Rubber Duckies and Other Oceanographic Equipment

Rubber ducks in the 2009 Ken-Ducky Derby, floating along an inland stream.  Image credit: Tony Crescibene (CC-BY)
Rubber ducks in the 2009 Ken-Ducky Derby, floating along an inland stream. Image credit: Tony Crescibene (CC-BY)

On January 10, 1992, on a voyage from Hong Kong to Tacoma, Washington, the cargo vessel Ever Laurel encountered rough seas and a container was washed off the ship. The container broke open and released its contents: 28,800 yellow rubber duckies and other floating bath toys. Since then, the duckies have been floating around, moved by wind and wave, and washed up on coasts around the world. By tracking the date and location of washed-up duckies, oceanographers can get a sense for the speed and direction of surface circulation at an oceanic scale. It’s like having 28,800 messages in bottles dumped from the same known location at the same known time.

Oceanographers sometimes want to be more precise in their measurements. The duckies probably floated very high in the water (at least at first), so that the wind could easily affect their direction and speed. Additionally, the rubber duckies are hard to track while they are at sea because they are small, few, and far between.

When more precise measurements are required, oceanographers turn to specially-designed drift buoys. These maintain a lower profile above water, and have a large “holey sock” sea anchor tethered to them in order to more accurately measure the ocean surface currents and not the wind. The buoys also have a thermometer—and sometimes additional sensors for salinity or barometric pressure—and a radio transmitter to establish the buoy’s position (by Doppler shift from 401.65 MHz, not GPS) and relay data via satellite back to the operations center.

Surface Velocity Program buoys around the world.  All instruments have sea surface temperature (SST), blue instruments have sea-level pressure (SLP).  Several red points near Heard Island and between Heard Island and Perth, Australia are from the recent R/V Investigator voyage the Heard Island area.  Image credit: NOAA (public domain).
Surface Velocity Program buoys around the world. All instruments have sea surface temperature (SST), blue instruments have sea-level pressure (SLP). Several red points near Heard Island and between Heard Island and Perth, Australia are from the recent R/V Investigator voyage the Heard Island area. Image credit: NOAA (public domain).

Different floats can be used to measure temperature and salinity profiles, rather than surface currents. Argo floats are autonomous diving instruments, which can maintain neutral buoyancy and perform controlled ascent/descent to 2000 m. These floats make their temperature, pressure, and salinity measurements during a 6–12 hour ascent. Upon reaching the surface, they transmit their GPS location and the recorded data back to the operations center via satellite. Argo floats are not cheap, with each carrying a price tag of around $15k.

On the Heard Island Expedition, our team will be deploying both of these types of instruments. These measurements will improve understanding of ocean circulation, heat content, and salinity, as well as providing ground-truth sea surface temperature measurements for use in weather forecasting models. No rubber duckies will be deployed, but we’ll document any we find washed up on the beaches.

Still want more marine science? Check out DeepSeaNews!

Ionospheric Science and Amateur Radio from Heard Island

Aurora Australis seen from the International Space Station as it flew over Heard Island on September 7, 2015.  Image credit: NASA (public domain).
Aurora Australis seen from the International Space Station as it flew over Heard Island on September 7, 2015. Image credit: NASA (public domain).

High above Earth’s surface, roughly 60–1000 km up, is an intriguing part of Earth’s upper atmosphere called the ionosphere. High-energy light (mostly ultraviolet and X-rays) causes electrons to be stripped away from gas molecules and neutral atoms, forming ions (and free electrons). The incoming light is most intense at the upper edge of the atmosphere (before it is absorbed), but the density of atoms and molecules is higher at lower altitudes (with atmospheric density highest at the Earth’s surface), leading to a peak in ionization in an intermediate region. Much of the interesting action in the ionosphere is in the regions between 60–300 km up, where the electron density is highest (though still very low compared to sea level).[1]

Under many conditions, radio waves between 160 m and 10 m (with frequencies of 1.8–30 MHz) can be refracted by the ionosphere, enabling wireless communication around the globe. This long-distance propagation is, at least to me, a wondrous phenomenon.

