Category Archives: Environmental Sensing

“Wearable” Sensors for Plants

I saw the headline about “wearable sensors for plants”, so I had to have a look.

Of course, the word “wearable” is kind of dumb here.

However, the technology is actually pretty cool: “a simple and versatile method for patterning and transferring graphene-based nanomaterials onto various types of tape to realize flexible microscale sensors.” [2]

Printing various patterns on tape can create sensors that measure strain, pressure, or moisture, for instance.  The sticky tape can attach to anything, including leaves of plants.  This is a cheap way to whip up and add sensors to the real world, including agricultural crops.

Pretty cool, even if plants don’t actually “wear” them.


  1. Liang Dong, Engineers make wearable sensors for plants, enabling measurements of water use in crops, in Iowa State University – News Service. 2018. https://www.news.iastate.edu/news/2018/01/03/planttattoosensors
  2. Seval Oren, Halil Ceylan, Patrick S. Schnable, and Liang Dong, High-Resolution Patterning and Transferring of Graphene-Based Nanomaterials onto Tape toward Roll-to-Roll Production of Tape-Based Wearable Sensors. Advanced Materials Technologies, 2 (12):1700223-n/a, 2017. http://dx.doi.org/10.1002/admt.201700223

 

Dusting the Ocean

One of the cool and important thing about Earth Observation from space is that it makes it possible to measure large scale events and interactions which are beyond the ability for puny humans to easily measure.

For example: dust.

In addition to silt from coasts and rivers, dust particles drift through the air from land, falling in the oceans (or distant land). While this dust is sometimes an important loss at the source (around here, we call it “soil erosion”, and we lament the loss of fertile, productive soil).  But it lands somewhere, and wherever it comes down, it is fertilizer from the sky.

For example, the vast dry lands of norther Africa are stripped of tons of dust every year, which blows across the Atlantic, where it falls to nourish the lush Amazon forests.   Wow!

This month NASA calls attention to another dust story, the annual rain of dust from Alaska out into the North Pacific.

image by Joshua Stevens, using MODIS data from LANCE/EOSDIS Rapid Response

This plume of dust is similar to the silt from a river or coast, except that it falls much farther off shore, potentially feeding plankton and other life there.

In particular, this dust contains iron, which is an important nutrient that is in short supply out in the ocean waters.

As is so often the case, the story is complex and not fully understood. It seems that this iron rich dust mainly blows out in the fall (the driest season, before the snow covers the land).  But plankton needs sunlight, too, so there isn’t much action until the next spring.  So the iron hangs around in the water over the winter somehow [2].

The research uses satellite imagery with measures from the land and sea.

This phenomenon is interesting for a second reason. Studies of paleoclimates using ice cores have found a negative correlation between atmospheric dust and carbon dioxide. There isn’t any obvious explanation for this relationship.

One possibility is that dust in the air fertilized plankton, which take up increased amounts CO2 from the air [3].

Maybe something like: glaciers grind the Earth, the dust blows out to sea, plankton blooms and eats more carbon dioxide, which reduces greenhouse effects, amplifying glaciation.


  1. Joanna E. Bullard, Matthew Baddock, Tom Bradwell, John Crusius, Eleanor Darlington, Diego Gaiero, Santiago Gassó, Gudrun Gisladottir, Richard Hodgkins, Robert McCulloch, Cheryl McKenna-Neuman, Tom Mockford, Helena Stewart, and Throstur Thorsteinsson, High-latitude dust in the Earth system. Reviews of Geophysics, 54 (2):447-485, 2016. http://dx.doi.org/10.1002/2016RG000518
  2. John Crusius, Andrew W. Schroth, Joseph A. Resing, Jay Cullen, and Robert W. Campbell, Seasonal and spatial variabilities in northern Gulf of Alaska surface water iron concentrations driven by shelf sediment resuspension, glacial meltwater, a Yakutat eddy, and dust. Global Biogeochemical Cycles, 31 (6):942-960, 2017. http://dx.doi.org/10.1002/2016GB005493
  3. Adam Voiland, Connecting the Dots Between Dust, Phytoplankton, and Ice Cores, in The Earth Observatory Image of the Day. 2017, NASA. https://earthobservatory.nasa.gov/IOTD/view.php?id=91267&src=eoa-iotd

 

 

Space Saturday

Antarctic Surface Under the Ice

In a valuable companion to research on the heat flux under Antarctica, a team of scientist from Edinburgh published new maps of the rocks under an important area of Antarctica.

