Greenland Calling: Iridium Satellite Phone

I have trouble calling Petermann Gletscher, Greenland where I am collecting ocean data that feeds into a remote weather station. This station is run on a pair of car batteries, because the solar panels do not work until the sun rises again in two months and the next electrical outlet is about 300 miles away. A computer controls power to sensors and a satellite phone. All calls from and to the station are routed via a commercial satellite phone system that consists of about 66 satellites orbiting our planet. They often appear as shooting stars in the night sky that are called Iridium flares. As beautiful as these orbiting satellites are, they have driven me mad.

Screen shot of Iridium satellite orbits observed in real-time from http://www.satflare.com/track.asp?q=iridium

Screen shot of Iridium satellite orbits observed in real-time from http://www.satflare.com/track.asp?q=iridium

Iridium satellite phones and modems connected to computers are the only way to get data from remote areas of the Arctic and Antarctic. Some modems send small text messages called Short-Burst-Data (SBD) while other modems support a true two-way dial-up connection that includes all the hand-shaking of a telephone call. This computer-to-computer calling is more tricky than the person-to-person calls that this system was originally designed for. Working near Petermann Fjord, we had much trouble with even the person-to-person calls. Senator John McCain’s of the U.S. Congress was rudely disconnected, when he called us on the ship while in Sweden working with Government officials. And the Iridium phones on our Swedish icebreaker I/B Oden were thoroughly checked by field technician Robert Holden:

Rob Holden testing Iridium phones above the bridge of I/B Oden.

Robert Holden testing Iridium phones above the bridge of I/B Oden in August of 2015.

The building and coding of this ocean weather station is cool stuff for someone like me who likes Legos, computer games, and hacking electronics. Our Greenland ocean observing system uses both the text message SBD system at two smaller stations and the dial-up system at the larger weather station. The SBD system is great for small burst of data smaller than 1960 bytes per message. The Greenland station makes the call to a ground station that then e-mails the message forward to us. The method is very reliable, but there are small connection gaps that become data gaps.

Inside of University of Delaware command and control of five ocean sensors and surface weather station. Two computers are stacked above each other on the left.

Inside of University of Delaware command and control of five ocean sensors and surface weather station. Two computers are stacked above each other on the left with satellite modem 9522B on bottom left with RS-232 cable connecting to computer (Campbell Scientific CR1000).

In contrast, the dial-up method delivers a gap-free data set, but its bi-polar behavior drives me nuts. There are periods when each scheduled call results in a connection and new data, but there are also periods when each scheduled call fails to connect. Over the last 4 months I made 1450 calls to Greenland. Only 189 of these 1450 calls resulted in a connection. That is a failure rate of 87%. It admittedly includes one desperate day (Sept.-18) when I made a call every 3 minutes and each call failed. This desperation was after a 10-day sequence of failed calls when I lost my cool. There were 86 out of 130 days when a successful connection was made, that’s still a large failure rate of 34%, but there are zero missing data so far. [The station was set up Aug.-20.]

Logs-OWS

The advantage of the fickle dial-up connection is that I only need one connection to recover all data that has been collected since the last successful call. This differs from the SBD text message, where a lost connection means lost data. Furthermore, the connection to the Greenland station is a regular RS-232 connection which acts the same as the iPhone connected to the computer from which I type these lines. Hence software changes are possible, too, as scary as they may be.

Now why is the Iridium connection acting in a such a bi-polar fashion, that is, working like a charm for weeks and months to suddenly shut down completely for days to weeks just as suddenly? My honest answer is that I do not know. Furthermore, nobody really knows for sure. There is some talk in hidden places that Iridium modems or phones “de-register” themselves from the Iridium network, if they do not start a phone call. This is no problem for the SBD message as the Greenland modem always does the calling. It does matter for my dial-up, because the Greenland modem never initiates a call, it only responds when called after the Greenland computer gives it the power to do so. Which brings me to

‘Fake call’
Register_Modem = “ATDT 1234″ & CHR(13) & CHR(10)
SerialOpen (ComRS232,19200,0,0,2000)
Delay (0,1,Sec)
SerialOut (ComRS232,Register_Modem,””,0,0)
SerialClose (ComRS232)

