Validation of SMAP L2 passive-only soil moisture products using in situ measurements collected in Twente, The Netherlands

Rogier van der Velde, Andreas Colliander, Michiel Pezij, Harm-Jan F. Benninga, Rajat Bindlish, Steven K. Chan, Thomas J. Jackson, Dimmie M.D. Hendriks, Dienie C.M. Augustijn, Zhongbo Su

Research output: Contribution to journalArticleAcademicpeer-review

3 Downloads (Pure)

Abstract

The Twente region in the east of the Netherlands has a network with twenty soil monitoring stations that has been utilized for validation of the Soil Moisture Active/Passive (SMAP) passive-only soil moisture products. Over the period from April 2015 until December 2018, seven stations covered by the SMAP reference pixels have fairly complete data records. Spatially distributed soil moisture simulations with the Dutch national hydrological model have been utilized for the development of upscaling functions to translate the spatial mean of point measurements to the domain of the SMAP reference pixels. The native and upscaled spatial soil moisture means have been adopted as in situ references to assess the performance of the SMAP i) Single Channel Algorithm at Horizontal Polarization (SCA-H), ii) Single Channel Algorithm at Vertical Polarization (SCA-V), and iii) Dual Channel Algorithm (DCA) soil moisture estimates. In the case of the Twente network it was found that the SCA-V soil moisture retrieved SMAP observations collected in the afternoon had the best agreement with the in situ references leading to an unbiased Root Mean Squared Error (uRMSE) of 0.059 m3 m−3. This is larger than the mission target accuracy of 0.04 m3 m−3, which can be attributed to large over- and underestimation errors (> 0.08 m3 m−3) in particular at the end of dry spells and during freezing, respectively. The strong vertical dielectric gradients associated with rapid soil freezing and wetting causes the disparity in soil depth characterized by SMAP and in situ that leads to the large mismatches. Once filtered for frozen conditions and antecedent rainfall the uRMSE improves to 0.043 m3 m−3.
Original languageEnglish
JournalHydrology and earth system sciences discussions
DOIs
Publication statusSubmitted - 9 Oct 2019

Fingerprint

in situ measurement
soil moisture
polarization
freezing
pixel
product
upscaling
soil depth
wetting
soil
rainfall

Keywords

  • ITC-ISI-JOURNAL-ARTICLE
  • ITC-GOLD

Cite this

@article{630c22395ade4c25a050d5abd6aa279d,
title = "Validation of SMAP L2 passive-only soil moisture products using in situ measurements collected in Twente, The Netherlands",
abstract = "The Twente region in the east of the Netherlands has a network with twenty soil monitoring stations that has been utilized for validation of the Soil Moisture Active/Passive (SMAP) passive-only soil moisture products. Over the period from April 2015 until December 2018, seven stations covered by the SMAP reference pixels have fairly complete data records. Spatially distributed soil moisture simulations with the Dutch national hydrological model have been utilized for the development of upscaling functions to translate the spatial mean of point measurements to the domain of the SMAP reference pixels. The native and upscaled spatial soil moisture means have been adopted as in situ references to assess the performance of the SMAP i) Single Channel Algorithm at Horizontal Polarization (SCA-H), ii) Single Channel Algorithm at Vertical Polarization (SCA-V), and iii) Dual Channel Algorithm (DCA) soil moisture estimates. In the case of the Twente network it was found that the SCA-V soil moisture retrieved SMAP observations collected in the afternoon had the best agreement with the in situ references leading to an unbiased Root Mean Squared Error (uRMSE) of 0.059 m3 m−3. This is larger than the mission target accuracy of 0.04 m3 m−3, which can be attributed to large over- and underestimation errors (> 0.08 m3 m−3) in particular at the end of dry spells and during freezing, respectively. The strong vertical dielectric gradients associated with rapid soil freezing and wetting causes the disparity in soil depth characterized by SMAP and in situ that leads to the large mismatches. Once filtered for frozen conditions and antecedent rainfall the uRMSE improves to 0.043 m3 m−3.",
keywords = "ITC-ISI-JOURNAL-ARTICLE, ITC-GOLD",
author = "{van der Velde}, Rogier and Andreas Colliander and Michiel Pezij and Benninga, {Harm-Jan F.} and Rajat Bindlish and Chan, {Steven K.} and Jackson, {Thomas J.} and Hendriks, {Dimmie M.D.} and Augustijn, {Dienie C.M.} and Zhongbo Su",
year = "2019",
month = "10",
day = "9",
doi = "10.5194/hess-2019-471",
language = "English",
journal = "Hydrology and earth system sciences discussions",
issn = "1812-2108",
publisher = "Copernicus",

}

Validation of SMAP L2 passive-only soil moisture products using in situ measurements collected in Twente, The Netherlands. / van der Velde, Rogier; Colliander, Andreas; Pezij, Michiel ; Benninga, Harm-Jan F.; Bindlish, Rajat; Chan, Steven K.; Jackson, Thomas J.; Hendriks, Dimmie M.D.; Augustijn, Dienie C.M.; Su, Zhongbo.