The research group assembled a higher resolution map of the rock underneath the Pine Island Glacier in West Antarctica [2]. This is, of course, critical information for understanding and predicting the flow of the ice.

This region is particularly important because the glacier has been thinning and flowing into the sea rather rapidly over the past 50 years, contributing 5-10% of global sea rise observed. Thus, the speed of this process has an important impact on projections of sea level rise.

“The retreating Pine Island Glacier (PIG), West Antarctica, presently contributes ~5–10% of global sea-level rise. PIG’s retreat rate has increased in recent decades with associated thinning migrating upstream into tributaries feeding the main glacier trunk.”

The study used ice-penetrating radar to measure the rock under more than a kilometer of ice. The radar was dragged across the ice surface, collecting data in 40 x 100 m patches.

The findings show a remarkably varied and mountainous surface under the ice. This means that there is quite a lot of friction, which will slow the ice flow in many places. These findings will provide much better parameters to computational models of this glacier.

High-resolution images of the bed across Pine Island Glacier. a Location and context. In b, the colourmap shows regional bed topography from Bedmap223, the black line is the ice divide, the white line is the grounding line51, and high-resolution survey patches are shown as black rectangles. Locations of offshore bathymetry shown in Fig. 2c, f are marked. c uses the same schema but demarcating survey patches with white rectangles, labelled by season of data acquisition (2007/08, 2010/11 and ‘iSTAR’ = 2013/14) and an end label denoting the location (where ‘tr’ = trunk; ‘it’ = intertributary and ‘t1, t5…’ denotes tributaries numbered after ref. 52. Surface ice velocities53 contoured at 100-m intervals are also shown. d–l Perspective views of the bed beneath Pine Island Glacier, together with parameters of ice flow. Vertical exaggeration in all images = 10. τ b and U b are the mean basal shear stress (kPa) and mean basal ice velocity (m a−1) from model inversion37; P r is the measured upstream propagation rate of ice thinning per ice-stream tributary from 1992 to 2015 using a thinning/non-thinning threshold of 1.0 m a−1 6 and β is the inverted basal traction coefficient equal to τ b/U b

 

The detailed information from this study required close up, on site measurements. Perhaps it would be possible to get similar data from aircraft or spacecraft, though I suspect it would be difficult. Of course, the topographical information from this study will be combined with long term satellite observations of the air, ice, and sea, to get a more complete picture of what is happening.

It is interesting to note that despite the high friction underneath that we now know about, this glacier has been absolutely cruising retreating at rapid pace. How fast would it be melting if it weren’t sliding over the teeth of a mountain range? Is the rugged terrain under the ice helping to preserve the ice cap as the air and sea warm up?

This detailed study covers only one small patch of the Antarctic coast. It will be interesting to see the results of similar studies on other glaciers, as are planned.


  1. Jonathan Amos, Antarctic glacier’s rough belly exposed, in BBC News – Science & Environment. 2017. http://www.bbc.com/news/science-environment-42052072
  2. Robert G. Bingham, David G. Vaughan, Edward C. King, Damon Davies, Stephen L. Cornford, Andrew M. Smith, Robert J. Arthern, Alex M. Brisbourne, Jan De Rydt, Alastair G. C. Graham, Matteo Spagnolo, Oliver J. Marsh, and David E. Shean, Diverse landscapes beneath Pine Island Glacier influence ice flow. Nature Communications, 8 (1):1618, 2017/11/20 2017. https://doi.org/10.1038/s41467-017-01597-y

Antarctica Heat Flux Map

One of the most important scientific questions of the early twenty first century is, “what’s going on in Antarctica?”

Antarctica is a the largest reserve of ice on the planet, and when (not if) the ice melts, it will raise sea levels by tens of meters. Glub.  (See a new NASA simulation of the effects of the melting ice.)

Just how fast is the ice melting?

This is a complex question to answer. The ice caps are gigantic (miles deep at places), and warmed by the air above and the Earth and sea underneath. Warmer air and water melt the ice, but may produce more new snow. There are liquid rivers and lakes under the ice which erode and melt from underneath. In some places glacier of ice are flowing down to the sea, where they will break up and melt.

It’s complicated.

This week a team of British researchers published a map that reflects an important piece of the picture: the heat flux under the ice [3]. This is the heat coming from the Earth’s interior, which they show is quite variable across the continent.

