What Is Eddy Covariance Flux Tower?

The eddy covariance technique provides a method by which the vertical transport of CO2 (or other gases) can be measured by correlating the fluctuations in concentration with fluctuations in vertical wind speed. …

What two sensors are required for measuring eddy covariance?

Studies of fluxes using the eddy covariance method typically use a CO2/H2O analyzer and sonic anemometer to evaluate carbon dioxide and water vapor fluxes, but some flux stations require additional instruments to achieve the study objectives.

What is eddy heat flux?

Eddy heat fluxes play the important role of transferring heat from low to high latitudes, thus affecting midlatitude climate. The recent and projected polar warming, and its effects on the meridional temperature gradients, suggests a possible weakening of eddy heat fluxes.

What is a flux tower?

Across the globe, towers stand among the landscape, with sensors monitoring these eddies for carbon dioxide, water vapor and other gasses. … These so-called “flux towers” collect data on carbon dioxide exchange rates between the earth and atmosphere.

How tall are flux towers?

To accurately capture re-suspended road dust concentrations, the flux tower must be at least 4.5, 5.1, 5.8, and 6.2 m high when located 2, 4, 6, and 8 m, respectively, from the road center.

What are carbon fluxes?

A carbon flux is the amount of carbon exchanged between Earth’s carbon pools – the oceans, atmosphere, land, and living things – and is typically measured in units of gigatonnes of carbon per year (GtC/yr). … These carbon pools contain enormous quantities of carbon and exchange this matter in various ways.

What is eddy covariance data?

2 Eddy Covariance. Eddy covariance is a micro-meteorological method that is currently popular to directly observe the exchanges of gas, energy, and momentum between ecosystems and the atmosphere. … This method is also able to directly measure the carbon, water, and heat flows between plant communities and the atmosphere.

How do you calculate eddy covariance?

In mathematical terms, “eddy flux” is computed as a covariance between instantaneous deviation in vertical wind speed (w’) from the mean value (w-overbar) and instantaneous deviation in gas concentration, mixing ratio (s’), from its mean value (s-overbar), multiplied by mean air density (ρa).

How often are the measurements taken on a typical eddy covariance tower?

The system operates on 5-20Hz frequency measuring data point of the different parameters 5-20times in 1second. Calculation of fluxes: The three dimensional wind speeds from sonic anemometer and other variables, usually gas concentration, temperature or momentum are decomposed into mean and fluctuating components.

How much does an eddy covariance tower cost?

A typical cost for a complete eddy covariance system is on the order of US$50,000. The cost of site infrastructure is additional and will vary according to the remoteness of the site, the height of the vegetation (whether a tall tower must be built), and the existence of other facilities.

How is Bowen ratio calculated?

The ratio of sensible to latent heat fluxes at the surface is called the Bowen ratio6: B = FHs/FEs. Due to the nonlinearity inherent in the Clausius-Clapeyron equation, the Bowen ratio over the oceans decreases with increasing sea surface temperature.

What is net ecosystem exchange?

Net ecosystem exchange (NEE) is a measure of the net exchange of C between an ecosystem and the atmosphere (per unit ground area) and is a primary gauge of ecosystem C sink strength (Kramer et al., 2002).

What are the 4 major carbon sinks?

Carbon is stored on our planet in the following major sinks (1) as organic molecules in living and dead organisms found in the biosphere; (2) as the gas carbon dioxide in the atmosphere; (3) as organic matter in soils; (4) in the lithosphere as fossil fuels and sedimentary rock deposits such as limestone, dolomite and …

Is respiration a flux?

Fluxes describe the movement of energy and matter between different pools. … For example, photosynthesis facilities fluxes for energy, oxygen and carbon. Other examples of fluxes include: respiration, evapotranspiration and the food web. During fluxes, energy and matter may transform from one form to another.

What are fluxes and reservoirs?

When viewing the Earth as a system, these components can be referred to as carbon pools (sometimes also called stocks or reservoirs) because they act as storage houses for large amounts of carbon. Any movement of carbon between these reservoirs is called a flux.

What is NEP vs NPP?

What is the difference between NPP and NEP? NPP quantifies the carbon absorption by plants only, while NEP includes carbon absorption by plants and carbon release by soils. In other words, NPP is a component of the carbon cycle, while NEP is net carbon exchange between the ecosystem and the atmosphere.

What NPP means?

Net primary productivity, or NPP, is gross primary productivity minus the rate of energy loss to metabolism and maintenance. In other words, it’s the rate at which energy is stored as biomass by plants or other primary producers and made available to the consumers in the ecosystem.

What is NPP and GPP?

Gross primary production (GPP) is the total rate at which material is produced and net primary production (NPP) is the rate at which material is accumulated in excess of respiration.

What fraction is evaporative?

The evaporative fraction is a ratio of latent heat flux to the sum of latent and sensible heat fluxes. It has been used to characterize the energy partition over land surfaces and has potential for inferring daily energy balance information based on midday remote sensing measurements.

Why is evapotranspiration higher in summer?

Potential Evapotranspiration

PET is higher in the summer, on less cloudy days, and closer to the equator, because of the higher levels of solar radiation that provides the energy for evaporation. … Average annual PET is often compared to average annual precipitation, P.

What is net radiation?

Earth’s net radiation, sometimes called net flux, is the balance between incoming and outgoing energy at the top of the atmosphere. It is the total energy that is available to influence the climate.

Which latitude is the coldest?

And as you should expect, on an annual basis the high latitudes (60 to 90 degrees N/S) are the coldest.

What is albedo effect?

Albedo is an expression of the ability of surfaces to reflect sunlight (heat from the sun). … Light-coloured surfaces return a large part of the sunrays back to the atmosphere (high albedo). Dark surfaces absorb the rays from the sun (low albedo).