Vegetation Effects on Soil Moisture Retrieval from Water Cloud Model Using PALSAR-2 for Oil Palm Trees
Abstract
:1. Introduction
2. Materials and Methods
2.1. Water Cloud Model (WCM)
- Case 1 where V1 = 1 and V2 = LAI
- Case 2 where V1 = LAI and V2 = 1
- Case 3 where V1 = LAI and V2 = LAI
- Case 4 where V1 = LWAI and V2 = LWAI
- Case 5 where V1 = NPWC and V2 = NPWC
2.2. Estimating Parameters of A, B, C and D in the WCM
2.3. Evaluating WCM
3. Study Area and Datasets
3.1. Study Area
3.2. Data and Processing
3.3. In-Situ Data Collection
4. Results and Discussion
4.1. In-Situ Results
4.2. Water Cloud Model Parameterization
4.3. Backscatter Simulation Based on the Proposed Vegetation Descriptors
4.4. Vegetation Effects on Soil Moisture Retrieval Based on Polarization
5. Conclusions
Author Contributions
Funding
Data Availability Statement
Acknowledgments
Conflicts of Interest
References
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Month | Daily Meana Temperature (°C) | Total Precipitation for the Month (mm) | Daily Mean Radiation (MJm−2) | Daily Mean Evaporation (mm) |
---|---|---|---|---|
January | 27.6 | 32.4 | 18.3 | 5.0 |
April | 29.0 | 89.4 | 20.8 | 5.0 |
July | 27.7 | 61.2 | 18.6 | 4.6 |
Date of Acquisition | Flight Direction | Mode | Resolution | Polarization | Incident Angle |
---|---|---|---|---|---|
17 January 2019 | Ascending | Strip Map 3 | 6.25 m × 6.25 m | HH + HV | 30.4–42.4° |
19 April 2019 | Ascending | Strip Map 3 | 6.25 m × 6.25 m | HH + HV | 41.2–53.3° |
9 July 2019 | Ascending | Strip Map 3 | 6.25 m × 6.25 m | HH + HV | 30.4–42.4° |
Observation Date | Soil Moisture (m3/m3) | LAI (m2/m2) | LWAI (% W in m2/m2) | NPWC (%) | ||||
---|---|---|---|---|---|---|---|---|
Range | Mean | Range | Mean | Range | Mean | Range | Mean | |
17 January 2019 | 0.075–0.419 | 0.240 | 0.680–3.251 | 1.748 | 0.123–0.532 | 0.205 | 0.169–0.228 | 0.205 |
19 April 2019 | 0.170–0.316 | 0.240 | 0.662–3.174 | 1.784 | 0.125–0. 668 | 0.353 | 0.185–0.233 | 0.198 |
9 July 2019 | 0.119–0.454 | 0.273 | 1.214–3.078 | 2.005 | 0.076–0.661 | 0.396 | 0.052–0.221 | 0.195 |
Overall | 0.075–0.454 | 0.251 | 0.661–3.251 | 1.845 | 0.076–0.668 | 0.368 | 0.052–0.233 | 0.199 |
Image Polarization | Combination Indicator | Vegetation Parameters | Soil Parameters | ||
---|---|---|---|---|---|
HH | Case 1 | 0.0118 | 0.0006 | −26.0150 | −2.8638 |
Case 2 | 0.2188 | 0.0027 | −26.0150 | −2.8638 | |
Case 3 | 0.8467 | 0.0134 | −26.0150 | −2.8638 | |
Case 4 | 0.7122 | 0.0063 | −26.0150 | −2.8638 | |
Case 5 | 0.7457 | 0.0089 | −26.0150 | −2.8638 | |
HV | Case 1 | 0.0850 | 0.0011 | 22.2070 | −23.8660 |
Case 2 | 0.1634 | 0.0047 | 22.2070 | −23.8660 | |
Case 3 | 0.2530 | 0.0019 | 22.2070 | −23.8660 | |
Case 4 | 0.4193 | 0.0321 | 22.2070 | −23.8660 | |
Case 5 | 0.0182 | 0.0751 | 22.2070 | −23.8660 |
Description (n = 96) | Case 1 | Case 2 | Case 3 | Case 4 | Case 5 | |||||
---|---|---|---|---|---|---|---|---|---|---|
HH | HV | HH | HV | HH | HV | HH | HV | HH | HV | |
R2 | 0.962 | 0.997 | 0.956 | 0.965 | 0.823 | 0.998 | 0.919 | 0.995 | 0.969 | 0.951 |
RMSE (dB) | 2.259 | 0.222 | 2.266 | 0.782 | 2.384 | 0.158 | 2.222 | 0.387 | 2.256 | 0.351 |
MAE | 1.821 | 0.212 | 1.814 | 0.212 | 1.872 | 0.150 | 1.789 | 0.366 | 1.811 | 0.280 |
Image Polarization | Description (n = 96) | Case 1 | Case 2 | Case 3 | Case 4 | Case 5 |
---|---|---|---|---|---|---|
HH | R2 | 0.598 | 0.512 | 0.490 | 0.727 | 0.558 |
RMSE (m3/m3) | 0.088 | 0.091 | 0.101 | 0.085 | 0.089 | |
MAE | 0.070 | 0.072 | 0.080 | 0.069 | 0.071 | |
HV | R2 | 0.805 | 0.609 | 0.675 | 0.459 | 0.301 |
RMSE (m3/m3) | 0.046 | 0.057 | 0.051 | 0.066 | 0.075 | |
MAE | 0.043 | 0.047 | 0.044 | 0.050 | 0.058 |
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Shashikant, V.; Mohamed Shariff, A.R.; Wayayok, A.; Kamal, M.R.; Lee, Y.P.; Takeuchi, W. Vegetation Effects on Soil Moisture Retrieval from Water Cloud Model Using PALSAR-2 for Oil Palm Trees. Remote Sens. 2021, 13, 4023. https://doi.org/10.3390/rs13204023
Shashikant V, Mohamed Shariff AR, Wayayok A, Kamal MR, Lee YP, Takeuchi W. Vegetation Effects on Soil Moisture Retrieval from Water Cloud Model Using PALSAR-2 for Oil Palm Trees. Remote Sensing. 2021; 13(20):4023. https://doi.org/10.3390/rs13204023
Chicago/Turabian StyleShashikant, Veena, Abdul Rashid Mohamed Shariff, Aimrun Wayayok, Md Rowshon Kamal, Yang Ping Lee, and Wataru Takeuchi. 2021. "Vegetation Effects on Soil Moisture Retrieval from Water Cloud Model Using PALSAR-2 for Oil Palm Trees" Remote Sensing 13, no. 20: 4023. https://doi.org/10.3390/rs13204023
APA StyleShashikant, V., Mohamed Shariff, A. R., Wayayok, A., Kamal, M. R., Lee, Y. P., & Takeuchi, W. (2021). Vegetation Effects on Soil Moisture Retrieval from Water Cloud Model Using PALSAR-2 for Oil Palm Trees. Remote Sensing, 13(20), 4023. https://doi.org/10.3390/rs13204023