The Large, the Small, and Statistical Significance

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By Nathan Kurtz, Sea Ice Scientist, NASA Goddard Space Flight Center

Gazing out the window of the IceBridge DC-8 aircraft is a bit unsettling. The Antarctic region is a vast and seemingly endless wilderness, and undoubtedly it is a dangerous place without the support of a fantastic array of technology and people. But there’s also a sense of comfort, even superiority, in that the modern wonders of technology and social organization can safely carry us through such forbidding terrain. Terrain that has already claimed the lives of many who have previously attempted to do so with more primitive means. Yet, any sense of superiority and safety is always to some degree an illusion. I’m reminded of the great physicist Richard Feynman who once said, “The first principle is that you must not fool yourself…and you are the easiest person to fool.”

sea ice shadow

The shadow of NASA’s DC-8 on Antarctic sea ice. Credit: NASA / Jim Yungel

With that in mind I am more appreciative of the power of nature and chance which helps to deflate any unnatural sense of superiority and self-importance. But it also brings to mind a paradox, our aircraft is little more than a mere speck to the size of the problem which we are studying, and yet this speck is tasked with carrying out a mission to provide meaningful information on the state of the Antarctic and the global impact of changes to the region.

Consider the scale of the problem: the Antarctic ice sheet is more than 5 million square miles and the surrounding sea ice reached an extent of 7.8 million square miles this past September. As a rough estimate, the IceBridge dataset will cover some 20,000 square miles, while this is quite large, it is still a mere fraction of a percent of the total area of Antarctica and the surrounding seas. This large difference in scale underscores one very difficult nature of the problem and illustrates the main reason I personally feel quite small in the face of something so immense.

Undoubtedly the Antarctic is seen as important to consider as a topic of interest beyond certain specialized branches of science. The Antarctic ice sheet has the potential to raise sea level by over 200 feet were it to melt in entirety, a number which carries significance to the large numbers of people living in coastal regions. Antarctic sea ice is an important regulator of the global temperature since it reflects a large portion of solar radiation back to space which helps to lower the mean global temperature. It also influences the deep ocean circulation allowing higher forms of life to thrive even at the greatest depths.

aboard the dc-8

Researchers aboard NASA’s DC-8 during an IceBridge survey flight. Credit: NASA / Michael Studinger

Acknowledgment of powerful factors such as these has captured the attention of a broad swath of people and was aptly demonstrated this past year with the release of two major stories by the media concerning changes in the Antarctic. The front page of the New York Times rang out “Scientists Warn of Rising Oceans From Polar Melt”. This story, (which IceBridge data played a role) was in reference to recent findings that the West Antarctic Ice Sheet is now in an irreversible decline to take place over the course of the next thousand years or so.

A second widely circulated story was on the observation that Antarctic sea ice had reached the highest extent ever observed in the satellite era this past September, a counter-intuitive phenomenon that superficially defies conventional expectations on what a warming climate should do to polar ice. Though it does have, in fact, a rational physical explanation, it is currently the subject of much scientific inquiry due to the complexity of factors involved.

Thus, this brings to my mind a sense of uncertainty that overwhelmingly powerful forces of nature are in control – despite our great technological capability – and yet it is our technological capability which allows us to see this on a grand scale. But the lack of control brings to mind doubt, how can we be so clever to see large forces at work and yet also be powerless to change a potentially negative course of action? This sense of doubt and uncertainty casts a long shadow, a shadow which also has bearing on the IceBridge mission. In essence, it comes from recognition of the fact that science is not perfect, and claims to the absolute validity of anything should be taken with doubt.

Shackleton Range

Mountains of Antarctica’s Shackleton Range seen from the DC-8 on the Oct. 25, 2014, IceBridge survey flight. Credit: NASA / Jim Yungel

The existence of doubt is paramount to how the scientific method works, in that ideas are questioned and tested. In another sense, a lack of doubt and skepticism is also harmful, for as Voltaire says “Those who can make you believe absurdities can make you commit atrocities.” It is exactly this type of doubt that sows mistrust, skepticism and at worst nihilism – that everything is too doubtful and meaningless, that the scales are too large and our measurements too small and uncertain. Essentially, a new paradox arises in that doubt and skepticism are necessary yet are harmful at the same time if not properly balanced.

The scientific process has a remedy for this in the use of numbers to bring order to chaotic processes which may seem otherwise too difficult to grasp. Numbers are a unique invention which allows us to unite the grand scale to the small scale at which we make actual observations.

