Tag: Alaska

NOAA Teacher at Sea
Mike Laird
Onboard NOAA Ship Rainier
July 24 – August 13, 2005

Mission: Hydrographic Survey
Geographical Area: North Pacific
Date: July 29, 2005

Weather Data

Latitude: 55° 53.36 ̍ N
Longitude: 158˚ 58.4 ̍ W
Visibility: 10 nautical miles (nm)
Wind Direction: Light Airs
Wind Speed: Light Airs
Sea Wave Height: 0΄
Swell Wave Height: 0΄
Sea Water Temperature: 12.2˚ C
Sea Level Pressure: 1013.5 mb
Cloud Cover: Sky 8/8 covered;
Lower-level: cumulus, stratocumulus
Mid-level: altostratus

Science and Technology Log 

Today I am on a team that is going ashore to set up two horizontal control-data collection stations. The horizontal control team is responsible for establishing accurate latitude and longitude coordinates for the location of the survey soundings. The RAINIER uses a Differential Global Positioning System (DGPS) to acquire precise readings for every collected depth sounding. The remote location of the Mitrofania Island work area has introduced an infrequently encountered challenge for the horizontal control team.  The two Coast Guard operated DGPS Beacon Stations that are closest to the work area (one on Kodiak Island and one in Cold Bay) are too far away (we are on the outer fringe of their transmitting capability) for the signal to reach the launches in some of the more isolated, shielded areas. As a result, we are out setting up the horizontal control data collection stations.

The first station is set up over an existing benchmark and will record data transmitted directly from a GPS satellite.  The receiver will record readings for six hours, shut down for twenty-four hours, and resume recording for a final six-hour time period. Finished with the first station, we travel across the bay to a point that extends out into the ocean. We will set up the second horizontal control data collection station at this location. However, there is not an existing benchmark, so we must establish one.  First, we drive three-foot sections of metal rod into the ground (normally benchmarks are fixed in rock but there is none at this site).  We sink two sections and decide that is enough to hold the benchmark in place for the two months that it will be in use (for a permanent benchmark the rod is driven until it can go no further).  The brass cap is then stamped with a name (SPIT) and date (2005) and affixed to the top of the rod.  We are now able to set up the second station. The receiver will follow the same collection pattern: collecting signals for six hours, resting for twenty-four hours, and collecting for another six hours.

At the end of the collection period, the data from the sensors will be uploaded to an onboard computer and transmitted to the National Geodetic Survey in Washington D.C. where corrections to account for error introduced by things such as the atmosphere are applied. The corrected data, returned to the ship, will establish very accurately (within cm) the latitude and longitude for the site.  One final correction is made to the data before the site can be used. This error source is the satellite itself and comes from the satellite’s perceived position (where it thinks it is in the sky) as compared to its actual position.  The precise location is monitored by the United States Air Force.  Final corrections using this information will provide pinpoint accuracy (within mm) of the benchmark’s location. A temporary, or “fly-away”, DGPS station can now be placed at this benchmark and transmit signals easily received by the launches.

Personal Log 

Yet another beautiful day! Once on shore the mosquitoes were terrible – swarming in clouds around our heads.  A little bug dope, the warm sun, and cool breeze soon took care of this problem.  A great day to be out working!

NOAA Teacher at Sea
Mike Laird
Onboard NOAA Ship Rainier
July 24 – August 13, 2005

Mission: Hydrographic Survey
Geographical Area: North Pacific
Date: July 26, 2005

Weather Data

Latitude: 55°53.3̍ N
Longitude: 158˚58.4 ̍ W
Visibility: 10 nautical miles (nm)
Wind Direction: 235˚
Wind Speed: 6 kts
Sea Wave Height: 0΄
Swell Wave Height: 0΄
Sea Water Temperature: 11.1˚ C
Sea Level Pressure: 1013.5 mb
Cloud Cover: Sky 7/8 covered, Cumulonimbus

Science and Technology Log 

Operations for the day begin at 8:00 with crews of four launches assembling on the fantail for a pre-launch briefing giving final details of the day’s assignments and a review of safety procedures. Each launch crew is composed of three members: an Officer in Charge (OIC) who has overall responsibility of the launch, a coxswain who is responsible for the physical operation of the launch, and a survey crew member who assists in data collection in the assigned survey area.  Some crews carry a fourth member who is frequently a Teacher at Sea or other visitor on the ship.

Once the briefing is completed, each crew assembles in their launch-loading zone and boards the launch as it is lowered into the water.  I have been assigned to launch RA5 (RAINIER launch 5) and will be working with Ensign Mike Stevenson (the OIC), Carl Verplank the (coxswain), and Greg King (the survey technician).  Our assignment is to work in conjunction with launch RA3 to collect seafloor data in Mitrofania Bay, an area to the northwest of the RAINIER’s anchor location.  The area has been designated as Sheet AW.  The area around Mitrofania Island has been divided into several sheet areas.  Each sheet is composed of a map of the area overlaid by a set of parallel lines or tracks that the launch or ship will follow as it is recording data.  During the two weeks we are working in the region, data will be collected for as many of those sheets as possible.

