Validation practices for satellite-based Earth observation data across communities (original) (raw)
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Estimating the impact of small-scale variability in satellite measurement validation
Journal of Geophysical Research, 2006
1] The necessity of validating satellite measurements of atmospheric chemical constituents with supplementary in situ measurements leads to problems with interpretation of the inevitable differences that arise because of measurement resolution or imperfect collocation, especially for highly heterogeneous fields. In this paper the contribution of small-scale structure to measurement differences is estimated from high-resolution aircraft measurements of atmospheric trace gases. The analysis uses the statistics of fractional differences in mixing ratio across a range of scales to estimate the contribution of real variability to differences in noncollocated measurements. The differences depend on the particular chemical tracer, location and season. We find a range of behavior: Differences of 50% across horizontal scales 100 km or less are fairly common for tropospheric water vapor under convective conditions, or carbon monoxide in regions influenced by biomass burning. Ozone varies by about 4-12% in the lower stratosphere and 15-25% in the upper/middle troposphere across scales of about 150 km. The effect of coarse satellite measurement resolution is also estimated by comparing point measurements to locally averaged measurements and is found to reduce the occurrence of large tracer differences. The choice of coincidence lengths should be based on both the scale-dependent variability and a priori estimates of satellite accuracy if real variability is to remain small relative to satellite measurement uncertainties. For satellite instrument uncertainties of about 10%, coincidence lengths for ozone should be less than 50 km in the upper troposphere and less than 100 km in the lower stratosphere. Citation: Sparling, L. C., J. C. Wei, and L. M. Avallone (2006), Estimating the impact of small-scale variability in satellite measurement validation,
ISPRS International Journal of Geo-Information
Earth observation (EO) data play a crucial role in monitoring ecosystems and environmental processes. Time series of satellite data are essential for long-term studies in this context. Working with large volumes of satellite data, however, can still be a challenge, as the computational environment with respect to storage, processing and data handling can be demanding, which sometimes can be perceived as a barrier when using EO data for scientific purposes. In particular, open-source developments which comprise all components of EO data handling and analysis are still scarce. To overcome this difficulty, we present Tools for Analyzing Time Series of Satellite Imagery (TATSSI), an open-source platform written in Python that provides routines for downloading, generating, gap-filling, smoothing, analyzing and exporting EO time series. Since TATSSI integrates quality assessment and quality control flags when generating time series, data quality analysis is the backbone of any analysis ma...
Developments in the'validation'of satellite sensor products for the study of the land surface
… Journal of Remote …, 2000
Increased availability of global satellite sensor data is resulting in an increase in satellite sensor products for global change research and environmental monitoring. The ensuing research and policy directives that will utilize these satellite products puts a high priority on providing statements of their accuracy. The process of quantifying the accuracy of these geophysical products is herein termed 'validation'. This Letter provides examples of international land product 'validation' research and describes a new international forum for coordination within the Committee on Earth Observation Satellites (CEOS) Calibration and Validation Working Group (CVWG). WWW 2, IGBP DIS Global 1 km land cover, http://edcdaac.usgs.gov/glcc/glcc.html WWW 3, IGBP DISCover 'Validation' Working Group, http://keystone.geog.ucsb.edu /igbp.html WWW 4, EOS 'Validation' Investigations, http://eospso.gsfc.nasa.gov /validation/frame.html WWW 5, Landsat Path nder Program, http://edcdaac.usgs.gov/path nder/pathpage.html WWW 6, EOS Land 'Validation' Core Sites, http://modarch.gsfc.nasa.gov /MODIS/Land/VAL/core_sites.html WWW 7, MERIS homepage, http://envisat.estec.esa.nl/instruments/meris WWW 8, Land-Surface Processes and Interactions Mission, http://www.estec.esa.nl/vrwww/LSPIM WWW 9, VEGETATION homepage, http://www-project.cst.cnes.fr:8050 / WWW 10, GLI homepage, http://www.eorc.nasda.go.jp /ADEOS-II/GLI WWW 11, MODIS homepage, http://modarch.gsfc.nasa.gov / WWW 12, Mercury homepage, http://mercury.ornl.gov/ WWW 13, Mercury Metadata Editor login, http://www-eosdis.ornl.gov /cgi-bin/MDE/MERCURY/access.pl WWW 14, Mercury Land 'Validation' Search, http://mercury.ornl.gov/servlet/landval WWW 15, AERONET homepage, http://aeronet.gsfc.nasa.gov:8080 / WWW 16, AERONET status at the EOS Land 'Validation' Core Sites, http://modarch.gsfc.nasa.gov /MODIS/Land/VAL/EOSaeronet.html WWW 17, FLUXNET homepage, http://daacl.esd.ornl.gov /FLUXNET WWW 18, EOS Airborne Information, http://eospso.gsfc.nasa.gov /eos_homepage/airborne.html WWW 19, MQUALS homepage, http://gaea.fcr.arizona.edu /MQUALS/newmqual.html WWW 20, Space Imaging: IKONOS, http://www.spaceimaging.com / WWW 21, NASA's Science Data Buy program, http://www.crsp.ssc.nasa.gov /databuy WWW 22, Landsat 7, ETM1 homepage, http://mtpe.gsfc.nasa.gov/landsat/ WWW 23, ASTER homepage, http://asterweb.jpl.nasa.gov /
Review of validation standards of biophysical Earth Observation products
In the context of remote sensing, validation refers to the process of assessing the uncertainty of higher level, satellite sensor derived products by analytical comparison to reference data, which is presumed to represent the true value of an attribute. Biophysical products characterise and map biotic and abiotic factors that influence the survival, development and evolution of organisms within the environment. Naturally, validation is an essential component of any earth observation program, since it enables the independent verification of the physical measurements obtained by a sensor as well as any derived products. After presenting some relevant definitions, this chapter draws on international and national validation campaigns to summarize some of the major components involved when using ground-reference data to validate biophysical products derived through Earth Observation (EO) data. These include site selection, site extent, and sampling design. Major Australian and internatio...
