Leaf Area Index#
This module computes the daily leaf area index per grid cell.
- lai.get_leaf_area_index(temperature, growth_status, days, initial_days, cum_precipitation, precipitation, leaf_area_index, min_leaf_area_index, max_leaf_area_index, land_cover, humid_arid)[source]#
Compute daily leaf area index per grid cells.
- Parameters:
- temperaturefloat
Daily temperature climate forcing, Units: [K]
- growth_statusfloat
Growth status per grid cell shows whether a specific land cover is (not) growing (value=0) or fully grown (value=1). Initially all landcovers are not growing This variable gets updated per time step.
- daysfloat
Days since start of leaf area index profile (counter for days with growing conditions), Units: [day] This variable gets updated per time step.
- initial_daysfloat
Landcover specific initial days
- cum_precipitationfloat
Cummulative precipitation per time step, Units: [mm/d]
- precipitationfloat
Daily precipitation climate forcing, Units: [mm/d] or [kg m-2 s-1] Units are converted from kg m-2 s-1 to mm/d
- leaf_area_indexfloat
leaf_area_index, Units: [-]
- min_leaf_area_indexfloat
Minimum Leaf area index over all grid cell, Units: [-]
- max_leaf_area_indexfloat
Maximum Leaf area index over all grid cell, Units: [-]
- land_coverfloat
Land_cover class based on [1], Units: [-]
- humid_aridfloat
Humid-arid calssification based on [1], Units: [-]
- Returns:
- leaf_area_indexfloat
Daily leaf area index, Units: [-]
- daysfloat
Day since start for current day, Units: [day]
- cum_precipitationfloat
Cummulative precipitation for current day, units: [mm/d]
- growth_statusfloat
Growth status per grid cell for current day, Units: [-]
Notes
A day is defined as part of the growing season when daily temperature is above 8◦C(281.15 K) for a land-cover-specific number of initial days (Table C1) and cumulative precipitation from the day when growing season starts reaches at least 40 mm [1].
In the beginning of the growing season, LAI increases linearly for 30 days until it reaches maximum LAI. For (semi)arid cells, at least 0.5 mm of daily precipitation is required to keep the growing season ongoing. LAI then stays constant for the stated land-cover-specific number of days and when growing season conditions are not fulfilled anymore, a senescence phase is initiated and LAI linearly decreases to minimum within the next 30 days
References
[1] (1,2,3)Müller Schmied, H., Cáceres, D., Eisner, S., Flörke, M., Herbert, C., Niemann, C., Peiris, T. A., Popat, E., Portmann, F. T., Reinecke, R., Schumacher, M., Shadkam, S., Telteu, C.E., Trautmann, T., & Döll, P. (2021). The global water resources and use model WaterGAP v2.2d: model description and evaluation. Geoscientific Model Development, 14(2), 1037–1079. https://doi.org/10.5194/gmd-14-1037-2021