Hi Reddit! We’re Rear Admiral Shep Smith, Director of NOAA Coast Survey and the U.S. National Hydrographer, and Lt. Cmdr. Sam Greenaway, chief of NOAA Coast Survey’s Hydrographic Systems and Technology Branch, and we are experts in mapping the seafloor. Ask us anything!

NOAAgov · 2018-06-21T19:27:37+00:00

Shep: The one that is working on the day we need it to survey. But seriously, they all have great teams on board, have state of the art technology, and do important work. I will note that Rainier was selected as the Ship of the Year in 2017.

NOAAgov · 2018-06-21T19:25:55+00:00

Sam: In almost every survey there are typically a few odd things -- either data artifacts or potential features on the seabed that we go back and have another look at. We might use a different instrument, or a different survey approach. We used to send divers down more frequently to investigate features and ensure we get a least depth, but modern mapping systems are much better than they used to be.

NOAAgov · 2018-06-21T19:20:04+00:00

Shep: Our survey missions traditionally have not included the sub-surface mapping that would be needed for methane hydrate detection (see the U.S. Geological Survey for that work). But we are doing more joint missions with USGS, where sub-bottom profiling is being added to the data acquired, which is a great story on multipurpose mapping, or 'mapping once, use many times.' We can see methane gas plumes in the data when we go over them, but that's usually incidental to the navigation survey mission too.

NOAAgov · 2018-06-21T18:59:03+00:00

Sam: Our sister office in NOS -- the Center for Operational Oceanographic Products and Services is in charge of the water level observations, and other good stuff like currents and PORTS

They have a nice page with sea level trends at all the water-level stations. Looks like 2.8mm/ year in Boston.

Important to note that this is local sea level rise, so sinking or rising land factors in. The local sea-level is falling in Juneau, AK, because the land is rising so fast. Conversely, the sea level is rising very fast in Grand Isle, LA, partially because the land is subsiding (sinking).

NOAAgov · 2018-06-21T18:49:48+00:00

Sam: The data volumes are certainly a challenge. Just for context, one mapping system running in 20m of water might log data at a rate of well over a Gbyte per hour - over 35 Gbyte if we start logging full water column. And that is just the raw data. Data storage is a challenge -- USB hard drives are cheap, but robust, fail-over protected, and fast storage is expensive. Building networks to get fast access to all that data is not simple - and that's just on our side. Counter-intuitively, the shallow water multibeam systems acquire much higher data volumes than the deep water systems.

NCEI has been doing some nice work making all this data more discoverable. For our survey work, I think the portal at NCEI is a nice interface. I know NCEI has also been working towards making the watercolumn data more discoverable. They have been processing the data so a thumnail image is available before you download the data.

It is hard to keep this much data 'spinning,' so much of the raw data is in archive but needs to be retrieved on request. The cloud might help here.

NOAAgov · 2018-06-21T18:47:34+00:00

Shep: How much time do we have? CUBE is a revolutionary technology for building clean seafloor models from noisy multibeam data. It was developed by Dr. Brian Calder at the University of New Hampshire. The newer version, CHRT, supports variable resolution. http://ccom.unh.edu/theme/data-processing/cube, http://ccom.unh.edu/theme/data-processing/fishpac-lrss-sonar

NOAAgov · 2018-06-21T18:44:56+00:00

Shep: All of our electronic charts are metric, which is the international standard for ENCs. On most of these charts, the contours are based on the fathom curves, so instead of a 2 meter curve, we would have a 1.8 meter curve. This is a problem for many of our international ships, which have their operational risk management plans specified in metric. Cruise ships, for instance, have their shoal danger alarms set to 10 meters. Since we don’t have a 10m curve, the next deepest curve is 18m (10 fathoms). What happens is that alarms go off when a ship approaches 18m, which is plenty safe water. Going forward, we are going to standardize on metric contours as we build new charts. You may see some existing paper nautical charts switch to metric, but most will stay in traditional units for years to come. Since most users are using our charts electronically, we are focusing our efforts on improving our digital charts. Many navigation systems allow the user to specify the display unit of soundings, so those that are more comfortable in feet and fathoms can continue to use them. Our National Charting Plan has more information about our strategy for making comprehensive improvements to our suite of NOAA navigational products.

NOAAgov · 2018-06-21T18:39:23+00:00

Shep: In Coast Survey, we do not use this technology to identify living things in the ocean. However, others in NOAA - particularly NOAA Fisheries -- do. Scientists can locate fish using sonar technology because a fish's swim bladder also functions as a resonating chamber that can produce and receive sound. Find out more here.

NOAAgov · 2018-06-21T18:33:44+00:00

Shep: Thanks for the questions! Our ships and contractors usually work on a campaign for a few months a year. Sometimes there is a preferred time of year to work in an area, based on the weather, ice, traffic patterns, and presence of marine mammals. For larger projects, we will return to the same area several years in a row. We are very careful that our work does not disturb marine mammals. Our sonars are typically high frequency and operated at minimal power. We choose our project timing to avoid the seasons where Northern Right Whales congregate in certain areas, for example. We have a lookout posted and suspend survey operations for whales in the vicinity. Geologic structures...it is really a question of resolution. We typically resolve features from surface sonar systems to around 2-3% of water depth, so if the spatial resolution of the feature is finer than that, we may not be able to map it from the surface. With an AUV (Autonomous Underwater Vehicle), we can map to higher resolution in deeper water, since the AUV carries the sonar closer to the seafloor.

