Remedy 1: Regular cell measurements and ILS retrievals are to be performed in a consistent manner

Primary gap remedy type: 
Secondary gap remedy type: 
Proposed remedy description: 

Regular cell measurements have to be performed at all NDACC sites and ILS retrievals have to be performed in a consistent manner regarding both, the technical setup of the retrieval (regularization, retrieval paramaters, cell measurement setup etc.) as well as the calculation of the total random and systematic uncertainty on the retrieved ILS. Ideally, the random and systematic uncertainties on the retrieved ILS are expressed as full uncertainty covariance matrix, but it is unrealistic and a computational burden to determine and propagate such full covariance matrices. A good approach would be to characterise the leading ILS uncertainty contributions, smoothing/noise, random/systematic and accordingly work on a realistic and not oversimplifying approach to accurately estimate and propagate the ILS uncertainties towards the retrieved target gas.

The second step in the proposal would be to implement this ILS uncertainty characterisation in both existing retrieval software packages PROFFIT and SFIT4. The outcome is a FTIR NDACC network-wide harmonized uncertainty budget that includes the propagated ILS uncertainty.


Improved traceability of uncertainties is a core objective of GAIA-CLIM and shall benefit applications including but not limited to satellite characterisation by FTIR instruments.

Measurable outcome of success: 

Traceable ILS uncertainty will allow a traceable estimation of the FTIR product uncertainty due to ILS uncertainties.

Expected viability for the outcome of success: 
  • High
Scale of work: 
  • Consortium
Time bound to remedy: 
  • Less than 3 years
Indicative cost estimate (investment): 
  • Low cost (< 1 million)
Indicative cost estimate (exploitation): 
  • Yes
Potential actors: 
  • Academia, individual research institutes