As an example, IceBridge took measurements of surface elevation over a circle centered at 88 degrees latitude. This is useful for both the CryoSat-2 and ICESat-2 satellites because their orbits take them across this region every revolution. On a broad scale, it is thought this is a useful target area because it is located on a part of the polar plateau which is not expected to change significantly in time.

south pole station

An overhead view of Amundsen-Scott Station at the South Pole captured by the Digital Mapping System cameras aboard the NASA DC-8. Credit: NASA / DMS Team

But looking out on the surface from the plane revealed a chaotic surface of ridges called sastrugi that are shaped by the howling winds blowing over the surface. Yet features such as these can be described in a simple numeric that distills the visual chaos into something more understandable. This then allows comparisons between different measurements at different spatial scales and times. That is, a point measurement may by itself may convey little information, but brought together in the form of a number (for ICESat-2 this is in the form of a mean difference or bias) it can be compared to a greater whole.

However, numbers can be misleading if cherry-picked to support a particular position. The descent into hair-splitting sophistry and (at heart) overly-emotional polemics so prevalent in many public forums today is evidence of this at work. This leads me to my final question, can numbers alone convey the truth such that their meaning is appropriately acted upon? Or does the associated ability to manipulate numbers to promote a subjective “truth” negate this? Perhaps what is needed to reconcile this dilemma is integrity, which derives from the Latin root “integer” meaning whole or undivided, and is perhaps not incidentally also a specific type of special numbers in mathematics. That is, if one can provide numbers, and do so with integrity, one can then have conviction such that the truth emerges, can gain acceptance, and be acted upon in a meaningful way. Yet even here it is wise to beware that this is some panacea which will solve all these complex problems.

In my opinion providing numbers is a step, at least the only way I personally can attempt to reconcile the large and small scales which have confronted me. As I prepare to head back home to begin working on data from past missions, I have hope that the seemingly small contributions of myself and the crew, engineers, and other scientists will provide some connection to be statistically significant at a much larger scale.

This entry originally appeared on the NASA Earth Observatory blog Notes from the Field.
http://earthobservatory.nasa.gov/blogs/fromthefield/2014/10/27/the-large-the-small-and-statistical-significance/

Check and Double-Check: Preparing for the Antarctic

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By George Hale, IceBridge Science Outreach Coordinator, NASA Goddard Space Flight Center

Before each IceBridge campaign, the mission’s aircraft and instrument teams spend weeks getting the plane and all its scientific equipment ready for the research ahead. On Oct. 7 and 8, 2014, IceBridge put the finishing touches on those with two instrument check flights, designed to ensure that everything is in working order.

On Oct. 7, the NASA DC-8 took off from the NASA Armstrong Flight Research Center facility in Palmdale, California, and headed out over the Pacific Ocean for a five-hour flight to test the various radar instruments aboard.

Shadow of DC-8 on desert ground

Shadow of the NASA DC-8 on the ground in the desert near Palmdale, California. Credit: NASA / Jim Yungel

The next day, the IceBridge team boarded the DC-8 for a second check flight, this time to test the laser altimeters, camera and gravity measuring instruments on board. To carry this out, the DC-8 flew repeatedly over one of the ramps at the Armstrong facility and over El Mirage, a dry lake bed in the Mojave Desert. The flat and light-colored surface of El Mirage makes it a good place to test how the laser altimeter will work on ice and snow.

El Mirage lake bed

El Mirage, a dry lake bed in the California desert, serves as a testing ground for IceBridge’s laser altimeters. Credit: NASA / Jim Yungel

The IceBridge team will leave California on Oct. 12 and travel to Punta Arenas, Chile, where the mission will fly surveys of Antarctic land and sea ice through late November.

More Flying With ARISE

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image12

By Michal Segal Rosenheimer, Research Scientist, NASA Ames Research Center

Editor’s note: The following is a first-hand account of ARISE survey flights by one of the mission’s researchers. To see the first two days’ accounts, visit:
http://earthobservatory.nasa.gov/blogs/fromthefield/2014/09/17/flying-with-arise/

Day 3 (Sept. 16, 2014)

Today was a long flight day. It started off by trying to guess where the high clouds (i.e. cirrus) will move in. We had to choose between three options, and our choice turned out to be a good bet. We flew to the edge of the sea ice to try to characterize both its exact mapping and see whether the clouds look different or have different characteristics, height and composition (i.e. water and ice) above the sea-ice versus open ocean. We had a mix of high clouds above ice but also clear regions, with black and white ice, as seen in the pictures. The sun was posing for us and we got to see some halo forming around the sun. This means that we had ice clouds (cirrostratus) with particular ice shapes of smooth hexagonal crystals are reflecting and refracting the sun rays to form this circle of light surrounding the sun.

