Emission Models

emiproc can also genereate emissions using various well known methods

VPRM

The VPRM simulates the vegetation respiration and photosynthesis using the following inputs:

  • temperature

  • radiation

  • satellite data

  • vegetation parameters

There are 4 implementation of the VPRM model:

  • standard (Mahadevan et al., 2008)

  • urban (Hardiman et al., 2017)

  • urban winbourne (Winbourne et al., 2021)

  • modified (Gourdij et al., 2021)

see emiproc.profiles.vprm

Standard VPRM

PAR (Photosynthetically Active Radiation) is calculated from the shortwave radiation:

\[\mathrm{PAR} = \frac{\mathrm{RAD}}{0.505}\]

Respiration is calculated from the temperature:

\[\mathrm{Resp} = \alpha * T + \beta\]

The Gross Ecosystem Exchange (GEE) is calculated from the temperature, PAR and the vegetation indices:

\[\mathrm{GEE} = - \lambda * T_{scale} * P_{scale} * W_{scale} * \mathrm{EVI} * \frac{ \mathrm{PAR} }{1 + \frac{\mathrm{PAR}}{PAR0}}\]

where the different scales are:

  • \(T_{scale}\): Temperature scale

\[T_{scale} = \frac{(T - T_{\text{min}}) \cdot (T - T_{\text{max}})}{(T - T_{\text{min}}) \cdot (T - T_{\text{max}}) + (T - T_{\text{opt}})^2} \text{if } T \geq T_{\text{min}} \text{ else } 0\]

  • \(P_{scale}\): Photosynthesis scale

\[P_{scale} = \frac{1 + \mathrm{LSWI}}{2}\]

  • \(W_{scale}\): Water scale

\[W_{scale} = \frac{1 + \mathrm{LSWI}}{1 + \mathrm{LSWI}_{max}}\]

The Net Ecosystem Exchange (NEE) is calculated from the respiration and GEE.

\[\mathrm{NEE} = \mathrm{Resp} + \mathrm{GEE}\]

Units for all fluxes (NEE, GEE, Resp, …) are

\[\frac{\mu mol_{\mathrm{CO2}}}{m^2 * s}\]

Urban VPRM

The VPRM model can be extended to urban areas according to [Urban_VPRM_Hardiman_2017].

  • A “urban temperature” is used instead of the global temperature to represent

    the urban heat island phenomenon.

  • The formula for \(P_{scale}\) is modified to

\[P_{scale} = \frac{\mathrm{EVI} - \mathrm{EVI}_{min}}{\mathrm{EVI}_{max} - \mathrm{EVI}_{min}}\]

  • The respiration is calculated differently

\[\mathrm{Resp} = \frac{\mathrm{Resp_{e-init}}}{2} * (1 - \mathrm{ISA}) + \frac{\mathrm{EVI} + \mathrm{EVI}_{min} * \mathrm{ISA}}{\mathrm{EVI}_{ref}} * \frac{\mathrm{Resp_{e-init}}}{2}\]

where \(\mathrm{Resp_{e-init}}\) is the basic vprm respiration and \(\mathrm{ISA}\) is the impervious surface area at the vegetation location.

Urban VPRM with winbourne

This is a variant of the urban VPRM model that uses a different formulation for \(T_{scale}\):

\[\begin{split}T_{scale} = \begin{cases} \frac{(T - 0) \cdot (T - 40)}{(T - 0) \cdot (T - 40) + (T - 20)^2} & \text{if } T \leq 20 \\ 1 & \text{if } 20 < T < 30 \\ \frac{(T - 0) \cdot (T - 40)}{(T - 0) \cdot (T - 40) + (T - 30)^2} & \text{if } T \geq 30 \end{cases}\end{split}\]

modified-VPRM

The modified-VPRM model follows the standard VPRM for GEE and has a different model for the estimate of respiration: for more details see [VPRM_modified_groudji_2022].

Heating Degree Days (HDD)

Calculates the demand of heating based on the temperature.

see emiproc.profiles.hdd

Human Respiration

Human respirations can be generated using maps of population density and emission factors per person.

see emiproc.human_respiration