Category: Sensors

Predicting Sea Surface Salinity from Space

The simplest definition of salinity is how salty the ocean is. Easy enough, right? Why is this basic property of the ocean so important to oceanographers? Well, along with the temperature of the water, the salinity determines how dense it is. The density of the water factors into how it circulates and mixes…or doesn’t mix. Mixing distributes nutrients allowing phytoplankton (and the rest of the food web) to thrive. Globally, salinity affects ocean circulation and can help us understand the planet’s water cycle. Global ocean circulation distributes heat around the planet which affects the climate. Climate change is important to oceanographers; therefore, salinity is important to oceanographers.

Spring Salinity Climatology for the Chesapeake

Spring Salinity Climatology for the Chesapeake

Salinity doesn’t vary that much in the open ocean, but it has a wide range in the coastal ocean. The coast is where fresh water from rivers and salt water in the ocean mix. Measurements of salinity along the coast help us understand the complex mixing between fresh and salty water and how this affects the local biology, physics, and chemistry of the seawater. However, the scope of our measurements is very small. Salinity data is collected by instruments on ships, moorings, and more recently underwater vehicles such as gliders. While these measurements are trusted to be very accurate, their spatial and temporal resolution leaves much to be desired when compared to say daily sea surface temperature estimated from a satellite in space.

So, why can’t we just measure salinity from a satellite?Well, it’s not as simple, but it is possible. NASA’s Aquarius mission http://aquarius.nasa.gov/ which was launched this past August is taking advantage of a set of three advanced radiometers that are sensitive to salinity (1.413 GHz; L-band) and a scatterometer that corrects for the ocean’s surface roughness. With this they plan on measuring global salinity with a relative accuracy of 0.2 psu and a resolution of 150 km. This will provide a tremendous amount of insight on global ocean circulation, the water cycle, and climate change. This is great new for understanding global salinity changes. What about coastal salinity? What if I wanted to know the salinity in the Chesapeake Bay? That’s much smaller than 150 km.

That’s where my project comes in. It involves NASA’s MODIS-Aqua satellite (conveniently already in orbit: http://modis.gsfc.nasa.gov/), ocean color, and a basic understanding of the hydrography of the coastal Mid-Atlantic Ocean. Here’s how it works: we already know a few things about the color of the ocean, that is, the sunlight reflecting back from the ocean measured by the MODIS-Aqua satellite. We know enough that we can estimate the concentration of the photosynthetic pigment chlorophyll-a. So not only can we see temperature from space, but we can estimate chlorophyll-a concentrations too! Anyway, there are other things in the water that absorb light besides phytoplankton and alter the colors we measure from a satellite.

Spring Salinity Climatology for the Mid-Atlantic

Spring Salinity Climatology for the Mid-Atlantic

We group these other things into a category called colored dissolved organic material or CDOM. CDOM is non-living detritus in the water that either washes off from land or is generated biologically. It absorbs light in the ultraviolet and blue wavelengths, so it’s detectable from satellites. In coastal areas especially, its main source of production is runoff from land. So, CDOM originates from land and we can see a signal of it from satellites that measure color. What’s that have to do with salinity?

You may have already guessed it, but water from land is fresh. So, water in the coastal ocean that is high in CDOM should be fresher than surrounding low CDOM water. Now we have a basic understanding of the hydrography of the coastal Mid-Atlantic Ocean, how it relates to ocean color, and why we need the MODIS-Aqua satellite to measure it. So, I compiled a lot of salinity data from ships (over 2 million data points) in the Mid-Atlantic coastal region (Chesapeake, Delaware, and Hudson estuaries) and matched it with satellite data from the MODIS-Aqua satellite in space and time. Now I have a dataset that contains ocean color and salinity. Using a non-linear fitting technique, I produced an algorithm that can predict what the salinity of the water should be given a certain spectral reflectance. I made a few of these algorithms in the Mid-Atlantic, one specifically for the Chesapeake Bay. It has an error of ±1.72 psu and a resolution of 1 km. This isn’t too bad considering the range in salinity in the Chesapeake is from 0-35 psu, but of course there’s always room for improvement. Even so, this is an important first step for coastal remote sensing of salinity. An algorithm like this can be used to estimate salinity data on the same time and space scale as sea surface temperature. That’s pretty useful. The folks over at the NOAA coastwatch east coast node thought so too. They took my model for the Chesapeake Bay and are now producing experimental near-real time salinity images for the area. The images can be found here: http://coastwatch.chesapeakebay.noaa.gov/cb_salinity.html. They will test the algorithm to see if it is something they want to use

Climatologies of salinity for all of my models can be downloaded here: http://modata.ceoe.udel.edu/dev/egeiger/salinity_climatologies/.

