# lt\_nonalg

The light extinction coefficient, $$k\_l$$, is calculated as a function of the algal density using the nonlinear equation:

$$k\_l=k\_{l,0}+k\_{l,1}*\alpha\_0*algae+k\_{l,2}*(\alpha\_0*algae)^{2/3}$$                

where $$k\_{l,0}$$ is the non-algal portion of the light extinction coefficient ($$m^{-1}$$), $$k\_{l,1}$$ is the linear algal self shading coefficient ($$m^{-1}(\mu g - chla/L)^{-1})$$, $$k\_{l,2}$$ is the nonlinear algal self shading coefficient $$m^{-1}(\mu g - chla/L)^{-2/3})$$, $$\alpha\_0$$is the ratio of chlorophyll *a* to algal biomass ($$\mu g$$ chla/mg alg), and $$algae$$ is the algal biomass concentration (mg alg/L).

#### Relevant chapter in the Theoretical Documentation: 

[Local Specific Growth Rate of Algae](https://swatplus.gitbook.io/io-docs/theoretical-documentation/section-7-main-channel-processes/in-stream-nutrient-processes/algae/algal-growth/local-specific-growth-rate-of-algae)