**4. Instrumentation and Remote Sensing Technologies Required to Cover the Future Measurement Gaps over Polar Regions**

The measurements with gaps that have been detected are of dominant importance to a wide variety of activities, from marine traffic, fishery and the environment. Therefore, in this section, these measurements are analyzed in terms of the available instrument technologies to cover the detected gaps. Additionally, the operational limitations of the potential instruments are identified from the viewpoint of measurement requirements. Table 3 summarizes the technologies identified to ensure that the measurements with gaps are covered. The state of the art of the instrumentation is presented and the technology limitations from the perspective of the measurement requirements.
