NOAA Teacher at Sea
Onboard R/V Roger Revelle
November 11-25, 2003
Mission: Ocean Observation
Geographical Area: Chilean Coast
Date: November 13, 2003
Data from the Bridge
1. 131700Z Nov 03
2. Position: LAT: 10-01.0S, LONG: 084-55.0W
3. Course: 180-T
4. Speed: 12.5 Kts
5. Distance: 299.5 NM
6. Steaming Time: 24H 00M
7. Station Time: 00H 00M
8. Fuel: 4238 GAL
9. Sky: OvrCst
10. Wind: 130-T, 21 Kts
11. Sea: 130-T, 2-3 Ft
12. Swell: 140-T, 3-5 Ft
13. Barometer: 1013.8 mb
14. Temperature: Air: 22.4 C, Sea 19.0 C
15. Equipment Status: NORMAL
16. Comments: Drifter array deployment in progress.
Science and Technology
We are still underway towards the Stratus buoy. We spent the day deploying Surface drifters and 2 radiosondes. Surface drifters are small instruments attached to a “drogue” or sock that is about 40 feet long. The are thrown off the back of the ship while it is still moving. They will float on the surface and the drogue will float about about 15 meters below the suface taking sea surface temperatures and sending the data back to a satellite that is operated by the French ARGOS System. The data is downloaded at Wallops Island in Virginia and processed at various laboratories. We deployed 10 surface drifters today and will send off another group tomorrow. We are deploying them for the Atlantic Oceanographic and Meteorological Laboratory in Miami, Florida. This is a NOAA research facility. A noted drifter researcher is being done by Dr. Pieter Niiler at the Scripps Institution of Oceanography in La Jolla, Ca.
The purpose of the drifters is to measure sea surface temperature and check the accuracy ( calibrate) satellite data on sea surface temperature. Infra-red satellite data is sometimes blocked by stratus clouds and volcano eruptions. This brings to the light the question of why we need to go to sea in ships to study oceanography when we can supposedly get all the information we need from satellites. I will be interviewing Dr. Weller on one of my webcasts and he will address this question. Since I needed some additional enlightenment on why ships and shipboard research are still so essential to the study of climatology, atmospheric science and, of course, oceanography and Dr. Weller was busy today, I went to Scripps Institution of Oceanography ( via e-mail….those satellites are quite useful) and asked Dr. Robert Knox to help me out. Dr. Knox is the Associate Director of Ship Operations and Marine Technical Support and has helped me many times in the past with education outreach. The following is his wonderful explanation of why ships are still an essential tool for scientists in our exploration of the oceans and atmosphere.
Dr. Robert Weller’s research is an excellent example of why this type of data collection is so important and cannot be replaced by satellite data. It absolutely depends on using ships to handle his systems and is vital to gain a quantitative understanding of what the satellite sensors are seeing. In the absence of programs like Dr. Weller’s we could be seriously misled as to what the satellite data are telling us about the properties we actually care about, like sea surface temperature, heat flux between air and sea, etc. No satellite ever has measured or ever will measure sea surface temperature (SST). Yet we often see “satellite maps” of “sea surface temperature.” How? The satellite measures some component of electromagnetic radiation coming upward from the sea surface. That in turn can be related to the temperature of the sea surface, but only by way of a number of assumptions and calibrations having to do with basic physics of the radiation, the interactions of that radiation with whatever is in the atmosphere between the sea and the satellite, and on and on. In order to construct the formulas or recipes used to convert the radiation numbers to temperature numbers, real temperature measurements at the sea surface will always be needed to some extent, and with some distribution around the globe and over time. This is particularly true for long-term climate purposes, where slow changes in, for example, the atmospheric properties could lead to slow, subtle and unrecognized shifts in the correct recipes/formulas, and thus to unrecognized shifts in the deduced temperature results that were not real. Temperature is just one parameter. There are others, most of them harder to do via satellites.