I view this project as an overall support of the NASA Aquarius mission by providing high resolution coastal salinity estimates that are rooted in in situ observations. I hope this information proves to be useful for coastal ocean modeling and understanding the complex process that effect the important resource that is our coasts.

Hurricane Katia Footprints

The ORB Lab was having a meeting in the GVis Lab this week and, as usual, the East Coast US 8-Day Averaged Sea Surface Temperature overlay was up on the screens. Dr. Oliver pointed to the screen and noted that there was a path cutting across the Gulf Stream that was cooler than usual and that it was probably due to upwelling and mixing from hurricane Katia. Sure enough, we loaded up a layer showing Katia’s track and they lined up.

Katia SST Trail

Katia SST Trail

We then checked to see if there was anything noticeable on the East Coast US 8-Day Average Chlorophyll layer and you can see what appears to be a slight bloom in chlorophyll along the track as well (slightly lighter blue).

Katia Cholorophyll Trail

Katia Cholorophyll Trail

Another neat view is the markedly cooler water that you flowing into the bays from the increased river discharge that resulted from the large amounts of rain dropped by hurricane Katia and tropical storm Lee as they passed through.

Cold river water 20110913

Cold river water 20110913

These layers and several others are processed and uploaded daily and made available via the Orb Lab website in the Public Access section. They are exposed via Google Maps interfaces as well as Google Earth embedded views and linkable KMZ file formats. Neat stuff!

Conch Reef Survey for NASA’s NEEMO 15 Project

Dr. Art Trembanis’ Coastal Sediments, Hydrodynamics & Engineering Lab (CSHEL) has been pretty busy lately. Not long ago I did a post about the prototype sub-bottom profiler section that he added to his Autonomous Underwater Vehicle (AUV) (see: Sub-Bottom Profiling using an AUV). I was down at the NASATweetup for the Endeavour (STS-134) launch not long ago and I got chatting with some folks from NASA’s Open Goverment Initative about the NEEMO 15 project (NEEMO stands for “NASA Extreme Environment Mission Operations“) and we discussed UD’s involvement.

It takes a village of roboticists to run a successful AUV campaign

It takes a village of roboticists to run a successful AUV campaign

When I emailed Dr. Trembanis upon my return to Delaware, he emailed me back with instructions to browse to UNCW’s Life Support Buoy live webcam above the Aquarius Reef Base. Sure enough, he was there aboard the RV George F. Bond monitoring his Gavia Scientific AUV as it acoustically mapped the Conch Reef around the Aquarius as a precursor robotic mission for NEEMO 15.

Go Pro Hero Attached to the AUV

Go Pro Hero Attached to the AUV

Here is video footage shot by an off-the-shelf HD Go Pro Hero digital video camera that was attached to the AUV:

httpv://www.youtube.com/watch?v=8n3nR9TaVGo

The mapping mission ran for 4 days and covered approximately 100km, resulting in about 15Gigabytes of raw data. Here’s an overview map of the mission.

Aquarius NEEMO 15 precursor survey

Aquarius NEEMO 15 precursor survey

Many thanks to Dr. Trembanis for the video and imagery to go along with the story. Be sure to visit NASA’s NEEMO site to learn more about the mission and what’s to come. Visit the CSHEL site to learn more about the research that’s going on there and to see other cool video and image products that they’re producing.

NASATweetup for the Final Endeavour (STS-134) Launch

Ocean Bytes AstroTweeter @cpuguru

Ocean Bytes AstroTweeter @cpuguru

It’s official – I’m heading to Kennedy Space Center in sunny Florida for the Space Shuttle Endeavour (STS-134) launch as part of what they call a “#NASATweetup”. I follow @NASA via my personal Twitter account – @cpuguru – and when they announced that they were accepting applicants for the 150 spots that could gain back-stage access to the Space Shuttle Endeavour’s final launch, I beat feet over to the site and entered the contest. Apparently there were over 4,000 applicants for these openings from around the world. It blew my mind when I finally got the email from NASA saying that I was selected. I am deeply honored to be included in this auspicious event.

What is a “NASA Tweetup” you ask? Well, according to the NASA Tweetup page:

“A Tweetup is an informal meeting of people who use the social messaging medium Twitter. NASA Tweetups provide @NASA followers with the opportunity to go behind-the-scenes at NASA facilities and events and speak with scientists, engineers, astronauts and managers. NASA Tweetups range from two hours to two days in length and include a “meet and greet” session to allow participants to mingle with fellow Tweeps and the people behind NASA’s Twitter feeds.”

