The SMAP post-launch Cal/Val activities are intended both to assess the quality of the mission products and to support analyses that lead to their improvement. A suite of complementary methodologies will be employed that will result in a robust global assessment. The specific role that field campaigns play in Cal/Val is to provide detailed information about targeted Cal/Val sites. In addition, they can also strengthen collaboration within and across disciplines that can address broader science questions.
Primary SMAP Field Campaigns
Soil Moisture Active and Passive Experiments (SMAPEx) -- 2010-2011, New South Wales, Australia.
San Joaquin Valley 2010 Field Campaign (SJV10)||]] -- Summer 2010, California, USA.
Canadian Experiment - Soil Moisture 2010 (CanEx-SM10) -- May 31-June 17, 2010, Saskatchewan, Canada.
SMAP Validation Experiment 2008 (SMAPVEX08) -- Sept 29-Oct 13, 2008, Maryland, USA.
Other Previous Campaigns - Provide useful data for SMAP algorithm development
Cloud and Land Surface Interaction Campaign (CLASIC) -- June 11-July 6, 2007, Oklahoma, USA.
Southern Great Plains Experiment 1999 (SGP99) -- July 8-14, 1999, Oklahoma, USA.
Role of Field Campaigns in SMAP Cal/Val
The Soil Moisture Active Passive (SMAP) mission currently provides Level 2 to 4 soil moisture products derived from its L-band passive microwave radiometer. Due to aggressive efforts to mitigate radio frequency interference, the accuracy and temporal and spatial coverage of the passive-based soil moisture products have been very good (Chan et al. 2016). Following the loss of its radar that was to provide a higher resolution soil moisture product, SMAP is currently exploring a suite of approaches to enhance the spatial resolution of the soil moisture products. These include combining active observations from the European Space Agency (ESA) Sentinel 1 radars with the SMAP passive radiometer.
The SMAP post-launch Cal/Val activities are intended both to assess the quality of the mission products and to support analyses that lead to their improvement. A suite of complementary methodologies is being employed (Table 1) that will result in a robust global assessment. Beyond the in-orbit checkout (IOC) (launch + 3 months), the first year of operations focused on assessing the products. However, Cal/Val is an activity that continues throughout the mission life, and some anomalies and poor performance issues were identified that would require intensive efforts to resolve.
As noted in Table 1, field campaigns are intended to provide detailed information about targeted Cal/Val sites. It is recognized that only a limited number of field campaigns can be conducted due to their cost and the extensive logistics and human resources required (especially if airborne instruments are involved). It should also be noted that data latency is expected in these campaigns because they are typically one-of-a-kind efforts. In planning post-launch Cal/Val activities it is important that airborne instruments in field campaigns are linked with objectives that can only be addressed using airborne systems.