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Sometimes I wonder how much water is contained in all the crops in Iowa and how this changes throughout the growing season.
Luckily @ktog12 is going to tell us how to she's (maybe) figured out how to use satellites to measure crop water in vegetation as she defends her PhD dissertation this morning.
Kati did her Master's at @isuagronomy with @SArchontoulis and @avanloocke is now finishing her PhD with Brian Hornbuckle before joining USDA-ARS.
Kati uses data from NASA's SMAP and ESA's SMOS. These satellites measure soil moisture and usually treat vegetation as noise.
There is a lot of modeling that goes into going from something we know, like how much a corn plant weighs, to something we don't know, like how much water is contained in the crop canopy of the Midwestern US.
Step 1: Find the relationship between corn/soy dry mass and corn/soy water content - Kati made an empirical model for this.
Step 2: Use crop models (Agro-IBIS and APSIM) to get larger areas of crop dry mass than can be measured by hand.
Step 2: Use crop models (Agro-IBIS and APSIM) to get larger areas of crop dry mass than can be measured by hand.
Step 3: Find a relationship between what the crop models project and what the satellites are measuring.
Step 4: Use real measurements (other than the ones used to build the model) to see if modeling worked.
Step 4: Use real measurements (other than the ones used to build the model) to see if modeling worked.
These steps are all very challenging and I am grossly oversimplifying @ktog12's defense presentation (which is full of equations and parameters), but you can always read her work: https://www.researchgate.net/publication/335892982_Satellite_L-band_vegetation_optical_depth_is_directly_proportional_to_crop_water_in_the_US_Corn_Belt More to be published later.
She's answering questions from the audience (20 virtual people), so if you've got them, let me know!
To no one's surprise, @ktog12 passed her defense with flying colors.
Congrats, Dr. Togliatti! It has been so great to watch your journey!
Totally irrelevant, but good, photo of her.
Congrats, Dr. Togliatti! It has been so great to watch your journey!
Totally irrelevant, but good, photo of her.