STS-134 Patch

STS-134 Patch

A list of the ~150 confirmed attendees of the #NASATweetup for space shuttle Endeavour’s launch can be found via the @NASATweetup/sts-134-launch list. A fellow attendee, @ChrisCardinal, has setup a comprehensive blog site that he’s using to post information pertinent to the launch and the STS-134 Tweetup at http://134tweetup.com. It’s been quite useful for tracking some of the behind-the-scenes information about the shuttle launch, as well as updates such as the delay of the launch from April 19 to a new (unless it changes again) April 29 launch date due to a overlap issue it would have with docking with the International Space Station by a Russian Progress supply vehicle. My understanding is that the delay came about because the Russian vehicle needed to be docked to the ISS during the same time frame as the Endeavour’s 14-day mission would have fallen. Apparently there are two docking ports on the ISS and the two vehicles could theoretically have been docked simultaneously, but I believe that process has not yet been fully vetted and approved yet so the safer alternative of delaying the shuttle launch was selected.

I’m taking you with me!

The bad news is that while I won the lottery to attend the NASA Tweetup, I am unable to physically take anybody else with me. The GOOD news is that doesn’t mean that you can’t come with me virtually. I’m brainstorming on what kinds of equipment I can pull together that would allow me to share as much of this experience with you as I can through the magic of modern portable electronics. I want to cobble together a high-def webcam and perhaps a tablet or laptop so that I can record (and maybe live stream) my adventure ala Hat Cam Guy (aka Joel Glickman). Since I don’t have an iPhone to hot-glue to my ball cap, I might have to rely on the generosity of others to help me pull this off. If you have some equipment and/or resources you’d like to donate to the cause please let me know by emailing me at 134Tweetup@oceanic.udel.edu.

Q&A for NASA

If you look in the menu above, you’ll see that I added a page called “Q&A for NASA” so that school kids (and adults ;?) can post questions that they’d like me to try to get answers for while I’m down there. If you have a question that you’d like me to try and find an answer to, please feel free to add it in a “comment” to the page and I’ll do my best to get it answered while I’m down at the Kennedy Space Center.

Government Shutdown?

Now we are apparently going to be playing the “chase the launch date” game as we worry about the possible impact that a US Government shutdown would have on the launch due to the lack of a budget from Congress. I’ve been following the Twitter hashtag “#NASATweetup” and keeping a watchful eye on what the latest rumors are as to whether the mission will be delayed from its current April 29 launch date if funding isn’t allocated to keep governmental operations rolling. I’m crossing my fingers and hoping that Congress can get matters worked out.

A HUGE shout-out to Tammy!

I’ve been emailing back and forth with our awesome Marine Public Education Office team about this incredible opportunity to reach out and help educate and include kids in this adventure. I mentioned that it would be cool to include more of a space theme in the Ocean Bytes header image and in the time it took me to drive home I had the awesome header image that you see above in my inbox from our incredibly talented Tammy Beeson. Tammy ROCKS!

Flat Stanley Rides a REMUS in Antarctica

httpv://www.youtube.com/watch?v=09uzDjDOmjo

Flat Stanley joined researchers at Palmer Station in Antarctica in search of penguins and environmental data about their feeding grounds in January.  This video showcases just how awesome this icon of international literacy and community can be. Armed with only a minimal amount of training, Flat Stanley managed to pilot a REMUS Autonomous Underwater Vehicle in a precision pattern through the frigid waters off the West Antarctic Peninsula  — gathering vital information that will allow scientists to understand the feeding habits of Antarctic penguin species.

You can see a map about the many locations this worldly traveler has gone and find out more about the Flat Stanley Project on their website. Many thanks to student travel coordinators at Sierra Canyon School in Chatsworth, CA for helping Flat Stanley make his way this far south.

Awesome job Stanley!

Trip to Penguin Colony on Biscoe Point

Folks seem to like penguins….so much so that we even made the front page of the University of Delaware website! Hurray! This shot is of the Adélie penguin colony on Humble Island. We had just deployed a satellite transmitter on one of the birds so we would know where to send the underwater robots (Gliders and REMUS’s).

University of Delaware Main Page

Remnants of the storm remain in the area and wind gusts are keeping the science boats at station today. Nevertheless, we did have a break in the clouds and the sun came out. The warm sun made the Gamage glacier very active and I happened to get a great video of calving. Right place, right time.

httpv://www.youtube.com/watch?v=vANNYwc2d_k

We headed out to Biscoe Point to deploy another satellite transmitter on a penguin. The plan was remove the transmitter from a Gentoo penguin which had been at Biscoe Point since mid-night. The challenge is to find the tagged bird amongst the rest! On the way, a large amount of brash ice had surrounded Biscoe Point, so we had 1-2km if slow travel through the ice. Marc Travers (our boat driver and expert birder) did an excellent job snaking in between the large chunks. Outboard motors and large chunks of brash ice don’t mix well. Hitting a large piece of ice can leave you on a boat with a busted motor. That is why we carry an extra motor in every boat.

httpv://www.youtube.com/watch?v=URLwiXtnZk0

When we arrived at Biscoe Pt. we found that an Elephant Seal had climbed into one of the Gentoo Penguin nesting areas. If the penguin chicks are too young or unguarded by its parents, they can be easily crushed by these massive seals.