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Day 4 (Sept. 18, 2014)

Today was a challenging day. We were after clouds, and oh, they are “hard-to-get” into a specific posture. We flew high to check the area and had a gorgeous stratus deck below us. The word stratus in Latin means “spread out” and boy, they were spread out all right.

At some point we saw an opportunity to dive below the clouds,  and cruising over the broken sea-ice, we felt like we were in a Star Trek episode.

Clouds are so diverse and changeable, so we want to sample them as often as possible to get a feel for their heights, thicknesses and what type of particles they include (water, ice or a mixture of both). This is important because their location in the atmosphere (how high or low they are) and their composition dictates the amount of radiation they absorb or scatter back into space and how they affect the surface below, either warming or cooling. This was a challenging and bumpy flight from all perspectives, but all in all it ended well.

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Summary

We had many more flights, some I flew myself, some were flown by my 4STAR team fellows. All flights were magnificent in that they covered pristine sea ice regions, where human access is difficult and low and high clouds over these regions (especially at this time of year) means even the satellites often cannot take measurements. We had some weather and technical hurdles some days, but we succeeded in most of our goals, which were to measure sea-ice formation and state, study sunlight and thermal energy over the sea-ice and open ocean, and characterize cloud spread and type in this complex and important region.

Our final science flight was on Oct. 2, and was dedicated to instrument calibration. It lasted for almost nine hours and ended after sunset, since some of the instruments (including our own SUN-photometer) needed to be calibrated by the sun, looking at the wide range of sunlight intensity during sunrise or sunset period. We flew over some dormant volcanos in the southern part of Alaska, over glaciers and Denali park. What a great finale to a great campaign! Looking forward for next year’s one already.

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This entry originally appeared on the NASA Earth Observatory blog Notes from the Field.
http://earthobservatory.nasa.gov/blogs/fromthefield/2014/10/08/more-flying-with-arise/

Picturing Sea Ice with ARISE’s Digital Camera Instrument

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By George Hale, IceBridge Science Outreach Coordinator, NASA Goddard Space Flight Center

Digital camera shot of large sea ice lead

The dark blue in this image is a lead, or opening in sea ice. If you look closely you can see where the lead is starting to refreeze at the edges. Credit: NASA

Flying above, below and through clouds in the Arctic gives the ARISE C-130 a different perspective on the world below. Nowhere is this more apparent than through the lenses of ARISE’s digital camera instrument. This instrument – one of many   ARISE uses – captures views of clouds, ocean and ice that are both scenic and scientifically important.

The heart of the digital camera instrument would look familiar to a casual observer. It is made up of two off-the-shelf digital cameras that point down through a clear window in the underside of the aircraft. These cameras are connected to a computer with software that allows the operator to preview images and change camera settings and to a hard drive for storing photographs. An average ARISE flight yields roughly 100 gigabytes of images.

Although the cameras are the same make and model, their lenses are different. Group photos and distant landscape shots call for different size lenses, and low-altitude and high-altitude flights do the same. One camera has a 14 millimeter, wide-angle lens to capture views of the surface during low-level flights. The other camera’s lens has a 50 millimeter focal length, making it useful higher up.

Broken sea ice

A collection of broken sea ice pieces floating together. Far from static, sea ice moves, flexes and breaks under the strain of winds and ocean currents. Credit: NASA

Similarly, the rate at which the shutters snap ranges between one per second to roughly one every three seconds. From high up the surface seems to pass slower than at low altitude, much like the way telephone poles beside the highway are a blur while far away mountains barely seem to move. Instrument operators can fine-tune this rate to best match the situation and can be managed in flight.

While many of the images these cameras capture are breathtaking, they are also useful in several ways. Researchers can use them to measure how much light is reflected from clouds and ice, also known as albedo. The images also show where there are leads, or openings, in sea ice. ARISE measures ice surface height using the Land, Vegetation and Ice Sensor, which bounces a laser off of the surface and times how long it takes to return to the plane. Locating leads gives scientists a reference for local sea level, helping ensure that measurements are accurate.