The “fake call” is a software update that tells the Greenland modem to, well, make a fake call. The text string Register_Modem contains a non-existing phone number (I hope) 1234 as well as a carriage return CHR(13) and a line feed CHR(10) and the string is send via SerialOut to the modem that is addressed here as ComRS232 after the serial port between Greenland computer and modem is opened via SerialOpen. Lets see how this works over the next days, weeks, and months. For the first time, I received this morning a response from Greenland that it was “BUSY.” I took this as a good sign …

PostScript: Data look awesome with new, large, and unexpected diurnal variations that started Dec.-8.

Ocean temperature (black) and salinity (red) below Petermann Gletscher from Dec.-6 (Day-340) through Dec.-31 (Day-365). Top panel is just below the glacier ice at 95-m below sea level while bottom panel shows data 810-m below sea level.

Ocean temperature (black) and salinity (red) below Petermann Gletscher from Dec.-6 (Day-340) through Dec.-31 (Day-365). Top panel is just below the glacier ice at 95-m below sea level while bottom panel shows data 810-m below sea level.

Below Petermann Glacier: The First 100 Days

I am still stunned to see data coming to me hourly from below a glacier in northern Greenland while I sip my breakfast coffee. Each and every day for the last 100 days I got my data fix from the Ocean Weather Station that was born 100 days ago. Every morning at 8:15 the station sends me data from 5 ocean sensors below the glacier. A year ago I did not even know that I would be going to northern Greenland with the Swedish icebreaker I/B Oden in the summer of 2015, never mind that we would be able to pull off the engineering challenge to set up the first and only ocean observing system of Greenland. Today, I am over-joyed to report, we got 100 days of data.

IMG_3029

University of Delaware PhD student Peter Washam at the Ocean-Weather station on Petermann Gletscher after final installation 2015-Aug.-20, 17:00 UTC at 80 39.9697 N and 60 29.7135 W.

It all started when a French PhD student approached me at a scientific meeting in San Francisco last December. Céline is a now a doctor of oceanography, but at the time she was not. At the meeting Dr. Céline Heuzé of the University of Gothenburg in Sweden asked me for data and insights on how the ocean circulation in Nares Strait worked, so that she could connect results from planned field work in northern Greenland to her science interests in the Labrador Sea more than 1000 miles to the south. She also introduced me to Dr. Anna Wåhlin and the three of us got very excited about Petermann Fjord, Sweden, and polar oceanography. Here we are in Sweden preparing and off Greenland working:

A few weeks prior the US government and Sweden had just agreed to work together on a joint expedition to Petermann Fjord in northern Greenland. Friends at Oregon State University needed a ship to collect data with which to reconstruct and understand changes of the land- sea-, and ice-scape of North Greenland during the last 10,000 to 50,000 years. They wanted to uncover where past glaciers were located and where sea level was at that time. For this, they needed many sediment cores from the adjacent ocean, fjord, and below the floating glacier. Today this glacier is as thick as the Empire State Building in Manhattan is high. The British Antarctic Survey (BAS) agreed to drill the holes, collect the sediment samples, and take a profile of ocean properties from below the glacier ice to the bottom of the ocean. They estimated it would take about 5 days to drill each hole. Our idea was to use these holes to keep sensors, computers, and satellite phones in place to collect hourly data into the future as long as possible … 100 days so far.

After the Dec.-2014 San Francisco meeting we decided to use these holes to measure ocean temperature, salinity, and pressure for as long as the batteries would last, about 3-4 years, but I had neither money, cables, data logging computers, nor satellite phones to do any of this, only the ocean sensors. When I told Keith Nicholls of BAS about the idea and my predicament, he said that he could find some computers and satellite phones from experiments he had done in Antarctica. I then said that I would organize cables, a weather station, and some funds to pay for it.