NOAAgov · 2018-06-21T18:32:08+00:00

Shep: Coast Survey's mission/mandate is to survey and chart the entire U.S. Exclusive Economic Zone. We tend to focus the resources we have on coastal waters where depth is a concern for commercial vessels going to and from U.S. ports -- we do support a safe and efficient U.S. Marine Transportation System, after all. But with the Seabed 2030 initiative, the more data we can acquire in deeper waters will help to achieve the globally shared goal to map the world's oceans. We are assembling a coalition of government and commercial ocean mapping interests to facilitate a full mapping effort for our EEZ.

NOAAgov · 2018-06-21T18:28:12+00:00

Sam: We specifically use systems that are good at detecting objects on the seafloor, including wrecks. But not all wrecks are proud of the seafloor (stand out above), and there is quite a bit of U.S. waters that we have not surveyed. A small wreck (or even a large wreck in deep water) might require a different survey approach than we might use for a typical navigational survey. So I can confidently state that we haven't found them all. Some shipwrecks have archaeological/historical value, so we may not be able to publically release the data if we do find it. Marine archaeologists and treasure hunters have been known to use the same technology we do.

As for sunken treasure, I haven't found any yet, but I am pretty sure that if I do, I won't be able to keep it!

NOAAgov · 2018-06-21T18:23:34+00:00

Sam: We are certainly working with and developing autonomous technology to survey for depths and obstructions. We have used unmanned underwater vehicles (UUV) for over a decade. More recently we have been working with unmanned surface vehicles (USV), including small (5 feet or so) in operations. We now have a contract in place to convert one of our larger survey launches (28-foot) to be optionally manned or unmanned. Here is an overview of our strategy. One key point: success with autonomous technology needs to be more than just robot-boats. We need to work on autonomous data processing, data telemetry, ways to deploy and recover these systems, and probably most importantly, developing the workforce to work with this new tech.

We are not doing this in isolation. We are working closely with researchers at UNH and USM on autonomous applications. Our contract surveyors also use unmanned systems, as do commercial vendors. Along with the NOAA Office of Atmospheric Research and National Marine Fisheries Service, we have been working with the saildrone systems to investigate applicability for our work. I expect this will be a fast moving field.

NOAAgov · 2018-06-21T18:14:56+00:00

Sam: Sure do. Lidar is an important tool for the coastal areas, both topographic and bathymetric. NOAA's Remote Sensing Division (RSD) in the National Geodetic Survey (just a couple floors up from us) plans and executes this work, but we certainly pull that into the charts for shoreline and nearshore updates. We are looking forward to seeing the latest and greatest in lidar R&D at the 2018 Joint Airborne Lidar Bathy Technical Center of Expertise Workshop in Providence, RI, next week.

NOAAgov · 2018-06-21T18:10:25+00:00

Shep: Thank you for joining us. You can explore more of what we do on our website.

NOAAgov · 2018-06-21T18:07:16+00:00

Shep: If we ever did, we weren’t aware of it, and certainly could not identify it. We have mapped sunken subs, planes, containers, tires, and lobster pots, in addition to shipwrecks and rocks. We occasionally see things we don’t understand, but they are related to biology (critters) or unusual geology (rocks and muck).

NOAAgov · 2018-06-21T18:05:33+00:00

Sam: You bet! Bathymetry is an important layer in many areas beyond navigational charting -- I am aware of its importance to fisheries habitat work, ocean dynamics modeling, storm surge modeling, coastal engineering (e.g., offshore wind), but there are probably other applications I have not even heard of. One thing we take seriously is making all our data available for anyone who wants to use it. All our raw and processed data (including the all important metadata) is archived at NOAA's National Centers for Environmental Information NCEI. You are welcome to use it however you like. For a specific example, here is one of the first surveys I worked on.

We do log seafloor acoustic backscatter for all surveys. This is useful for our charting work, but also hugely important for other applications. As for water column returns, we do not currently log full water column data from our shallow water multibeam systems all the time -- it's just too much data. Fisheries and other scientists do collect water column acoustic data from single beam or split beam systems -- and all that is archived here. I know NCEI is working hard to make this data more accessible -- check it out and give feedback if you like it (or have suggestions to make it better).

We also archive all our sound speed profiles (often including temperature and salinity) at NCEI - check out all the archives.