Larger broken ice

Larger chunks of sea ice, some with melt ponds on the surface. Credit: NASA

Laser altimeters and other instruments can reveal a great deal about the surface, but through photographs the variety of conditions ranging from open stretches of water to broken bits of floating ice to solid white expanses. The images captured by these cameras benefit researchers studying sea ice, but the views can also be breathtaking.

This entry originally appeared on the NASA Earth Observatory blog Notes from the Field.
http://earthobservatory.nasa.gov/blogs/fromthefield/2014/09/24/picturing-sea-ice-with-arises-digital-camera-instrument/

Bringing It All Together: Planning ARISE

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By Christy Hansen, ARISE Project Manager, NASA Goddard Space Flight Center

Christy Hansen in front of NASA C-130

ARISE project manager Christy Hansen stands in front of the NASA C-130. Credit: NASA

By Christy Hansen, ARISE Project Manager, NASA Goddard Space Flight Center

Eielson Air Force Base, Fairbanks, Alaska, day 9 of our deployment: We are currently sitting together in our mission support and flight planning room, next to the Thunderdome Hangar on base. We have appropriately named this room, where we dedicate up to 10 hours each day, our WAR room – where we passionately discuss which ARISE science objectives we’ll fly each day.  Our broad instrument suite provides us with a great number of options for interesting science flights, yet ironically poses additional challenges, as each instrument requires meteorological conditions that often conflict with one another. It is here where we follow the C-130 as it flies our science trajectories, a combination of radiation cloud studies and cryospheric sciences. We can communicate with the science team on board via a basic chat system, send them occasional updated satellite imagery, track their flight, and talk on a satellite-based phone system.

ARISE team at work

Members of the ARISE team operating scientific gear aboard the C-130 during a survey flight. Credit: NASA / Richard Moore

It is the first NASA airborne science mission of its kind, combining a unique instrument suite that would have been unlikely to fly together on the same airborne platform in missions past. And this is what makes ARISE a very exciting mission from a scientific standpoint. New data sets will be combined and studied at the conclusion of this mission.  Our general science goal is to develop an understanding of the Arctic regional energy budget. The amount of sea-ice contributes to how much sunlight is reflected back to space, and thus is an important factor in the radiation balance of the Earth. In additional, we are hoping to learn more about how clouds might interact with sea ice to build a more comprehensive understanding of the Arctic energy budget as a whole. Why is this important?  Because it will help us better understand our Earth system; changes to atmospheric and ocean circulations, precipitation and temperature patterns, and potential sea level rise.

Sea ice through clouds

A view of broken sea ice through low clouds. Credit: NASA / Richard Moore

We are surrounded by  F-16 and F-18 jets taking off and landing all day, against a radiant and beautiful sky. We see an occasional moose on base and along the interstate during our drives in and out, all the while reminding us we are far away from home. We greet the plane as it lands each day – with a swarm of gnats in our face.

I love it when a plan comes together.

As the Project Manager for ARISE, I am reflecting on how far this team has come is such short time. In less than seven months, ARISE has evolved from the initial concept phase, to a fully operational airborne science mission – collecting unique data sets in the Arctic.  This includes identifying science objectives, identifying team members, identifying instruments to meet the mission goals, defining data products, selecting an aircraft, performing research to establish a base of operations that could meet our C-130 aircraft and science team requirements, obtaining country diplomatic clearances, flight planning,  performing C-130 aircraft engineering modifications, completing field logistics, testing and re-testing, and all associated approvals. Bringing a large unique team together, to meet a new set of NASA science goals and requirements, in a challenging environment, within regulations and expected timelines – from start to finish, is what my job is all about.

Weather briefing

ARISE mission planners and a member of the Eielson Air Force Base weather office review forecasts before a survey flight. Credit: NASA / Christy Hansen

The team of professionals and experts I work with each day, from scientists, to flight crew and aircraft maintainers, to logistics teams, and engineers to managers – have each contributed a unique puzzle piece to the overall mission picture. In just one week, we have completed six new science missions together. And “together” means that greater than 30 people have to work together, on time, in a changing and challenging environment with tight deadlines, every single day. Without all pieces of the puzzle working together well, the mission would not be complete.

This first week has proven that we can do it – we have met all initial obstacles and challenges as a team together. We have been moved from our location on base twice, scraped frost from our windows using credit cards, over-heated and froze all in the same day, laughed and politely argued together, heated up ramen noodles and pizza to get us through — all while remembering that we are here together to do GREAT science.