Effectively, there is a low-frequency limit below which the radio waves are strongly absorbed by the atmosphere. At a sufficiently high frequency, the radio waves will not refract back down to Earth, and will simply pass into space. However, in the Goldilocks zone between those two frequencies (the lowest usable frequency and maximum usable frequency), propagation can occur.

Schematic cartoon of ionospheric propagation.  Image credit: NOAA (public domain).
Schematic cartoon of ionospheric propagation. Image credit: NOAA (public domain).

With the amount and intensity of sunlight reaching the ionosphere changing throughout the course of the day, year, and solar cycle, the maximum and lowest usable frequencies will change as well. Additionally, since not all of the globe is illuminated at the same time, these limiting frequencies will vary spatially. Consequently, the maximum usable frequency in one location may be below the lowest usable frequency somewhere else, and no radio contact can be made between those points at that time.

Scattered around the world are many, many radio stations operated by licensed amateurs (sometimes also called hams; etymology unclear).[2] One aspect of the hobby which many amateurs enjoy is making contact with amateurs in other countries around the world. Just like birders have a life list of the species of birds they have seen, amateur radio operators often keep a list of other countries and territories they have contacted, splitting this list further by frequency and operating mode (Morse code, voice, or digital). Currently, there are 340 recognized entities worldwide.[3] Of those 340, many are small reefs, islands, or archipelagos, and may not have any permanent population—such as Heard Island, making them very rare. The last time Heard Island was heard on amateur radio was in 1997. It’s presently the longest-inactive of the 340 entities and ranks around #5 on most-wanted lists. Many amateurs have been looking forward to this expedition for a long time, and have been very generous in supporting it financially.

On Heard Island, our team will put up several amateur radio antennas at Atlas Cove, and set up approximately 6 radios. We will then make contacts with as many stations as we can on the various amateur frequencies, in a combination of voice, Morse code, and digital modes, using the callsign VKØEK. Contacts are extremely brief which helps keep the throughput high, giving more stations a new entity for their list and us a more statistically significant sampling of the ionospheric conditions.

Here’s how a voice contact might proceed:

[VKØEK]: Victor kilo zero echo kilo, listening up
[Din of thousands of stations calling with their callsigns]
[VKØEK]: Kilo zero bravo bravo charlie, five nine4
[KØBBC]: Five nine, thanks
[VKØEK]: Thank you

It’s not a long, drawn-out conversation, but is enough to be logged on both ends as having happened. Under ideal circumstances, within a minute or two, that contact will be shown on a near-real-time map of contacts from Heard Island. With luck and the cooperation of stations around the world, we should be able to log >100,000 contacts over the three-week period and gather some very interesting data about which frequencies work to which places at which times.

Simulated near-real-time map of contacts with Heard Island, shown on the DXA3 website.  QSO is radio shorthand for contact.  Numbers under Currently Working heading are approximate wavelengths in meters, corresponding to the amateur radio allocations.
Simulated near-real-time map of contacts with Heard Island, shown on the DXA3 website. QSO is radio shorthand for contact. Numbers under Currently Working heading are approximate wavelengths in meters, corresponding to the amateur radio allocations.

Of course, one other advantage of the amateur radio operation is that it is yet another means of communication in the case of an emergency. While we hope that no emergency communications are needed of any type, and we have a number of satellite communications options, amateur radio provides one more level of redundancy, and has been shown to be reliable in places where little or no infrastructure exists (e.g. following major earthquakes, hurricanes, etc.).

The ionosphere does amazing things, and our amateur radio operation will both yield data on the ionosphere as well as make many thousands of amateur radio operators happy that they were able to contact a new entity.