Southern Elephant Seal in Gentoo Penguin Colony overshadowed by Mt. William

Luckily it looked like the Gentoo chicks were old enough to avoid it. Occasionally a Gentoo adult would peck at the Elephant Seal’s thick blubber, but the giant beast didn’t seem to be bothered by it at all.  We made our way around the Gentoo colony looking for our tagged bird. She happened to be perched right on a rock preening herself where we could see her plain as day. The birders quickly removed the tag and she went back to her nest.

Penguin Chick Eaten by Skua Birds

Elephant Seals aside, the biggest threat to the chicks are Skua’s. These are aggressive scavenger birds swoop down and grab chicks right from their nests and make a meal out of them. There was plenty of evidence at Biscoe Pt. that the Skua birds had been active here.

Still, even with the ever present Skua, there were plenty of Gentoo chicks that were starting to look more and more like their parents. They are are starting to get their adult feathers. Their feathers are not waterproof yet, but they will be soon.

Gentoo Chick with Parent at Biscoe Pt.

The next step was downloading the dive information from the tag. This data will help us understand how deep the penguins are feeding. The dive data will help us properly analyze the data coming from the underwater Gliders and REMUS vehicles. The Birders are able to download and ready the tag for its next deployment in just a few minutes with a laptop computer in the field. These are amazing little tags.

httpv://www.youtube.com/watch?v=v-lLPVhjnMY

We walked around a small bay to the neighboring Adélie Penguin colony and were able to quickly identify an Adélie penguin that would be good for carrying our satellite

Adélie Penguin packed with a satellite transmitter.

transmitter. She was quickly tagged and released back to her nest. Her two grey puffy  chicks are just to her right. We will be watching the satellite data closely to find out where she is eating. Then, we will send our underwater robots to sample that section of ocean.  In a few days the Birders will head to Biscoe Pt. again to retrieve the tag, and thank her for her contribution to science.

Penguins, AUV’s, Satellites: together at last

Adélie Penguin Rookery

Adélie Penguin Rookery on Humble Island

Satellite tagged Adelie Penguin

Satellite tagged Adelie Penguin

Penguin swimming tracks near Palmer Station

Penguin swimming tracks near Palmer Station

Ballasting the Glider (Blue Hen)

Ballasting the Glider (Blue Hen)

Is it possible to follow penguins from space to understand where and how they are feeding in Antarctica? Absolutely!..but not without an excellent team from University of Delaware, Rutgers University, Polar Oceans Research Group, and Cal Poly San Luis Obispo. The sequence starts with the “Birders”. The “Birders” are from Polar Ocean Research and they have been studying penguins in the West Antarctic Peninsula for years. The “Birders”, headed by Bill and Donna Fraser, head out to local rookeries to identify good penguins to tag with satellite transmitters. Finding the right breeding pair is key. The pair should have two chicks with both parents still around. Some chicks only have one parent, probably because one parent was killed by a Leopard Seal. We want to choose one of the parents, because we are pretty certain they will return to their chicks to feed them. This also helps in recovering the transmitter. If the bird does not return, the transmitter comes off during their natural annual molt cycle. Once a penguin is selected, it is gently fitted with a satellite transmitter. Special waterproof tape is used to connect the transmitter to the thick feathers on the back of the penguin. The penguins are remarkably calm during the process.  Once the tag is attached, the penguin is released back to its nest. The next part of the sequence is for the birds. The penguins head out to feed on krill and small fish in the area. Their tags relay their position information to ARGOS satellites and we get nightly updates. The Birders pass on their data to me nightly, and I filter and map the penguin tracks. I put them into Google Earth, so we can see where the penguins have been feeding. Then, through the magic of mathematics, we turn their tracks into predicted penguin densities. Based on these densities, we plan our AUV missions to intersect with the feeding penguins (Slocum Electric Gliders and REMUS AUV’s).  The first priority is to make sure the AUV’s are ballasted correctly. This means that they need to be trimmed with weights just right so they travel correctly under the water. We use small balances and scales to get the weight of the vehicle just right, then put them into ballasting tanks to make sure we did it correctly. The vehicles should hold steady just under the surface of the water.

Getting ready for the launch of the "Blue Hen"

Getting ready for the launch of the "Blue Hen" (M. Oliver and K. Coleman)

Once we have a planned mission, we head out in small zodiacs from the station to a pre-determined point. For the Gliders, we call mission control at Rutgers University (Dave, Chip, John) and let them know a glider will be in the water shortly. Once it is in, control of the glider is accomplished via satellite telephone directly to the glider. The glider calls in and reports data and position to mission control. We can see the data coming in live over the web, and in Google Earth as we navigate the vehicle to where the penguins are feeding. The gliders move by changing their ballast, which allows them to glide up and down in the water while their wings give them forward momentum. They “fly” about 0.5mph for weeks at a time!

