Impact model: PEGASUS

PEGASUS is one of the 14 models following the ISIMIP2a protocol which form the base of simulations for the ISIMIP2a agricultural sector outputs; for a full technical description of the ISIMIP2a Simulation Data from Agricultural Sector, see this DOI link: http://doi.org/10.5880/PIK.2017.006

Sector
Agriculture
Region
global
Contact Person

Information for the model PEGASUS is provided for the simulation rounds shown in the tabs below. Click on the appropriate tab to get the information for the simulation round you are interested in.

Output Data
Experiments: historical
Climate Drivers: WATCH (WFD), WATCH+WFDEI
Date: 2016-02-11
Resolution
Spatial Aggregation: regular grid
Spatial Resolution: 0.5°x0.5°
Temporal Resolution Of Input Data: Climate Variables: Daily
Temporal Resolution Of Input Data: Co2: Annual
Temporal Resolution Of Input Data: Land Use/Land Cover: Annual
Temporal Resolution Of Input Data: Soil: Constant
Input data sets used
Observed Atmospheric Climate Data Sets Used: WATCH (WFD), WATCH+WFDEI
Climate Variables: tasmax, tas, rlds, rsds, pr
Additional Input Data Sets: GGCMI harmonized planting, maturity and fertlizer dataset.
Spin-up
Was A Spin-Up Performed?: Yes
Spin-Up Design: 4-years based on 1971
Management & Adaptation Measures
Management: Prescribed planting window; fully irrigation assumes water is available to reduce water stress; fix fertiliser inputs from Ag-GRID harmonised dataset
Extreme Events & Disturbances
Key Challenges: PEGASUS simulates crop responses to extreme temperature events occuring around anthesis
Key input and Management
Crops: maiz, whe(s), soy
Land Cover: potential suitable cropland area according to climatic conditions, current harvested areas (Monfreda et al., 2008)
Planting Date Decision: Simulate planting dates according to climatic conditions or fixed planting dates (Sacks et al., 2010)
Planting Density: planting density=0.95
Crop Cultivars: Simulate crop Growing Degree Days (GDDs) requirement according to estimated annual GDDs from daily temperature; Number of cultivars
Fertilizer Application: NPK (national stat. IFA) Annual application
Irrigation: no restriction on actual water availability, irrigated water applied when water stress, limited water availability, MIRCA 2000: crop specific irrigated area (Portmann et al., 2010)
Initial Soil Water: 4 year spin up
Key model processes
Leaf Area Development: Dynamic simulation based on development and growth processes
Light Interception: Simple approach
Light Utilization: Simple (descriptive) Radiation use efficiency approach
Yield Formation: partitioning during reproductive stages
Crop Phenology: temperature (heat unit index)
Root Distribution Over Depth: no roots-just soil depth zone
Stresses Involved: Water stress, Nitrogen stress, heat stress
Type Of Water Stress: ratio of supply to demand of water
Type Of Heat Stress: vegetative, number of grain (pod) set during the flowering period
Water Dynamics: soil water capacity approach with 2 soil layers
Evapo-Transpiration: Priestley -Taylor
Co2 Effects: Radiation use efficiency, Transpiration efficiency
Methods for model calibration and validation
Parameters, Number And Description: 1: light-use efficiency factor (beta factor)
Calibrated Values: Specific for each crop
Output Variable And Dataset For Calibration Validation: Yield (M3 yield data - gridded dataset of crop specific yields and harvested areas for the year 2000 (Monfreda et al., 2008))
Spatial Scale Of Calibration/Validation: Calibration at gridcell level (0.5º resolution)/validation at national level
Temporal Scale Of Calibration/Validation: Average for 1997-2004
Criteria For Evaluation (Validation): Wilmott