A crowd-funding experiment in February failed to generate funds, but NASA came to the rescue by opening a way to compete for the needed $60,000 to cover the cost of hardware, travel, and satellite phone charges. The funds allowed us to ship about 1200 pounds of gear from Delaware to Sweden where it had to be loaded onto the ship in May of 2015. We did not have much time to built the system and had no time left to test it. Two drums of cable arrived with only 5 hours to spare before the ship left Sweden in June for Greenland. We met the ship in Thule, Greenland in July.

Fast-forward to the 20th of August 2015 when our ocean observing system went into the salty ocean waters below Petermann Gletscher. The surface weather station with satellite connections was deployed 10 days earlier to test satellite communications and collect weather data for Oden’s extensive helicopter flight operations on and around the glacier. It included a rushed visit by a large team from CBS News 60 Minutes who were flown and shown all over the place. We last saw the station during 24 hours of day light on 27th August when we calibrated the wind sensors, but to me the daily satellite phone call of the station with new data is a sign of life from an ocean outpost that survived another day in the total darkness of the polar night. It draws energy from two car batteries that run even at the -36 degree Centigrade (-33 F).

AWS

First 100 days of ocean and weather observations from the University of Delaware Ocean Weather Station on Petermann Gletscher, Greenland. Panels show (from bottom to top) time series of 1. battery voltage, 2. ocean (red) and air (black) temperatures, 3. wind speed, 4. wind direction, 5. glacier movement, and 6. atmospheric pressure. Time is given in year-day, Nov.-28 is Day-332. The sun set on Day-290 or Oct.-17.

New data are posted at

http://ows.udel.edu

which over the next few weeks we will develop into a web-site to distribute the daily observations to everyone. I am most thankful to many of scientists, engineers, technicians, sailors, and women in England, Sweden, and the United States of America, but this Thanks-Giving weekend I am grateful to the men and women of a great nation that gave me a place to study, work, and live doing while exploring ocean and now glacier physics as well.

EDIT: I just discovered this 7 minute video on our expedition, credits go to Saskia Madlener at 77th Parallel Productions:

Sun Sets over Petermann Gletscher

Lights are out. Our ocean weather station on a floating glacier of northern Greenland confirms what the U.S. Naval Observatory reports for location 60 degrees and 30 minutes West longitude and 80 degrees and 40 minutes North latitude: As of today the sun is no longer above the horizon and will not rise until 23 February 2016. Total darkness means no solar power for the station that will have to survive on a fancy car battery temperatures as low as -50 degrees centigrade. Last week with the sun still up our station recorded -30.4 degrees celsius about 4 feet above the ice. How long will the station survive on that car battery?

Petermann Gletscher at dawn on 5 Oct. 2015 as captured by NASA Operation IceBridge. Our Ocean Weather Station is in the corner bottom left.

Petermann Gletscher at dawn on 5 Oct. 2015 as captured by NASA Operation IceBridge. Our Ocean Weather Station is in the corner bottom left.

Without power the station does not function, because each sensor, each computer, and each telephone call via the Iridium satellite system requires electricity. Without power I am in the dark about what the station does or what ocean or air temperatures are. Since I do have power at the moment, well, I got new data. For example, there is a voltage that the station sends me …

Voltage at Ocean Weather Station on Petermann Gletscher.

Voltage at Ocean Weather Station on Petermann Gletscher.

… whenever the sun is up, the solar panels recharge the battery and the voltage goes up. As I use electricity, the voltage goes down. Lets ignore a small temperature effect and details on how much electricity we draw at what “amperage.” Instead, lets focus on the regular up and down of voltage for the last 60 days and how it suddenly went flat. The flat line at 12.5 Volts tells me that the sun is down. The station now uses the car battery, but how long will this last? Quick answer is … a day, if I am dumb. Or 150 days, if I am smart. Time will tell, if I made a mistake in either my power budget or my computer code that gives and takes power to a range of sensors. Scary stuff, and my little sister Christina Parsons can attest, how nervous I was, when I uploaded new power-saving software that I wrote from my attic at home to the station in Greenland. The station did take the new software, restarted itself, and works making one data call each day instead of three. Data are still collected every hour, but I save 20% of total power.