Mark Moline with REMUS's

Mark Moline with REMUS's

In contrast to the Gliders, the REMUS vehicles are very fast and are designed for shorter, 1 day missions. Daily missions are planned around the penguin foraging locations. The Cal Poly Group (Mark Moline and Ian Robbins) have been launching 2 Remus Vehicles per day to map areas the gliders can’t get too. Like the gliders, these vehicles call back via iridium to let us know how they are doing in their mission.

MODIS Chlorophyll, Penguins, and Gliders

Glider Dances around Adélie Penguin Tracks in a sea of chlorophyll

Finally, we are getting satellite support from my lab at U.D. Erick, Megan and Danielle have been processing temperature and chlorophyll maps in near-real time to support our sampling efforts, as well as AUV operations up and down the West Antarctic Peninsula. Just today, we saw that the penguins in Avian Island (south by a few hundred miles) have been keying off of a chlorophyll front. RU05 was deployed by the L. M. Gould and will be recovered soon. All in all, it is a pretty awesome mission to track these penguins from space and AUV’s. We will see how the season develops!

Note: I will be uploading photos and videos to the ORB Lab Facebook page throughout my stay in Antarctica. Be sure to check there for my latest updates.

Penguins from Space


The West Antarctic Peninsula (WAP) is one of the most rapidly warming regions on Earth, with a 6°C temperature rise since 1950.  Glaciers are retreating and the duration and extent of sea ice has significantly decreased. Many species rely on the sea ice as a resting platform, breeding ground, protective barrier or have life histories linked to sea ice thaw and melt cycles. With the declines in sea ice, many species are having a difficult time surviving and adapting to the new warming conditions.

The food web along the WAP is short and allows energy to be transferred efficiently. Phytoplankton (tiny plants that capture energy from the sun) are ingested by zooplankton (such as krill) which are in turn eaten by penguins, seals and whales. Due to the rapid nature of the warming around Palmer Station and the short food chain, it is an ideal location to study the effects of the acute changes in a warming environment.

Palmer Station, Antarctica

In particular, Adélie penguins are experiencing significant population declines near Palmer Station, Antarctica.  On Anvers Island, populations have decreased by 70%. Declines in sea ice have also led to declines in the preferred food of Adélies.  Silverfish have nearly disappeared and krill have decreased by 80%. Currently, Adélies are having a difficult time finding a satisfying meal. In turn, many species are migrating southward to look for new places to live and better food resources. On the other hand, ice-avoiding species (Gentoo and Chinstrap penguins) have been able to move south into the Adélies home range.

Adélies are a prime vertebrate species to study in relation to a changing environment.  Tagging Adélies in summer breeding colonies with satellite-linked transmitters, allow foraging locations to be monitored. Their foraging tracks can be compared to satellite derived oceanic properties such as sea surface temperature, chlorophyll, sea-ice, and wind. Since conditions have changed so quickly over the last few decades, the recent development of satellites can easily detect these changes. The UD-134 Slocum Glider (underwater robot) will be deployed in January 2011 and 2012, to do additional surveys near breeding hotspots.  This will allow us to combine satellite data with high resolution in-situ glider data to predict how ideal foraging locations for Adélies may change as warming continues. This will also test the satellites ability to accurately describe ecological changes that are occurring along the WAP.

Adélie Penguin

The Palmer Long Term Ecological Research Program (PAL LTER) began in 1990, and investigates aspects of this polar environment while maintaining historical records for marine species.  Historical satellite data and species records will be useful in predicting phytoplankton, krill and penguin abundances and distributions.  Models will be used to predict future foraging locations of Adélies in PAL LTER region of the WAP. It is important to study this region because changes are happening faster than predicted and these changes can lead to dramatic effects in our lifetimes.

OSU Ships Underway Data System

One of the highlights of going to the RVTEC meeting is getting to hear about some of the cool projects that are underway at the various institutions. One talk that caught my attention was the SUDS system, an NSF sponsored project that was given by the techs at Oregon State University.

I talked David O’Gorman and Toby Martin into doing a quick rundown on their SUDS system on camera during one of the breaks. SUDS is an acronym for the Ships Underway Data System, which consists of software and two data acquisition boards that they designed in-house – one analog and one digital. Each board can be programmed with metadata about the sensors that are attached to them. When the boards are plugged into the ships network they broadcasting XML data packets which include both data and metadata about the data via UDP for a back-end data acquisition to capture and store. For redundancy, there can be multiple acquisition systems on the network as well I’m told.

The data acquisition cards can be either powered directly or via POE (Power Over Ethernet). They can also supply power to the sensor if needed. The digital cards can accept RS232 and RS485. The analog has 4 differential input channels which can do 0-5v on two of the channels and 0-15v on the other two and range from 600Hz to 20kHz input signals.