In: Hydrology and earth system sciences discussions, 09.10.2019.

Research output: Contribution to journalArticleAcademicpeer-review

TY - JOUR

T1 - Validation of SMAP L2 passive-only soil moisture products using in situ measurements collected in Twente, The Netherlands

AU - van der Velde, Rogier

AU - Colliander, Andreas

AU - Pezij, Michiel

AU - Benninga, Harm-Jan F.

AU - Bindlish, Rajat

AU - Chan, Steven K.

AU - Jackson, Thomas J.

AU - Hendriks, Dimmie M.D.

AU - Augustijn, Dienie C.M.

AU - Su, Zhongbo

PY - 2019/10/9

Y1 - 2019/10/9

N2 - The Twente region in the east of the Netherlands has a network with twenty soil monitoring stations that has been utilized for validation of the Soil Moisture Active/Passive (SMAP) passive-only soil moisture products. Over the period from April 2015 until December 2018, seven stations covered by the SMAP reference pixels have fairly complete data records. Spatially distributed soil moisture simulations with the Dutch national hydrological model have been utilized for the development of upscaling functions to translate the spatial mean of point measurements to the domain of the SMAP reference pixels. The native and upscaled spatial soil moisture means have been adopted as in situ references to assess the performance of the SMAP i) Single Channel Algorithm at Horizontal Polarization (SCA-H), ii) Single Channel Algorithm at Vertical Polarization (SCA-V), and iii) Dual Channel Algorithm (DCA) soil moisture estimates. In the case of the Twente network it was found that the SCA-V soil moisture retrieved SMAP observations collected in the afternoon had the best agreement with the in situ references leading to an unbiased Root Mean Squared Error (uRMSE) of 0.059 m3 m−3. This is larger than the mission target accuracy of 0.04 m3 m−3, which can be attributed to large over- and underestimation errors (> 0.08 m3 m−3) in particular at the end of dry spells and during freezing, respectively. The strong vertical dielectric gradients associated with rapid soil freezing and wetting causes the disparity in soil depth characterized by SMAP and in situ that leads to the large mismatches. Once filtered for frozen conditions and antecedent rainfall the uRMSE improves to 0.043 m3 m−3.

AB - The Twente region in the east of the Netherlands has a network with twenty soil monitoring stations that has been utilized for validation of the Soil Moisture Active/Passive (SMAP) passive-only soil moisture products. Over the period from April 2015 until December 2018, seven stations covered by the SMAP reference pixels have fairly complete data records. Spatially distributed soil moisture simulations with the Dutch national hydrological model have been utilized for the development of upscaling functions to translate the spatial mean of point measurements to the domain of the SMAP reference pixels. The native and upscaled spatial soil moisture means have been adopted as in situ references to assess the performance of the SMAP i) Single Channel Algorithm at Horizontal Polarization (SCA-H), ii) Single Channel Algorithm at Vertical Polarization (SCA-V), and iii) Dual Channel Algorithm (DCA) soil moisture estimates. In the case of the Twente network it was found that the SCA-V soil moisture retrieved SMAP observations collected in the afternoon had the best agreement with the in situ references leading to an unbiased Root Mean Squared Error (uRMSE) of 0.059 m3 m−3. This is larger than the mission target accuracy of 0.04 m3 m−3, which can be attributed to large over- and underestimation errors (> 0.08 m3 m−3) in particular at the end of dry spells and during freezing, respectively. The strong vertical dielectric gradients associated with rapid soil freezing and wetting causes the disparity in soil depth characterized by SMAP and in situ that leads to the large mismatches. Once filtered for frozen conditions and antecedent rainfall the uRMSE improves to 0.043 m3 m−3.

KW - ITC-ISI-JOURNAL-ARTICLE

KW - ITC-GOLD

U2 - 10.5194/hess-2019-471

DO - 10.5194/hess-2019-471

M3 - Article

JO - Hydrology and earth system sciences discussions

JF - Hydrology and earth system sciences discussions

SN - 1812-2108

ER -