Understanding the Various Perspectives of Earth Science Observational Data Uncertainty
2019
Information about the uncertainty associated with Earth science observational data is fundamental to use, re-use, and overall evaluation of the data being used to produce science and support decision making. The associated uncertainty information leads to a quantifiable level of confidence in both the data and the science informing decisions produced using the data. The current breadth and cross-domain depth of understanding and application of uncertainty information, however, are still evolving as the practices associated with quantifying and characterizing uncertainty across various types of Earth observation data are diverse. Since its re-establishment in 2015, the Information Quality Cluster (IQC) of the Earth Science Information Partners (ESIP) has convened numerous sessions within the auspices of ESIP and the American Geophysical Union (AGU) to help collect expert-level information focusing on key aspects of uncertainty of Earth science data and addressed key concerns such as:...
An interactive software package for validating satellite data
2004
Earth observation satellite launched in the last three decades have made vital contributions to the understanding of the planet. The earth system consisting of land, oceans and atmosphere is linked together by a number of complicated processes. Potential of microwave sensors in studying the boundary layer dynamics of the ocean-atmosphere system is well documented. Technology has revolutionized the application of such sensors and several missions are planned to take off in near future for meeting specific objectives. Launching of such sensors need to be followed by an extensive validation campaign for providing accurate and reliable information to the users. A PC-based interactive system has been developed and presented here for validating satellite mounted microwave sensors. The program, coded in Visual Basic, is user interactive and runs on Windows-98 platform. The system prepares the data base on a selected platform according to the global/regional nature of the satellite data. Preset space-time windows are selected to study the nature of satellite-sea truth relationship. The program design a scheme to discard spurious satellite data by keeping the relationship and its significance intact. The best relationship obtained is used to predict the new set of correct satellite data for application purpose. The program has, therefore, several added advantages over the conventional method of validation which involves strenuous efforts to incorporate subroutines to meet every minute requirements. Geophysical data retrieved from the sensor 'Multi-channel Scanning Microwave Radiometer (MSMR) onboard the Indian satellite IRS-P4 (Oceansat I)' has been validated on this system by making use of various sea truth platforms. Drifting buoy SST's appear to be highly correlated (r = 0.75) with the satellite data. Very good correlation (r = 0.80) is Gayana (Concepción)-AN INTERACTIVE SOFTWARE PACKAGE FOR VALID ... 8/11/2006 http://www.scielo.cl/scielo.php?script=sci\_arttext&pid=S0717-65382004000300018&lng=... obtained for wind speed measured from both Moored buoy and Autonomous Weather Station. Night time SSTs are found to be closer to the satellite values for wind speed less that 10 m/s and day time SSTs are better correlated for wind speed greater than 10 m/s. Wind speed from stationary platforms are better correlated with the satellite values when compared with moving platform like ship. Wind speed measured from ocean platforms (Moored buoy and Ship) during day time appears to be closer to the satellite measurement but the night time wind gives better correlation when measured from the island-based weather station.
Accuracy assessment and validation of remotely sensed and other spatial information
International Journal of Wildland Fire, 2001
Today, validation or accuracy assessment is an integral component of most mapping projects incorporating remotely sensed data. Other spatial information may not be so stringently evaluated, but at least requires meta-data that documents how the information was generated. This emphasis on data quality was not always the case. In the 1970s only a few brave scientists and researchers dared ask the question, 'How good is this map derived from Landsat MSS imagery?' In the 1980s, the use of the error matrix became a common tool for representing the accuracy of individual map categories. By the 1990s, most maps derived from remotely sensed imagery were required to meet some minimum accuracy standard. A similar progression can be outlined for other spatial information. However, this progression is about 5 years behind the validation of remotely sensed data. This paper presents a series of steps moving towards better assessment and validation of spatial information and asks the reader to evaluate where they are in this series and to move forward.
2007 IEEE International Geoscience and Remote Sensing Symposium, 2007
The harmonization of operational data products and the creation of higher level information products such as global maps and time series (from different sensor sources) are required to satisfy the operational service requirements of the societal benefit areas as outlined in the GEOSS implementation plan. The CEOS Working Group on Calibration and Validation (WGCV) concentrates on defining standards and procedures aimed at allowing for the inter-comparison and ultimate utilization of data from all Earth observing platforms, both current and future. WGCV strives to establish common approaches to validation, calibration and data exchange formats to ensure effective cooperative use of all CEOS member space assets in addressing important global scale problems. This paper reviews the WGCV data assurance strategy, detailed system element requirements to guarantee data quality, and current WGCV activities for the generation and validation of products..
Addressing and Presenting Quality of Satellite Data via Web-based Services
2011
Abstract-With the recent attention to climate change and proliferation of remote-sensing data utilization, climate model and various environmental monitoring and protection applications have begun to increasingly rely on satellite measurements. Research application users seek good quality satellite data, with uncertainties and biases provided for each data point. However, different communities address remote sensing quality issues rather inconsistently and differently.