Hotspots are located under West Antarctica; in contrast, the East is broadly relatively cold. British Antarctic Survey.

The study used several measures of the magnetic properties of the rock under the Antarctic ice, including surface, air craft, and satellite surveys. Molten rock loses its magnetic field at a specific temperature, so the magnetic measurements can show where the rock cools below this limit. This can be used to infer the temperature at various depths below the surface.

The resulting map shows considerable variation across the continent. The warmest locations will presumably tend to melt more than cooler places (on the underside of the ice).

One interesting point from the map is that West Antarctica is melting faster than other areas, but the heat flux from the Earth is low. This suggests that the melting is due to warmer seas and ice flows, with little contribution from geothermal heat.

This dataset will contribute to many studies of the Antarctic ice. (It will be literally the foundation for many simulations.)


  1. Jonathan Amos, Antarctica’s warm underbelly revealed, in BBC News – Science & Environment. 2017. http://www.bbc.com/news/science-environment-41972297
  2. Eric Larour, Erik R. Ivins, and Surendra Adhikari, Should coastal planners have concern over where land ice is melting? Science Advances, 3 (11) 2017. http://advances.sciencemag.org/content/3/11/e1700537.full

Yasmina M. Martos, Manuel Catalan, Tom A. Jordan, Alexander Golynsky, Dmitry Golynsky, Graeme Eagles, and David G. Vaughan, Heat flux distribution of Antarctica unveiled. Geophysical Research Letters:n/a-n/a, http://dx.doi.org/10.1002/2017GL075609

 

Listening for Mosquitos

The ubiquitous mobile phone has opened many possibilities for citizen science. With most citizens equipped with a phone, and many with small supercomputers in the purse or pocket, it is easier than ever to collect data from wherever humans may be.

These devices are increasing the range of field studies, enabling the identification of plants and animals by sight and sound.

One key, of course, is the microphones and cameras. Sold to be used for deals and dating, not to mention selfies, these instruments are outstripping what scientists can afford.

The other key is that mobile devices are connected to the Internet, so data uploads are trivial. This technology is sold for commerce and dating and for sharing selfies, but it is perfect for collecting time and location stamped data.

In short, the vanity of youngsters has funded infrastructure that is better than scientists have ever built. Sigh.


Anyway.

This fall the Stanford citizen science folks are talking about yet another crowd sourced data collection: an project that identifies mosquitos by their buzz.

According to the information, Abuzz works on most phones, including older flip phones (AKA, non-smart phones).

It took me a while to figure out that Abuzz isn’t an app at all. It is a manual process. Old style.

You use the digital recording feature on your phone to record a mosquito. Then you upload that file to their web site. This seems to be a manual process, and I guess that we’re supposed to know how to save and upload sound files.

The uploaded files are analyzed to identify the species of mosquito. There are thousands of species, but the training data emphasized the important, disease bearing species we are most interested in knowing about.

A recent paper reports the details of the analysis techniques [2]. First of all, mobile phone microphones pick up mosquito sounds just fine. As we all know, the whiny buzz of those varmints is right their in human hearing, so its logical that telephones tuned ot human speech would hear mosquitos just fine.

The research indicates that the microphone is good in a range of up to 100mm. This is pretty much what you would expect for a hand held phone. So, you are going to have to hold the phone up to the mosquito, just like you would pass it to a friend to say hello.

At the crux of the matter, they were able to distinguish different mosquitos from recordings made by phone. Different species of mosquito have distinct sounds from their wing beats, and the research showed that they can detect the differences from these recordings.

They also use the time and location metadata to help identify the species. For example, the geographic region narrows down the species that are likely to be encountered.

The overall result is that it should be possible to get information about mosquito distributions from cell phone recordings provided by anyone who participates. This may contribute to preventing disease, or at least alerting the public to the current risks.


This project is pretty conservative, which is an advantage and a disadvantage. The low tech data collection is great, especially since the most interesting targets for surveillance are likely to be out in the bush, where the latest iPhones will be thin on the ground.

On the other hand, the lack of an app or a plug in to popular social platforms means that the citizen scientists have to invest more work, and get less instant gratification. This may reduce participation. Obviously, it would be possible to make a simple app, so that those with smart phones have an even simpler way to capture and upload data.

Anyway, it is clear that the researchers understand this issue. The web site is mostly instructions and video tutorials, featuring encouraging invitations from nice scientists. (OK, I thought the comment that “I would love to see is people really thinking hard about the biology of these complex animals” was a bit much.

