Heat flux sensor detects soil heat flux distribution

Heat flux sensor could help detect soil heat flux distribution

Soil heat flux is the amount of heat that passes through the soil profile per unit of time. Its value depends on the temperature gradient between the upper and lower soil layers and the thermal conductivity of the soil. Soil temperature is an important factor in forest climate and is closely related to plant growth. Different light conditions in forest stands with different slopes and slope orientations cause corresponding changes in soil temperature and soil heat flux.

Different vegetation types and stand conditions determine the pattern of change in soil temperature, which can affect the transpiration of plants, the respiration and absorption of the root system, as well as the dissolution rate of various inorganic salts in the soil solution, thus affecting the growth of trees.

Land productivity can be improved by studying the effects of different cover and tillage practices on soil temperature and moisture. Complete and accurate data on the spatial and temporal distribution of soil temperature are required for global climate change, modeling of environmental processes, elemental geochemical cycling, and evolution of soil physical and chemical properties.

When the surface absorbs solar radiant energy, the heat is transferred to the deeper layers by molecular conduction, warming the lower layers. Conversely, heat is exported from the deeper layers when the soil surface cools and the temperature drops below the deeper layers.

The thermal state of the soil is expressed in terms of temperature, which is not a physical property of the soil itself. Soil thermal properties are the physical properties of the soil that affect heat flow and temperature changes in the soil, mainly including thermal conductivity, heat capacity and heat diffusivity, while soil heat flux is one of the important components of the energy balance at the earth's surface.

What is a soil heat flux sensor?

Soil heat flux sensor is also known as, soil heat flux plate, heat flux plate, heat flux meter, soil heat flux sensor is a traditional soil thermal performance tester, mainly used to measure the energy balance of the soil and the thermal conductivity of the soil layer, its value depends on the temperature gradient between the upper and lower soil layers and the thermal conductivity of the soil, the value of heat flux inside the object to be measured are relatively small.

How do you measure heat flux?

The soil heat flux sensor uses a thermopile to measure the temperature gradient, the thermopile has two different metal materials to form the thermopile detector receives thermal radiation, the thermal radiation can make the two junctions that do not use the material to generate a temperature difference potential between the two junctions, in the form of voltage output, the voltage is proportional to the heat flux.

Soil thermal conductivity and heat capacity are commonly used to estimate soil heat flux. The magnitude of change in soil heat flux is greater on sunny days than on cloudy days, and the magnitude of change in soil heat flux is greater outside the forest than inside the forest; with decreasing temperatures, the exchange of soil heat flux changes from surface-downward conduction to lower-surface conduction, and the value of soil heat flux gradually decreases to a negative value, which is especially pronounced on cloudy days.