SMAP Vegetation Optical Depth is Directly Proportional to Crop Water in the US Corn Belt

Kaitlin Togliatti, Theodore Hartman, Timothy Arkebauer, Andrew Suyker, Andy Vanloocke, Brian K. Hornbuckle

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

NASA's Soil Moisture Active Passive (SMAP) is a satellite L-band radiometer whose primary mission is to measure soil moisture. However, it also retrieves vegetation optical depth (VOD), the degree to which vegetation attenuates microwave radiation. We believe that VOD has the potential to monitor crop growth in the US Corn Belt. To show its value, we compare SMAP VOD to satellite-scale estimates of crop productivity created using the Agricultural Integrated BIosphere Simulator (Agro- IBIS) and observed weather at the South Fork SMAP Core Validation Site in the Corn Belt state of Iowa. We find that SMAP VOD is directly proportional to crop water, the mass of liquid water in crop tissue. We discovered this relationship by using new empirical models that relate crop water to crop dry mass, the standard output for Agro-IBIS as well as all other crop models, created with in situ data spanning multiple years and stages of crop development. The value of the proportionality constant (or "b-parameter") relating VOD to crop water at the satellite scale is half as large as the SMAP value. Because L-band VOD is directly proportional to crop water at the satellite scale, SMAP has the potential to evaluate the large-scale performance of crop models in the Corn Belt on a near daily basis.

Original languageEnglish (US)
Title of host publication2019 IEEE International Geoscience and Remote Sensing Symposium, IGARSS 2019 - Proceedings
PublisherInstitute of Electrical and Electronics Engineers Inc.
Pages5445-5448
Number of pages4
ISBN (Electronic)9781538691540
DOIs
StatePublished - Jul 2019
Externally publishedYes
Event39th IEEE International Geoscience and Remote Sensing Symposium, IGARSS 2019 - Yokohama, Japan
Duration: Jul 28 2019Aug 2 2019

Publication series

NameInternational Geoscience and Remote Sensing Symposium (IGARSS)

Conference

Conference39th IEEE International Geoscience and Remote Sensing Symposium, IGARSS 2019
Country/TerritoryJapan
CityYokohama
Period7/28/198/2/19

ASJC Scopus subject areas

  • Computer Science Applications
  • General Earth and Planetary Sciences

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