October News from the BALDRIGE
October Mail Call
Captain Nelson writes...
Welcome back, to the 6th grade students from Alta Loma Elementary School, Connie Pfahlert, Misty, and to The Year 5 and 6 students from Wanniassa Hills Primary School in Canberra, Australia.
Since July, the crew on the MALCOLM BALDRIGE has been spending their time at sea working on that are part of the the United States' contribution to the Climate and Global Change Program. One of these projects, the Global Ocean Ecosystem Dynamics (GLOBE) program is biological in nature, and the other two, the Ocean-Atmosphere Carbon Exchange Study (OACES) and the World Ocean Circulation Experiment (WOCE) are projects that are based on physcial and chemical measurements taken in the deep ocean basins in the Indian Ocean and in the major basins of the Atlantic and Pacific Oceans.
In late July and during August, the MALCOLM BALDRIGE was at sea making biological measurements for the project in the northern Arabian Sea, along the coast of Oman, and off the coast of Somalia. During the summer (in the northern hemisphere), the southwest monsoons blow steadily and strongly along the coasts of Somalia and Oman and across the western Arabian Sea for several weeks to up to 3 months. We experienced winds of 25 to 30 knots and seas of between 10 and 14 feet high every day for just about 2 weeks. Even a ship as large as the MALCOLM BALDRIGE (length of 278 ft, width of 51 ft, and weight of 2800 tons) gets bounced around like a cork in seas like we encountered off Somalia.
During the southwest , very strong upwelling occurs near the coast. The winds that blow along the coast from the southwest to the northeast tend to drag the surface water along with them. The Earth's rotation then deflects the resulting surface currents toward the right away from the coast in the Northern Hemisphere. As the surface waters are deflected away from the coast, colder, nutrient-rich water comes up from below to replace it. This phenomenon is known as upwelling. Strong upwelling also occurs in the open ocean where there are strong variations in the speed and direction of the wind.
In the coastal upwelling region, stirring by the wind mixes the nutrient rich water with the surface water. In the presence of sunlight near the surface, tiny, microscopic plant species called use the nutrients to produce chlorophyll, the same biological material required for growth that is found in allOman and large predators (such as sharks, whales, and seals) sit at the top of the food chain to catch and eat the larger fish in the ocean. By the way, because the surface water in the coastal upwelling regions of the world are usually colder than the surrounding water, and because the phytoplankton "blooms" are usually wide spread, we can observe and map the coastal upwelling regions around the world by using satellites to measure the surface temperatures and the surface chlorophyll content. In fact, during our GLOBEC cruise we received satellite images of sea surface temperature each day on the ship, and we used the patterns of cold water that depicted the coastal upwelling regions to determine exactly where we would make biological net tows, take water samples, and release drifting buoys each day during the cruise.
Back to the MidLink Home Page
The scientists on the GLOBEC cruise wanted to measure the amount of food production during the strong monsoons and compare those measurements to the data that we collected in the same area earlier in the year when the monsoon winds were not blowing. Of course, when the winds were not blowing strongly along the coast in April and May, there was no coastal upwelling, the surface temperatures were much warmer, the surface waters were poor in nutrients, and there was not much phytoplankton or zooplankton in the water. There was a very big difference in the amount and type of biological material that we collected in our nets between the April/May cruise and the August cruise in the same area.
During the cruise leg from Victoria, Seychelles to Muscat, Oman in late July, our marine mammal and sea bird observers, Bob Pitman, Lisa Ballance, and Michael Force completed one last survey in the Gulf of Oman. During that part of the cruise, they spotted 69 schools of 7 different species of marine mammals, including several types of dolphins and whales, and a few sperm whales. Many of the schools that they spotted contained several hundred animals - quite a spectacular sight when viewed from the bridge or bow of the ship.
We are now working on our last major cruise of the year in the Indian Ocean before the ship leaves this part of the world, and returns to the more familiar waters of the Equatorial Pacific Ocean. We have 26 scientists aboard the ship, who are from various NOAA laboratories and universities in the United States, and they are all participating in either the OACES or the WOCE project during this cruise. With my crew of 50, we now have quite a full ship, packed with both people and instruments. The measurements that we will take as part of the OACES project will help scientists determine the regions of the sources and sinks of carbon dioxide (CO2) in the South Central Indian Ocean during the austral winter. The data that we collect on the temperature, salinity, oxygen, and currents in the deep ocean basin as part of the WOCE project will help scientists understand, model, and predict the general circulation (flow) in the global ocean, and, for example, how heat is transported from one part of the ocean to another to effect our weather and climate.