Their website has links to a PDF of the presentationthey did at the 2010 UNOLS RVTEC meeting as well as various examples of data packets that the system broadcasts. Definitely something that could be quite useful to handle the ever-changing data acquisition needs on today’s research vessels. I look forward to learning more about the SUDS system in the days to come.

New Polar and Geosynchronous Satellite Receivers for Delaware

A few weeks ago they fired up a new satellite receiving station from SeaSpace at the University of Delaware’s main campus in Newark, DE. Two receivers were brought online, one for L-Band reception from Geosynchronous Satellites and one for X/L-band reception from Polar Orbiting Satellites. Both receiving systems have dishes that are mounted on the roof of Willard Hall as it presented the least obstructed view of the sky. The adds additional capability to an east coast satellite operations contingent which includes:

  • University of Maine
  • City College of New York
  • Rutgers University
  • University of Delaware
  • University of South Florida
  • Louisiana State University
  • Purdue University

For this blog posting, I’ll only cover the geosynchronous satellite capabilities. In a future posting I’ll cover the polar orbiting hardware and its capabilities.

Geosynchronous Satellite

UD Geosynchronous Satellite Dish

The beauty of geosynchronous satellites is the simplicity with which they can be tracked. Rather than flitting all about and requiring fancy calculations and equipment to track them, you merely point the dish to a point in the sky where the satellite remains fixed relative to the motion of the earth and pretty much lock the receiving dish down. Since the satellite is moving with a trajectory and speed that matches the rotation of the earth, the satellite is said to be “geo-stationary”.

The dish used to receive the signals from the geosynchronous satellites is therefore simple in its design. It is mounted with only one axis of movement, meaning it can only be adjusted along an arc of the sky either to the east or to the west. There is a motor and lead screw mounted on the back that will either push the dish one way, or pull the dish the other in order to position it for the best signal strength. The current intent of the UD dish seems to be dedicated to constantly receiving real-time data from the GOES-EAST satellite (also known as “GOES-13”). GOES East outputs full disk imagery of the the earth from a longitude of 75 degrees west, which gives a good view of pretty much all of North and South America and a good chunk of the Pacific and Atlantic Ocean.

GOES stands for “Geostationary Operational Environmental Satellite” and it is operated by NOAA’s NESDIS or “National Environmental Satellite, Data, and Information Service” primarily to support meteorological operations and research, which includes weather forecasting and storm tracking. The dish is oriented in such a way that it could also be programmed to point to GOES-WEST (aka GOES-11)  for a satellite view of the Pacific Ocean (centered around 135 degrees west longitude) as well if the need arises.

GOES East Full Disk Infrared GOES West Full Disk Infrared

GOES Sensors

One thing to bear in mind is that GOES-13 hasn’t always been “GOES East” – it took over for GOES-12 in April 2010, with GOES-12 moving to 60 degrees West to replace GOES-10 (decommissioned) for coverage of South America. I note this so that you don’t assume that the sensors (and/or their calibration factors)  for a particular GOES station are always the same.

Imager

The current GOES-East has optical imagers with 6 channels with resolutions of 1.1km for the visible channel (one); and 4km and 8km resolutions for the near infrared, water vapor and thermal infrared channels (two through six). The imager is basically a rotating mirror and lens configuration that scans the earth from north to south, line by line to receive reflected visible light, water vapor as well as infrared radiation channels. Each line scanned is digitized and transmitted back towards the earth with measurement units of percent albedo for visible light and temperature for the water vapor and infrared information. Spectral response functions can now also be downloaded online from the NOAA Office of Satellite Operations as well as other GOES calibration information.

Sounder

GOES satellites are also equipped with a sounder with 8km resolution. The sounder scans the atmosphere over the land and ocean and provides vertical profiles which include the temperature of the surface and cloud tops as well as derived wind velocities from these measurements.

Real-time Access to Data

The key feature to having a satellite receiving station on-site is the access to the raw, real-time satellite data. Sure, you can get pull some images down from the NOAA Geostationary Satellite Server, but they would be just derived images. Scientists here at UD and elsewhere are interested in getting the latest raw data feeds from the satellites so that they can research and develop algorithms that process the raw channel data into other products in support of their research projects.

Next on my agenda is to try to give some insight into the polar orbiting satellite tracking station and the fancy gear that sits inside the radome enclosure. Cheers!

CTD and Dissolved Oxygen Measurement via Winkler Titration

Last fall I was on the RV Hugh R Sharp for a short research cruise out in the Delaware Bay. We were sharing the Sharp with chief scientist Dr. George Luther, who was doing a mooring deployment that contained a dissolved oxygen sensor (among several other sensors). As part of the calibration check to make sure the readings were correct while we were on station, Dr. Luther did several CTD casts to take some water samples at various depths. I snagged the trusty video camera and got him to explain what he was doing and why.