Power is something in Watts (40 W Light bulb anyone?) and you have to multiply voltage by current draw (0.5 Amps anyone?) to estimate the power needs of the device drawing 0.5 Amp current at 12 Volts. Incidentally, 0.5 Amps is what the Iridium satellite phone draws when it calls me with new data. Let me check my power budget, if this is true … nope, it only takes 0.365 Amps, so it takes 12 volts times 0.365 Amps equal 4.4 Watts which is about 1/10 of that 40 W light bulb you are looking at, perhaps, or the station we put up: the yellow box is the car battery powering all the gadgets you see and many more you do not:

What I just showed you is the beginning of a power budget that I had to make to get my station through the night, now that there is no more sun for the next 4-5 months. My car batteries are rated to give 110 Watts for an hour, so if I run my 4.4 W satellite phone all the time, I would be out of battery juice after 110 Watt-Hours divided by 4.4 Watts equals 25 hours. That’s bad, real bad, especially since one should not run a car battery to zero and the battery at -30 degrees Celsius may only give me half the power than it would at the more usual 15 degrees Celsius we got outside. The solution to this problem is to use the phone only for a few minutes each day, say 5 minutes. So, since I am using the phone only 5 minutes out of the 1440 minutes that each day has, it takes about 1440 minutes divided by 5 minutes times 25 hours equals 300 days for the phone running 5 minutes each day to run down the battery. Magic this math is not, but it shows how important it is to use resources (electricity) wisely. There are times and places where it is not possible to plug your iPhone into a power outlet. You get the picture … well, here are some that University of Delaware PhD student Peter Washam took who was part of the ice drilling team during last summer’s deployment of the ocean weather station:

So, as of this morning at 4 am Delaware time, the station now in total darkness tells me that the ocean temperatures 700 meters below the 100 meter thick glacier are +0.3 degrees Celsius while air temperatures 2 meters above the ice are -11.1 degrees Celsius. Now what that means to the melting of the glacier by the ocean, I will have to tell you at another time in more detail. These data are the ONLY data from below any glacier to the north of the equator. We are really breaking new ground and are making new discoveries as we go along … as long as there is power. Hopefully there is no dumb mistake in my power budget.

Sun over the horizon of Greenland as seen during NASA's Operation IceBridge Flight in October 2015.

Sun over the horizon of Greenland as seen during NASA’s Operation IceBridge Flight in October 2015.

New ocean data from floating Petermann Glacier

#UDel Ocean-Weather station #Greenland on #petermann2015 calls home from 800 m under floating glacier with 2 weeks of new hourly data.

University of Delaware Ocean-Weather station on Petermann Glacier with the hot-water drilling team UDel and British Antarctic Survey after deployment Aug.-20, 2015 [Credit: Peter Washam, UDel]

University of Delaware Ocean-Weather station on Petermann Glacier with the hot-water drilling team UDel and British Antarctic Survey after deployment Aug.-20, 2015. Cables from ocean sensors emerge from the ice where the wooden cross is located on the right. [Credit: Peter Washam, UDel]

Map of Greenland's Petermann Gletscher, Fjord, and adjacent Nares Strait. The UDel Ocean-Weather station is the green dot on the floating ice shelf that does not have a red triangle. Blue dots in the ocean are where we collected ocean data from I/B Oden in August 2015. Green dots are ocean moorings which report via Iridium while red triangles are "fancy" GPS locations we instrumented for 12 days to measure vertical tidal elevations of the glacier.

Map of Greenland’s Petermann Gletscher, Fjord, and adjacent Nares Strait. The UDel Ocean-Weather station is the green dot on the floating ice shelf that does not have a red triangle. Blue dots in the ocean are where we collected ocean data from I/B Oden in August 2015. Green dots are ocean moorings which report via Iridium while red triangles are “fancy” GPS locations we instrumented for 12 days to measure vertical tidal elevations of the glacier.

