[lemma=the] [word=IRS | □]
[lemma=the] [word=IRS | !□]
[lemma=the] [word=IRS | □ & □]
Further , truly global coverage is unlikely , even with a space mission , because of orbital limitations and the requirement for two cloud-free scenes with compatible imaging geometry . As with the roughness case , the effect of vegetation on the active microwave sensing of soil moisture is greatly dependent upon the instrument incidence angle , frequency , and polarization . Thus , the soil moisture problem becomes one of determining the roughness effect independently so that a model can be inverted to yield a soil moisture estimate . This section will define the science issues and application opportunities that can be addressed by microwave remote sensing of soil moisture and snow water equivalence , describe the capabilities and limitations of the passive and SAR systems , describe the progress to date and document the research still needed to take this technology to an operational status . Continuous monitoring of the temperature is important . These problems have analogs in the stereo-optical domain in shadows and distortions away from the principal point , but are exacerbated by the relatively larger look angles ( about 30deg .