Capturing agricultural soil freeze/thaw state through remote sensing and ground observations: A soil freeze/thaw validation campaign

Rowlandson, Tracy; Berg, Aaron; Roy, Alex; Kim, Edward; Lara, Renato Pardo; Powers, Jarrett; Lewis, Kristin; Houser, Paul R.; McDonald, K. C.; Toose, Peter; Wu, An-Ming; Marco, Eugenia De; Derksen, Chris; Entin, Jared; Colliander, Andreas; Xu, Xiaolan; Mavrovic, Alex

doi:10.1016/j.rse.2018.04.003

Cited by 47 publications

(42 citation statements)

References 37 publications

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“…However, some regions show important discrepancies, especially along coastal margins and in mountainous and open areas (such as in northern Europe, Kazakhstan (and surroundings) and the Canadian Prairies). Those lower percentages correspond to regions where lower accuracies to detect the FT were already noted in Roy et al (2015) and Kim et al (2017a) (see Sect. 4).…”

Section: Weather Stationssupporting

confidence: 51%

Final answer to reviewers

Prince¹

2018

Preprint

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In the Northern Hemisphere, seasonal changes in surface freeze-thaw (FT) cycles are an important component of surface energy, hydrological and eco-biogeochemical processes that must be accurately monitored. This paper presents the weekly polar-gridded Aquarius passive L-band surface freeze-thaw product (FT-AP) distributed on the Equal-Area Scalable Earth Grid version 2.0, above the parallel 50 • N, with a spatial resolution of 36 km × 36 km. The FT-AP classification algorithm is based on a seasonal threshold approach using the normalized polarization ratio, references for frozen and thawed conditions and optimized thresholds. To evaluate the uncertainties of the product, we compared it with another satellite FT product also derived from passive microwave observations but at higher frequency: the resampled 37 GHz FT Earth Science Data Record (FT-ESDR). The assessment was carried out during the overlapping period between 2011 and 2014. Results show that 77.1 % of their common grid cells have an agreement better than 80 %. Their differences vary with land cover type (tundra, forest and open land) and freezing and thawing periods. The best agreement is obtained during the thawing transition and over forest areas, with differences between product mean freeze or thaw onsets of under 0.4 weeks. Over tundra, FT-AP tends to detect freeze onset 2-5 weeks earlier than FT-ESDR, likely due to FT sensitivity to the different frequencies used. Analysis with mean surface air temperature time series from six in situ meteorological stations shows that the main discrepancies between FT-AP and FT-ESDR are related to false frozen retrievals in summer for some regions with FT-AP. The Aquarius product is distributed by the U.S. National Snow and Ice Data Center (NSIDC) at https://nsidc.org/data/aq3_ft/versions/5 with the DOI https://doi.org/10.5067/OV4R18NL3BQR.

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Section: Weather Stationssupporting

confidence: 51%

Final answer to reviewers

Prince¹

2018

Preprint

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“…Aquarius operated three non-scanning radiometers at different incidence angles (29.2, 38.4 and 46.3 • ) and with different 3 dB footprint sizes (respectively 76 km × 94 km, 84 km × 120 km and 97 km × 156 km). Based on the LCC BU , the thresholds found in Roy et al (2015) were used to create FT maps for each radiometer. The three FT maps were then blended to create a fourth map, which offers more complete spatial coverage.…”

Section: Aquarius Passive Ft Product (Ft-ap)mentioning

confidence: 99%

“…In the L band, the shallow depth contributing to the radiation (around 5 cm for an unfrozen soil) and the strong permittivity difference between water and ice ( ε ice/water ) make it favorable for FT retrieval (Rautiainen et al, 2012(Rautiainen et al, , 2014. In recent years, passive Lband FT algorithms were created for NASA's Aquarius (Roy et al, 2015), ESA's soil moisture and ocean salinity (SMOS) (Rautiainen et al, 2016) and NASA's soil moisture active/passive (SMAP) (Derksen et al, 2017) missions. An FT Earth Science Data Record (FT-ESDR) was also produced using a higher microwave frequency at the Ka band (37 GHz) (Kim et al, 2017a).…”

Section: Introductionmentioning

confidence: 99%

“…org/data/AQ3_TB/versions/5). The algorithm uses a relative frost factor (FFrel; see, e.g., Rautiainen et al, 2014) based on normalized polarization ratio (NPR) temporal change detection (Roy et al, 2015). To our knowledge, few intercomparisons between L-and Ka-band FT products exist (Derksen et al, 2017), and none evaluated interannual variability differences.…”

Section: Introductionmentioning

confidence: 99%

“…The main objective of this study is to present and evaluate the weekly FT-AP by comparing it to the FT-ESDR and to SAT observations across the Northern Hemisphere. First, we describe the new FT-AP product, designed by the algorithm developed by Roy et al (2015), but applied across the Northern Hemisphere. Then, we investigate the spatial and temporal FT variations from both FT-AP and FT-ESDR products over the Northern Hemisphere.…”

Section: Introductionmentioning

confidence: 99%

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Northern Hemisphere surface freeze–thaw product from Aquarius L-band radiometers

Prince

Roy

Brucker

et al. 2018

Earth Syst. Sci. Data

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Abstract. In the Northern Hemisphere, seasonal changes in surface freeze–thaw (FT) cycles are an important component of surface energy, hydrological and eco-biogeochemical processes that must be accurately monitored. This paper presents the weekly polar-gridded Aquarius passive L-band surface freeze–thaw product (FT-AP) distributed on the Equal-Area Scalable Earth Grid version 2.0, above the parallel 50° N, with a spatial resolution of 36 km × 36 km. The FT-AP classification algorithm is based on a seasonal threshold approach using the normalized polarization ratio, references for frozen and thawed conditions and optimized thresholds. To evaluate the uncertainties of the product, we compared it with another satellite FT product also derived from passive microwave observations but at higher frequency: the resampled 37 GHz FT Earth Science Data Record (FT-ESDR). The assessment was carried out during the overlapping period between 2011 and 2014. Results show that 77.1 % of their common grid cells have an agreement better than 80 %. Their differences vary with land cover type (tundra, forest and open land) and freezing and thawing periods. The best agreement is obtained during the thawing transition and over forest areas, with differences between product mean freeze or thaw onsets of under 0.4 weeks. Over tundra, FT-AP tends to detect freeze onset 2–5 weeks earlier than FT-ESDR, likely due to FT sensitivity to the different frequencies used. Analysis with mean surface air temperature time series from six in situ meteorological stations shows that the main discrepancies between FT-AP and FT-ESDR are related to false frozen retrievals in summer for some regions with FT-AP. The Aquarius product is distributed by the U.S. National Snow and Ice Data Center (NSIDC) at https://nsidc.org/data/aq3_ft/versions/5 with the DOI https://doi.org/10.5067/OV4R18NL3BQR.

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Effects of freeze-thaw cycles on distribution and speciation of heavy metals in pig manure

Zhang

Chen

et al. 2020

Environ Sci Pollut Res

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Capturing agricultural soil freeze/thaw state through remote sensing and ground observations: A soil freeze/thaw validation campaign

Cited by 47 publications

References 37 publications

Final answer to reviewers

Final answer to reviewers

Northern Hemisphere surface freeze–thaw product from Aquarius L-band radiometers

Effects of freeze-thaw cycles on distribution and speciation of heavy metals in pig manure

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