Ensuring the Climate Record from the NPOESS and GOES-R Spacecraft Elements of a Strategy to Recover Measurement Capabilities Lost in Program Restructuring (2008) / Chapter Skim
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4 Elements of a Long-Term Climate Strategy
4 Elements of a Long-Term Climate Strategy
Pages 68-78
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From page 68... ...
OPERATIONAL VERSUS SUSTAINED CLIMATE OBSERVATIONS The NRC decadal survey Earth Science and Applications from Space describes the overlapping nature, similarities in, and differences between exploratory, operational, and sustained observations. Briefly, exploratory measurements are new observations designed to shed light on poorly understood processes and so advance scientific understanding; operational measurements serve day-to-day critical activities such as weather forecasting that require high reliability and near-real-time data availability; and sustained measurements support the development of long-term records of key variables that are required to uncover slowly evolving dynamics or long-term climate changes.
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From page 69... ...
However, the specific measurement requirements for each application can vary, leading to less synergism than was initially intended. The ALT instrument on NPOESS, for example, is a well-designed and very capable instrument; however, climate science clearly requires an orbit different from
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From page 70... ...
, for example, is one of the longest consistent climate records obtained from satellite observations and has become a key indicator of climate change, signaling unexpectedly large and accelerating decreases in sea ice extent, especially in the recent past. Maintaining the consistency of this 30-year record, as well as ensuring that the recorded trends signify real climate change rather than instrument artifacts, requires sustained climate-quality observations.
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From page 71... ...
Moreover, other characterization parameters can also be updated in orbit, including spectral bandpass, spectral response, and spectral band registration. FIGURE 4.1 Arctic sea ice extent from passive microwave sensors 1979-2007.
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From page 72... ...
Operational data systems, such as the NPOESS data system, are designed for low data latency and high reliability rather than the active archival and evolutionary reprocessing required for establishment and maintenance of climate data records. An appropriate and cost-effective data system for climate measurements should seek to leverage the best attributes of both systems, while avoiding cost-driving capabilities that are not associated with climate needs.
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From page 73... ...
Elements of this needed national policy are discussed in the following sections, which draw heavily on previous NRC reports and careful consideration of the needs of sustained versus operational observations as discussed above. Clear Agency Roles and Responsibilities The issues noted above were recognized explicitly in the NRC decadal survey Earth Science and Applications from Space, whose authors stated, "The committee is concerned that the nation's civil space institutions (including NASA, NOAA, and USGS)
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From page 74... ...
In addition to the obvious coordination of observations and ground systems, national agencies should incorporate standard calibration and validation processes including the use of ground-based and lunar virtual calibrations, and establish "best practices" recommendations for measurements, calibration, and use of standards. COMMUNITY INVOLVEMENT IN THE DEVELOPMENT OF CLIMATE DATA RECORDS The National Research Council has produced a number of reports on the subject of climate data records (CDRs)
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From page 75... ...
However, mitigation of these recent losses is only the first step in establishing a viable long-term climate strategy that builds on the lessons learned from the well-intentioned but poorly executed merger of the nation's weather and climate observation systems. Specifically, a coherent, integrated, and viable long-term climate observation strategy is needed that explicitly seeks to balance the myriad science and applications objectives of climate data stakeholders, while properly considering both the similarities in and the differences among the exploratory, sustained, and operational measurements needed for climate science.
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From page 76... ...
Precision Aperture Determines Area Absorptive Radiometer T Shutter Modulates Incoming Sunlight Electrical Heating to Maintain Constant Temperature As Sunlight Is Modulated Determines Radiant Power FIGURE 4.3.1 Irradiance (i.e., 1361 W/m2) requires two measurements: power and area.
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From page 77... ...
• hermistor calibrations T • Shutter response • Scattered light and field-of-view angular dependences • End-to-end comparison with ground-based irradiance reference links current and future TSI instruments TIM on-orbit calibrations and calibration tracking supporting CDR development: • Dark background measurements of deep space correct for instrument thermal contributions • Degradation tracking due to solar exposure since pre-flight cavity absorptance calibration via regular infre quent simultaneous observations with lesser-used cavities • Servo system gain calibrations • Pointing sensitivity G
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From page 78... ...
The advisory council should be supported by instrument and science teams responsible for overseeing the generation of climate data records."
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