G1.07   Need for a scientific approach to the assessment of gaps in the existing networks measuring ECVs.

Gap detailed description

Significant gaps in our observing capabilities limit our ability to provide a comprehensive characterization of the important physical parameters, and limit the accuracy of our predictive models and the satellite  cal/val.  Existing ground-based assets have not all been integrated into a coordinated observing network. Inadequacies include some large continental regions that are not monitored by any measurement stations or other assets. It is essential to understand the impacts of and, if scientifically necessary, reduce these gaps in the measurement data coverage, or at a minimum, to prevent these gaps from expanding if they would have deleterious impacts. Considering the importance of continuous, long-term observations for ECVs for many applications, an assessment of gaps on a scientifically sound basis is a necessary step for future improvements of the global observing system.

Activities within GAIA-CLIM related to this gap

GAIA-CLIM  will  start addressing  this  gap, proposing  an assessment  of the geographical gaps in  the current  surface-based  and sub-orbital  observing  capabilities for  a few variables  like  water vapour  and aerosol  on the basis  of  two different  techniques (functional  regression  technique, Markov-chain  Monte Carlo). GAIA-CLIM will also use insights arising from modelling studies through Task 1.5.

GAIA-CLIM Tasks 1.4 and 1.5 will provide an innovative approach to remedy to this gap. GAIA-CLIM  results  will  be delivered  before  the  end of the  project (deliverable D1.9, M36).

Gap remedy(s)

Remedy

Specific remedy proposed

Many non-satellite observing systems are inadequate to address the needs of satellite data characterisation, particularly so for climate monitoring purposes. Some systems are in a state of decline, with limited resources for investment available, and some past investments have under-delivered. This highlights the need for network design methods and analyses that guarantee investments are appropriate for addressing the science questions being posed. A comprehensive scientific approach to assessing the gaps in the current observing capabilities of the system of observing systems does not exist. Such an approach would support the identification of research questions that could be answered with current or posited observational capabilities.  Typically, such decision-making has been performed without a scientific basis or using an ad hoc approach, but has never been applied in an extensive and systematic way. Often the assessment is carried out on the basis  of  the experience  gained  by the  international  experts  in  the  context of past research  projects.

Recent research to assess gaps in the global observing system is based the use of natural variability on appropriate time scales to understand the power of a system to address a testable hypothesis (Weatherhead et al., 2016 ICM-8 Boulder available at http://www.dwd.de/EN/research/international_programme/gruan/download/ic…).

GAIA-CLIM Task 1.4 will undertake an assessment of the geographical gaps in the current  surface-based and sub-orbital  observing  capabilities for temperature, water vapour and aerosols on the basis of two different techniques (functional regression technique, Markov-chain  Monte Carlo). GAIA-CLIM Task 1.5 is using NWP and atmospheric chemistry models to assess the impacts of gaps for a number of additional target ECVs.

Measurable outcome of success

Success will come from the identification of gaps in the global observing system in a consistent manner that is actionable by observational program stakeholders. Use of different techniques will assure confidence.

Achievable outcomes

Technological / organizational viability: medium, some challenges are still related to the insufficient number of reference measurements available to precisely address the proposed gap (e.g. gap G1.10) and the poor characterization of measurements from baseline networks.

Indicative cost estimate: low (<1 million)

Relevance

GAIA-CLIM will approach this gap using modelling and advanced statistical approaches whose application may be generalized and extended to other ECVs with the potential to become a robust assessment framework available to the community. The proposed approach will also support the remedy to gap G1.12.

Timebound

GAIA-CLIM will deliver results to address this gap by end of the project (Feb. 2018). Nevertheless, several studies are likely required in order to comprehensively assess existing gaps and this can only be accomplished through fostering closer cooperation between the measurement community, geo-statisticians and modellers to design different solutions to assess the gaps and then to inter-compare the elaborated  approaches  to provide  robust  and reliable solutions. GAIA-CLIM has setup such a cooperation (that includes US partners like NOAA-CIRES, B. Weatherhead) that needs to be extended and consolidated in the future to support global stakeholders.

Gap risks to non-resolution