@article{PAR00012704,
  title = {{C}atchment scale validation of {SMOS} and {ASCAT} soil moisture products using hydrological modeling and temporal stability analysis},
  author = {{R}otzer, {K}. and {M}ontzka, {C}. and {B}ogena, {H}. and {W}agner, {W}. and {K}err, {Y}ann and {K}idd, {R}. and {V}ereecken, {H}.},
  editor = {},
  language = {{ENG}},
  abstract = {{S}ince soil moisture is an important influencing factor of the hydrological cycle, knowledge of its spatio-temporal dynamics is crucial for climate and hydrological modeling. {I}n recent years several soil moisture data products from satellite information have become available with global coverage and sub-monthly resolution. {S}ince the remote sensing of soil moisture is an indirect measurement method and influenced by a large number of factors (e.g. atmospheric correction, vegetation, soil roughness, etc.), a comprehensive validation of the resulting soil moisture products is required. {H}owever, the coarse spatial resolution of these products hampers the comparison with point-scale in situ measurements. {T}herefore, upscaling of in situ to the scale of the satellite data is needed. {W}e present the validation results of the soil moisture products of the years 2010-2012 retrieved from the {S}oil {M}oisture and {O}cean {S}alinity ({SMOS}) and the {A}dvanced {S}catterometer ({ASCAT}) for the {R}ur and {E}rft catchments in western {G}ermany. {F}or the upscaling of in situ data obtained from three test sites of the {T}errestrial {E}nvironmental {O}bservatories ({TERENO}) initiative we used the hydrological model {W}a{S}i{M} {ETH}. {C}orrelation of the {SMOS} product to modeled and upscaled soil moisture resulted in a mean correlation coefficient of 0.28 whereas for {ASCAT} a correlation coefficient of 0.50 was obtained. {H}owever, for specific regions the {SMOS} product showed similar correlation coefficients as the {ASCAT} product. {W}hile for {ASCAT} correlation was mainly dependent on topography and vegetation, {SMOS} was also influenced by radiofrequency interferences in our study area. {B}oth products show dry biases as compared to the soil moisture reference. {H}owever, while {SMOS} showed relatively constant bias values, {ASCAT} bias is variable throughout the year. {A}s an additional validation method we performed a temporal stability analysis of the retrieved spatio-temporal soil moisture data. {T}hrough investigation of mean relative differences of soil moisture for every pixel, their standard deviations and their rankings, we analyzed the temporal persistence of spatial patterns. {O}ur results show high standard deviations for both {SMOS} and {ASCAT} soil moisture products as compared to modeled soil moisture, indicating a lower temporal persistence. {T}he consistence of ranks of mean relative differences was low for {SMOS} and relative {ASCAT} soil moisture compared to modeled soil moisture, while {ASCAT} soil moisture, converted to absolute values, showed higher rank consistence.},
  keywords = {{SMOS} ; {ASCAT} ; {M}icrowave remote sensing ; {M}odel ; {W}a{S}i{M}-{ETH} ; {T}emporal stability ; {ALLEMAGNE}},
  booktitle = {},
  journal = {{J}ournal of {H}ydrology},
  volume = {519},
  numero = {{A}},
  pages = {934--946},
  ISSN = {0022-1694},
  year = {2014},
  DOI = {10.1016/j.jhydrol.2014.07.065},
  URL = {https://www.documentation.ird.fr/hor/{PAR}00012704},
}