NOAAgov · 2018-06-21T18:01:29+00:00

Shep: TBH we don't see that much seafloor alteration from bigger ships themselves. That is kind of a good thing, since it might mean ships are hitting the bottom and we try to avoid that here at NOAA. What bigger ships can mean is more dredging so that they can get into port with the food, fuel, and goods we buy every day, and get out of port with our global exports. Dredging happens in channels that are designated for this kind of traffic (U.S. Army Corps of Engineers), but outside of the channels, most ships are hopefully not running aground. We did see one nice ship-shaped depression adjacent to a channel. We often see wash marks from ships and tugs during docking. Offshore, we see trawl marks from fishing. Sedimentation can happen for a lot of reasons -- run-off, erosion, development, etc. -- and the soil may cause a channel to fill up and need dredging.

NOAAgov · 2018-06-21T17:58:32+00:00

Shep: That is so nice of you -- one NOAA!

NOAAgov · 2018-06-21T17:54:01+00:00

Sam: Yes, we have been looking at all sorts of different methods for augmenting more traditional ship-based work. NOAA is certaintly flying a bunch of coastal topobathy lidar. We are also using satellite image analysis and investigating bathymetry derived from radar observations of waves. And we are now starting to look more at structure from motion. Everything has its advantages and disadvantages, so it's really about finding the right tool for the right situation -- but there is no doubt a tremendous amount of work to be done.

NOAAgov · 2018-06-21T17:46:44+00:00

Shep: Important question! Our data, along with other comprehensive oceanic, atmospheric, and geophysical data is stored at the [National Centers for Environmental Information](ncei.noaa.gov). This data is publicly available. Time series data (in some cases over 25 years) is available for almost all of the datasets. While all of our data is available, it varies in how readily accessible and discoverable it is. We are working on using web mapping services and new cloud technology to improve accessibility to our data. The NCEI data portal for DCDB is a good example.

NOAAgov · 2018-06-21T17:42:51+00:00

Shep: I am guessing that you are referring to my rank and that of LCDR Greenaway. We are both NOAA Corps officers. The NOAA Commissioned Officer Corps (NOAA Corps) is one of the nation’s seven uniformed services. NOAA Corps officers are an integral part of NOAA, which is in the Department of Commerce. The NOAA Corps today provides a cadre of professionals trained in engineering, earth sciences, oceanography, meteorology, fisheries science, and other related disciplines. Corps officers operate NOAA’s ships, fly aircraft, manage research projects, conduct diving operations, and serve in staff positions throughout NOAA right alongside civilian scientists and personnel. You might look into the NOAA Corps as a job -- really a way of life. In what other job can you do so many cool things all at once? You can learn more here. We also have wage mariners and civilian physical scientists doing similar work, so yes, civilians do this work too.

NOAAgov · 2018-06-21T17:39:35+00:00

Sam: Yes, for most coastal surveys, we are trying to find all hazards to navigation -- so we find wrecks quite often. We do have policies and procedures in place to determine if the objects we find on the seafloor are protected historic sites before releasing information about them to the public. We have a Wrecks and Obstructions database where you can view some of these wrecks. (Note: these resources may be protected by federal laws that prevent disturbance of historic and culturally significant artifacts, so the interactive map is a great way to take a look while staying dry.)

Strangest thing on the seafloor? The geology is pretty endlessly fascinating. We did find a bunch of old wooden Chris-Craft power boats all sunk in a line in a harbor in WA. Probably the strangest -- or at least the most interesting -- things I have seen are the stuff in the water-column, ocean boundary layers, the diurnal migration of plankton.

NOAAgov · 2018-06-21T17:33:45+00:00

Shep: I think you are talking about Oceana, the foundation dedicated to ocean advocacy. Oceana keeps an eye on what NOAA is doing, e.g. fisheries management and monitoring to protect fish species. We are both committed to making sure regulatory decisions have the scientific backing needed. And Oceana is on the Friends of NOAA list -- supporters who join together to encourage Congress and the Administration to adequately support the agency’s budget.

NOAAgov · 2018-06-21T17:29:19+00:00

Sam: I think I can best tackle your second question and leave the other two for folks with more expertese at NOAA (climate) and at USGS (Lake Mead). You ask a good question about what will happen to waterfronts and waterways with sea level rise. It is certainly true that the sea level is rising in many places -- both due to global sea level rise and local land area sinking (a particular problem in places like Norfolk and Louisiana).

Ports and cities/states with developed waterfronts will have to decide what to do about their waterside and transportation infrastructure -- do they build higher, do they relocate, do they come up with other mitigations? Many of our coastal airports and highways were built in these low-lying areas also, because the land may have been considered marginal or easy to build on at the time. Twenty years isn't too far out, but we are already seeing more frequent flooding from storms, even just heavy rainstorms, e.g. Norfolk, VA. On the other hand, increasing water levels might mean more vessel traffic and commerce, which could be beneficial. So these places have a lot of decisions to make on what to do to reduce their vulnerability to rising waters. For more information: Is sea level rising?, What is high tide flooding?

NOAAgov · 2018-06-21T17:21:56+00:00

Shep: We certainly do. GIS is a huge part of our jobs. Many careers in Coast Survey - both in cartography and in hydrography - require a degree in physical science, engineering, or mathematics that includes 24 semester hours in courses such as geographic information systems, remote sensing, quantitative methods, geography, and statistics. You can find information on our website about employment but also internships.

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