In yesterday's log, I told you that the MALCOLM BALDRIGE left Fremantle, Australia on 22 September 1995, and that we are working our way towards the southwest, before we turn north to head for Sri Lanka. The ship is now in position 33-07 S, 090-22 E (at 1230 ship time, 0230 Eastern Standard Time, and 1630 in Canberra on 3 October 1995) and we are just about one-third of the way to our southern turning point near Amsterdam Island in the Southern Indian Ocean. [See if you can find Amsterdam Island on a world chart]. During this cruise we have been taking deep ocean samples with our conductivity-temperature-depth (CTD) and water sampling instrument to study the ocean currents and circulation in the eastern part of the Indian Ocean. The water samples will be analyzed for temperature, salinity, oxygen, nutrients, and trace gases, such as freon and other chlorofluorocarbons (CFCs) that can only enter the ocean through the boundary between the atmosphere and the ocean. The scientists are especially interested in determining the amount of carbon dioxide in the water and in determining how much carbon dioxide is exhanged between the atmosphere and the ocean. These studies are very important to understand how and where carbon dioxide is exchanged between the ocean and the atmosphere and what effect this exchange has on the "greenhouse effect" and on global climate change.
Back to the MidLink Home Page
In her recent message, Misty [lgarrett@legend.txdirect.net] wanted me to explain the I'm sure that many of you may have gone into a greenhouse to look at or to buy flowers, and when you were in the greenhouse, I'm sure that you thought it was quite hot. Well, a greenhouse is mostly constructed of glass (or perhaps fiberglass). The glass is transparent to sunlight, so the short-wave solar radiation that comes directly from the sun penetrates through the glass into the inside of the greenhouse. Now the things in the greenhouse (plants, soil, concrete, etc.) heat up under the sunlight, and as they heat up, longer-wave [solar] radiation is reflected back up, but because it is longer wave radiation, it cannot penetrate as easily through the glass to escape into the atmosphere. Instead, the longer wave length radiation is mostly trapped inside the greenhouse, and it adds to the amount of heating that takes place within the greenhouse.
Now if we expand a small greenhouse to the size of the Earth, then instead of a glass enclosure, we have a rather thin atmosphere that surrounds our planet. The atmosphere is composed of a lot of invisible gases (primarily nitrogen and oxygen [otherwise we couldn't breathe and we wouldn't be living on this planet]), but for this discussion, the important parts of the atmosphere are the clouds, water vapor, and carbon dioxide. So the clouds, water vapor, and carbon dioxide in the atmosphere are like the glass in a greenhouse. Incoming sunlight (shortwave solar radiation) penetrates through the atmosphere and heats up the surface of the Earth. The Earth, in turn, reradiates at a longer wavelength, and this radiation is trapped between the lower atmosphere and the surface of the Earth. The result is that the lower atmosphere is warmed because there are clouds, water vapor, and other gases like carbon dioxide in the atmosphere. Without the clouds and water vapor in the atmosphere, the surface of the Earth would be much colder (several degrees to tens of degrees) and it would be much more difficult to live comfortably on this planet. In simple terms, the clouds and water vapor form a NATURAL greenhouse for the Earth.
When scientists talk about the "greenhouse effect" and its relation to "global climate warming" they are usually referring to the effects that human activities have had on ENHANCING the NATURAL greenhouse effect and possibly causing the surface of the Earth to heat up more than what might be expected. One of the other important compoents in the atmosphere that contributes to the ENHANCED greenhouse effect is carbon dioxide. We know from measurements that have been taken over the past 4 decades that the amount of carbon dioxide in the atmosphere has been increasing steadily. As CO2 in the atmosphere increases, the greenhouse warming effect on the surface may also increase. A large part of the steady increase in CO2 in the atmosphere has been the result of burning of fossil fuels (oil, gas, etc.). A concern among scientists is that if the amount of CO2 that is in the atmosphere continues to increase over the next 50 to 100 years, the average temperature of the Earth could increase by a few degrees. The resulting changes in climate and weather experienced in different parts of the world would have major impacts on how we live on this planet.
