## 2 Requirements Specifications and Measurements Gaps
Surface soil moisture can be estimated with a high spatial resolution by the Advanced Scatterometer (ASCAT) on the meteorological Operational (MetOp) mission and SAR-C on the Sentinel-1. However, the accuracy, revisit time and temporal resolution are insufficient to meet the user requirements. New developments in the miniaturization of cameras in the visible and infrared bands with high-resolution data make new techniques available for remote observation of crops [7; 8]. However, for precision agriculture applications, the use of remote sensing can be limited because of inadequate spatial, temporal and thematic products tailored to the needs of farmers. Future satellites carrying sensors in the thermal infrared band present coarse spatial and temporal resolutions and are also limited to clear sky conditions. Due to these limitations, thermal imagery is not useful at the plot scale for precise irrigation monitoring. There is also an emerging need to consider L-band microwave radiometers (with high spatial resolution) to support crop condition monitoring. \begin{table}
\begin{tabular}{l l l l l l} \hline \hline \multirow{2}{*}{**Measurements**} & \multirow{2}{*}{**Use Cases**} & \multirow{2}{*}{**Requirements [E]**} & \multicolumn{2}{c}{**(2020-2030)**} \\ \cline{5-6}  & & & **Depperics** & **Contributing** & **Cap** \\  & & & **Instruments/Mission [9]** & **Instruments/Mission [10]** & **Gap** \\ \hline \multirow{3}{*}{Ocean} & 1. Marine weather forecast & Spatial resolution: 1-25 km & \multirow{3}{*}{ \begin{tabular}{} \end{tabular}  } & \multirow{3}{*}{\ \begin{tabular}{} \end{tabular}  } & \multirow{3}{*}{ \begin{tabular}{} \end{tabular}  } & Revisit time \  
\begin{table}
\begin{tabular}{p{108.4 pt} p{108.4 pt} p{108.4 pt} p{108.4 pt} p{108.4 pt} p{108.4 pt}} \hline \hline \multirow{2}{*}{**Measurements**} & \multirow{2}{*}{**Use Cases**} & \multirow{2}{*}{**Requirements** I2I} & \multicolumn{2}{c}{**(2020-2030)**} \\ \cline{3-6}  & & & **Computations** & **Contributing** & **Cap** \\  & & & **Instruments/Mission [9] & **Instruments/Mission [10]** & **Instruments/Mission [11]** & **In** \\ \hline \multirow{4}{*}{Atmospheric pressure over sea surface} & 1. Marine weather forecast  
+++ ==WARNING: Truncated because of repetitions==
Sea Ice Monitoring and Marine Weather Forecast over Polar Regions as an Emerging Need for Future Copernicus Missions  
Over the past few decades, the polar regions have been subjected to significant changes. Total sea ice extent has decreased, and it has thinned [11]. Arctic sea ice melts, and it is increasingly influencing human activities, as some Arctic marine routes have gone from being covered by sea ice to being navigable during part of the year. In this direction, the Arctic and Northern Ocean have been considered as interesting areas to extend the commercial operations related to fishing, oil and gas. As shown in Table 2, 65% of the measurements with gaps correspond to sea ice monitoring, and marine weather forecasts represent around 30%. Here, there is potential to cover these use cases. The sea ice monitoring (extent and thickness) and marine weather forecast use cases would benefit enormously from the improvement of the latency time, revisit time and accuracy. In response to the end-user needs, instrumentation and remote sensing technologies have to be explored to cover the future measurement gaps of the Copernicus system. In this way, we focus on EO over polar regions, where there is a high priority to monitor the previously-mentioned domains. New remote sensing opportunities will be explored to provide real time data to ensure navigation safety, to increase the operational monitoring capability on sea ice to understand climate change and for marine weather forecast information to a wide variety of activities such as fishing, oil and gas operation. In this direction, the measurements and requirements to cover are detailed in the next section.