Technical Note on GHGSat Validation

This technical note details the results of the preliminary data quality assessments (methaneCH4 emission rates and CH4 abundance maps) performed on a dataset of CH4 productsgenerated from the GHGSat constellation.The aforementioned data quality assessments are performed in accordance with theassessment guidelines, detailed in [RD-1, RD-2], that constitute the European SpaceAgency (ESA) Earthnet Data Assessment Pilot (EDAP+) project’s Earth Observation (EO)Mission Data Quality Assessment Framework. An important representation of the latterframework, constructed by the National Physical Laboratory (NPL), is what is known as thematurity matrix. It is a diagrammatic summary of the following:• Documentation Review: the EDAP+ Atmospheric team reviews materialsprovided by the data provider (documentation), some of which may not be publiclyavailable, or even the scientific community (e.g. published papers). The results aredetailed in Section 2 (covering the first column of the maturity matrix, see Table2-1).• Data Quality Assessments: SRON (Netherlands Institute for Space Research)and University of Leicester performs data quality assessments (i.e. validationassessments), independently of those performed by the data provider. The resultsare detailed in Section 3 and Section 4 (covering the last column of the maturitymatrix, see Table 2-1 and Table 2-2).The above data quality assessments are performed by the EDAP+ team using theappropriate in-house and open-source ad-hoc scripts and tools.It is important to note the purpose of the EDAP+ EO Mission Data Quality AssessmentFramework is to ensure that the delivered commercial mission data is fit for purpose andthat all decisions regarding the inclusion of the commercial mission as an ESA third partymission can be made fairly and with confidence