I haven’t actually tried to submit data yet. (It’s winter here, the skeeters are gone until spring). I’m not really sure what kind of feedback you get. It would be really cool to return email a rapid report (i.e., within 24 hours). It should say the initial identification from your data (or possibly ‘there were problems, we’ll have to look at it), along with overall statistics to put your data in context (e.g., we’re getting a lot of reports of Aegyptus in your part of Africa).

To do this, you’d need to automate the data analysis, which would be a lot of work, but certainly is doable.


I’ll note that this particular data collection is something that cannot be done by UAVs. Drones are, well, too droney. Even if you could chase mosquitos, it would be difficult to record them over the darn propellers. (I won’t say impossible—sound processing can do amazing things).

I’ll also note that this research method wins points for being non-invasive. No mosquitos were harmed in this experiment. (Well, they were probably swatted, but the experiment itself was harmless.) This is actually important, because you don’t want mosquitos to selectively adapt to evade the surveillance.


  1. Taylor Kubota, Stanford researchers seek citizen scientists to contribute to worldwide mosquito tracking, in Stanford – News. 2017. https://news.stanford.edu/2017/10/31/tracking-mosquitoes-cellphone/
  2. Haripriya Mukundarajan, Felix Jan Hein Hol, Erica Araceli Castillo, and Cooper Newby Using mobile phones as acoustic sensors for high-throughput mosquito surveillance. eLife. doi: 10.7554/eLife.27854 October 11 2017, https://elifesciences.org/articles/27854#info

BeePi: Open Source Hardware

OK, I have my reservations about the Internet of Things (AKA the Internet of Way Too Many Things, or the Internet of Things That Don’t Work Right).  And I have also expressed concerns about DIY environmental sensing, which is usually long on sensing and short on validity.

But let’s combine IoT concepts with useful environmental monitoring, and validate the measurements, and I’m all for it.

Plus, I’m really worried about the bees.

So I am very interested in Vladimir Kulyukin’s BeePi, a Respberry Pi based bee hive monitor. Over the past decade, his team has developed low cost sensors and in situ data analysis that measures the sound, sight, and temperature of a bee hive. The sensors are minimally invasive, and collect data more or less continuously.

Vladimir Kulukin downloads data from a BeePi system at a honey bee hive in Logan on Monday afternoon. The USU computer science professor started a Kickstarter campaign for the device and surpassed his goal within the first two weeks. John Zsira/Herald Journal

Unlike bogus “Pigeon backpack” projects, this group has actually developed, validated, and published analytics that turn the sensor traces into potentially useful data about the behavior of bees. (E.g. see [1].)

The sound recordings can, in principle, give clues about the number and activity of the bees. At the coarsest level, they have easily documented the daily cycle of activity. I.e, they have confirmed day and night.

The visual imagery is used to detect bees entering and leaving the hive. This is an important indicator of foraging activity and overall health of the colony, and might give early warning of trouble in the hive.

The temperature measures correlate with overall activity, and abberant readings would indicate serious problems inside the colony.

The researchers aim to publish their hardware and software designs, so others can build and improve the idea. (It isn’t immediately clear what kind of licensing is intended, other than it is open source.)

In a sad sign of the times, they are doing a kickstarter to raise money ($1,000 !?) to build some more prototypes. In a sane world, funding agencies and companies would be beating down their doors trying to give them research support. And it would be many tens of thousands.

Another sign of the times is that the kickstarter is the most complete information about the project. Get a web page, guys!!


This project is pretty cool, and made me think.

As a distributed systems guy, the need for manual downloads is just too crude. A future version should have some kind of low power networking that, ideally, will automatically upload data to archives, e.g., in a cloud. A concomitant upgrade would be to beef up the data formats (they need to be documented, and would be better with standard metadata). It would be nice to have standard APIs for pushing and grabbing the data.

Bee hives tend to be scattered and far from networks, though. But perhaps a small UAV “data harvester”, might fly around, hover a couple of meters away to suck out the data through a short range link, and return to base after its rounds. Sort of “sneaker net” in the age of ubiquitous drones.  Such a drone might be useful for many environmental sensing tasks.

On the sensor front, I would think that humidity sensors would be a simple and important addition to the system. I think (but I’m not sure) that humidity is linked to some possible colony problems.

