Pre-Launch phase 2 rehearsal of the calibration and validation of soil moisture active passive (SMAP) geophysical data products

Authors: COLLANDER, ANDREAS - Jet Propulsion Laboratory; Jackson, Thomas; DUNBAR, R.S. - Jet Propulsion Laboratory; CHAN, S. - Jet Propulsion Laboratory; DAS, N. - Jet Propulsion Laboratory; KIM, S. - Jet Propulsion Laboratory; REICHLE, R. - National Aeronautics And Space Administration (NASA); DE LANNOY, G. - National Aeronautics And Space Administration (NASA); KIMBALL, J. - University Of Montana; YI, Y. - Jet Propulsion Laboratory; STEVENS, N. - Jet Propulsion Laboratory; DERKSEN, C. - Environment Canada; XU, X. - Jet Propulsion Laboratory

Submitted to: International Geoscience and Remote Sensing Symposium Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 4/1/2014
Publication Date: 7/13/2014
Citation: Collander, A., Jackson, T.J., Dunbar, R., Chan, S., Das, N., Kim, S., Reichle, R., De Lannoy, G., Kimball, J., Yi, Y., Stevens, N., Derksen, C., Xu, X. 2014. Pre-Launch phase 2 rehearsal of the calibration and validation of soil moisture active passive (SMAP) geophysical data products. International Geoscience and Remote Sensing Symposium Proceedings. July 13-17, 2014. Quebec, Canada. 2014 CDROM.

Interpretive Summary:

Technical Abstract: NASA’s Soil Moisture Active Passive (SMAP) Mission is scheduled for launch in early November 2014. The objective of the mission is global mapping of soil moisture and landscape freeze/thaw state. SMAP utilizes L-band radar and radiometer measurements sharing a rotating 6-meter mesh reflector antenna. The instruments will operate onboard the SMAP spacecraft in a 685-km Sun-synchronous near-polar orbit, viewing the surface at a constant 40-degree incidence angle with a 1000-km swath width. Merging of active and passive L-band observations will enable an unprecedented combination of accuracy, resolution, global coverage and revisit-time for soil moisture and freeze/thaw retrievals. SMAP measurements will contribute to improved estimates of water, energy and carbon transfers between the land and atmosphere. The SMAP science data product suite of geophysical parameters will include estimates of surface (top 5 cm) and root-zone (down to 1-m depth) soil moisture, net ecosystem exchange (NEE), and classification of the predominant frozen/non-frozen state of the landscape. The primary validation reference of the data products will be ground-based measurements. Well characterized sites with calibrated in situ measurements will be used to determine the quality of the data products; these sites will be designated as core validation sites. The mission success criteria will be evaluated with respect to these core site comparisons. Other remote sensing and model-based products will be used as additional resources to expand the spatial and temporal scope of the evaluation. The post-launch timeline of the mission requires that the geophysical data products are validated during the Cal/Val Phase which is 12 months in duration and starts after a 3-month in-orbit check-out phase. In an effort to ensure the geographic distribution and diversity of conditions of the core validation sites, SMAP is partnering with investigators across the globe. These Cal/Val Partners play a crucial role in the execution of the SMAP Cal/Val Plan. The SMAP mission team is taking several preparatory steps to meet the challenging schedule and guarantee efficient and productive collaborations with the Cal/Val Partners, one of which is conducting pre-launch rehearsals to exercise calibration and validation procedures planned for the operational Cal/Val Phase of the mission. The SMAP Cal/Val Rehearsal exercises are divided into two stages. Phase 1, which was conducted in June-August 2013, focused on validation methodologies for the geophysical data products. Phase 2, which will be conducted in May-June 2014, expands the activities to include operational aspects and a fully functioning SMAP Science Data System (SDS). These rehearsals will incorporate all of the validation methodologies identified in the Cal/Val Plan except airborne field campaigns. Phase 1 of the rehearsal included: generation of simulated SMAP data products for the soil moisture (L2/L4_SM) and NEE (L4_C) products (freeze/thaw product was not included); establishing automated data transfers of both candidate core validation sites and sparse in situ networks operated by a subset of SMAP Cal/Val Partners; exercising tools that will be used for formatting, comparison and metric computations; and running inter-comparisons between the simulated products and other satellite and model-based products. The simulated products were mostly based on climatological data rather current observations. However, concurrent SMOS brightness temperature measurements were used as the basis of the simulation of the radiometer-based soil moisture product. The comparisons were made with data from a period starting in May 2013 and continued during the course of the activity, which exercised procedures for obtaining and processing recently acquired data. A large part of the activity was devoted to establishing regular data transfers