This entry originally appeared on the NASA Earth Observatory blog Notes from the Field.
http://earthobservatory.nasa.gov/blogs/fromthefield/2014/09/18/bringing-it-all-together-planning-arise/

Flying With ARISE

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By Michal Segal Rosenheimer, Research Scientist, NASA Ames Research Center

Above the clouds

Above the clouds on NASA’s C-130 during an ARISE survey flight. Credit: NASA / Michal Segal Rozenhaimer

Day 1 (Sep-11-2014)

My first ARISE day started early in the morning after a late arrival into Fairbanks on the night before. This important mission’s goal is to map the sea ice and understand the relation between the complex cloud scene over the Arctic, the sea ice and Earth’s radiation budget,the balance between incoming and outgoing sunlight and infrared.

After arriving on base and seeing our instrument (4STAR) on the plane, I am ready to go out there, realizing again that since I am with NASA I get this great opportunity not only to analyze data as many scientists do, but to actually take part in generating this important dataset.

A view of the ground through clouds

Peering down through a thin cloud layer. Credit: NASA / Michal Segal Rozenhaimer

After initial preparations like getting used to the noise on the planeand figuring out how to buckle myself in (none of my degrees were proven useful in this case) we took off to the northern parts of our planet. From this big bird’s view, cutting through various cloud deck formations, seeing land cover, ocean and ice I suddenly grasp the immense variability of this region and how we, as a mobile platform, can bridge satellites and ground measurements by going above, in and below clouds. Yes, as is probably obvious from my text and images, I am interested in clouds!

More clouds

Another view of clouds. Credit: NASA / Michal Segal Rozenhaimer

The 4STAR instrument can measure clouds from below, and can also look at the sun and characterize the thin cloud wisps surrounding the sun in this third image. Harmless as they seem, these cirrus (which means a curling lock of hair in Latin) clouds are hard to detect from space and have a large effect on warming/cooling of our planet.

After a seven hour flight it is time to land and think about the next flight.

Day 2 (Sep-13-2014)

solid sea ice

Solid sea ice seen during an ARISE survey flight. Credit: NASA / Michal Segal Rozenhaimer

My second ARISE flight day started with lots of adrenaline and excitement. We would fly low over the sea-ice sheets!
Some regions are broken, with small water lakes in between and some are rock-solid.

Flying so low over the sea-ice makes me wonder whether I’ll be able to detect a polar bear out there.

The views are so awe-inspiring that I am practically out of words or breathe. After eight hours above these amazing surfaces, with some roller-coaster ups and downs, we are back on the ground, and I am with a big smile that will last for many more hours after that.

broken sea ice

Broken sea ice seen during an ARISE survey flight. Credit: NASA / Michal Segal Rozenhaimer

This entry originally appeared on the NASA Earth Observatory blog Notes from the Field.
http://earthobservatory.nasa.gov/blogs/fromthefield/2014/09/17/flying-with-arise/

May the 4STAR Be With You

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By Michal Segal Rosenheimer, Research Scientist, NASA Ames Research Center

4STAR on top of C-130

The Spectrometer for Sky-Scanning, Sun-Tracking Atmospheric Research (4STAR) mounted on top of NASA’s C-130 research aircraft.
Credit: NASA

The Spectrometer for Sky-Scanning, Sun-Tracking Atmospheric Research, or 4STAR, is an airborne instrument that measures aerosols (small particles suspended in the atmosphere), gases (ozone for example), and a variety of cloud properties. Currently it is being deployed on the NASA C-130 aircraft on its quest to measure aerosol and cloud properties in the Arctic, helping to answer some of the most difficult questions of climate change: what is the link between sea ice changes, clouds and global warming?

How does it work?

The 4STAR instrument has three different modes. The first of these, and the instrument’s main mode, is Sun-Tracking. This is where the instrument tracks the sun’s location in the sky, staring at it to measure the light transmitted from the sun to the instrument as it travels through the atmosphere. If the atmosphere is clean, we would measure the sun’s intensity. But because the atmosphere contains aerosols, gases and cirrus clouds, which are high, thin clouds made of ice crystals, we measure the amount of light that makes it through instead of being scattered and absorbed by these components of the atmosphere. By comparing measured light through the atmosphere to what we would have seen with no atmosphere we can deduce the amount of aerosol and gases in the air.

