The Final Flight: February 14th, at 2:30am New Zealand time.

We have just barely over two weeks until the sun sets and temperatures are already starting to drop quickly. The day of station closing, temperatures were around -40F. Today it is the coldest since I’ve been here at -63F, and tomorrow it’s suppose to bottom out at almost -70F. It’s amazing how quickly it drops when that sun gets low. The cold temperatures also make everyday things difficult to deal with. We had an emergency response drill today that took place outside and I volunteer on the fire team. You have to be really conscious about your gear because the SCBA (Self Contained Breathing Apparatus) hoses start to freeze and can crack easily. A fire fighter isn’t much good without a working SCBA. Frostbite is a big concern as well. The fire gear gloves and boots are not insulated for cold and do a very poor job of keeping your fingers and toes warm.

South Pole Station from ARO.

As for the science here at ARO (Atmospheric Research Observatory), not too much has changed. I’m still coming out here every day to check to make sure everything us running as it should be and taking air samples in flasks every week. One thing that is starting to change is our ability to do Dobson observations. The Dobson Spectrophotometer is an instrument that uses sunlight to measure total column ozone in the atmosphere. When the sun is this low on the horizon, there is a lot of stray refracted light that affects the measurements and can give us bad results. You may ask, “How do you take measurements in the winter?” Well this is done by using the reflected sunlight off of the moon. So we are able to take sporadic observations to coincide with our balloon flights through the winter. The solar radiation instruments on the roof will be coming down soon after sunset as well, which will be a small project for us. Here is a brief description of the solar radiation measurements we have at ARO and why we are measuring it.

Incoming solar radiation is the backbone of what drives our climate. Changes in the amount of radiation reaching the earth from the sun can be the difference between being in an ice age or not. It is important for us to know how much radiation is a) reaching the surface, b) what type of radiation it is (wavelength), and c) how much is bouncing back off the surface. This is what’s called the “Radiation Budget” in its most basic form. The “Radiation Budget” involves many other processes but the pictures and descriptions below show how we break down the “Radiation Budget” into its basic components at ARO.

The Solar Tracking NIP (Normal Incidence Pyroheliometer)

The NIP tracks the sun in all 360 degrees. It measures direct incoming solar radiation of specific wavelengths.

Diffuse Pyranometer

The diffuse pyranometer blocks out the incoming direct solar radiation and measures any radiation that is getting reflected and refracted from substances in the atmosphere (or any radiation taking an indirect path to the surface).

Pyranometers

These pyranometers detect all incoming solar radiation both direct and indirect. The two outer ones have filters on them to divide it up into shortwave (UV) and longwave (infrared) radiation.

Albedo Instruments

The “Albedo Rack” is basically exactly the same as the pyranometers except that they are turned upside down. They then measure the amount of solar radiation that is reflected off of the earth’s surface. Roughness and color play a role in Albedo meaning that a smooth surface is going to reflect more than a rough surface, and a white surface is going to reflect more than a black surface.. Therefore, it is important not to disturb the snow under these instruments because we want the natural state of the surface. In addition to reflected radiation, it monitors infrared radiation emitted by the earth.

A more complex version of the “Radiation Budget” or “Energy Balance” pulled from the IPCC Fourth Assessment Report.

As you can see, in the above figure, there is a lot that really goes into the “Radiation Budget” and it is a very complex system. When the solar energy comes into the atmosphere, it can take a variety of paths. It can get interrupted by clouds, gases, aerosols and other substances. Two of these processes in the system we observe at ARO as well such as Aerosols, and Greenhouse Gases which I will talk about in a later post.

Hopefully this explains a little bit what’s behind the solar radiation observations that we take at ARO. The South Pole and Mauna Loa have the longest continuous running solar radiation observations of this kind. It’s extremely important that we understand what happens to solar radiation as it passes through the atmosphere and hits the earth’s surface if we want to gain a good understanding of how earth’s climate works. It is even more important as we try to predict future climates.

Position: 66º 33’ 39’’S, 136º 59’E
Water Depth: 1000 meters
Exact Location: The Antarctic Circle

ABOARD THE JOIDES RESOLUTION, OFF THE COAST OF WILKES LAND, ANTARCTICA– Yes, we crossed the Antarctic Circle today! It is perhaps only the 3rd time this ship has ever done so. All points south of the Antarctic Circle experience at least one day every year of total darkness and likewise one day every year when the sun never completely sets. We are now in early February so the sun does set but only for 4 hours and it never gets really dark. As a member of the night shift out here, I love this…I get up at 11PM, come on shift at midnight. The sun sets around 1 AM and rises again around 5 AM. I get to see both and when the weather is good, the colors are spectacular.

Moon set behind our drilling derrick.

Dawn at 0330 in the AM.

We are now working at one of our shallow continental shelf sites, called U1358. We just finished the major site for which I am the lead scientist. This site was cored very successfully. The water is a 1000 meters deep and the spot we cored is like a big dish at the seafloor, with lots of small sediment particles drifting into it.

Here you can see the annual layers in the sediment cores we collected.

The sediments accumulate at a rate of 2 cm every year and leave an annual layer – a summer deposit made up of microscopic plants and a winter layer made up of dust and silts carried by the wind and the ice. We can see each layer and each layer represents one year. It looks as though we can count these layers back over 10,000 years. The record may not be perfectly continuous, we don’t know yet, but we do know that we have 470 meters of layered mud to work on and that it will tell how the sea ice and temperature of Antarctic surface and deep waters has changed on a year-to-year basis for many thousands of years…..

The core sampling table where this bag holds the last of more than 2300 samples taken from one Hole.

We save EVERYTHING There are more boxes on this ship than you would believe.

Everyone on board worked long hours to get this site completed, many for 18 to 20 hours each day. So, when we have a transit day to another site we get to rest, but we also have a chance to cross the Antarctic Circle. Everyone is excited and a bit relaxed, both at the same time! The weather is sunny and warm today but tonight we expect a big storm to begin, one with winds gusting to over 60 kts and waves as high as 25 feet. It might last 2 to 3 days, a problem for us as it is difficult to work in such stormy conditions. I’ll let you know how it turns out!

This is mainly the night shift at the bow of the Joides Resolution as we cross the Antarctic Circle.

Your correspondents Rob and Christina on the Antarctic Circle.