The list goes on. Ships are needed for any number of laboratory-style experiments and measurements that simply cannot be done by remote sensors, but require samples of water, organisms or seafloor to be acquired and dealt with at sea. Questions in biology, chemistry and geology figure prominently here. New remote sensors, whether destined for satellites or unmanned vehicles in the ocean, in most cases require lengthy periods of development, testing and comparison against existing (shipboard) techniques before they can really be trusted to deliver the data desired – and even then (as in the case of SST above) there may well be an open-ended need for some level of ship-based, high-quality measurements to serve as a calibration standard in space and time. There are a host of chemical and biological parameters for which no remote sensor exists or is even imagined, yet shipboard/manned techniques do exist and can be used to answer important research questions. Take for example the identification and quantification of species or species assemblages in water samples (plankton, etc) and how these change over time, perhaps as a result of climate variations. If we waited until a remote sensor existed we might wait ad infinitum, yet we can do this identification and quantification now, using people and samples. The accumulation of those observations over time (more than 50 years thus far in the case of the CalCOFI program) sheds considerable light on the actual ecological changes taking place in the ocean and will continue to do so; we should most certainly not stop doing these measurements just because we cannot do them remotely. Or consider the business of measuring trace metals, notably iron, in seawater. This has gone from a curiosity to an important set of research programs in just the last couple of decades. It depends on exquisitely sensitive shipborne lab-style analyses of seawater samples for minute concentrations of these metals. Yet the tiny amount of iron in seawater may be a key limiting nutrient for phytoplankton under some circumstances. So iron trace concentrations get connected to important policy and economic questions such as whether deliberate iron fertilization could be a viable technique to enhance phytoplankton growth, thereby drawing down atmospheric CO2 via photosynthesis, and thus ameliorating greenhouse warming. Both the scientific and policy answers are far from clear at this juncture, but you can readily see the basic importance of the shipboard effort underlying the whole issue.
Finally, the advent of various remote sensors, on satellites and on unmanned vehicles, creates a whole new possibility for joint ship/other device campaigns that can do a much better job of focussed observation than has been possible in the ship-alone mode characteristic of nearly all history to date. The ship can serve as home base/deployment platform/data integration and analysis center/command post for adaptive, real-time control of a fleet of these devices, for ingesting streams of satellite data from overhead, and for deploying its own specialty ship-deployed instruments. Sort of a vision of the ship as the AWACS centerpiece of a flotilla or network of tools aimed at some common experimental objectives. Oceanography historically has been bedeviled by the inability to measure with coverage in both space and time matched to the problems of interest. A single ship can never be “here” and “there” simultaneously, nor can it cover the distance between “here” and “there” fast enough for some purposes. But operating as the mother ship/control center, many of these gaps can be closed. It’s going to be fascinating to see how some of these potentials are used in the coming decades.
As a teacher at sea one of the things I have learned in the short time I have been on the ship is that many times observing the conditions under which the data are collected can be as essential as the actual data itself in enabling a scientist to analyse it and put the data in the proper perspective. For example: when we retrieved the Equadorial Buoy and brought up all the instruments that were hanging on the mooring it was absolutely amazing to see the vast numbers of animals that had made these instruments their home ( see my pictures). Could these animals have effected the instruments and their data collections by blocking water flow or changing environment around the instruments? Yes. Is it important to note this and take this into consideration when analysing the data? Very possibly. The ship I am travelling on is named for a very famous and well respected oceanographer, Dr Roger Revelle, who understood how important it is for scientists to actively participate in the collection of their data by going to sea in order to get a more accurate perspective on what the data they collect is telling them about the oceans. As a teacher I hope I can share this with my students, I know that in my classroom, no amount of lecture or reading can replace the experience of doing a laboratory and collecting and analysing your own data. My watch is almost over and I have 2 more surface temperature readings to take before I sleep……the old fashioned way, drop the bucket with the thermometer over the side, fill it with water and read the thermometer. We are just checking those computerised sensors to make sure everything is working:)