Susan Moran

The Soil Moisture Active Passive (SMAP) Mission

The Soil Moisture Active Passive (SMAP) mission is one of the first Earth observation satellites being developed by NASA in response to the National Research Councils Decadal Survey. SMAP will make global measurements of the soil moisture present at the Earths land surface and will distinguish frozen from thawed land surfaces. Direct observations of soil moisture and freeze/thaw state from space will allow significantly improved estimates of water, energy, and carbon transfers between the land and the atmosphere. The accuracy of numerical models of the atmosphere used in weather prediction and climate projections are critically dependent on the correct characterization of these transfers. Soil moisture measurements are also directly applicable to flood assessment and drought monitoring. SMAP observations can help monitor these natural hazards, resulting in potentially great economic and social benefits. SMAP observations of soil moisture and freeze/thaw timing will also reduce a major uncertainty in quantifying the global carbon balance by helping to resolve an apparent missing carbon sink on land over the boreal latitudes. The SMAP mission concept will utilize L-band radar and radiometer instruments sharing a rotating 6-m mesh reflector antenna to provide high-resolution and high-accuracy global maps of soil moisture and freeze/thaw state every two to three days. In addition, the SMAP project will use these observations with advanced modeling and data assimilation to provide deeper root-zone soil moisture and net ecosystem exchange of carbon. SMAP is scheduled for launch in the 2014-2015 time frame.

NASA's Soil Moisture Active Passive (SMAP) Mission and Opportunities for Applications Users

Water in the soil, both its amount (soil moisture) and its state (freeze/thaw), plays a key role in water and energy cycles, in weather and climate, and in the carbon cycle. Additionally, soil moisture touches upon human lives in a number of ways from the ravages of flooding to the needs for monitoring agricultural and hydrologic droughts. Because of their relevance to weather, climate, science, and society, accurate and timely measurements of soil moisture and freeze/thaw state with global coverage are critically important.

In situ soil moisture network for validation of remotely sensed data

An automated soil moisture network for continuous measurement of soil moisture in the top 30 cm of the soil over an 8000 km2 region has been established. The network consists of 32 stations encompassing a diversity of soil types. The measurements are being used to improve drought, flood, and agronomic production forecasts. In addition, the data are being used to examine the accuracy of remotely sensed measurements of soil moisture and the degree to which they represent natural variability across the landscape. The data were used to evaluate soil moisture conditions during the SMEX03 experiment. The data are being used to support testing of AMSR, AMSR-E, PSR, and synthetic aperture radar (SAR) observations. Gravimetric samples were collected for the period from June 23, 2003 to July 2, 2003 for comparison to both the in situ network and the remotely sensed data. During the experiment, daily in situ soil moisture measurements were taken and plant and soil samples collected for oven drying and determination of moisture content. The automated network provided continuous in situ soil moisture measurements throughout the coverage area. A wide variation in soil moisture was observed both over the time period and from site to site

The Soil Moisture Active Passive (SMAP) applications activity

The Soil Moisture Active Passive (SMAP) mission is one of the first-tier satellite missions recommended by the U.S. National Research Council Committee on Earth Science and Applications from Space. The SMAP mission 1 is under development by NASA and is scheduled for launch late in 2014. The SMAP measurements will allow global and high-resolution mapping of soil moisture and its freeze/thaw state at resolutions from 3–40 km. These measurements will have high value for a wide range of environmental applications that underpin many weather-related decisions including drought and flood guidance, agricultural productivity estimation, weather forecasting, climate predictions, and human health risk. In 2007, NASA was tasked by The National Academies to ensure that “emerging scientific knowledge is actively applied to obtain societal benefits” by broadening community participation and improving means for use of information. SMAP is one of the first missions to come out of this new charge, and its Applications Plan forms the basis for ensuring its commitment to its users. The purpose of this paper is to outline the methods and approaches of the SMAP applications activity, which is designed to increase and sustain the interaction between users and scientists involved in mission development.