To verify the accuracy of modern electronic oxygen sensors, oceanographers still verify the dissolved oxygen concentration using what’s called the Winkler test for dissolved oxygen. Dr. Luther showed the process of fixing oxygen into a MnOOH solid, which is then measured by the Winkler titration. This allows scientists to compare the oxygen readings they’re getting now with historical records of oxygen levels going back to the late 1800’s (an important thing to do when you’re trying to determine long-term trends by comparing historical records against more recent observations). It also allows them to verify the readings that they’re getting from modern electronic oxygen sensors.

I’ll sneak down to Dr. Luther’s lab soon and video the second part of the process, where they add the additional chemicals to the mix and determine the actual concentration of dissolved oxygen. Thanks again to Dr. Luther for taking time to explain the process.

APEX Floats 101

Some students and I went on a road trip to Rutgers University in New Jersey and then ended up heading up the coast to East Falmouth, Massachusetts to meet with the fine folks at Teledyne Webb Research. During a tour of the facilities, we were introduced to the APEX floats, whose data (through the ARGO program) the students were accessing for various projects in the ORB lab. James Truman, an engineer at Webb, graciously agreed to do a quick 101 overview of the APEX on camera.

Profiling floats like the APEX are able to sink or float by varying their internal volume. A standard equation for Buoyant Force is:

F(buoyant) = –pVg

where p=density of the fluid, V=volume of the object (in this case the float) and g=standard gravity (~9.81 N/kg). By adjusting the internal volume of the float by pumping fluids in and out of the interior, we are able to make the device either more or less buoyant.  There’s a really neat cut-away animation on the UCSD Argo site that shows the guts of the units quite well.

Float technology has evolved rather quickly, with the original floats only serving as a mechanism for tracking deep ocean circulation – also called Lagrangian Drifters or ALACE (Autonomous Lagrangian Circulation Explorer) floats. They would pop up to the surface and transmit back their positions and the temperature at depth.  Using the drifters last known position and its new position gave scientists an idea of how fast and in what direction the deep ocean currents were moving. Later these drifters were equipped with CTD sensors (Conductivity-Temperature-Depth) and they took sensor readings all the way up the water column and transmitted a “profile” reading back to the mother ship. These were called PALACE or “Profiling ALACE” floats (see WHOI’s site on ALACE, PALACE and SOLO Floats).

These predecessors bring us to the modern world of the ARGO Float fleet, which consists of APEX floats from Webb Research, the PROVOR floats from MARTEC and the SOLO floats from Scripps Institute of Oceanography. My understanding is that these floats dive to a depth of around 2000 meters and drift for 10 days and then float to the surface, profiling the water column along the way. They then communicate their readings via Iridium Satellite or the ARGO system and then dive again for another 10 days or so.

NOAA has a site called ARGO KMZ Files that makes it really easy to get started tracking ARGO floats and their data. You just need to install Google Earth first – which can be downloaded at: http://earth.google.com/. Below is a screen shot of the ARGO floats in the Atlantic.

GoogleEarth_Argo

Thanks again to James Truman and the awesome people at Webb Research for taking us under their wing and spending a lot of time showing us the ropes. It was an excellent experience that the students are still talking about.

REU Intern on FIRe

It has been a great pleasure to have Lauren Wiesebron on the Lewes campus this summer. Lauren is a summer intern from Johns Hopkins and is here as part of an NSF funded Research Education for Undergraduates program (aka REU). For her summer project, Lauren worked in Dr. Matt Oliver’s lab (the ORB Lab) and chose “photosynthetic efficiency” as her summer research project.  To gather data for her project, she set up shop in a portable scientific lab van on the dock in which she set up a Fluorescence Induction and Relaxation System (FIRe Sensor), a Coulter Counter and a Submersible Ultraviolet Nitrate Analyzer (SUNA).  Dr. George Luther’s lab was also taking readings from the same lab van and Lauren included some of their data into her analysis.  The past few weeks Lauren analyzed the results and tomorrow she will present a talk called “Conditions for increased photosynthetic efficiency in an estuarine area”.  Here is a walk-through of the lab van that I did earlier this week with Lauren.

Excellent work Lauren and we hope to see you back here for Grad school!

