SMAP L2/L3 Soil Moisture Product Validation with Core Validation Sites

The Soil Moisture Active Passive (SMAP) mission was launched by NASA in January, 2015 and entered its one year calibration and validation (cal/val) phase in May, 2015. This began with a focus on instrument measurements, brightness temperature and backscatter, and has now evolved to the geophysical products that include three different spatial resolutions of Level 2/3 surface soil moisture (36, 9, and 3 km). The goal is to provide validated products by May, 2016. SMAP utilizes five methodologies in soil moisture cal/val: core validation sites, sparse networks of in situ sensors, inter-comparisons with products from other satellite programs, inter-comparison with model-based products, and field campaigns. Each methodology has a role; however, the core validation sites are of particular value. Core validation sites are designated as those that meet a set of standards that include replication within the domain at a specific product scale. SMAP has collaborated with its Cal/Val Partners over the past five years to enhance and focus existing efforts around the world that collect and provide in situ soil moisture measurements. These sites provide a basis for both the assessment of mission performance as well for algorithm development and improvement. Both activities have been ongoing since April; however, early analysis must proceed cautiously to allow for the refinement of L1 products and for longer periods of record that capture a wide range of soil moisture and vegetation conditions. By the Fall of 2015 and the release of beta versions of the L2/L3 products, there will be five months of SMAP observations that will include the North America summer where a large number of core validation sites are located. In this presentation the process and early results of validating the SMAP surface soil moisture using in situ observations obtained at core validation sites will be described.