Assessment of Soil Moisture SMAP Retrievals and ELBARA-III Measurements in a Tibetan Meadow Ecosystem

Donghai Zheng, Xin Wang, R. van der Velde, Mike Schwank, Paolo Ferrazzoli, Jun Wen, Zuoliang Wang, Andreas Colliander, Rajat Bindlish, Zhongbo Su

Research output: Contribution to journalArticleAcademicpeer-review

Abstract

This letter presents the results evaluating retrievals of liquid water content (θ liq ) performed with a zero-order radiative transfer (τ-ω) model under frozen and thawed soil conditions from Soil Moisture Active Passive (SMAP) and ELBARA-III brightness temperature (T B p ) measurements collected over a Tibetan meadow ecosystem. A good agreement is found between time series of the SMAP and ELBARA-III measured T B p resulting in a Pearson product-moment coefficient (R) larger than 0.87. Differences noted between the two data sets can be associated with discrepancies in θ liq measured in the specific footprints, whereby the SMAP measurements are best explained by the in situ θ liq . Furthermore, the in situ θ liq has a better agreement with the horizontally polarized SMAP and ELBARA-III measurements (THB ) in the cold season, whereas the vertically polarized measurements (TVB ) are1111better correlated with θ liq in the warm season. With the implementation of new vegetation and surface roughness parameterizations for the τ-ω model, the dynamics of in situ θ liq is better reproduced by corresponding retrievals for both frozen and thawed soil conditions, leading to the reduction in the unbiased root-mean-square error (ubRMSE) by more than 31% in comparison with these retrievals using SMAP default parameterizations. Notably, the single-channel algorithm configured with the new parameterizations using SMAP TVB measured during the ascending overpass provides the best θ liq retrievals with a ubRMSE of 0.035 m 3 ·m -3 that is well within the SMAP mission requirements.
Original languageEnglish
Pages (from-to)1407-1411
Number of pages5
JournalIEEE geoscience and remote sensing letters
Volume16
Issue number9
DOIs
Publication statusPublished - 5 Mar 2019

Keywords

  • Frozen and thawed soil
  • grassland
  • L-band microwave radiometry
  • liquid water content
  • Soil Moisture Active Passive (SMAP)
  • Tibetan Plateau
  • ITC-ISI-JOURNAL-ARTICLE

Cite this

Zheng, Donghai ; Wang, Xin ; van der Velde, R. ; Schwank, Mike ; Ferrazzoli, Paolo ; Wen, Jun ; Wang, Zuoliang ; Colliander, Andreas ; Bindlish, Rajat ; Su, Zhongbo. / Assessment of Soil Moisture SMAP Retrievals and ELBARA-III Measurements in a Tibetan Meadow Ecosystem. In: IEEE geoscience and remote sensing letters. 2019 ; Vol. 16, No. 9. pp. 1407-1411.
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abstract = "This letter presents the results evaluating retrievals of liquid water content (θ liq ) performed with a zero-order radiative transfer (τ-ω) model under frozen and thawed soil conditions from Soil Moisture Active Passive (SMAP) and ELBARA-III brightness temperature (T B p ) measurements collected over a Tibetan meadow ecosystem. A good agreement is found between time series of the SMAP and ELBARA-III measured T B p resulting in a Pearson product-moment coefficient (R) larger than 0.87. Differences noted between the two data sets can be associated with discrepancies in θ liq measured in the specific footprints, whereby the SMAP measurements are best explained by the in situ θ liq . Furthermore, the in situ θ liq has a better agreement with the horizontally polarized SMAP and ELBARA-III measurements (THB ) in the cold season, whereas the vertically polarized measurements (TVB ) are1111better correlated with θ liq in the warm season. With the implementation of new vegetation and surface roughness parameterizations for the τ-ω model, the dynamics of in situ θ liq is better reproduced by corresponding retrievals for both frozen and thawed soil conditions, leading to the reduction in the unbiased root-mean-square error (ubRMSE) by more than 31{\%} in comparison with these retrievals using SMAP default parameterizations. Notably, the single-channel algorithm configured with the new parameterizations using SMAP TVB measured during the ascending overpass provides the best θ liq retrievals with a ubRMSE of 0.035 m 3 ·m -3 that is well within the SMAP mission requirements.",
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Assessment of Soil Moisture SMAP Retrievals and ELBARA-III Measurements in a Tibetan Meadow Ecosystem. / Zheng, Donghai; Wang, Xin; van der Velde, R.; Schwank, Mike; Ferrazzoli, Paolo; Wen, Jun; Wang, Zuoliang; Colliander, Andreas; Bindlish, Rajat; Su, Zhongbo.

In: IEEE geoscience and remote sensing letters, Vol. 16, No. 9, 05.03.2019, p. 1407-1411.

Research output: Contribution to journalArticleAcademicpeer-review

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AU - Zheng, Donghai

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AB - This letter presents the results evaluating retrievals of liquid water content (θ liq ) performed with a zero-order radiative transfer (τ-ω) model under frozen and thawed soil conditions from Soil Moisture Active Passive (SMAP) and ELBARA-III brightness temperature (T B p ) measurements collected over a Tibetan meadow ecosystem. A good agreement is found between time series of the SMAP and ELBARA-III measured T B p resulting in a Pearson product-moment coefficient (R) larger than 0.87. Differences noted between the two data sets can be associated with discrepancies in θ liq measured in the specific footprints, whereby the SMAP measurements are best explained by the in situ θ liq . Furthermore, the in situ θ liq has a better agreement with the horizontally polarized SMAP and ELBARA-III measurements (THB ) in the cold season, whereas the vertically polarized measurements (TVB ) are1111better correlated with θ liq in the warm season. With the implementation of new vegetation and surface roughness parameterizations for the τ-ω model, the dynamics of in situ θ liq is better reproduced by corresponding retrievals for both frozen and thawed soil conditions, leading to the reduction in the unbiased root-mean-square error (ubRMSE) by more than 31% in comparison with these retrievals using SMAP default parameterizations. Notably, the single-channel algorithm configured with the new parameterizations using SMAP TVB measured during the ascending overpass provides the best θ liq retrievals with a ubRMSE of 0.035 m 3 ·m -3 that is well within the SMAP mission requirements.

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KW - ITC-ISI-JOURNAL-ARTICLE

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