Monitoring Crop Status in the Continental United States Using the SMAP Level-4 Carbon Product

Area of Science:

• Agricultural Science
• Remote Sensing
• Ecology

Background:

• Accurate crop condition monitoring is vital for agricultural economic viability and understanding climate variability impacts.
• Satellite remote sensing offers continuous, affordable crop monitoring solutions.
• Existing methods like state-scale crop condition indices (CCI) and county-level yield data lack high spatial and temporal detail.

Purpose of the Study:

• To compare weekly anomalies in accumulated gross primary production (GPP) from the SMAP Level-4 Carbon (L4C) product with crop condition and yield anomalies.
• To evaluate the performance of the SMAP L4C GPP product for monitoring crop status across different growth stages and regions in the continental United States.
• To assess the potential of the L4C GPP product as an operational tool for agricultural decision-making and research.

Main Methods:

• Utilized the SMAP Level-4 Carbon (L4C) product for weekly gross primary production (GPP) estimates at a 1-km scale.
• Compared L4C GPP anomalies with anomalies from state-scale weekly crop condition index (CCI) data.
• Correlated L4C GPP anomalies with county-level crop yield anomalies for barley, spring wheat, corn, and soybeans (2000-2018).

Main Results:

• Consistency between SMAP L4C GPP anomalies and crop condition/yield anomalies increased with crop development (emergence to maturity).
• Agreement was stronger in drier regions (r: 0.4-0.9) compared to wetter regions (r: -0.8-0.4).
• The 1-km scale of L4C GPP provides higher spatial detail than state-level CCI or county-level yield data.

Conclusions:

• The SMAP L4C GPP product demonstrates strong potential for operational crop condition monitoring.
• Its high spatial and temporal resolution enhances anomaly detection compared to traditional methods.
• L4C GPP can serve as a valuable tool for agricultural decision-making and research, improving our understanding of crop responses to environmental factors.