My nerves are shot and I get depressed when the Ocean-Weather station does not call home when she should. We deployed the station last months on the floating section of Petermann Gletscher where she has moved steadily towards the ocean at about three meters per day. We measure this with GPS which is the black dot next to the temperature sensor above the head of the team that drilled the hole. It connected 5 ocean temperature, salinity, and pressure sensors to 800 meter depth below sea level. The data come from this great depth to the surface where it feeds into the weather station that then transmits data via an Iridium antenna to another Iridium antenna that sits atop my house. Let me run out and take a quick photo of it …

Iridium antenna atop my house in Newark, Delaware that receives data calls from Greenland.

Iridium antenna atop my house in Newark, Delaware that receives data calls from Greenland.

My problem with Iridium over the last 6 weeks has been that its (data) connectivity is spotty. For example, I received no data the last 2 weeks. This has been the longest time with no call and no new data. Designing the system, I decided against the more robust “Short-Burst-Data” SBD text messages. Instead I opted for a truly 2-way serial connection which, if a connection is established, allows more control as well as a more complete and gap-free data stream. The drawback of this serial connection via Iridium is lack of connectivity. Sometimes days or weeks go by without a successful connection even though computer codes are written to connect every 8 hours. I can change that by uploading new codes to the two Campbell CT1000 data loggers that control all sensors as well as data collection and communication via Iridium.

Today’s call was the first in two weeks, but it provided a complete data download without ANY gaps in the hourly time series of weather in the atmosphere (wind, temperature, humidity) and weather in the ocean (temperature, salinity, pressure). The ocean data show that about every 2 weeks with the spring-neap cycles, we see very large excursions of colder and fresher water appear at 2 sensors within about 30 meters of the glacier ice. It is too early to speculate on how this may relate to ocean circulation and glacier melting, but the large and frequent up and down do suggest a lot of ocean weather.

I am anxiously awaiting the next data call in about 5 hours to get the 8 hours of data. Wish me luck and a healthy Iridium satellite system where calls are about $0.90/minute. Today’s call took 5 minutes. This is what some of the (uncalibrated) data look like:

Ocean-Weather station data from Aug.-20 through Sept.-25 (today). Ocean temperatures at 5 vertical levels are shown as 5 red curves  in 5th panel from top. The black lines in that panel are air temperatures that reached -20 C this week.

Ocean-Weather station data from Aug.-20 through Sept.-25 (today). Ocean temperatures at 5 vertical levels are shown as 5 red curves in 5th panel from top. The black lines in that panel are air temperatures that reached -20 C this week.

Ocean Weather Below a Greenland Floating Glacier

Sensing the oceans below ice as thick as the Empire State Building is tall, we are revealing some of the mysteries of ocean melting of one of Greenland’s largest glaciers. The expedition to Petermann Fjord last month made possible the deployment of three ocean sensing stations that all call home daily via Iridium satellite phone to send us new data from 800 meters below sea level. The ice of the glacier at our stations is 100 to 300 meters thick and a whimsical cable with 3 tiny wires connects the instruments under the glacier to a home-made computer that calls home daily with new data. I am still stunned at the many marvels of technology that all came together to make this happen.

University of Delaware PhD student Peter Washam at the Ocean-Weather station on Petermann Gletscher after final installation 2015-Aug.-20, 17:00 UTC at 80 39.9697 N and 60 29.7135 W.

University of Delaware PhD student Peter Washam at the Ocean-Weather station on Petermann Gletscher after final installation 2015-Aug.-20, 17:00 UTC at 80 39.9697 N and 60 29.7135 W.

Panoramic view of the ocean-weather station on Petermann Gletscher. View is towards the south-east with Washington Land in the background.  [Photo credit: Peter Washam].

Panoramic view of the ocean-weather station on Petermann Gletscher. View is towards the south-east with Washington Land in the background. [Photo credit: Peter Washam].

It started with an off-the-shelf automated weather station that David Huntley at the University of Delaware put together for me with the non-standard addition of 5 serial ports that each allow one ocean sensor to be connected by cable to the weather station. It continued with the holes that Paul Anker and Keith Nicholls of the British Antarctic Service drilled through Petermann Gletscher. My PhD student Peter Washam was on the ice helping with the drilling, preparing the ocean sensors, and he is now processing some of the new ocean data.

