The CEAM operates several flux towers stations, located in different ecosystems in Spain, that continuously measure the carbon, water and energy fluxes between the ecosystem and the atmosphere.

The collected data are then used to study the carbon and water cycle of these Mediterranean ecosystems, and their response to seasonal and inter-annual climate variability.


FLUX TOWERS

The flux towers experimental stations use the eddy covariance technique to perform continuous measurements of fluxes (exchanges) of energy and trace gases, such as water vapour (H2O) and carbon dioxide (CO2), between terrestrial ecosystems and the atmosphere.

The eddy covariance technique is a direct and non-intrusive method and currently one of the most defensible ways to measure vertical turbulent fluxes at the interface biosphere atmosphere, at the full ecosystem (soil + vegetation) scale. It has become a popular tool to determine exchange rates of water and carbon over natural ecosystems, agricultural fields, other land or water areas, and is also frequently used to measure other trace gas exchange such as methane or ozone. Nevertheless, this method relies on major assumptions and implies some mathematically complex calculations, requiring expertise and care for both selecting the experimental site, setting up of instruments, processing the data applying appropriate corrections, and assessing the data quality.


Flux towers stations also perform routine measurements of a standard set of micrometeorological and environmental variables, including meteorological variables (incoming solar radiation, net radiation, air temperature and relative humidity, atmospheric pressure, precipitation, wind direction and velocity) and soil variables (soil temperature profile, soil moisture profile).

Depending of specific objectives, additional continuous measurements can be integrated to flux tower stations, such as proximal in-situ remote sensing (surface IR temperature, surface reflectance measurements for vegetation indexes), soil CO2 efflux chamber systems, sapflow sensors, lysimeters, others traces gases fluxes by eddy covariance, etc…

For most of the variables, the continuous measurements are automatically averaged and logged at 10-min and 30-min periods by data loggers or computers. Data are then transferred every day through ·g mobile connection form the experimental sites to the servers of Fundation CEAM to be stored and archived.

All these variables are then primarily used to calculate and analyze the carbon, water and energy budgets of the studied ecosystems, and characterize their variability at temporal scales from hours to decades. As global climate change is mostly driven by the increase of CO2 in the atmosphere, scientists are particularly interested in these measurements for robust quantification of current ecosystem services, such as carbon sequestration or hydrological fluxes regulation, predictions of futures changes and planning for mitigation and adaptation. Data from flux tower stations are also extensively used for tuning and validation of models (global climate models, mesoscale and weather models, complex biogeochemical and ecological models), as well as for calibration and validation of remote sensing products from satellites and aircraft.

Sites

Las Majadas, Holm oak open woodland (Majadas de Tietar, Caceres, Spain)

Location: 39°56'25''N, 5°46'29''W
Elevation: 260 m a.s.l.
Ecosystem type: Dehesa(Holm Oak Savanna)
Dominant species: Quercus Ilex s.ballota
Herbaceous Species
Measurement period: 2003 ~ ongoing

Moncada-IVIA, s Citrus orchard (Moncada, Valencia, Spain)

Location: 39°35'17''N, 0°23'59''W
Elevation: 60 m a.s.l.
Ecosystem type: Citrus orchard
Dominant species: Citrus sinensis
Measurement period: 2018 ~ ongoing

Sueca, Paddy rice field (Sueca, Valencia, Spain)

Location: 39°16'28''N, 0°18'59''W
Elevation: 1 m a.s.l.
Ecosystem type: Paddy rice field
Dominant species: Oryza sativa
Measurement period: 2004 ~ ongoing

Cortes de Pallas, Shrubland (Cortes de Pallas, Valencia, Spain)

Location: 39°13'27''N, 0°53'11''W
Elevation: 810 m a.s.l.
Ecosystem type: Shurbland
Dominant species: Rosmarinus officinalis L., Ulex parviflorus P.
Measurement period: 2009 ~ ongoing

Vall d'Alinya, Mountain grassland (Figols i Alinya, Lleida, Spain)

Location: 42°09'04''N, 1°26'50''E
Elevation: 1770 m a.s.l.
Ecosystem type: Mountain Grassland
Dominant species:
Measurement period: 2003 ~ ongoing


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