4STAR sun tracking diagram

A diagram showing 4STAR’s sun-tracking mode. The instrument locks on to the sun and measures the amount of light that makes it through clouds, gases and aerosols. Comparing this with what would be seen in clear air lets researchers calculate the amount of aerosols and gases in the atmosphere. 
Credit: NASA

Another operating mode, which will be used heavily during ARISE, would be the zenith (or upward) viewing mode. Here, we look upward to the sky and measure the diffused radiation that originated from the sun, but now is scattered due to aerosols and clouds. We use this measurement, along with assumptions on ground surface properties, cloud height, and the surrounding atmospheric composition to derive cloud properties such as optical depth (how much light gets through the cloud) and the size of water droplets in the cloud.

4STAR zenith mode diagram

Diagram of how 4STAR measures cloud properties above the aircraft in zenith mode. In this mode, researchers can derive cloud water droplet size and how much light is transmitted through the cloud, or its optical depth.
Credit: NASA

The last and most involved measurement mode we have is the Sky-Scanning mode. Here we measure the diffused sun radiation, that is light not coming directly from the sun, at different distinct angles from the sun (remember that we know where the sun is because we are tracking its location). This radiation is the result of scattered light from aerosols in the atmosphere. The amount of light at the different angles can tell us something about these aerosol particles, such as how well they absorb sunlight (and heat the earth), their shape (sphere or irregular), and their size.

4STAR sky scanning diagram

Diagram showing 4STAR’s sky-scanning mode. The instrument scans the sky above the aircraft to measure how light is scattered by aerosol particles in the air.
Credit: NASA

This entry originally appeared on the NASA Earth Observatory blog Notes from the Field.
http://earthobservatory.nasa.gov/blogs/fromthefield/2014/09/08/may-the-4star-be-with-you/

Preparing for the Trip North

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By George Hale, IceBridge Science Outreach Coordinator, NASA Goddard Space Flight Center

A new NASA airborne campaign known as ARISE, or the Arctic Radiation – IceBridge Sea and Ice Experiment, will take measurements intended to help researchers better understand the role that clouds play in Arctic warming as sea ice conditions change. From Sep. 3 to Oct. 3, researchers flying aboard NASA’s C-130 research aircraft will measure incoming and reflected sunlight, thermal infrared radiation, ice surface elevation and various cloud properties to gain a better understanding of changes to the Arctic climate.

C-130 in hangar

NASA’s C-130 research aircraft sitting in the hangar at Wallops Flight Facility as it is being prepared for the ARISE field campaign. Credit: NASA / Christy Hansen

For the past few weeks, aircraft technicians and instrument experts have been preparing the C-130 for its upcoming trip to the Arctic. A large part of this process was installing and testing the scientific gear that the ARISE team will use to collect data on clouds and ice.

  • Ice Land, Vegetation and Ice Sensor (LVIS) – LVIS is a laser altimeter used to measure ice surface elevation. Data from this instrument can tell researchers about surface conditions below the plane.
  • Broadband Radiometer (BBR) and Solar Spectral Flux Radiometer (SSFR) – These instruments measure the strength of incoming and outgoing sunlight and thermal radiation.
  • Spectrometer for Sky-Scanning, Sun Tracking Atmospheric Research (4STAR) – 4STAR studies aerosol and cloud properties by measuring sunlight as it passes through the atmosphere.
  • Probes – The C-130 is also equipped with probes to measure properties like cloud water content and droplet size to better understand Arctic clouds.
Instrument equipment inside C-130

Land, Vegetation and Ice Sensor (LVIS) instrument and control racks aboard the NASA C-130 research aircraft seen during instrument integration at Wallops Flight Facility in Virginia. LVIS is a laser altimeter that will be used to measure land and sea ice elevation during NASA’s ARISE campaign.
Credit: NASA / David Rabine

Once the instruments are installed and tested on the ground, the ARISE team carried out a pair of check flights – one to make sure the C-130 is flying in peak condition and one to verify that the mission’s various instruments are working properly.

C-130 flying a check flight

A view of NASA’s C-130 research aircraft seen from the T-34 chase plane during the ARISE engineering check flight on August 24, 2014.
Credit: NASA / Dennis Rieke and Mark Russell

For the next few weeks, the ARISE team will fly out of Eielson Air Force Base, Alaska, to collect data on Arctic ice and clouds.

