Comparative Study Of Temporal Decorrelation At P, L And C-Bands: First Insights From The Tropiscat-2 Experiment

Essebtey, S. El Idrissi; Villard, Ludovic; Borderies, P.; Koleck, T.; Burban, Benoît; Toan, Thuy Le

doi:10.1109/m2garss47143.2020.9105253

Cited by 4 publications

(3 citation statements)

References 8 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Coherence decreased in spring and summer, when vegetation was growing, and increased in autumn and winter, when vegetation was dormant and W was lower; the lowest coherence was observed in spring for VH polarizations. Minimum values of coherence were lower for tower-based acquisitions (≈ 0.1) than for Sentinel-1 data (≈ 0.2), 0.2 having already been observed as a minimum for Sentinel-1 data over temperate forest [20]. Sentinel-1 coherence varied greatly in autumn and winter 2020, but unfortunately, tower-based sensors were not operating at that time.…”

Section: Baselines Corresponding To the Satellite Configurationmentioning

confidence: 82%

“…However, this hypothesis is the most probable given the sensitivity of microwaves to the dielectric constant of plant matter, as highlighted by many studies [10], [11], [13], [38]. Previous studies using tower-based acquisitions installed over boreal forests (BF) [19] or tropical forests (TF) [17], [18], [19], [20] hypothesized this sensitivity to vegetation physiology. However, the diurnal cycles of coherence of the olive orchard differed from those of BF and TF.…”

Section: Baselines Corresponding To the Satellite Configurationmentioning

confidence: 99%

See 1 more Smart Citation

Analysis of C-Band Radar Temporal Coherence Over an Irrigated Olive Orchard in a Semi-Arid Region

Chakir,

Frison,

Villard

et al. 2024

IEEE J. Sel. Top. Appl. Earth Observations Remote Sensing

View full text Add to dashboard Cite

This study aimed to monitor vegetation using Cband radar data at a sub-daily time step. To this end, radar measurements using tower-mounted antennas with a 15-min time step, along with physiology-related information (sapflow and micrometric dendrometry), were acquired quasi-continuously from March 2020 to December 2021 in an olive orchard located near Marrakech, Morocco. The study focused on temporal coherence, whose clear diurnal cycle (highest at night and lowest at the end of the afternoon) had been highlighted over tropical and boreal forests in previous studies. The results showed that coherence was highly sensitive to (1) wind-induced movement of scatterers, since coherence was lowest when wind speed was highest in late afternoon, and (2) vegetation activity, especially its water dynamics, since the morning coherence drop coincided with the onset of sapflow and the daily evapotranspiration cycle, as well as the good agreement between the temporal drop rate of coherence and the daily residual variation in trunk circumference (i.e., deviation from long-term trend). Finally, coherence remained high for temporal baselines of several days, showing that Sentinel-1 data (when both satellites are operational) may be well suited for such studies, especially with acquisitions made during morning passes, when wind speed is low. These results open perspectives for monitoring tree crop physiology using high-revisit-time radar observations.

show abstract

Section: Baselines Corresponding To the Satellite Configurationmentioning

confidence: 82%

Section: Baselines Corresponding To the Satellite Configurationmentioning

confidence: 99%

Analysis of C-Band Radar Temporal Coherence Over an Irrigated Olive Orchard in a Semi-Arid Region

Chakir,

Frison,

Villard

et al. 2024

IEEE J. Sel. Top. Appl. Earth Observations Remote Sensing

View full text Add to dashboard Cite

show abstract

“…However, both experiments could not provide enough statistical samples to address the evolution of temporal decorrelation beyond one month. With the aim of extending these time series as well as completing the P and L-band observations with C-band acquisitions, a follow-on experiment referred to as TropiScat-2 has been set up since March 2018 over the same forest site as for TropiScat [16], [17]. A long time series of P-band measurements has been acquired quasi-continuously ever since.…”

Section: Introductionmentioning

confidence: 99%

Long-Term Trends of P-Band Temporal Decorrelation Over a Tropical Dense Forest-Experimental Results for the BIOMASS Mission

Essebtey

Villard

Borderies

et al. 2022

IEEE Trans. Geosci. Remote Sensing

View full text Add to dashboard Cite

Fostered by the upcoming BIOMASS mission, this article explores long-term trends of P-band temporal decorrelation over a tropical forest due to a time series of 617 days acquired during the TropiScat-2 experiment. The interest in this unique time series is twofold. First, it provides consistent statistics to monitor the yearly evolution of temporal coherences according to specific time scales of the BIOMASS tomographic and interferometric phases. Second, it provides key insights to explore new processing approaches with the combination of data from different orbit directions (ascending/descending) and different mission cycles separated by about seven months according to the current acquisition plan. For the first time, this study shows that 18-day coherences (corresponding to the time interval between the first and last acquisitions of the BIOMASS tomographic processing) can vary significantly according to rainy and dry seasons (medians from 0.3 to 0.9). The extension to time intervals of up to 90 days within both seasons and over two consecutive years puts forward the key role of the typical sporadic rainfalls occurring during dry periods in tropical rainforests, with a stronger impact on temporal coherence evolution compared to the more reproducible rainy seasons. Furthermore, outstanding values significantly above zero have been obtained for the 7and 14-month coherences (medians of 0.35 and 0.2, respectively), opening the way to new methods of change detection. Overall, this study highlights the role of P-band temporal decorrelation not only as a disturbance factor for coherent applications but also as a relevant indicator of forest changes.

show abstract

A Tower-Based Radar Study of Temporal Coherence of a Boreal Forest at P-, L-, and C-Bands and Linear Cross Polarization

Monteith

Ulander

2022

IEEE Trans. Geosci. Remote Sensing

View full text Add to dashboard Cite

Cross-polarized temporal coherence observations of a boreal forest, acquired using a tower-based radar, are presented in this article. Temporal coherence is analyzed with respect to frequency, temporal baseline, time of day of observation, season, meteorological variables, and biophysical variables. During the summer, P-and L-band temporal coherence exhibited diurnal cycles, which appeared to be due to high rates of transpiration and convective winds during the day. During the winter, freezethaw cycles and precipitation resulted in decorrelation. At temporal baselines of seconds to hours, a high temporal coherence was observed even at C-band. The best observation times of the day were midnight and dawn. Temporal coherence is the main limitation of accuracy in interferometric and tomographic forest applications. The observations from this experiment will allow for better spaceborne SAR mission designs for forest applications, better temporal decorrelation modeling, and more accurate forest parameter estimation algorithms using interferometric and tomographic SAR data.

show abstract

Comparative Study Of Temporal Decorrelation At P, L And C-Bands: First Insights From The Tropiscat-2 Experiment

Cited by 4 publications

References 8 publications

Analysis of C-Band Radar Temporal Coherence Over an Irrigated Olive Orchard in a Semi-Arid Region

Analysis of C-Band Radar Temporal Coherence Over an Irrigated Olive Orchard in a Semi-Arid Region

Long-Term Trends of P-Band Temporal Decorrelation Over a Tropical Dense Forest-Experimental Results for the BIOMASS Mission

A Tower-Based Radar Study of Temporal Coherence of a Boreal Forest at P-, L-, and C-Bands and Linear Cross Polarization

Contact Info

Product

Resources

About