@article{PAR00009538,
  title = {{F}irst evaluation of the simultaneous {SMOS} and {ELBARA}-{II} observations in the {M}editerranean region},
  author = {{W}igneron, {J}. {P}. and {S}chwank, {M}. and {B}aeza, {E}. {L}. and {K}err, {Y}ann and {N}ovello, {N}. and {M}illan, {C}. and {M}oisy, {C}. and {R}ichaume, {P}. and {M}ialon, {A}. and {A}l {B}itar, {A}. and {C}abot, {F}. and {L}awrence, {H}. and {G}uyon, {D}. and {C}alvet, {J}. {C}. and {G}rant, {J}. {P}. and {C}asal, {T}. and de {R}osnay, {P}. and {S}aleh, {K}. and {M}ahmoodi, {A}. and {D}elwart, {S}. and {M}ecklenburg, {S}.},
  editor = {},
  language = {{ENG}},
  abstract = {{T}he {SMOS} ({S}oil {M}oisture and {O}cean {S}alinity) mission was launched on {N}ovember 2, 2009. {O}ver the land surfaces, simultaneous retrievals of surface soil moisture ({SM}) and vegetation characteristics made from the multiangular and dual polarization {SMOS} observations are now available from {L}evel-2 ({L}2) products delivered by the {E}uropean {S}pace {A}gency ({ESA}). {T}herefore, first analyses evaluating the {SMOS} observations in terms of {B}rightness {T}emperatures ({TB}) and 12 products ({SM} and vegetation optical depth {TAU}) can be carried out over several calibration/validation (cal/val) sites selected by {ESA} over all continents. {T}his study is based on {SMOS} observations and in situ measurements carried out in 2010 over one of the main {SMOS} cal/val sites in {E}urope: the {VAS} ({V}alencia {A}nchor {S}tation) site in the region of {U}tiel-{R}equena, close to {V}alencia, {S}pain. {T}he main vegetation types in the region are vineyards, orchards and natural {M}editerranean vegetation. {T}he {SMOS} observations were analyzed in conjunction with those carried out by the {L}-band {ELBARA}-{II} radiometer over a vineyard which is considered as representative of the main land use of the {VAS} site. {T}ime series of {TB} and retrievals of {SM} and {TAU} based on both the {SMOS} ({L}2 products) and the {ELBARA}-{II} observations were compared and evaluated against in situ measurements. {A} good agreement was found between the time variations in {TB} and in the retrieved {SM} values computed over the site from the {SMOS} and {ELBARA}-{II} observations (the determination coefficient {R}-2 was > 0.88 for the {TB} values and {R}-2 > 0.64 for the retrieved {SM} values). {H}owever, it was found that the {SMOS} {L}2 {SM} products underestimated the {SM} values retrieved from {ELBARA}-{II} by similar to 0.2 m(3)/m(3). {I}t is likely this offset can be partially explained by differences between the observed scenes: while the {ELBARA}-{II} footprint includes a single vineyard, the heterogeneous {SMOS} footprint includes not only a large number of vineyards but also a natural {M}editerranean vegetation with persistent leaves overlaying rocky soils. {T}he time variations in {TAU} retrieved from the {ELBARA}-{II} observations were found to be closely related to those of the {NDVI} ({N}ormalized {D}ifference {V}egetation {I}ndex) vegetation index obtained from {MODIS} ({M}oderate {R}esolution {I}maging {S}pectroradiometer) ({R}-2 = 0.61) and revealed the vegetation cycle over the year. {C}onversely, the time variations in the {SMOS} {L}evel-2 {TAU} product did not reveal any trends in relation to the vegetation development over the site.},
  keywords = {{SMOS} ; {S}oil moisture ; {O}ptical depth ; {R}etrievals ; {M}editerranean ; environment ; {L}evel 2 algorithm ; {B}rightness temperature ; {V}ineyards ; {S}oil ; {NDVI} ; {MODIS} ; {ELBARA}},
  booktitle = {},
  journal = {{R}emote {S}ensing of {E}nvironment},
  volume = {124},
  numero = {},
  pages = {26--37},
  ISSN = {0034-4257},
  year = {2012},
  DOI = {10.1016/j.rse.2012.04.014},
  URL = {https://www.documentation.ird.fr/hor/{PAR}00009538},
}