*** Notes and References ***

[1] For a point of reference, airplanes generally fly at a height of 10–13 km, the highest jet aircraft flight record is 37.6 km, and the International Space Station is at a height of roughly 340 km; even high-altitude weather balloons and rarely exceed 40 km.

Features of Earth's atmosphere.  Image credit: NOAA (public domain).
Features of Earth’s atmosphere. Image credit: NOAA (public domain).

[2] In the US, getting an entry-level amateur radio license requires passing a 35-question multiple-choice test on terminology, regulations, basic electronic theory, and operating practices, and is roughly equivalent to a written driver’s exam. Knowledge of Morse code is not required. For more on US licensing, see this page.

[3] Islands and outlying territories beyond certain distances from the main entity are considered separate, so Hawaii, Alaska, Puerto Rico, and the US Virgin Islands all count as separate entities even though they are US states, territories, or possessions. The gritty details on criteria for listing as separate entities is found in section 2 here.

[4] “Five nine” is a signal report, meaning “I hear you loud and clear”.

Show Me the Data: Satellite Observations

Heard Island, March 27, 2013.  Elephant Spit imagery (at right) is from March 3, 2013.  Image has been adjusted to increase bring out detail in exposed land.  Image credit: processed by Bill Mitchell (CC-BY) using data from NASA/EO-1 (public domain).
Heard Island, March 27, 2013. Elephant Spit imagery (at right) is from March 3, 2013. Image has been adjusted to increase bring out detail in exposed land. Image credit: processed by Bill Mitchell (CC-BY) using data from NASA/USGS/EO-1 ALI (public domain).

With Heard Island being remote and uninhabited, studying it can be a bit difficult. However, as readers of this blog (and my Twitter followers) are aware, one of the ways I have been preparing for the expedition is by keeping an eye on it using various satellites and their remote sensing capabilities. Sure, there is often cloudcover at Heard, but some days it’s clearer and on a few of those days, the satellites pass over.

Most of my information comes from NASA’s MODIS instruments, aboard the Terra and Aqua satellites. These have at least every-other-day coverage of everywhere on Earth, although with a moderate resolution of 250 m/pixel. In the morning when I’m catching up on email and comics, I’ll check the near-real-time MODIS image page to see whether there are clear images of Heard Island from either instrument. Finding Heard Island can be difficult: I still usually find the Kerguelen Islands first, then look to the south-southeast. Many times there are indications such as vortices or gravity waves (not gravitational waves, those are different).

A related page is MODVOLC, which uses MODIS for volcano monitoring. In addition to visible light, MODIS can detect several wavelengths of infrared, and the signature from those wavelengths can be used to determine whether there is a likely volcanic eruption occurring at a given place.

MODIS is a great instrument in that it has daily or every-other-day coverage. However, the 250 m/pixel resolution can be quite limiting. For higher-resolution imagery, I look to the ALI instrument on NASA’s EO-1 satellite. These images are available (free registration required) from EarthExplorer, a data search portal from the USGS. ALI has a 30 m/pixel resolution on its color imagery, and 10 m/pixel resolution on the panchromatic image (total light intensity). These can be combined using QGIS into 10 m/pixel color images. By exploring the EO-1 page I found that members of the public can make requests for image targets! Imaging requests are subject to a bunch of conditions (availability of satellite, >30-day lead time, recommended >3 month window for imaging), but the request and any data generated from fulfillment of the request are free.

How did I come to know about these great resources? It takes time, searching, and some attention to detail. MODIS I learned about as a graduate student, from friends who used data products (not the true-color imagery) in their doctoral research on atmospheric chemistry. I came across EO-1 ALI from searching for images of Heard Island: I found some higher-than-MODIS resolution images from NASA which were good about indicating the source satellite/instrument. Citing image sources is incredibly useful, and I’m always disappointed when images (at least, non-screenshot images) are given without any sort of source information.

