scholarly journals A two-point iteration method to predict canopy water content from RF loss

2021 ◽  
Vol 1 ◽  
pp. 100008
Author(s):  
Sonam Peden ◽  
Ronald C. Bradbury ◽  
David William Lamb ◽  
Mark Hedley
Keyword(s):  
Water Content ◽  
Iteration Method ◽  
Rf Loss ◽  
Canopy Water

Soil moisture variation drives canopy water content dynamics across the western U.S.

2021 ◽  
Vol 253 ◽  
pp. 112233
Author(s):  
Drew S. Lyons ◽  
Solomon Z. Dobrowski ◽  
Zachary A. Holden ◽  
Marco P. Maneta ◽  
Anna Sala
Keyword(s):  
Soil Moisture ◽  
Water Content ◽  
Moisture Variation ◽  
Canopy Water ◽  
Soil Moisture Variation

Inferring the effects of surface canopy water on VOD estimation from L-band backscatter 

2021 ◽  
Author(s):  
Saeed Khabbazan ◽  
Paul.C. Vermunt ◽  
Susan.C. Steele Dunne ◽  
Ge Gao ◽  
Mariette Vreugdenhil ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Linear Relationship ◽  
Water Content ◽  
Growing Season ◽  
Empirical Parameter ◽  
Vegetation Water Content ◽  
L Band ◽  
Vegetation Water ◽  
Canopy Water ◽  
Effect Of Surface

<p>Quantification of vegetation parameters such as Vegetation Optical Depth (VOD) and Vegetation Water Content (VWC) can be used for better irrigation management, yield forecasting, and soil moisture estimation. Since VOD is directly related to vegetation water content and canopy structure, it can be used as an indicator for VWC. Over the past few decades, optical and passive microwave satellite data have mostly been used to monitor VWC. However, recent research is using active data to monitor VOD and VWC benefitting from their high spatial and temporal resolution.</p><p>Attenuation of the microwave signal through the vegetation layer is parametrized by the VOD. VOD is assumed to be linearly related to VWC with the proportionality constant being an empirical parameter b. For a given wavelength and polarization, b is assumed static and only parametrized as a function of vegetation type. The hypothesis of this study is that the VOD is not similar for dry and wet vegetation and the static linear relationship between attenuation and vegetation water content is a simplification of reality.</p><p>The aim of this research is to understand the effect of surface canopy water on VOD estimation and the relationship between VOD and vegetation water content during the growing season of a corn canopy. In addition to studying the dependence of VOD on bulk VWC for dry and wet vegetation, the effect of different factors, such as different growth stages and internal vegetation water content is investigated using time series analysis.</p><p>A field experiment was conducted in Florida, USA, for a full growing season of sweet corn. The corn field was scanned every 30 minutes with a truck-mounted, fully polarimetric, L-band radar. Pre-dawn vegetation water content was measured using destructive sampling three times a week for a full growing season. VWC could therefore be analyzed by constituent (leaf, stem, ear) or by height. Meteorological data, surface canopy water (dew or interception), and soil moisture were measured every 15 minutes for the entire growing season.</p><p>The methodology of Vreugdenhil et al.  [1], developed by TU Wien for ASCAT data, was adapted to present a new technique to estimate VOD from single-incidence angle backscatter data in each polarization. The results showed that the effect of surface canopy water on the VOD estimation increased by vegetation biomass accumulation and the effect was higher in the VOD estimated from the co-pol compared with the VOD estimated from the cross-pol. Moreover, the surface canopy water considerably affected the regression coefficient values (b-factor) of the linear relationship between VOD and VWC from dry and wet vegetation. This finding suggests that considering a similar b-factor for the dry and the wet vegetation will introduce errors in soil moisture retrievals. Furthermore, it highlights the importance of considering canopy wetness conditions when using tau-omega.</p><ul><li>[1] Vreugdenhil,W. A. Dorigo,W.Wagner, R. A. De Jeu, S. Hahn, andM. J. VanMarle, “Analyzing the vegetation parameterization in the TU-Wien ASCAT soil moisture retrieval,” IEEE Transactions on Geoscience and Remote Sensing, vol. 54, pp. 3513–3531, 2016</li> </ul>