And what about lidar or sonar? The cost of lidar and sonar is crashing, so you might be able to add these to the sensors. Combined with the imagery, this would give even better bee counts (and in all weather, assuming the bees are active in all weather, which I’m not sure about).

Finally, I would suggest that the creators define how they want to share their system and data from it. Creative commons would be a place to look for ideas. <<link>> I would think that the plans and software might be shared through some existing maker community archive. E.g., Instructables, SparkFun, or AdaFruit would be plausible possibilities.  (Call me.)


This is a good example of low cost environmental sensing.  They are doing the hard work of validating the measurements.

There is a lot of work that could be done to make this a slicker and easier to use open source project. Documentation, publishing the design, and setting up a data archive are pretty straightforward, but would make a huge difference.  (Call me.)


  1. Vladimir Kulyukin and Sai Kiran Reka, A Computer Vision Algorithm for Omnidirectional Bee Counting at Langstroth Beehive Entrance, in nternational Conference on Image Processing, Computer Vision, and Pattern Recognition (IPCV’16). 2016: Las Vegas. p. 229-235. http://worldcomp-proceedings.com/proc/p2016/IPC3835.pdf
  2. John Zsiray, USU professor hopes ‘BeePi’ hive sensors will help honeybees, in The Herald Journal – HJNews.com. 2017. https://news.hjnews.com/agriculture/usu-professor-hopes-beepi-hive-sensors-will-help-honeybees/article_7c205ecb-1d64-51d3-96c1-b1754de27d6f.html

Sun2ice: Solar Powered UAV

One of the important use cases for UAVs is surveillance in all its forms. Small, cheap aircraft can cover a lot of area, carry a lot of different sensors, and swoop in to obtain very close up information.   In some cases, a human can directly control the aircraft (as in selfie cams and drone racing), but for many cases the UAV needs to be substantially autonomous.

Furthermore, remote observation generally needs long, slow flights, rather than short, fast ones. Range and flight duration are critical.

Remote sensing by UAVs is ideal for many kinds of environmental research, especially in remote areas such as deserts, oceans, or polar regions. A fleet of (inexpensive) UAVs can multiply the view of a single (very expensive) scientist by orders of magnitude, measuring a broad area, and identifying points of interest for detailed investigation.

This summer a group of researchers from ETH and the AtlantikSolar company have demonstrated a UAV that continuously monitored glaciers in Greenland. The Sun2ice is solar powered, so it charges its batteries as long as the sun is shining. In the polar summer, there is essentially 24 hour sunlight, so the UAV has power to fly continuously for months, at least in principle. Like other solar powered aircraft and boats, the AtlantikSolar needs not fuel and should be capable of extremely long missions.

Of course, flying over Greenland is difficult for any aircraft, and flying a small UAV continuously over remote and rugged glaciers is very challenging. The aircraft must deal with high winds and cold temperatures, even in good weather. With no pilot on board, the control systems must be highly automated.

The UAV must navigate over uninhabited territory, far from the humans back at base. It has to stay on station to collect data continuously, with little help from people. Magnetic compasses don’t work on Greenland, and continuous daylight means that celestial navigation is not possible either.

The researchers also had to deal with take off and landing from a remote field station. The video shows the UAV being delivered to its launch point via dogsled—Pleistocene technology deploying twenty first century technology. The test flights were successful, though flying time was less than a full day.

Flying an experimental solar-powered UAV as AtlantikSolar in Arctic conditions is very challenging due to the narrow sun angle, extreme climatic conditions, the weakness of the magnetic field used for the compass, and the absence of smooth grass-covered terrain to land a fragile airplane.

This technology is ideal for intense observation of glaciers and other natural phenomena. The UAV flies low enough to obtain high resolution images, and if it can stay on station, can provide updated data every hour or less. The UAV is cheaper than a satellite, and even than a piloted aircraft. It would be possible to deploy a fleet of UAVS to monitor a glacier or volcano in great detail for substantial periods.

Cool.


  1. Philipp Oettershagen, Amir Melzer, Thomas Mantel, Konrad Rudin, Thomas Stastny, Bartosz Wawrzacz, Timo Hinzmann, Stefan Leutenegger, Kostas Alexis, and Roland Siegwart, Design of small hand-launched solar-powered UAVs: From concept study to a multi-day world endurance record flight. Journal of Field Robotics, 34 (7):1352-1377, 2017. http://dx.doi.org/10.1002/rob.21717

 

Robot Wednesday