saying what I study... glaciology... I feel its something a bit different....even spell checker doesn't recognise the word (it gave gynecology as an alternative). But of course saying it's unique is a load of crap, considering that there are and have been thousands of wonderful and smart people immersing themselves in various aspects of the glaciers we see (and no longer see) on our planet.  From those looking at the water moving through the glacier, under it, out of it, melting from it and generally doing 'cool' stuff to those looking at the impacts of climate change and temperature on the rate of it's disappearance (That's me!!!).  Nevertheless it gives me a feeling of great satisfaction to say that i'm one of those people.

I feel very fortunate to have experienced some of these amazing features of our world, but for me, the experience only really started a year and a half ago on a research trip to the Arctic archipelago of Svalbard (Norway).  It was there where I experienced my first glacier walk with a pair of awful outdoor shoes worth a tenner that kept my feet lovely and wet (and cold) for the entire month I was there.  Even so, I fell in love with the whole glacier thing straight away... I fell in love with Svalbard and will likely be for a long time to come.  The thing that surprised me was that I had reached the age of 22 without experiencing anything like that at all before.  I had never been on skiing holidays and never thought about hiking across ice before.  Even though I was (and still am) very much interested in climate change and the way glaciers provide an amazing visual response to it, I had never been to see one.... why!???.

Just to demonstrate some of the amazing changes of glaciers......

These images are just two selected from many to demonstrate the point.  The top image shows the retreat of the Muir Glacier (and Riggs, not seen) in Alaska between 1941 and 2004.  The bottom image shows the retreat of the Athabasca Glacier, Canadian Rockies between 1917 and 2005.
However without some sense of scale... these images may not seem as impacting.

A wonderful demonstration of a glacier terminating into the ocean and breaking off (termed 'calving') can be seen by a clip from Chasing Ice, a documentary film from nature photographer James Balog.  This clip filmed at Ilulissat Glacier in Western Greenland, sums up the awesome scale of some of these calving events!

At the other end of the world, at the end of last year, a Singapore sized iceberg broke off from the Pine Island Glacier in Antarctica and now poses as a potential threat to shipping lanes.  Estimated at a size of 700 square km, I wouldn't want to wake up one morning to find that hovering toward my shore.... though I would secretly be excited.  BBC news report here:

While there are several factors at play here, the rate of change witnessed from the Chasing Ice example demonstrates how a changing climate is creating a more rapid response of these glacier systems.  While human influence has very likely shaped the fate for these giant ice masses, there are also the natural cycles over far greater timescales to consider (a debate for another time I think).  Even so, the rate at which our glaciers are disappearing is very important for many because it can largely impact the availability of water into the future..... That's where I come into things.

The reason I've been ranting about how amazing glaciers are for the last 36 lines or so is that I have recently started a PhD at Northumbria University (Newcastle, UK) to study the effect of temperature variations over glaciers when they are melting over the spring/summer period.  By understanding how exactly glaciers respond to temperature increases (and fluctuations) we can aim to better predict how much water we will have in the year... 2050 or whatever (if they will even last that long).  Essentially I created this blog to provide a general overview to what I will be studying, how I will study it and all the processes and problems involved.  I feel this is a good way to try to explain some of the phenomena I have briefly thrown on the page right now, also providing my own views (from a researcher's perspective rather than a news page) and an idea what a PhD in physical geography involves.  I am very far from having all the answers, especially only 2 months into my research... but then again, we are all guessing really, aren't we??

I will try and update this blog as often as possible and as often is there actually something reasonable to write.  As this is my first blog, I have likely clicked the wrong button and/or it looks a mess or not quite what I wanted with Blogger presets and all..... blah blah blah...