Mission
Hydroterra+, hereafter referred to as “H+”, is a proposed mission aimed at monitoring rapid processes (ranging from hours to days) of the water cycle, with a particular focus on Europe, the Mediterranean basin, and certain parts of Africa.
These areas are highly vulnerable to climate change, and H+ specifically targets a significant gap in observations related to the water cycle – processes occurring on timescales of hours to days at a regional level (current and planned low Earth orbit missions do not adequately address this requirement).
H+ represents an evolution of the Hydroterra concept initially proposed for Earth Explorer 10, benefiting from the insights gained during its Phase 0 study and subsequent field experiments to enhance scientific preparedness.
The design of H+ revolves around its science objectives (SO), specifically selected to target crucial uncertainties in water cycle science that require improved temporal sampling:
- SO1: intense storms (Mesoscale Convective Systems, frontal systems, and thunderstorms) which are responsible for the most damaging weather events and for the largest part of annual rainfall in the Mediterranean region as well as in the Tropics;
- SO2: the diurnal land surface water budget (soil moisture, vegetation, irrigation) – key processes which are poorly observed and understood currently;
- SO3: the cryosphere water budget – snow accumulation and melting, since this has significant daily variation, is poorly observed currently, and controls water downstream of mountain areas.
This area of research requires the quantification of water at the land surface and in the atmospheric layer. Frequent radar imaging is well-suited for such measurements and contributes to a fourth objective related to hazards posed by the solid Earth:
- SO4: ground motion on timescales of hours to days related to earthquakes, volcanoes and landslides.
Along these lines, the main technical objectives for the Phase 0 study are:
- Develop significant testable science objectives which are robustly related to geophysical observables and corresponding Level 1 data products, for each of the candidate science areas (hydro-meteorology, etc.);
- Ensure that the mission concept has sufficient technical maturity to present a convincing implementation case and with imaging performance to satisfy the science objectives.
This is requiring for:
- Formulating convincing cases in each scientific discipline that clearly define and justify specific, testable scientific objectives;
- Establishing the measurement requirements associated with these scientific objectives, framed in terms of relevant geophysical variables and their association with Level 1 measurements;
- Assessing the viability of the mission concept’s imaging performance to ensure it meets the quality criteria essential for providing Level 1 observations that align with the scientific objectives