U31D-01
ESA's Future Earth Explorer: new candidate mission concepts
The European Space Agency has released the call for the next Earth Explorer Core Mission Ideas in March 2005 with the aim to select the 7th Earth Explorer mission to be launched in the 2014 timeframe. Twenty-four proposals were received and subject to detailed scientific and technical assessment. Six proposals have been selected to be further investigated in a detailed scientific and technical assessment study, after which a down-selection will be made. The six candidate missions selected are: A-SCOPE - (Advanced Space Carbon and Climate Observation of Planet Earth) – Improving the understanding of the global carbon cycle and regional carbon dioxide fluxes, BIOMASS - global measurements of forest biomass and extent, CoReH2O - (Cold Regions Hydrology High-resolution Observatory) – Detailed observations of key snow, ice and water cycle characteristics, FLEX - (FLuorescence EXplorer) – Observation of global photosynthesis through the measurement of fluorescence, PREMIER - (PRocess Exploration through Measurements of Infrared and millimetre- wave Emitted Radiation) – Understanding the processes that link trace gases, radiation, chemistry and climate in the atmosphere and TRAQ - (TRopospheric composition and Air Quality) - Air quality monitoring and long-range transport of air pollutants. This paper will give an overview of the science objectives and preliminary requirement specifications for each candidate mission.
U31D-02 INVITED
The Mauna Loa CO2 story: lessons for long-term earth observations
The long-term measurements of atmospheric CO2 concentrations at Mauna Loa Observatory provide an interesting test case for assessing the benefits and challenges of long-term earth observations. The Mauna Loa story illustrates how repetitive measurements can provide a rich opportunity for discovering new phenomena. As the CO2 records have continued to grow in length, important opportunities for discovery have continued to arise. Now spanning 50 years, the records are among the first places to turn for addressing certain questions relevant to future climate change, such as the detection of feedbacks of climate on CO2. This talk will provide a brief historical perspective on the challenges that were faced in sustaining the Mauna Loa CO2 record. Examples will be given to illustrate the continuing discovery process derived from the Mauna Loa and related records, and to illustrate the lessons learned in this process.
U31D-03
Climate Effects on Atmospheric Carbon Dioxide Over the Last Century
Since 1958, the buildup of atmospheric CO2 can be quite accurately explained by the simple premise that 56% of the industrial emissions (fossil fuel burning and cement manufacture) has remained airborne. The constancy of this airborne fraction is in contrast to the large variations in the airborne fraction seen in the 19th and early 20th centuries. The constancy since 1958 is also surprising because the airborne fraction was expected to decline after ~1980, when the growth rate of fossil fuel emissions decreased, allowing the oceans to absorb a greater fraction. We show that these features can be reconciled assuming that a portion of the CO2 variability is driven by variations in global land temperature, with a proportionality of around 10 ppm/degrees C. Using a simple land biospheric model, we show that the global land temperature can drive this CO2 variability through temperature-dependent respiration using a Q10 of approximately 2, as expected. Our analysis suggests that the constancy of the airborne fraction over the past 50 years is coincidental: a warming trend started around the same time as the decrease in the growth rate of fossil fuel emissions, and compensated for the expected decrease in the airborne fraction. If the land biosphere behaves similarly over the next century, this will contribute to a small but significant positive feedback on future global warming.
U31D-04
Space Age Geodesy: Global Earth Observations of Ever Improving resolution and Accuracy
The launch of Sputnik-I by the USSR in 1957, and the resulting competitive US-USSR space exploration and weapons programs, led to the need for global geodetic measurements of unprecedented accuracy, and the means to develop new observing techniques to meet those needs. By the 1970s the geodetic community developed very long baseline interferometry (VLBI), lunar laser ranging (LLR), and satellite laser ranging (SLR), and launched international tests that led to the establishment of the International Earth Rotation Service (IERS). Today the IERS provides a stable International Celestial Reference Frame (ICRF), and accurate earth orientation parameters (EOP) values, using a combination of VLBI, LLR, SLR, and the Global Positioning System (GPS). There are hundreds of continuously operating GPS stations around the world, providing centimeter station locations and millimeter per year station velocities, in the International Terrestrial Reference Frame (ITRF). The location of any point on earth can be determined relative to the ITRF to within a few centimeters from a few days of GPS observations, and using kinematic GPS, the positions of moving objects can be tracked to a few centimeters at distances of tens of kilometers from the nearest GPS ground stations. This geodetic infrastructure and space age technology has led to the development of new airborne topographic mapping techniques, most significantly, airborne laser swath mapping (ALSM). With ALSM, it is now possible to map thousands of square kilometers of terrain with sub-decimeter vertical accuracy in hours. For example, the entire length of the San Andreas fault, in California, was mapped in a few hundred hours of flying time. Within the next few decades, global ALSM observations will make it possible for scientists to immediately access (by the internet) data bases containing the locations (cm accuracy) and rates of motion (mm per year accuracy) of points on the surface of earth, with sub-meter spatial resolution, for any area of interest. Digital elevation models (DEMs) and other products derived from ALSM observations are already revolutionizing such diverse fields of research as hydrology, geomorphology and earth surface dynamics, neotectonics, and coastal dynamics. Expanding the coverage of and access to ALSM observations can only lead to new scientific findings about our ever changing planet Earth.
