Atmosphere, wind and waves

Studying atmospheric effects, marine meteorology and the impact of ocean features and conditions on the weather are all possible using altimetry data.

Big waves are fun - for surfers. For seafarers, coastal equipment designers and inhabitants, they are potential dangers that have to be taken into consideration. Altimetry cannot give the wave heights every hour at least not without many many more satellites. Altimetry data are used in near-real time (within 3 to 48 hours) to improve weather forecasting models by assimilating these data in them. By comparing in-situ observations with models (with or without assimilation of altimetric data), many studies have shown their positive impact, bringing models to the real conditions. Moreover, with 15 years of altimetry data, wave height and wind speed statistics, and seasonal and interannual variations can be used to study the whole ocean, or regional areas, for purposes such as offshore industries or navigation.

Using altimetry to study hurricanes is not limited to measuring the very high waves and strong winds, and assimilating them real-time in some forecasting models. It can also help identify the warm features that can cause these storms to intensify. Thus sea surface height anomalies can be used as proxies of the warm currents that provide the hurricanes with their energy source.

Another application of altimetry linked to atmospheric phenomena is the use of dual-frequency altimeters to acquire rain rates over the entire ocean, where there are very few meteorological stations.

Wind and waves
Wave height can be derived by looking at how the sea surface reflects the radar signal.
Hurricanes
Tropical cyclones are characterised by very high waves and strong winds, that can be measured by altimeters (provided that the satellite flies close enough to the area affected by the cyclone) and assimilated in real-time in some forecasting models. However, altimetry can also help identify the warm features that can cause these storms to intensify.
Rain
Each frequency of a dual-frequency altimeter responds differently to rain. This not only makes it possible to accurately detect rain events, but can also be used to yield quantitative values.

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