MODVOLC I learned about from the Smithsonian’s Global Volcanism Program, which cites the sources of their eruption reports. Information about the source plus a little searching yielded an interesting and useful data source.

A One-Stop Heard Island Expedition Primer

North-up view of Heard Island seen from the International Space Station, Nov. 24, 2011.   Image credit: NASA (public domain)

North-up view of Heard Island seen from the International Space Station, Nov. 24, 2011. Image credit: NASA (public domain)

Heard Island, the southernmost surface exposure of the Kerguelen Plateau, is an uninhabited Australian territory situated in the southern Indian Ocean, roughly 450 km SE of the Kerguelen Islands. It is classified as a UNESCO World Heritage Site both for its geologic significance as well as its relatively undisturbed ecosystem. Heard Island is unique among sub-Antarctic islands for having no known human-introduced species.

Physically, Heard Island is roughly circular, with a diameter of 20 km. In the center is Big Ben, a volcano which reaches to 2700 m and was observed erupting within the last 10 days. To the southeast is Elephant Spit, a long sandy spit which protrudes 10 km past the circular shape of the island. In the northwest is the Laurens Peninsula, where volcanoes have added another 10 km to the windward side of the island, against the erosive power of the heavy Southern Ocean seas.

On March 10th, an expedition team of 14 scientists and a ship’s crew of five will depart Cape Town, South Africa, aboard the Braveheart and begin the roughly (and rough) 10-day voyage southeast to the island. Upon arrival at Heard Island, our team will wait for sufficiently calm surf to safely land boats on the beach. About three weeks will be spent on the island before a 10-day voyage to Fremantle, Australia.

For accommodations, two HDT Global air-beam shelters (20’x21′) will be erected at Atlas Cove, in the northwestern part of the island and in the lee of the Laurens Peninsula. A covered walkway, also from HDT Global, will allow travel between tents without full exposure to the elements. Nearby is an emergency refuge (condition unknown) from previous Australian Antarctic Division expeditions, as well as the potentially asbestos-containing ruins of the Australian research base from the 1947-1955 expedition. The ruined base is in a restricted area on account of the asbestos, and expedition members will not enter that area. Restrooms will be in the form of a portable toilet, and portable generators will provide electricity for the site.

Airbeam tent set up at HDT Global headquarters.  This is one of two which will be set up on Heard Island.  Image credit: Cordell Expeditions.
Airbeam tent set up at HDT Global headquarters. This is one of two which will be set up on Heard Island. Image credit: Cordell Expeditions.

Although featuring a large, vegetation-free sand and gravel plain, Atlas Cove is not devoid of life. Our neighbors will include elephant seals, fur seals, four species of penguin—gentoo, king, macaroni, and rockhopper—and many other types of seabirds. Leopard seals have been seen at Atlas Cove as well. To the northeast on the Azorella Peninsula, a colony of the endemic Heard Island cormorants nests atop a moss-covered lava field (access is forbidden due to the sensitive mosses and potential for lava tube collapse).

Communications is an important part of this project. Already we have done a major outreach effort in person, via the internet, and on social media. Many different levels of communications need to be covered: ship-to-civilization, ship-to-island, on-island, island-to-civilization, and amateur radio from the island. We will have several different satellite phone/data systems, marine radios for ship-to-island contacts, and amateur radios for both on-island and worldwide communications. Being able to talk with field teams, the ship, and the outside world is a important for a safe expedition.

Soon after the tents and generators are set up, the antennas used to make contacts around the world will be erected. Amateur radio operators have given generously to support this expedition, and are often curious about science. Making contacts with these amateur stations helps to bring visibility to Heard Island, its unique geology and ecology, and the science being done to better understand and protect the World Heritage Site. Large numbers of amateur radio contacts will also provide an interesting dataset, because the locations one can reach will vary depending on conditions in the upper atmosphere (ionosphere). During the expedition, near-real-time maps of contacts can be found here.

