earth science

Surface Water and Ocean Topography

Surface Water and Ocean Topography is a earth science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Surface Water and Ocean Topography rather than just read about it. In short: The Surface Water and Ocean Topography (SWOT) mission is a satellite altimeter jointly developed and operated by NASA and CNES, the French space agency, in partnership with the Canadian Space Agency (CSA) and UK Space Agency (UKSA). The objectives of the mission are to make the first global survey of the Earth's surface water, to observe the fine details of the ocean surface topography, and to measure how terrestria…

Key takeaways

Surface Water and Ocean Topography belongs to earth science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Surface Water and Ocean Topography to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Surface Water and Ocean Topography from memory before moving on to harder problems.

Reference excerpt

The Surface Water and Ocean Topography (SWOT) mission is a satellite altimeter jointly developed and operated by NASA and CNES, the French space agency, in partnership with the Canadian Space Agency (CSA) and UK Space Agency (UKSA). The objectives of the mission are to make the first global survey of the Earth's surface water, to observe the fine details of the ocean surface topography, and to measure how terrestrial surface water bodies change over time. While past satellite missions like the Jason series altimeters (TOPEX/Poseidon, Jason-1, Jason-2, Jason-3) have provided variation in river and lake water surface elevations at select locations, SWOT will provide the first truly global observations of changing water levels, stream slopes, and inundation extents in rivers, lakes, and floodplains. In the world's oceans, SWOT will observe ocean circulation at unprecedented scales of 15–25 km (9.3–15.5 mi), approximately an order of magnitude finer than current satellites. It does this using synthetic aperture radar interferometry. Because it uses wide-swath altimetry technology, SWOT will almost completely observe the world's oceans and freshwater bodies with repeated high-resolution elevation measurements, allowing observations of variations.

Context SWOT builds on a long-standing partnership between NASA and CNES to measure the surface of the ocean using radar altimetry. This partnership began with the TOPEX/Poseidon mission (launched in 1992) and continued with the Jason series. SWOT brings together the hydrology and oceanography communities and will extend the precise, high-resolution surface topography observations into the coastal and estuarine regions.

Scientific objectives The mission's science goals are to:

Provide sea surface heights and terrestrial water heights over a 120 km (75 mi) wide swath with a ±10 km (6.2 mi) gap at the nadir track. Over the deep oceans, provide sea surface heights within each swath with a posting every 2 km × 2 km (1.2 mi × 1.2 mi), and a precision not to exceed 2.7 cm (1.1 in) at 1 km × 1 km (0.62 mi × 0.62 mi), or 1.35 cm (0.53 in) at 2 km × 2 km (1.2 mi × 1.2 mi) when averaged over the area. Over land, download the raw data for ground processing and produce a water mask able to resolve 100 m (330 ft) wide rivers and 250 m × 250 m (820 ft × 820 ft) lakes and reservoirs. Associated with this mask will be water level elevations with an accuracy of 10 cm (3.9 in) for water bodies whose non-vegetated surface area exceeds 1 km2 (0.39 sq mi). The slope accuracy is 1.7 cm/km (1.1 in/mi) over a maximum 10 km (6.2 mi) of flow distance. The satellite will overfly Earth from 78° S to 78° N, covering at least 86% of the globe. SWOT’s orbit extends from 78° S to 78° N, covering at least 86% of the globe in its three-year-long mission. SWOT revisits the same path all over the Earth every 21 days in 292 unique orbits.

Applications SWOT is designed for the study and monitoring of inland waters and the oceans, such as:

Management of water-sharing issues The sharing of river water often causes friction between neighboring states, especially when there is no common technology for verification. SWOT will provide global information as input for systems monitoring transboundary river basins, including measurements of variations in reservoir water storage and estimates of river discharge.

More accurate weather and climate forecasting SWOT will enable more accurate weather and climate forecasting, especially seasonally. The quality of weather and climate forecasting largely depends on numerical modeling that uses the state of the ocean surface and the hydrological conditions of catchment areas in their initial and boundary conditions.

Managing freshwater for urban, industrial, and agricultural consumption Accurate knowledge of sources of available water is a key factor in decision-making for organizations involved in the distribution of water for agricultural, urban, and industrial needs. Data from SWOT will contribute at a global level by providing water supply services and distribution companies with information about major reservoirs and the largest rivers and catchment areas, thus enabling them to plan the management of water stocks further into the future.

Improved flood modeling Flooding, whether from rivers overflowing their banks or in coastal regions, is among the most costly natural disasters. Altimetry data from the SWOT mission will make it possible to measure the 3-dimensional shape of flood waves, track floodwater levels, and improve measurements of local topographic details in floodplains. All of these will improve prediction capabilities for future floods.

Coastal ocean dynamics Coastal ocean dynamics are important for many societal applications. They have smaller spatial and temporal scales than the dynamics of the open ocean and require finer-scale monitoring. SWOT will provide global, high-resolution observations in coastal regions for observing coastal currents and storm surges. While SWOT is not designed to monitor the fast temporal changes of the coastal processes, the swath coverage will allow us to characterize the spatial structure of their dynamics when they occur within the swath.

Reducing environmental risk and contributing to public policy-making More broadly, SWOT enhances the global observation of water storage and fluxes, providing unique data to clarify the physics of ocean dynamics and the terrestrial water cycle. This data has practical applications across multiple disciplines, from disaster mitigation—such as flood and hurricane forecasting—to the management of agricultural, energy, and public health resources.

Sensor payload

… excerpt ends here. Continue reading the full article.

Illustrations

Worked examples

Example 1 — a first encounter with Surface Water and Ocean Topography

Start with the simplest possible case. Write down what Surface Water and Ocean Topography claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In earth science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Surface Water and Ocean Topography before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Surface Water and Ocean Topography ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Surface Water and Ocean Topography

In research: Surface Water and Ocean Topography appears in earth science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Surface Water and Ocean Topography in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Surface Water and Ocean Topography is common in secondary-school and first-year university syllabi. It links to neighbouring topics 2022 in California, CNES satellites, December 2022 in the United States, so understanding it makes those chapters shorter.
In everyday life: Look for Surface Water and Ocean Topography outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Surface Water and Ocean Topography in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Surface Water and Ocean Topography means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Surface Water and Ocean Topography out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Surface Water and Ocean Topography in simple terms?

Why does Surface Water and Ocean Topography matter?

Because it connects several earth science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Surface Water and Ocean Topography?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Surface Water and Ocean Topography.