Continuity of NASA Earth Observations from Space A Value Framework (2015) / Chapter Skim
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2 Measurement Continuity
2 Measurement Continuity
Pages 12-29
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From page 12... ...
The first Earth science and applications from space decadal survey (NRC, 2007) , initiated in 2005, was organized thematically, dividing Earth system science into the following topics: weather science and applications; climate variability and change; land-use change, ecosystem dynamics, and biodiversity; water resources and the global hydrologic cycle; solid-Earth hazards, natural resources, and dynamics; and human health and security.
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From page 13... ...
The current and potential future NASA missions respond to the challenge of understanding the integrated Earth system globally in the pursuit of knowledge to address pressing societal needs -- for example, weather and climate prediction; climate change impacts; the health of ecosystems; adaptation and protection from natural hazards. In general, they are also aligned with the Administration's overarching emphasis on climate research and monitoring while being consistent with and informed by the 2007 NRC decadal survey.
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From page 14... ...
For some variables, NASA pursues the construction of climate-quality records from requisite measurements made from the vantage point of space. For example, instruments placed on satellites in appropriate orbits measure total solar irradiance, ozone (total column and vertical profile)
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Not shown are mid-2014 selections in the Venture-class: GEDI (Global Ecosystem Dynamics Investigation) and ECOSTRESS (Ecosystem Spaceborne Thermal Radiometer Experiment on Space Station)
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From page 16... ...
Thus, it is necessary to maintain the ability to carry forward the science information essential to reconstruct a consistent time series of a geophysical variable from various instrument data sets. Reprocessing of instrument data acquired in the past is typically a necessary component for developing consistent climatological time series.
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From page 17... ...
The quality of a measurement is characterized by its combined standard uncertainty, which includes instrument calibration uncertainty, repeatability, time and space sampling, and data systems and delivery for climate variables (algorithms, reprocessing, and availability) -- each of which depends on the scientific objective.
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From page 18... ...
. In lieu of the calibration uncertainty needed to detect climate change without overlapping measurements, most instruments in orbit attempt to use overlapping observations to cross-calibrate successive instruments with each other and then attempt to estimate instrument calibration stability over its lifetime (see Box 2.2 for an example for total solar irradiance observations)
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From page 19... ...
11 Relying on measurement repeatability alone to achieve the needed long-term climate observations requires that instrument overlap be assured and the overlapping data record be rigorously compared. To date, the primary example of this is the record for total solar irradiance.
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it is not possible to achieve a solar irradiance climate record with the needed repeatability without cross-calibration of the radiometric scales of individual solar instruments. Securing this cross calibration requires overlap of the individual measurements.
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From page 21... ...
Kopp and J.L. Lean, 2011, A new, lower value of total solar irradiance: Evidence and climate significance, Geophysical Research Letters 38:L01706.
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From page 22... ...
However, EarthCARE is 1400LT, roughly 30 minutes later, which adds to uncertainty in climate trends of cloud properties because of the systematic time difference in regions with large cloud diurnal cycles. However, this type of uncertainty can be estimated from observations (geostationary satellites, surface lidar network, surface cloud observations)
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From page 23... ...
This report does not define continuity of a measurement as a simple continuous time series of Type 1 gaps while avoiding all Type 2 gaps. Instead, measurement continuity pertains to maintaining the quality of the geophysical measurement, at the level needed to accomplish the quantified objective (see Section 3.1.1)
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From page 24... ...
24 CONTINUITY OF NASA EARTH OBSERVATIONS FROM SPACE 50 Latitude 0 BOX 2.4 Continued -50 LECT (Hrs.) 18 A NOAA-11 14 C TLT Diurnal Correction, this work 50 B TLT Diurnal Correction, Christy et al.
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From page 25... ...
but must be is therefore important in may retain common biases we would strongly argue making a fair geophysical variables using consistent, state-of-the-art algorithms that evolve of recently published radio to retrieve comparison between the spatially complete both this result and the suite as knowledge of relevant satellite data and spatially incomplete radiosonde products time series is essential to achieve consistent climate datacon processes increases, so that reprocessing of the longer sonde‐satellite comparisons cannot be used to make [Free and Seidel, 2005]
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From page 26... ...
Thorough, independent validation of geophysical retrievals often can discern calibration or algorithm errors; conversely, instruments having a consistent calibration and algorithm approach to reprocessing typically provide the continuous data records of the highest quality. For satellite remote sensing observations, the accuracy of long-term, continuous geophysical data products also depends on retrieval algorithms and the effect on these algorithms of changes in instrument characteristics.
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From page 27... ...
Yang, 2013, Assessment of IDPS VIIRS Cloud Products and Recommendations for EOS era Cloud Climate Data Record Continuity, Report to NASA Headquarters, Washington, D.C.
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From page 28... ...
2011. A new, lower value of total solar irradiance: Evidence and climate significance.
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From page 29... ...
2013. Assessment of IDPS VIIRS Cloud Products and Recommendations for EOS-era Cloud Climate Data Record Continuity.
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