## 5 Overall Strategy and Readiness Level
### Readiness Level
Figure 3: The figure presents the summary readiness level for L1 TOA, L2 BOA and L2 geophysical products. \begin{table}
\begin{tabular}{p{113.8 pt} p{113.8 pt} p{113.8 pt}} \hline \hline
**Element** & **Readiness** & **Comments** \\ \hline RTM and Intercomparison & 3/5 & Significant progresses were made thanks to ACIX [118], although there are still gaps in fully understanding the discrepancies between the AC algorithms and in characterising SR products’ uncertainties [IDN-12]. These challenges will be addressed within RAMI4 ATM [125]. Similar knowledge and data gaps were identified for cloud mask validation [IDN-09, IDN-10, IDN-11]. \\ \hline FRM and supersites & 3/5 & An initial set of super-sites has been defined as part of FRM4 VEG following metrological practices. The SRIX4 VEG [154] will build on that by consolidating best-practices with a focus on the use of UAV-based hyperspectral measurements. The readiness level for this element is therefore expected to rise in the next 2 years as a result of these activities. \\ \hline Protocols & 2/5 & There are no community-endorsed protocols for SR validation, this is currently on-going work in the frame of FRM4 VEG [152] and SRIX4 VEG [154]. The readiness level is therefore expected to rise in the next 2 years. \\ \hline Networks & 1/5 & No network is currently available for validating SR [IDN-07]. HYPERNETS project [136] aims to fulfil this need. Likewise, there is a lack of a global network for cloud mask validation [IDN-08]. \\ \hline Ad-hoc campaigns & 3/5 & Several campaigns have been carried out in the past years using field spectrometry, airborne, and recently UAV-based spectrometry. The use of UAV platforms is today considered a very flexible and cost-effective solution. \\ \hline Database and Tools & 1/5 & No database and tools are currently available for SR validation. \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Readiness level for L2 BOA data with references to needs identified in Table 3. \begin{table}
\begin{tabular}{p{113.8 pt} p{113.8 pt} p{113.8 pt}} \hline \hline
**Element** & **Readiness** & **Comment** \\ \hline RTM and Intercomparison & 4/5 & Good understanding of radiometric uncertainties, though progress should be made to embed metrological practices in the mission design phase [IDN-01], to enhance discoverability of pre-launch characterisation data [IDN-02] and to improve characterisation of geometric mismatch errors [IDN-03]. \\ \hline FRM and supersites & 5/5 & RadCalNet [107] sites are compliant to FRM guidelines since SI-traceability and metrological practices are fully embedded in the design. The TRUTHS mission [114] will allow reaching full SI-traceability in space. \\ \hline Protocols & 4/5 & Community-agreed protocols have been developed in the past decades and consolidated in the frame of CEOS-IVOS and GSICS. Yet, there is a need to provide uncertainty per-pixel at Level 1 [IDN-04] and to enhance the accuracy of RTMs [IDN-05] and of the Lunar irradiance models [IDN-06]. \\ \hline Networks & 5/5 & The RadCalNet network [107] is fully operational and will be expanded with additional new sites to increase geographical coverage. New technological solutions are also being successfully tested [183]. \\ \hline Ad-hoc campaigns & 4/5 & Several ad-hoc campaigns and inter-comparison exercises were run in the past and there is a very good understanding of the required methodologies. \\ \hline Database and Tools & 5/5 & Various databases are available, on ESA side, the DIMITRI tool, operationally used for S2 and S3 radiometric assessment [74]. \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Readiness level for Level 1 TOA data with references to needs identified in Table 2.