Carbon dioxide is found in the atmosphere as a gas, and it is also contained in the ocean as a dissolved gas. In some parts of the world there is more carbon dioxide in the atmosphere than there is in the ocean, so in these regions carbon dioxide is transferred from the atmosphere to the ocean. In other parts of the world, cardon dioxide is released from the ocean and enters the atmosphere. In terms of the ENHANCED greenhouse effect, where the ocean releases carbon dioxide to the atmosphere, the ENHANCED greenhouse effect may be increased, and where the ocean absorbs carbon dioxide from the atmosphere, the ENHANCED greenhouse effect may be decreased.
During our OACES project, we are attempting to map out those regions in the South Central Indian Ocean that are SOURCES for carbon dioxide (where CO2 is released from the ocean into the atmosphere) and those that are SINKS for carbon dioxide (where CO2 is absorbed into the ocean from the atmosphere). If the ocean could absorb all of the CO2 that is continually added to the atmosphere, then there would not be as much of a global problem with ENHANCED greenhouse warming. But remember that there are many ways in which CO2 is added to the atmosphere - burning of oil and gas, burning of wood, destruction of forests, etc.
There are active debates and discussions going on among scientists, politicians, and the general public about whether or not "global warming" is actually occurring, and about what the global consequences will be if the Earth heats up by several degrees. Will all parts of the Earth warm up uniformly or will certain areas that are lush and green now turn into deserts, and will the more polar regions of the Earth become warm, wet, and green? There are not yet any definite answers to questions such as this one. However, whether the Earth is actually warming or not, we do know that climate is changing all over the Earth, and many of the climatic changes that we are observing today have been the result of human activities (for example, burning of fossil fuels - oil and gas, burning and clearing of forests, use of CFC aerosols, etc.).
We also know that climate change and the resulting changes in local weather are a global phenomenon. For example, whether we have a cold and wet winter along the U.S. east coast, or a warm and dry one, or whether California gets flooded out again in the winter, or whether there is wide-spread drought and disastrous forest fires in Australia, as there were in 1982-83, depends upon oceanic and atmospheric conditions in the western and central Pacific Ocean. In fact, as some scientists are beginning to learn and understand, changes in that part of the ocean-atmosphere system may be triggered by similar changes in the Indian Ocean, where we are right now.
If we were just worried about whether the weather was going to be nice enough for a picnic in July or if we are going to have snow for Christmas (up north), then these climate changes might not be too important to you or me. But, in fact, these changes in climate and weather caused by changing conditions in the atmosphere-ocean system have tremendous impacts on the economies of the countries of the world. During 1982-83, scientists monitored one of the largest of these inter-annual climate changes, a phenomenon called El Nino. Because of the El Nino conditions in the Pacific Ocean in 1982 and 1983, there were major shifts in weather patterns around the world, and many billions of dollars of damage was done to crops, property, and lives. In the U.S. alone, there was over $1 billion in flood damage. At the same time, it is estimated that there was over $2.5 billion lost in Australia due to drought and fires.
In 1995, we are also witnessing the effects of a non-El Nino year. For those of you who live in Florida, I'm sure that you have been watching closely the tracks of the many hurricanes that have been generated in the Atlantic Ocean and in the Gulf of Mexico. We are already up to Hurricane Opal (in the Gulf of Mexico), the largest number of named tropical storms in recent weather history, and there is still one month to go. In El Nino years, there are few, if any hurricanes. In non-El Nino years, just the opposite may occur, and this year is a record by all accounts.
As the MALCOLM BALDRIGE makes its way into the Pacific Ocean to begin our two months of work on the buoys that are moored near the equator, I will provide more information on El Nino, how we monitor and attempt to predict El Nino, and how major changes in the ocean and atmosphere in the Pacific Ocean can affect your weather and climate thousands of miles away in the United States.
Well, we've finally arrived on our station, so I will have to close the log for today, and go collect data. If you have any questions that I might be able to answer, please write to me at [CSNelson@rdc.noaa.gov].
Your Friend and Chief Navigator,
Captain Craig S. Nelson, NOAA
Commanding Officer
NOAA Ship MALCOLM BALDRIGE
Back to the MidLink Home Page