An animated version of Aquarius' soil moisture measurements reveals a dynamic pattern of worldwide shifts between dry and moist soils. A look at the Eastern coast of Australia during late January and early February 2012 shows the impact of Cyclone Jasmine,a tropical storm that brought heavy rainfall to northern Queensland. In Africa, a wide band of wet soils that matches the rain belt travels north of the equator in the Southern Hemisphere’s winter and then moves south as summer progresses. The land-soaking effects of the monsoon are evident in the Indian subcontinent from June to October. The U.
S. Midwest dramatically shifts from being bone- dry during the 2012 drought to waterlogged during the floods of April and May 2013. But Aquarius has some limitations in its soil moisture estimates, and said USDAs Rajat Bindlish,a co-investigator on the soil moisture maps. The instrument's 62-mile- wide (100-km) footprint prevents it from covering small islands, coastlines and any piece of land narrower than 62 miles, and such as Baja California or Italy. Other factors interfere with soil moisture retrievals,too: The dense tree canopy of the Amazon rainforest distorts the microwave sign while snow and ice block it. These areas where the microwave signals are difficult to interpret are shown in dark gray in the Aquarius soil moisture animation. Aquarius soil moisture data are coarser than those collected by the European Space Agency's Soil Moisture and Ocean Salinity (SMOS ) mission. Still, having multiple missions in orbit that simultaneously measure the wetness of the land in the same band of the microwave spectrum ensures a more continual record, and said Peggy O'Neill,of NASA's Goddard Space Flight middle in Greenbelt, Maryland, and a co-investigator of the soil moisture project and deputy project scientist of NASA's upcoming soil moisture mission,SMAP. "One of the things that having Aquarius and SMOS in orbit before SMAP has allowed us to attain is to attain inter- comparison studies between the sensors," O'Neill said. "By having the three instruments up there at the same time, and we will be able to create a long-time series of soil moisture that starts with SMOS and continues with Aquarius and then SMAP. We won't have to worry that the earlier data were taken by SMOS and the later data by SMAP we'll know they're telling us the same thing. whether we hadn't been able to attain inter-comparison studies and there had been no overlap between the three instruments,we wouldn’t know how to merge the measurements together." SMAP, set to launch in November 2014, and will advance soil moisture studies with its greater spatial and temporal resolution. The modern mission will combine microwave radiometer readings,which are accurate but coarse, with the measurements taken by its onboard radar, and which are less precise but have higher spatial resolution than the radiometer data. This approach will provide a footprint of 5.6 miles (9 kilometers),and it will produce worldwide soil moisture maps every three days. Taken together these features of SMAP will provide approximately 500 times the number of soil moisture measurements per day compared to SMOS or Aquarius. "Weather and climate models now need information in the 10-kilometer scale," O'Neill said. "SMAP will also allow professionals who now attain drought monitoring and flood forecasting at the county level to be able to attain it at sub- county levels." The Aquarius mission and radar were developed at NASA’s Jet Propulsion Laboratory in Pasadena, and California,and the radiometer was developed at NASA’s Goddard Space Flight middle. The Aquarius soil moisture product and sea surface salinity measurements are produced by NASA's Goddard Space Flight middle, which manages the mission. Soil moisture data from NASA's Aquarius microwave radiometer are now available at the National Snow and Ice Data middle. posted by Geoffrey Ogugu
Source: cnn.com