U31D-05
Satellite Measurements of Sea Level Change: Looking Back and Ahead
Over the last few decades, satellite geodetic measurements together with in situ measurements, have revolutionized our understanding of present-day sea level change. With measurements from satellite altimeter missions and satellite gravity missions, we are now able to start answering some important questions with regards to global sea level change and its regional variations. What have we learned from these measurements? Would we change any of the decisions we made in the past? What are the remaining questions to be answered? What suite of measurements are needed to answer these questions? The record of sea level change from satellite altimetry (TOPEX/Poseidon and Jason) will be reviewed and the results placed in context with other estimates of sea level change from tide gauges, in situ measurements, and global climate models. The much shorter, but just as important, record of ocean mass variations from satellite gravity measurements (GRACE) will be similarly reviewed. The coupling of changes in the global water cycle with sea level change will be discussed. Finally, the need for continuing the satellite measurements of sea level change, and possibly developing new measurements, will be discussed in the context of future missions and the scientific gain that would result. http://sealevel.colorado.edu
U31D-06
Observing Ocean Surface Wind-stress With Spacebased Scatterometers
Seven microwave scatterometers have been launched since the short life span of Seasat in 1978; they have provided ocean surface wind-stress vectors, night and days, under clear and cloudy conditions. The evolution of their capability will be summarized. The unique capability of measuring stress, as distinguished from winds, will be clarified, and major impact on scientific research and operational application will be highlighted. Potential increase in spatial resolution, reduction in directional ambiguities, improvement in strong wind retieval, and reduction rain attenuation will be discussed. Future international constellation in meeting the operational weather application requirement of six-hourly revisit time will be described.
U31D-07
The Ocean Observatories Initiative: Getting Wet Behind the Ears
The U.S. National Science Foundation's Ocean Observatories Initiative (OOI) is constructing an integrated network to provide the oceanographic research and education communities with continuous, interactive access to the oceans. The program will build permanent science–focused infrastructure that will enable geoscientists to simultaneously study multiple phenomena in the oceans over time scales from milliseconds to decades, and over spatial scales from sub-meter to global. An integrative computer architecture or cyberinfrastructure will allow researchers to communicate with and configure globally situated experiments in near-real time, forming virtual observatories by designing customized data streams readily incorporated into adaptive models. The project, approved for planning activities by the National Science Board in 2000, will undergo its Preliminary Design Review for readiness in December 2007 and is expected to receive the first installment of a total anticipated capital investment of $330M in 2008. Specific assets include autonomous platforms at high-latitude sites in the northern and southern hemispheres, a submarine ackbone cable spanning the seafloor of the Juan de Fuca tectonic plate, and moorings and mobile assets studying the coastal ocean continental shelf and slope in the Middle Atlantic Bight and offshore the Pacific Northwest. With its global dimension and unifying cyberinfrastructure, the OOI is expected to catalyze new understanding of the oceans in a way that ship-based measurements and experiments, with their shorter observation window and inherent limitations on power and bandwidth, are unable to accomplish.
U31D-08
100 Million Years of Earth Observations from Scientific Ocean Drilling
Much of what we know about the last 100 million years of Earth history derives from scientific ocean drilling. On hundreds of expeditions conducted since 1964, in deep and shallow water and from the tropics to the poles, scientists have collected and analyzed thousands of kilometers of sediment and rock cores from below the seafloor and measured a wide variety of physical and chemical properties in the corresponding boreholes. The enormous body of results has greatly improved our knowledge of Earth's climate history, continental drift, earthquake genesis, and many other geological phenomena. For example, scientific ocean drilling has confirmed the basic tenet of plate tectonics and the three-layer model of oceanic crust that explains the primary source of marine magnetic anomalies. Scientists also have documented and quantified the occurrences of extreme climates and rapid climate change over the last 100 million years and established the hypothesis that Himalayan uplift enhanced global cooling. Upcoming expeditions aim to recover records of past time periods with different climatic boundary conditions to help answer questions about the mechanisms that produce climate oscillations and their global extent. Other expeditions will examine the microbial communities that compose the deep biosphere. Scientists also will investigate fault mechanics and seismogenesis along subduction megathrusts through direct sampling, in situ measurements, and long-term monitoring as part of the Nankai Trough Seismogenic Zone Experiment (NanTroSEIZE). The observations from these new expeditions and complex drilling projects of the ten-year Integrated Ocean Drilling Program (IODP) will significantly enhance our understanding of the Earth system history and lead to the next set of important discoveries about our planet.