This entry originally appeared on the NASA Earth Observatory blog Notes from the Field.
http://earthobservatory.nasa.gov/blogs/fromthefield/2014/09/02/preparing-for-the-trip-north

IceBridge 2014 Summer Science Team Meeting

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Group photo

Members of the IceBridge team gather for a group photo on the last day of IceBridge’s 2014 summer science team meeting. Credit: UCI / Bernd Scheuchl

On June 24 and 25, 2014, the IceBridge science team met at the University of California Irvine. Twice a year, the IceBridge science team meets to share scientific presentations, discuss the mission’s performance and prepare for the next campaign.

Joint session

A joint session of the land ice and sea ice teams. Credit: UCI / Bernd Scheuchl

Meetings typically begin with a joint session of the land ice and sea ice teams. These sessions focus on items of interest to the entire team such as updates from NASA Headquarters.

Sea ice team

A breakout session for IceBridge’s sea ice team. Credit: UCI / Bernd Scheuchl

Later in the meeting the sea ice and land ice teams separate to discuss upcoming flight lines, opportunities for collaboration and the status of new and existing data products. The above photo shows a meeting of the sea ice team.

Flight line printouts

Printed copies of proposed Antarctic flight lines for 2014. Credit: UCI / Bernd Scheuchl

One of the major accomplishments in each IceBridge science team meeting is prioritizing the next campaign’s flight lines. Here we see printed copies of flight lines over different parts of Antarctica.

IceBridge Data on the Web

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By George Hale, IceBridge Science Outreach Coordinator, NASA Goddard Space Flight Center

During each campaign IceBridge’s suite of instruments collects a vast amount of data on polar land and sea ice. These data have proven themselves useful with the research community using them in seasonal sea ice forecasts and computer simulations of ice sheets, and to build maps of the bedrock beneath the Greenland and Antarctic ice sheets. But getting IceBridge’s data into a place where researchers can use them is a big task.

After the end of a campaign researchers process instrument data and upload it to the National Snow and Ice Data Center (NSIDC) in Boulder, Colorado. NSIDC then archives and publishes the datasets on the web where it is freely available to the public. IceBridge has a significant presence on the NSIDC website with more than 60 available datasets.

screenshot of IceBridge data portal page

The IceBridge data portal on the National Snow and Ice Data Center (NSIDC) website allows users to select individual IceBridge flight lines.

Preparing data is a time-intensive process and can take weeks or months to finish, but researchers are required to have their data in to NSIDC within six months of the campaign’s end.

The first step to making measurements public – after collecting them of course – is to back up the data. A good deal of this is done in the field. After each flight, instrument operators copy data onto media like external hard drives to be processed later. Following the campaign, instrument teams go through the data to process it and produce different data products suitable for posting.

Hard drive array

Array of disks used to store instrument data during scientific flights. Credit: NASA / George Hale

These data products are categorized into different groups depending on how much processing they’ve undergone, following standards based on NASA’s Earth Science Reference Handbook, which was published in 2006. The level of processing for each dataset is noted by a letter L followed by a number (e.g., L0, L1B, L3) ranging from 0 (least processed) to 4 (most processed).

Data Level Definitions

  • Level 0 – raw instrument data with minimal processing to remove duplicate information, noise and other errors
  • Level 1B – instrument data with timestamps and geo-referencing information
  • Level1BX – Level 1B data in a format useable for comparing measurements between different instruments
  • Level 2 – variables derived from level 1 data
  • Level 3 –  level 2 variables mapped on a uniform grid
  • Level 4 –  results from computer models or combination of multiple datasets

As an example, data from the Airborne Topographic Mapper go from distance between the surface and the instrument (L0), to ice elevation (L1B) and elevation, slope and roughness (L2), to surface elevation rate of change (L4).

Racks containing instrument hardware aboard the P-3

Racks of instrument hardware aboard the NASA P-3 during a data collection flight. Credit: NASA / George Hale

Once processing is complete instrument teams send the data products to NSIDC, who stores the data on a public website. The NSIDC site contains separate pages for each instrument and data product and maintains a data portal where researchers can select individual IceBridge flights on an interactive map. Product pages contain a description of the dataset and links to documentation and software like file viewers.

For news about newly released IceBridge data products, visit:
http://nsidc.org/data/icebridge/news.html

To see a list of IceBridge data broken down by instrument with descriptions and links, visit: http://nsidc.org/data/icebridge/instr_data_summary.html

To see the IceBridge data portal, visit:
http://nsidc.org/icebridge/portal/

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