AWS2015

The map above shows Petermann Gletscher (bottom right), Petermann Fjord, and adjacent Nares Strait. The red lines are bottom depths at 500 and 1000 meters while the thick black line shows the location where the 550-m thick glacier sits on bed rock. All glacier ice seaward of this black line is floating with warm ocean waters below. These waters enter the fjord at he sill at the entrance to Petermann Fjord which is about 450 meters deep. The blue dots are locations where last months we collected detailed profiles of ocean temperature salinity, and oxygen. The warmest water inside the fjord and under the glacier enters near the bottom at this sill. The green dots on the glacier are the 3 drill sites where we put our ocean sensors down while red triangles are “fancy” GPS receivers that we placed for almost 2 weeks on the glacier. The one triangle on land (bottom right) is a permanent GPS station at Kap Schoubye that UNAVCO maintains under the code name SCBY. We will reference our moving glacier GPS station (the glacier moves) to this fixed station on bed rock, but that’s a story for another day.

The ocean data are worked up by a small, but wonder group of men and women of all ages working out of the universities of Gothenburg (Sweden), Oxford (England), and Delaware (USA) as well as BAS (England). It is very much an informal group of people who like each other and met in strange ways over the last year or so with all of us juggling way too many projects for which we all have way too many ideas. Bottom-up collaboration and sharing at its best from the bottom up.

Two quick highlights rushed onto these pages before I have to run off to teach a class on signal processing:

Measurements from the ocean weather station up until 2015-Sept.-11 as a function of time where Day-20 is Aug.-20 and Day-32 is Sept.-1. The station provides battery voltage (bottom panel), air and ocean temperatures, wind speed and direction, ice drift from GPS, and atmospheric pressure (top panel).

Measurements from the ocean weather station up until 2015-Sept.-11 as a function of time where Day-20 is Aug.-20 and Day-32 is Sept.-1. The station provides battery voltage (bottom panel), air and ocean temperatures, wind speed and direction, ice drift from GPS, and atmospheric pressure (top panel).

Ocean temperature (black) and salinity (red) observations from below the ice shelf of Petermann Gletscher at 5 different vertical levels from near the bottom (bottom panel) to the ice-ocean surface (surface panel).

Ocean temperature (black) and salinity (red) observations from below the ice shelf of Petermann Gletscher at 5 different vertical levels from near the bottom (bottom panel) to the ice-ocean surface (surface panel).The bottom of the ice shelf is about 90 meters below sea level.

Note that the scales for temperature and salinity are different at different vertical levels. The warmest water is always found near the bottom while both temperature and salinity under the ice shelf vary by a larger amount that we had initially expected. This means that there are direct and fast connections of the ocean under the glacier with waters inside the fjord and beyond. Notice also that air temperatures are well below freezing (0 degrees Celsius) for 2-3 weeks now while the ocean waters are well above freezing (-1.7 degrees Celsius) everywhere. Hence there is no melting at the surface while there is much melting at the bottom of the glacier. While trivial, this emphasizes the controlling influence that the oceans have on glaciers and ice shelves such as Petermann Gletscher. In the meantime, we got much exciting and fun work ahead of us.

Shout of thanks to NASA (and the US tax-payers) who funded this ocean-weather station at the University of Delaware at about $64,000 for a single year and NSF (and again the US taxpayers) who funded the larger ocean- and land-based experiments within which small part was embedded.

Münchow, A., Padman, L., and Fricker, H.A. (2014). Interannual changes of the floating ice shelf of Petermann Gletscher, North Greenland from 2000 to 2012, Journal of Glaciology, Vol. 60, No. 221, doi: 10.3189/2014JoG13J135

Johnson, H., Münchow, A., Falkner, K., & Melling, H. (2011). Ocean circulation and properties in Petermann Fjord, Greenland Journal of Geophysical Research, 116 (C1) DOI: 10.1029/2010JC006519

Rignot, E., & Steffen, K. (2008). Channelized bottom melting and stability of floating ice shelves Geophysical Research Letters, 35 (2) DOI: 10.1029/2007GL031765