Having reached the target area, a “cast” must be taken before the actual scanning of the bottom can begin.  The purpose of the cast is to gather information about the behavior of the water column we are working in.  The waters’ conductivity, temperature, and pressure will all affect the velocity of sound traveling through the column, and will be factored into the processing of the collected data.  The cast is conducted by lowering a CTD sensor, called a SEACAT, to the floor of the ocean.  When the cylinder is raised back to the surface, the data is uploaded to the launch computers and we are ready to go.  Launch RA5 is equipped with a Reson SeaBat 8101, a hull mounted extended echo sounder system.  This system is used to record seafloor information in water depths not exceeding approximately 110 meters.  This sonar system is a multi-beam system using 101 beams.  Each beam is composed of pings emitted from the sounder.  One beam drops vertically below the launch and fifty beams each fan out to the port and starboard sides.

To help picture this, imagine a set of right triangles below the launch.  Each triangle originates with the junction of the vertical beam and seafloor where two opposed right angles are formed.  The hypotenuse of each triangle is one of the fifty beams to the left or right of the vertical beam, and the seafloor forms the base of the triangle. Collectively the bases are referred to as the footprint (area covered by the sounding).  This footprint increases in size as the depth of the water increases.  As the size of the footprint grows, additional “noise” or interference is introduced into the sound wave pattern in those beams further from center.  This less accurate data will usually be eliminated during data analysis.

We spend the day transiting the lines designated on our sheet as the sonar feeds seafloor data to the launch computers.  At the end of the day, the launch nested safely back on the RAINIER, the data is downloaded from the launch to the ship.  Now begins the next phase analysis and “cleaning” of the raw data.  However, that is for another day!

Note: This is my understanding of the information I received.  If there are errors or inaccuracies,  I apologize.

Personal Log 

We have been very fortunate so far – the weather has been great since we arrived in Mitrofania. Partially cloudy but lots of sun!  The salmon (pinks and silvers) are constantly rolling and jumping. I tried my hand at a little salmon fishing yesterday with mixed results.  I hooked two! Key word there hooked. I didn’t land them – both shook the hook. Pretty lame, but I’ll get them next time!  Other crew members have tried some halibut fishing, but so for have only brought up what they call Irish Lords (“An ugly, junk fish.”) The fish is unique – a tan, brown and black with bulging eyes and poisonous spines that apparently cause pain and discomfort if you are cut or poked.

NOAA Teacher at Sea
Mike Laird
Onboard NOAA Ship Rainier
July 24 – August 13, 2005

Mission: Hydrographic Survey
Geographical Area: North Pacific
Date: July 25, 2005

Weather Data

Latitude: 55°37.1̍ N
Longitude: 156˚46.6 ̍ W
Visibility: 10 nautical miles (nm)
Wind Direction: 140˚
Wind Speed: 5 kts
Sea Wave Height: 0-1΄
Swell Wave Height: 2΄
Sea Water Temperature: 12.2˚ C
Sea Level Pressure: 1009.8 mb
Cloud Cover: Stratus

Science and Technology Log 

My name is Mike Laird, and I am a 5^th and 6^th grade Science and Math teacher from Flagstaff, AZ. I am onboard the NOAA ship RAINIER participating in a three-week hydrographic research cruise. The primary objective of the scientists and crew of the RAINIER is to gather data that can be used to create accurate maps of the ocean floor and coastline. I joined the team in Kodiak, AK.

We put to sea Monday afternoon after completing repairs on one of the six survey launches carried by the RAINIER.  Our destination is Mitrofania Island, a small island southwest of Kodiak. This location has been selected for data collection, because there is little information available on current nautical charts.  Our route took us through Shelikof Strait (between the Alaska Peninsula and Kodiak Island).

We then tracked south between the Semidi Islands and Chirikof Island.  As we transited this track, the RAINIER used its onboard sonar to gather ocean depth information for this location. As other NOAA hydrographic ships follow this course, they will also gather data. Over time and using all the data collected by the various ships, an accurate nautical map of this area will be constructed.

Having completed this pass, we headed northwest toward Mitrofania.  We sailed around the southern tip of the island and head for Cushing Bay, where we anchored for the initial phases of the data collection work.  As we neared Cushing Bay, a small work team was deployed in one of the ship’s skiffs to check a temporary (in place for thirty days or less) tide station. The station must be checked to insure that it is operating correctly and transmitting accurate information back to the RAINIER.  Data from the temporary tide station will be compared to data from the nearest official Coast Guard Tide Station and accurate tidal information for the area around Mitrofania Island can be derived.  Accurate tidal information is critical, since it is used in the processing of the collected data.  In addition to checking the tide station, the work crew will attempt to locate a spot on the shore to install a temporary GPS system.  The closest land-based GPS systems are a distance away and could introduce error of up to three meters in the collected data.  The successful installation of a closer, more reliable GPS would help increase the reliability of the data the team collects.

The end of the day has come.  We are anchored in Cushing Bay, and I eagerly await tomorrow’s arrival as I will be joining the launch 5 survey team.