Retrieving Grassland Canopy Water Content by Considering the Information from Neighboring Pixels

2017 ◽  
Vol 83 (8) ◽  
pp. 553-565
Author(s):  
Binbin He ◽  
Xingwen Quan ◽  
Dasong Xu ◽  
Changming Yin ◽  
Zhanmang Liao ◽  
...  
Keyword(s):  
Water Content ◽  
Canopy Water

scholarly journals Testing the Relevance of Daily MODIS Data to Monitor Mediterranean Shrubland Canopy Water Content with Temporal Cross-Correlation Analyses

2013 ◽  
Vol 4 (1) ◽  
pp. 1-19 ◽  
Author(s):  
Carole Delenne ◽  
Jean-Stéphane Bailly ◽  
Michel Deshayes
Keyword(s):  
Water Content ◽  
Forest Fire ◽  
Fire Hazard ◽  
Statistical Tests ◽  
Delay Effect ◽  
Field Surveys ◽  
Modis Data ◽  
Mediterranean Shrubland ◽  
Canopy Water ◽  
Water Indices

Drought alert systems for forest fire prevention often rely on vegetation water content (VWC) monitoring which is a key parameter in forest fire hazard. In southern France, VWC is now monitored through regular field surveys. Thanks to the theoretical sensitivity of shortwave infrared reflectance to VWC, MODIS satellite data are potentially able to monitor VWC depending on plant species VWC magnitude. In this paper, a specific statistical approach based on temporal cross-correlations is developed in order to test the correlation between two MODIS water indices and VWC measurements coming from field surveys. This test assesses the ability of daily MODIS data to monitor Mediterranean shrubland canopy water content and detect any delay effect between MODIS and field survey temporal series. Statistical tests are carried out for 29 sites containing 18 dominant shrubland Mediterranean species. 67% and 54% of significant correlation were found using respectively the NDII and NDWI indices from MODIS data. Correlation were found low with a dominant negative delay effect, i.e., with a MODIS signal that reacts a few days after the field VWC. Test results show that, even if deeper pre-processing of MODIS data may be required, site soil, site vegetation cover, and heterogeneity at MODIS pixel scale, as well as species VWC sensitivity make correlation between field VWC and MODIS water indices non univoque and highly variable. Many obstacles are still to overcome, for an accurate monitoring of Mediterranean shrubland canopy water content using MODIS daily data.

Detection of diurnal variation in orchard canopy water content using MODIS/ASTER airborne simulator (MASTER) data

2013 ◽  
Vol 132 ◽  
pp. 1-12 ◽  
Author(s):  
Tao Cheng ◽  
David Riaño ◽  
Alexander Koltunov ◽  
Michael L. Whiting ◽  
Susan L. Ustin ◽  
...  
Keyword(s):  
Diurnal Variation ◽  
Water Content ◽  
Master Data ◽  
Canopy Water

scholarly journals Remote Estimation of Leaf and Canopy Water Content in Winter Wheat with Different Vertical Distribution of Water-Related Properties

2015 ◽  
Vol 7 (4) ◽  
pp. 4626-4650 ◽  
Author(s):  
Shishi Liu ◽  
Yi Peng ◽  
Wei Du ◽  
Yuan Le ◽  
Lu Li
Keyword(s):  
Winter Wheat ◽  
Vertical Distribution ◽  
Water Content ◽  
Remote Estimation ◽  
Canopy Water

Remote sensing of canopy water content: scaling from leaf data to MODIS

2009 ◽  
Author(s):  
E. Raymond Hunt, Jr. ◽  
John J. Qu ◽  
Xianjun Hao ◽  
Lingli Wang
Keyword(s):  
Remote Sensing ◽  
Water Content ◽  
Canopy Water
Sign in / Sign up

Export Citation Format

Share Document