modelBiosphere

Biosphere 2 main model

Information

This is the top-level model of the Biosphere 2 model. This is the program that needs to be compiled and simulated.

The iconic representation represents Biosphere 2, modeled as a single biome, i.e., we assume that the entire air inside Biosphere 2 is at the same temperature. This is certainly not realistic, but doesn't truly matter, as long as the air conditioning is left out of the model.

We are now ready to assemble the Biosphere 2 model from its components. At this point, the modeling task has become quite simple.

Each of the five modeling elements:

  1. the inside air,
  2. the dome,
  3. the pond,
  4. the vegetation, and
  5. the top layer of the soil

is represented by a 0-junction with a heat capacity attached to it that calculates the temperature of that modeling element. The dome 0-junction was split into two 0-junctions connected by a bond due to the large number of connections to it.

A sixth 0-junction is used to represent the moisture of the air. It has its own special moisture capacitor element attached to it.

The six modeling elements are connected among each other by convection, radiation, condensation, and evaporation as appropriate.

Each modeling element has furthermore a modulated power source attached to it, which represents the solar input to that modeling element. Rather than modeling the distribution of solar energy in any detail, the model uses a fairly global approach to railroad the available solar input to the five modeling elements.

At the top of the model, we have the usual computation of ambient temperature (for external convection), night sky temperature (for radiation), solar radiation, and that's it.

Of course, the devil is in the detail. Each of these models contains a substantial number of parameters that need to be set, and getting the correct parameter values together for such a complex model is no easy task.

Enjoy!

Parameters

TypeNameDefaultDescription
Modelica.SIunits.CelsiusTemperatureT0Modelica.Constants.T_zeroConversion between Centigrade and Kelvin
Realsigconv3.6Conversion factor of Stephan-Boltzmann constant to appropriate units
Reallambda2501Latent heat of vaporization
Modelica.SIunits.Areaag2368.9Ground area of Biosphere
Modelica.SIunits.Areaac5667.0Cover area of Biosphere
Realpao87.848Atmospheric pressure
Realalph0.2Portion of absorbed power
Realtau0.6Portion of transmitted power
Realavix0.4Portion of Biosphere covered by vegetation
Realapix0.4Portion of Biosphere covered by pond
Reallaix2Leaf area index
Realvkx0.6Canopy light extinction coefficient
Realrhos0.13Reflectance of soil for solar radiation
Modelica.SIunits.Volumevai35000Air volume of Biosphere
Realrefl0.05Reflectance of pond
Realhai39.6Convection coefficient equation intercept
Realhai20.0034Convection coefficient equation slope
RealCt2842Heat capacity of air
Modelica.SIunits.Lengthhpd5Average depth of pond
RealCp4190*ag*apix*hpdHeat capacity of pond
Realfcsky0.67Sky radiation view factory
Realepsc1Sky radiation correction factor

Components

TypeNameDefaultDescription
Modelica.SIunits.CelsiusTemperatureTdomeTemperature of the dome
Modelica.SIunits.CelsiusTemperatureTlakeTemperature of the lake
Modelica.SIunits.CelsiusTemperatureTvegTemperature of the vegetatione
Modelica.SIunits.CelsiusTemperatureTsoilTemperature of the top layer of the soil
Modelica.SIunits.CelsiusTemperatureTgr1Temperature of the topmost layer inside the soil
Modelica.SIunits.CelsiusTemperatureTgr2Temperature of the middle layer inside the soil
Modelica.SIunits.CelsiusTemperatureTgr3Temperature of the lowermost layer inside the soil
Modelica.SIunits.CelsiusTemperatureTairTemperature of the air in degrees Centigrade
RealHairInside air humidity ratio
RealHsatHumidity ratio of saturated air
RealHrelRelative humidity of the air
BondLib.Junctions.J0p6J0p6_1
BondLib.Junctions.J0p6J0p6_2
BondLib.Junctions.J0p6J0p6_3
BondLib.Junctions.J0p5J0p5_3
BondLib.Junctions.J0p5J0p5_4
BondLib.Junctions.J0p2J0p2_1
BondLib.Junctions.J0p2J0p2_2
BondLib.Bonds.fBondB1
BondLib.Bonds.fBondB2
BondLib.Sources.mSemSe1
NightSkyTempNightSkyTemp1
BondLib.Bonds.fBondB3
BondLib.Thermal.RARA1
BondLib.Bonds.eBondB4
AmbientTempAmbientTemp1
BondLib.Sources.mSemSe2
BondLib.Bonds.fBondB5
BondLib.Bonds.fBondB6
CVextCVext1
BondLib.Bonds.eBondB7
BondLib.Bonds.eBondB8
BondLib.Thermal.CthCth1
BondLib.Bonds.eBondB9
BondLib.Sources.mSPmSP1
GlassGlass1
SolarInputSolarInput1
Modelica.Blocks.Math.GainGain1
AbsorptionAbsorption1
BondLib.Bonds.eBondB10
BondLib.Sources.mSPmSP2
GlassGlass2
BondLib.Bonds.eBondB11
BondLib.Sources.mSPmSP3
BondLib.Bonds.eBondB12
BondLib.Sources.mSPmSP4
BondLib.Bonds.eBondB13
BondLib.Sources.mSPmSP5
BondLib.Bonds.eBondB14
BondLib.Thermal.CthCth2
BondLib.Bonds.eBondB15
BondLib.Thermal.CthCth3
BondLib.Bonds.fBondB16
SoilSoil1
BondLib.Bonds.eBondB17
BondLib.Thermal.CthCth4
BondLib.Bonds.eBondB18
BondLib.Thermal.RARA2
BondLib.Bonds.eBondB20
BondLib.Thermal.RARA3
BondLib.Bonds.eBondB22
BondLib.Thermal.RARA4
BondLib.Bonds.fBondB19
BondLib.Bonds.fBondB21
BondLib.Bonds.fBondB23
CVCV1
BondLib.Bonds.fBondB24
BondLib.Bonds.eBondB25
BondLib.Bonds.eBondB26
BondLib.Thermal.CthCth5
BondLib.Bonds.fBondB27
CVCV2
BondLib.Bonds.eBondB28
BondLib.Bonds.fBondB29
CVCV3
BondLib.Bonds.eBondB30
BondLib.Bonds.fBondB31
CVCV4
BondLib.Bonds.eBondB32
BondLib.Junctions.J0p6J0p6_4
BondLib.Junctions.J0p6J0p6_5
BondLib.Bonds.eBondB33
BondLib.Bonds.fBondB34
CWcovCWcov1
BondLib.Bonds.eBondB35
BondLib.Bonds.eBondB36
CWvegCWveg1
BondLib.Bonds.fBondB37
BondLib.Bonds.eBondB38
CWpondCWpond1
BondLib.Bonds.fBondB39
BondLib.Bonds.eBondB40
CWsoilCWsoil1
BondLib.Bonds.fBondB41
CWbulkCWbulk1
BondLib.Bonds.fBondB42
BondLib.Bonds.eBondB43
CmoistCmoist1
Modelica.Blocks.Sources.ClockClock1
Modelica.Blocks.Nonlinear.LimiterLim1
Junctions.J0p3J0p3_1
BondLib.Bonds.eBondB44
BondLib.Bonds.fBondB45
Sensors.Detair