Figure 2 GOME-2/MetOp data showing Analyzed Total Ozone Columns from DLR EUMETSAT. Image credit goes to the ICSU/WMO World Data Center for Remote Sensing of the Atmosphere. This link shows videos of this over time:

Climate Sensor Update

Still Needed: Standards and Continuity

Karen Nozik
Boulder, Colo.

EDITOR'S NOTE The May eNewsletter included a summary of the Earth Observations portion of the National Space Symposium.

Turns out, the topic of monitoring climate change using climate sensors is not as straightforward as it might seem. In 1934, poet and critic T.S. Eliot wrote, "Where is the wisdom we have lost in knowledge? Where is the knowledge we have lost in information?" He might have been writing of the twenty-first century.

Dr. Alexis Livanos, Corporate Vice President and Chief Technology Officer for Northrop Grumman, may concur with the writer. In a speech he gave April 1st at the 25th National Space Symposium in Colorado Springs, Dr. Livanos said, "The solution must include the technical... Finding solutions to climate change will require space and other systems that include all the many types and generations of sensors, platforms and communications that space facilitates." Then he added, "...but also the non-technical; the familiar, but also the unconventional. It must be flexible and adaptable and provide a variety of information that allows decision makers to make intelligent choices."

Climate sensors—yes, absolutely, almost everyone agrees they are important to controlling climate change. But that's just the beginning. The hard part will be figuring out what kinds of instruments we need, and then to help us decide whether to mitigate changes, or, if we're too late on such things as melting glaciers, then to help us adapt. Dr. Livanos said that the United States undoubtedly must address the impact of climate change using a multi-faceted approach.

Climate change could potentially affect every sector of society. A recent report from the Center for Strategic and International Studies estimates that $3 trillion of the U.S. GDP of $13 trillion is sensitive to climate change. Dr. Livanos used the $18 billion wine industry as his example, citing how the slightest increase in average temperature will have a devastating effect on the product and profits. He suggests partnering with the private sector industries that have the most to lose, for issue and policy advocacy. And think of any number of others: ski resorts, insurance companies, firefighters... even Wal-Mart (it's someone's job to decide how many raincoats to buy in southern Florida during the rainy season). With so many potentially affected, masses of industries certainly have a dog in the fight.

Reducing our vulnerability to these impacts depends not only upon our ability to understand climate science and the implications of climate change, but also upon our ability to integrate and use that knowledge effectively. We are only beginning to find the "knowledge we have lost in the information." The Orbiting Carbon Observatory satellite was the latest science mission in NASA's ongoing study of the global carbon cycle; unfortunately, it crashed earlier this year. It was to be the first spacecraft dedicated to studying atmospheric carbon dioxide, the most signifi-cant human-produced greenhouse gas and the principal human-produced driver of climate change.

Today, as Dr. Livanos pointed out at the Space Symposium, data collected on the ground comes from either a scientist who hand-counts species on site—one square meter at a time—or from a vast, space-based global view. This leaves a knowledge gap big enough to fly a satellite through in monitoring systems central to future climate change mitigation and adaptation efforts.

The National Polar-orbiting Operational Environmental Satellite System (NPOESS) is the next generation of low Earth orbiting environmental satellites meant to meet the nation's needs for environmental measurements from satellites. NPOESS is a tri-agency Department of Defense, Department of Commerce, and NASA program that merges two environmental satellite systems into one in order to globally measure atmospheric, land and oceanic environmental parameters. NPOESS will circle the Earth approximately once every 100 minutes, providing global coverage, monitoring environmental conditions, collecting, disseminating and processing data about the Earth's weather, atmosphere, oceans, land, and near-space environment.

NPOESS will collect a massive amount of very precise Earth surface, atmospheric and space environmental measurements from a variety of on-board sensors. This volume of data will allow scientists and forecasters to monitor and predict weather patterns with greater speed and accuracy.

Distinctions need to be made between observations predicting the weather, and measurements required to monitor and understand the Earth's climate. This is where the topic of climate sensors becomes complex. For starters, predicting weather requires a good set of observations at a single time; monitoring climate fluctuations calls for a longer time series of observations.

In general, two kinds of climate variations—short-term and longer-term—concern us. Short-term climate fluctuations depart from average weather conditions over a period of a month or more; these are referred to as climate variations. (Think of El Niños and droughts.) Variations in the weather and climate over the longer-term (decades, centuries, etc.) are generally referred to as climate changes.