At the camp, an automated weather station will be set up. Being far from human civilization and in the middle of the ocean, a record of weather at Heard Island would be valuable for assessing climate change in an under-sampled region of the globe.

Automated weather station for temperature, pressure, relative humidity, and wind measurements.  Our station will be similar but not identical to this one.  Image credit: US Marine Corps (public domain)
Automated weather station for temperature, pressure, relative humidity, and wind measurements. Our station will be similar but not identical to this one. Image credit: US Marine Corps (public domain)

When weather permits, a small field party will venture out to collect rock samples from the Laurens Peninsula. These samples will be used to answer questions like the environmental conditions when the rock was deposited, the processes that produced the unit (glacial, marine, volcanic, etc.), the duration of deposition, and the age (via biostratigraphy or radioisotopic dating). It is unknown when volcanism began on Heard Island, and whether the volcanism has been relatively continuous or more episodic. There have been no geologic research parties on the island since 1987, so this is an opportunity to collect important samples—especially because glacial retreat has exposed areas which were previously inaccessible. Field parties will not only collect samples, but will map the extent of glaciation and vegetation using GPS.

I will be taking the lead on a different geology project: capturing high-resolution panoramic pictures. Through collaboration with Prof. Callan Bentley and the GEODE project supported by the National Science Foundation (NSF DUE 1323419), we will have a Gigapan system on Heard Island. Using a robotic camera mount and a telephoto lens, a series of images are taken from one location. Upon return to camp, the images are transferred to a computer, where they are automatically stitched together with specialized software. The resulting images, which can be several gigapixels large, can be viewed using a web browser and offer pan-and-zoom capabilities (example from Axel Heiberg Island, Nunavut, Canada). We will use these high-resolution images to provide context for geologic sampling, to document the extent of glaciers and the appearance of landforms, and potentially to estimate populations of seabirds or marine mammals. Because the images will be very large, they may not be available online until after we return to the developed world.

Another project I have in mind, which may or may not be feasible, is to do at least some basic population counts for eBird. There have been four eBird checklists submitted for Heard Island, but none in March or April. I feel fairly confident on my ability to distinguish different types of penguins (at least at close range). Other seabirds, such as albatrosses, petrels, and prions, will be more difficult for me. Perhaps another team member will be able to help out.

Rockhopper penguins in the Falkland Islands.  Image credit: David Stanley (CC-BY)
Rockhopper penguins in the Falkland Islands. Image credit: David Stanley (CC-BY)

Along the shoreline, our team will record the concentrations of anthropogenic marine debris (plastic bits, fishing gear, etc.). The amount of debris and extent to which it is interfering with seabirds and marine mammals at Heard Island is unknown, and we are particularly interested in documenting cases where skeletal remains have associated debris.

There are a few more projects, and more detailed project descriptions can be found on the expedition website project page. If the winds are calm enough a few quadcopters may even be deployed to take pictures in areas too dangerous for us to reach on foot.

Heard Island is home to virtually pristine ecosystems, and our expedition will take care to keep it that way. Rodents are a particularly high concern, so before the ship sails from Cape Town, it needs to be certified free of rodents and must follow several rat prevention protocols. All gear has to be thoroughly cleaned and sanitized before being brought onto the island. On the island, when we move between ice-free areas (Atlas Cove and Spit Bay), we have to clean everything again. Even the food we eat must be in line with ecosystem preservation: no fresh fruit or vegetables, no poultry or eggs (except egg powder kept in sealed containers opened only indoors), and no brassicas (broccoli, cabbages, turnips). This expedition isn’t just an extra-large camping trip.

After three weeks of science, radio, documentation, and outreach, we will pack everything back up onto the Braveheart and embark on a 10-day voyage to Fremantle, Western Australia. On the ship, to the extent we are functioning on what could well be very rough seas, we will probably get started on data analysis, further documentation, and the task of identifying the most compelling photographs.

