@article{PAR00014174,
  title = {{G}lobal {SMOS} soil moisture retrievals from the {L}and {P}arameter {R}etrieval {M}odel},
  author = {{V}an der {S}chalie, {R}. and {K}err, {Y}ann and {W}igneron,  {J}. {P}. and {R}odriguez-{F}ernandez, {N}. {J}. and {A}l-{Y}aari, {A}. and {D}e {J}eu, {R}. {A}. {M}.},
  editor = {},
  language = {{ENG}},
  abstract = {{A} recent study by {V}an der {S}chalie et al. (2015) showed good results for applying the {L}and {P}arameter {R}etrieval {M}odel ({LPRM}) on {SMOS} observations over southeast {A}ustralia and optimizing and evaluating the retrieved soil moisture (theta in m(3) m(-3)) against ground measurements from the {O}z{N}et sites. {I}n this study, the {LPRM} parameterization is globally updated for {SMOS} against modelled theta from {MERRA}-{L}and ({MERRA}) and {ERA}-{I}nterim/{L}and ({ERA}) over the period of {J}uly 2010-{D}ecember 2010, mainly focusing on two parameters: the single scattering albedo (omega) and the roughness (h). {T}he {P}earson's coefficient of correlation (r) increased rapidly when increasing the omega up to 0.12 and reached a steady state from thereon, no significant spatial pattern was found in the estimation of the single scattering albedo, which could be an artifact of the used parameter estimation procedure, and a single value of 0.12 was therefore used globally. {T}he h was defined as a function of theta and varied slightly for the different angle bins, with maximum values of 1.1-1.3 as the angle changes from 42.5 degrees to 57.5 degrees. {T}his resulted in an average r of 0.51 and 0.47, with a bias (m(3) m(-3)) of -0.02 and -0.01 and an unbiased root mean square error (ubrmse in m(3) m(-3)) of 0.054 and 0.056 against {MERRA} (ascending and descending). {F}or {ERA} this resulted in an r of 0.61 and 0.53, with a bias of -0.03 and an ubrmse 0.055 and 0.059. {T}he resulting parameterization was then used to run {LPRM} on {SMOS} observations over the period of {J}uly 2010-{D}ecember 2013 and evaluated against {SMOS} {L}evel 3 ({L}3) theta and available in situ measurements from the {I}nternational {S}oil {M}oisture {N}etwork ({ISMN}). {T}he comparison with 13 shows that the {LPRM} theta retrievals are very similar, with for the ascending set very high r of over 0.9 in large parts of the globe, with an overall average of 0.85 and the descending set performing less with an average of 0.74, mainly due to the negative rover the {S}ahara. {T}he mean bias is 0.03, with an ubrmse of 0.038 and 0.044. {I}n this study there are three major areas where the {LPRM} retrievals do not perform well: very dry sandy areas, densely forested areas and over high latitudes, which are all known limitations of {LPRM}. {T}he comparison against in situ measurement from the {ISMN} give very similar results, with average r for {LPRM} of 0.65 and 0.61 (0.64 and 0.59 for 13) for the ascending and descending sets, while having a comparable bias and ubrmse over the different networks. {T}his shows that {LPRM} used on {SMOS} observations produce theta retrievals with a similar quality as the {SMOS} {L}3 product.},
  keywords = {{R}emote sensing ; {P}assive microwave radiometry ; {S}oil moisture ; {S}oil moisture and ocean salinity ({SMOS}) ; {L}and {P}arameter {R}etrieval {M}odel ({LPRM})},
  booktitle = {},
  journal = {{I}nternational {J}ournal of {A}pplied {E}arth {O}bservation and {G}eoinformation},
  volume = {45},
  numero = {{B}},
  pages = {125--134},
  ISSN = {0303-2434},
  year = {2016},
  DOI = {10.1016/j.jag.2015.08.005},
  URL = {https://www.documentation.ird.fr/hor/{PAR}00014174},
}