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Uncertainty information in climate data records from Earth observation

Merchant, Christopher and Paul, Frank and Popp, Thomas and Ablain, Michael and Bontemps, Sophie and Defourny, Pierre and Hollmann, Rainer and Lavergne, Thomas and Laeng, Alexandra and de Leeuw, Gerrit and Mittaz, Jonathan and Poulson, Caroline and Povey, Adam and Reuter, Maximilian and Sathyendranath, Shubha and Sandven, Stein and Sofieva, Viktoria and Wagner, Wolfgang (2017) Uncertainty information in climate data records from Earth observation. Earth System Science Data, 9, pp. 511-527. Copernicus Publications. DOI: 10.5194/essd-9-511-2017 ISSN 1866-3508

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Official URL: https://www.earth-syst-sci-data.net/9/511/2017/

Abstract

The question of how to derive and present uncertainty information in climate data records (CDRs) has received sustained attention within the European Space Agency Climate Change Initiative (CCI), a programme to generate CDRs addressing a range of essential climate variables (ECVs) from satellite data. Here, we review the nature, mathematics, practicalities, and communication of uncertainty information in CDRs from Earth observations. This review paper argues that CDRs derived from satellite-based Earth observation (EO) should include rigorous uncertainty information to support the application of the data in contexts such as policy, climate modelling, and numerical weather prediction reanalysis. Uncertainty, error, and quality are distinct concepts, and the case is made that CDR products should follow international metrological norms for presenting quantified uncertainty. As a baseline for good practice, total standard uncertainty should be quantified per datum in a CDR, meaning that uncertainty estimates should clearly discriminate more and less certain data. In this case, flags for data quality should not duplicate uncertainty information, but instead describe complementary information (such as the confidence in the uncertainty estimate provided or indicators of conditions violating the retrieval assumptions). The paper discusses the many sources of error in CDRs, noting that different errors may be correlated across a wide range of timescales and space scales. Error effects that contribute negligibly to the total uncertainty in a single-satellite measurement can be the dominant sources of uncertainty in a CDR on the large space scales and long timescales that are highly relevant for some climate applications. For this reason, identifying and characterizing the relevant sources of uncertainty for CDRs is particularly challenging. The characterization of uncertainty caused by a given error effect involves assessing the magnitude of the effect, the shape of the error distribution, and the propagation of the uncertainty to the geophysical variable in the CDR accounting for its error correlation properties. Uncertainty estimates can and should be validated as part of CDR validation when possible. These principles are quite general, but the approach to providing uncertainty information appropriate to different ECVs is varied, as confirmed by a brief review across different ECVs in the CCI. User requirements for uncertainty information can conflict with each other, and a variety of solutions and compromises are possible. The concept of an ensemble CDR as a simple means of communicating rigorous uncertainty information to users is discussed. Our review concludes by providing eight concrete recommendations for good practice in providing and communicating uncertainty in EO-based climate data records.

Item URL in elib:https://elib.dlr.de/113775/
Document Type:Article
Title:Uncertainty information in climate data records from Earth observation
Authors:
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Merchant, ChristopherReading universityUNSPECIFIED
Paul, FrankUniversität ZürichUNSPECIFIED
Popp, Thomasthomas.popp (at) dlr.dehttps://orcid.org/0000-0002-1970-8733
Ablain, MichaelCLSUNSPECIFIED
Bontemps, SophieUniversite de LouvainUNSPECIFIED
Defourny, Pierreearth and life institute, université catholique de louvainUNSPECIFIED
Hollmann, Rainerrainer.hollmann (at) dwd.deUNSPECIFIED
Lavergne, ThomasMetNoUNSPECIFIED
Laeng, AlexandraKITUNSPECIFIED
de Leeuw, GerritfmiUNSPECIFIED
Mittaz, JonathanNPLUNSPECIFIED
Poulson, CarolineRALUNSPECIFIED
Povey, AdamOxford universityUNSPECIFIED
Reuter, Maximilianiup-ife, universität bremenUNSPECIFIED
Sathyendranath, ShubhaPMLUNSPECIFIED
Sandven, SteinNERSCUNSPECIFIED
Sofieva, Viktoriafinnish meteorological instituteUNSPECIFIED
Wagner, Wolfgangtu wien, ipfUNSPECIFIED
Date:2017
Journal or Publication Title:Earth System Science Data
Refereed publication:Yes
Open Access:Yes
Gold Open Access:Yes
In SCOPUS:Yes
In ISI Web of Science:Yes
Volume:9
DOI :10.5194/essd-9-511-2017
Page Range:pp. 511-527
Publisher:Copernicus Publications
ISSN:1866-3508
Status:Published
Keywords:uncertainty, satellite remote sensing
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Space
HGF - Program Themes:Earth Observation
DLR - Research area:Raumfahrt
DLR - Program:R EO - Erdbeobachtung
DLR - Research theme (Project):R - Remote sensing and geoscience
Location: Oberpfaffenhofen
Institutes and Institutions:German Remote Sensing Data Center > Atmosphere
Deposited By: Popp, Dr.rer.nat Thomas
Deposited On:28 Sep 2017 14:51
Last Modified:02 May 2019 14:17

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