Polar projection map of the route to and from Heard Island.  Image credit: Bob Schmieder/Cordell Expeditions
Polar projection map of the route to and from Heard Island. Image credit: Bob Schmieder/Cordell Expeditions

When possible, I will try to maintain my presence on Twitter (@i_rockhopper) and here on this blog during the expedition. However, I do not expect to have much time or bandwidth for such things when there is a lot of important field work to do. My hope is that I will get some posts queued up and scheduled for release during the expedition. However, failing that, the best place to find news will be the expedition website and the radio-focused website.

I’m very excited about these projects, and look forward to being on Heard Island in about six weeks!

Update Feb. 11, 2016: There has been a correction on the project collaboration for the Gigapans. The first version wrongly credited the NSF support to the MAGIC project, rather than its umbrella project, GEODE.

Geoscientist’s Toolkit: Pressure Vessels

Pressure vessels ("bombs") used for high-temperature dissolution of zircon.  Image credit: Bill Mitchell (CC-BY).
Pressure vessels used for high-temperature dissolution of zircon. Image credit: Bill Mitchell (CC-BY).

When scientists are measuring the uranium and lead in a rock—specifically in the mineral zircon, found in many igneous rocks—to determine its age (U/Pb geochronology), they need to dissolve the zircon. Zircon is a very stable mineral, so to dissolve zircon, the mineral grains are subjected to acids at high temperatures (~200 °C) and pressures. Thick steel pressure vessels are needed to contain an inner teflon vessel when it heats up and the liquid inside boils.

In the picture above, there are two pressure vessels. On the right of the red marker, a smaller vessel is used when the zircons from one rock sample are being partially dissolved to remove the exterior surface (chemical abrasion). To the left of the red marker, the large vessel is used for the final dissolution, when zircon grains are on teflon racks with individual teflon capsules.

Eruption on Heard Island

Today there is a new video out from scientists aboard the R/V Investigator which shows a volcanic eruption occurring from Mawson Peak, Heard Island. This is an exciting video not because it is unusual for an eruption to happen on Heard Island—the Global Volcanism Program shows activity on about an annual basis for the last few years—but because it is unusual for someone to be there to see it!

In the video above, a small plume can be seen over Mawson Peak, and a few lava flows. Given the terrain near the summit and the imagery below from lava flows in 2013, I think it is safe to say that the flows are heading down the southwest flank. As someone going to this island in less than two months, the direction of lava flows is important: it is away from the campsites which we intend to use.

Lava flow on Heard Island, April 20, 2013. Image credit: NASA Earth Observatory image by Jesse Allen and Robert Simmon, using EO-1 ALI data from the NASA EO-1 team.
Lava flow on Heard Island, April 20, 2013. Image credit: NASA Earth Observatory image by Jesse Allen and Robert Simmon, using EO-1 ALI data from the NASA EO-1 team.

From the video above, this appears to be an effusive eruption, where lavas gently flow out of the volcano. That eruptive style is consistent with a hot (~1100 °C), basaltic (low-SiO2) melt—eruptions with a high SiO2 content tend to have cooler lava and are more often explosive in nature. Basalts or other lavas (trachybasalts and basanites) with low SiO2 (48–52%) are typical of the Big Ben series of lavas (Big Ben being the volcano upon which Mawson Peak is located).[1] Predicting that the lavas from this eruption would be generally low-SiO2 seems fairly safe, although our expedition is not equipped to undertake the sampling required to test that prediction.

Finally, if you’re wondering what happens when a basaltic lava flows out onto ice and snow, know that experimental volcanologists at Syracuse University have asked that question and made a video.

***

[1] Barling, J.; Goldstein, S. L.; Nicholls, I. A. (1994) Geochemistry of Heard Island (Southern Indian Ocean): Characterization of an Enriched Mantle Component and Implications for Enrichment of the Sub-Indian Ocean Mantle. Journal of Petrology 35:1017-1053, doi 10.1093/petrology/35.4.1017.