Dr. Shaida Johnston, PhD, a remote sensing policy analyst, said the weather models have been in place for 50 years, are agreed upon, and work very well at predicting storms, anticipating hurricanes, etc. The climate models are much more theoretical, and are not yet in place.

Dave Jones, Founder, President & CEO of StormCenter Communications (Ellicott City, Md.) frames it this way: "Weather is what you get. (It's raining outside.) Climate is what you expect. (There will be snow in Colorado in January.) Climate is average weather over time."

Jones explains that in general, the weather is governed mainly by the atmosphere, its circulation and the processes within it, such as the formation of clouds and rain. Climate depends on additional atmospheric processes, including chemical reactions that determine the concentrations of important constituents such as ozone and methane, and processes that alter the Earth's radiation budget such as the interactions between clouds and radiation. Climate depends also on the important interactions between the atmosphere and other components of the planet's climate system—the oceans, the land, the snow and ice cover, the biosphere—and the sun. Unfortunately, no single "environmental sensor" exists that can provide scientists with a critical single measurement of the Earth's long-term climate system.

Dr. Shelley Petroy, PhD, Advanced Program Manager for Weather, Climate & Earth Sciences at Ball Aerospace & Technologies Corporation adds, "One of the issues for the last 20-30 years has been how to migrate a NASA science mission into a NOAA operational mission. With the release two years ago of the National Research Council's Decadal Survey for Earth Sciences, NASA and NOAA have kick-started a dialogue on exactly this issue—how do we anticipate which Decadal Survey Science Missions are best suited to transition to operations, and how do we accomplish this transition most effectively? NASA and NOAA leadership meet weekly to work through these issues and generate concepts. It's a great step forward."

Figure 1 This chart shows the future gaps in the U.S.’s ozone monitoring program. Note that ozone mapping is really done by the international community, as several of these missions are European.

Ball Aerospace has identified future gaps in the U.S. ozone monitoring shown in the chart in Figure 1. Figure 2 shows Analyzed Total Ozone Columns from DLR (German Space Agency). Figure 3 shows OMPS (Ozone Mapping Profile Suite), the next operational ozone mission for the U.S., which is referenced in the Chart in Figure 1.

Figure 3 OMPS (Ozone Mapping Profiler Suite) from Ball Aerospace will fly on the NPP (NPOESS Preparatory Project) as the next operational ozone mission in 2010/2011. OMPS consists of a hyperspectral UV, visible and near IR limb sensor, a wide-field hyperspectral UV nadir sensor, and a dual-redundant main electronics box. Integration and risk reduction testing of OMPS for NPP were completed in February 2009.

Dr. Leopold Andreoli, PhD, Director, Chief Scientist Civil Systems for Northrop Grumman Aerospace System agrees that if global climate change is anything, it is complex. "We are simply the measurers," he states. "The sun's radiation striking the Earth is the driving force for climate. The most basic measurement is energy entering the system, compared to energy leaving the system. Trying to measure climate change 1/10 of a degree over a decade requires extremely well-calibrated and stable instruments. We must continue to monitor, we must continue to measure, and we must create a worldwide collection system."

Satellites orbiting above the atmos-phere are ideal for measuring the radiative energy streaming into and out of the earth-atmosphere system. But the expected travails associated with global climate change such as temperature increases or sea level rise represent difficult measurement challenges. Observations must be able to resolve very small variations and must be made continuously over a sufficiently long period of time. For accuracy, all sensors need to be calibrated against known standards.

The Open Geospatial Consortium (OGC) is an international consortium of industry, academic and government organizations working collaboratively to develop standards for geospatial and location services. Members of the OGC have approved a unique and revolutionary framework of open standards called Sensor Web Enablement (SWE) to exploit Web-connected sensors and sensor systems of all types: flood gauges, air pollution monitors, stress gauges on bridges, mobile heart monitors, Web-cams, satellite-borne Earth imaging devices and countless others. According to Carl Reed of the OGC, the SWE will enable much more effective utilization of sensor information for use in policy.

The voluntary consensus standards setting process, coupled with strong OGC support in domains that depend on sensors, will result in SWE specifications that will quickly become establ-ished in all application areas where such standards are of use. A number of these standards, such as the Sensor Observation Service, are already widely implemented.

Figure 4 CERES (Cloud and Earth Radiant Energy System) measures the energy emitted by the surface and atmosphere of the Earth with longwave radiation. This image shows an oppressive summer heat wave (Outgoing Longwave Radiation) on August 2, 2006. The blue shows a cooling front, with orange and yellows showing hotter temperatures. Source: NASA Earth Observatory Website Image of the Day on 8/12/2006; Instrument: CERES/Aqua; Credit: NASA image by Takmeng Wong with the CERES Science Team at NASA Langley Research Center.