Reson Seabat 8101 Multibeam Echosounder

I lucked out not too long ago and happened to be at the right place at the right time (usually it’s the other way around). I ran into Brian Kidd, our resident expert on Multibeam Echosounder systems (also known as a Swath system) and he said he just happened to have the multibeam components apart for servicing.  I ran to get my camera and followed Brian around and asked all kinds of insightful questions (of course).  Echosounders are a version of Sonar (which stands for SOund Navigation And Ranging) wherein a transmitter emits a sound pulse downward into the water and then the amount of time that the pulse takes to come back to the ship is measured. A single beam echosounder will shoot a beam straight down and and use a single receiver to receive the pulse that bounced back from the bottom of the body of water. This is used to determine how deep the water is beneath the ship. A multibeam echsounder will emit a broad pulse of sound into the water and then will use multiple receivers aimed at various angles to measure the reflected sound.  These times are then processed by the computer to generate a “swath” beneath the ship and at some distance to either side which shows the height of the sea floor.  Moving the ship forward will give a band of height information beneath the ships track, and by moving in parallel, overlapping tracks, an ever-growing patch of sea floor heights can be mapped.

Okay, I’ve exhausted my general knowledge of the subject.  I’ll let Brian take the reigns and kick back and learn from the master…

 

At the 2009 RVTEC meeting, I sat in on the Swath/Multibeam workshop and updated the Swath/Multibeam section of OCEANIC’s International Research Vessels database for the UNOLS vessels. There were some huge swath transducer arrays being discussed at the workshop on some of the deep water vessels, so I was pretty surprised to see just how compact the shallow water multibeam systems can be. In the second part of the video, Brian shows us what the Reson Seabat 8101 transducer assembly looks like and how they mount the unit to the ship.

 

Many thanks to Brian for putting up with me and for taking time to share his knowledge of the Reson Seabat 8101 Multibeam System (PDF of specs here) onboard the RV Hugh R. Sharp.

Why two videos and not one? Apparently YouTube has a 10 minute max length for uploaded videos, so I broke the video into two parts.  Part 1 covers the monitoring and display station and Part 2 covers the mounting infrastructure and the transducer assembly. This works well for me as I doubt that too many people are able to sit through a 20+ minute video anyways, so breaking it up into two more digestible chunks is better in my opinion.

Portable “Castaway CTD” by YSI

How many times have you been standing on a dock or a bridge or even out on a kayak or large research vessel and found yourself wondering what the temperature, sound and salinity profile was for the water beneath you?  Well, you need wonder no more!

Here’s the last of the videos from the BEST Workshop last week. I talked with Chris from YSI about their new product the portable “Castaway CTD”. Just a tad larger than your standard handheld GPS, the Castaway CTD is a battery operated unit that allows you to do on-the-spot CTD casts at depths up to 100 meters. Chris did a quick rundown of the unit and its operations and then we stepped inside to see what software they are supplying to pull the data off the units, manipulate it and export it for use. Again the venue was quite noisy, so my apologies for the poor sound quality.

Specs for the unit are available on the YSI site, just click on the “Specifications” tab. The unit runs on two AA batteries, which they claim will run the unit for over 40 hours.  Communications with the unit are via an internal BlueTooth radio and the unit ships with a tiny USB BlueTooth dongle for you to use in your computer. The recorder comes with 15MB of storage, which they claim will store over 750 casts. It contains a built-in GPS so that you can get a geographic fix on your location within 10 meters and it will record the following:

  • Conductivity
  • Pressure
  • Temperature
  • GPS
  • Salinity (derived)
  • Sound Speed (derived)

A PDF of the whitepaper for the unit can be downloaded here.

Scanfish Undulating Towed Vehicle

Lucky me, I happened to be in the right place at the right time.  I was over at the CEOE Marine Operations Building and I ran into Brian Kidd, a marine technician aboard the RV Hugh R. Sharp. Brian is the resident expert on multibeam echosounder systems and he agreed to talk on camera about some of the data acquisition systems that he’s involved with. While we were talking I noticed that the Scanfish was opened up and getting prepped for an upcoming science mission, so Brian volunteered to talk about the Scanfish as well.  The segment on the multibeam is a tad longer as we had to do some travelling around the ship and ashore to cover the various components as it was being serviced. The multibeam video will be posted shortly has been posted and is available here

Background:

The Scanfish was originally a product of GMI of Denmark. GMI was purchased by EIVA, who integrated the Scanfish into their suite of hardware and software solutions in support of marine science and surveying. EIVA hosts a PDF showing specs for the Scanfish MK II on their site. The MK II looks like it is the equivalent of the Scanfish we discussed with Brian. EIVA also provides smaller Scanfish units including the Scanfish Mini and the Scanfish MK I.

The Scanfish is “flown” and monitored via a conductive cable that feeds data and parameters back to EIVA’s “Flight Software” – which the technician uses to control the Scanfish, the winch and to display and log the data being collected.

In addition to housing a CTD (which stands for Conductivity + Temperature + Depth) sensor, the Scanfish also supports the following optional sensors:

  • Fluorometer
  • Turbidity sensor
  • Transmissiometer
  • Oxygen sensor
  • Optical Plankton Counter
  • ADCP (Acoustic Doppler Current Profiler)
  • Video Camera
  • Other customer supplied sensors

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