Dr. Andreoli offers up Northrop Grumman's Clouds and the Earth's Radiant Energy System (CERES) as an example of measuring clouds and their impact on Earth's radiant energy. One of the most precisely calibrated radiometers ever to fly in space, the CERES instrument is measuring emitted and reflected radiative energy from the surface of the earth and the atmosphere. Previous space-based observations have shown that the role of clouds, which reflect, absorb, and trap radiant energy, is critical in maintaining the Earth's radiant energy balance. The balance is threatened by the build-up of carbon dioxide and other greenhouse gases in the atmosphere. An image appears in Figure 4.

The CERES experiment is flying broadband scanning radiometers on polar-orbiting and low-Earth-orbit inclined platforms. NASA's EOS Terra and EOS Aqua satellites each carry two broadband CERES instruments, one scanning crosstrack and one rotating while scanning. The rotating scan provides complete angular sampling for more accurate modeling of the scattering of reflected energy from target areas. Each scanner has three channels. A shortwave channel measures reflected sunlight (0.3 to 5 microns) to 1 percent accuracy; a longwave channel measures earth-emitted radiation (8 to 12 microns) to 0.3 percent accuracy; and a total channel (0.3 to >50 microns) accurate to 0.5 percent. Other instruments typically quote radiometric accuracies of 5 to 10 percent.

CERES must provide highly reliable data across platforms over the 15-year span that the instruments will fly. To ensure the highest quality data, CERES' sensors have been precisely calibrated using standards traceable to the National Institute of Standards and Technology.

"We need satellites that measure the essential climate variables (ECV's), and we need to agree on what the key variables are," says Dave Jones. "Observing long-term climate change requires instruments whose measurement characteristics do not change appreciably with time. The generation of satellite-based climate data records requires many inter-related activities and steps. These include inter-calibration of ident-ical instruments carried on different NPOESS spacecraft as well as inter-comparison with similar instruments carried on other spacecraft such as NASA research satellites, development of processing algorithms, detection and elimination of systematic errors in data, generation of stable time series, validation of data products, reprocessing of data as improvements are made to processing algorithms, and quality control and analysis of data."

Measuring the required climate variables and doing so with the accuracy and long-term stability needed to detect climate variations and changes are major challenges for NPOESS. Satellite systems require that certain factors be minimized or accounted for in the creation of stable climate data records (CDRs). These include the biases inherent in the observing instruments, changes in instrumentation, satellite orbital drift, system calibration, sensor degradation, and system malfunctions.

Natural climatic cycles like the Arctic Oscillation further complicate the job of measurement and the job of prediction. Rob Mitrevski, Vice President and Director of Commercial and Space Sciences for ITT's Space Systems Division, agrees that we need broader capabilities, ground-based and space-based sensors over the longer-term, to draw conclusions. And he too calls for an integrated, coordinated approach among governments, industries, universities, and non-governmental organizations: "Ultimately this is a question of political will to drive the technology based on society's needs."

At the University of Colorado Conference on World Affairs on April 9, Dr. James Hansen, Director since 1981 of the NASA Goddard Institute for Space Studies (GISS), spoke to a standing room only crowd about climate threats to the planet and implications for intergenerational and environmental justice. Dr. Hansen has long held the belief that the most exciting planetary research involves increasing our knowledge of climate change on Earth, particularly changes caused by human influences on atmospheric composition. With colleagues at GISS and abroad, he is developing and applying global numerical models to better understand climate trends. Still, when asked about climate sensors being a key to solving climate change, Dr. Hansen said, "The crisis is because of inertia, both scientific (it takes a long time for the ocean to warm up) as well as political (there is a gap between what is understood and what is known.) Policies do not correspond with what is happening."

So, are climate sensors important to solving climate change? Yes, but standards and political will are still needed. If newer, more precise climate sensors tell us that the ice is melting faster than our previous models have shown, should we then also mobilize limited resources towards adapting to rising ocean levels instead of mitigating CO2 levels?

It seems a lot of people concur with poet Eliot that wisdom stands a chance of getting lost in the knowledge. A smart guy named Albert Einstein once said that wisdom is not a product of schooling, but of the lifelong attempt to acquire it. As if to underscore the complexity of it, he also said, "Whoever undertakes to set himself up as a judge of Truth and Knowledge is shipwrecked by the laughter of the gods..." In the matter of climate sensors, perhaps the wise use of them is as important as the knowledge they provide.


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