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

The water in green vegetation is detectable using reflectances in the near infrared and shortwave infrared. Canopy water content is estimated from the product of leaf water content and leaf area index (LAI). The Normalized Difference Infrared Index [NDII = (R850 - R1650)/(R850 + R1650)] was found to be strongly related to canopy water content using various moderate resolution sensors (Landsat TM, ASTER, AWiFS) during the SMEX02, SMEX04, SMEX05, and OTTER experiments. With the high temporal resolution of MODIS, changes in canopy water content may perhaps be used to estimate plant water stress and wild-fire potential. However, the low spatial resolution of MODIS does not allow the relationship between NDII and canopy water content to be determined experimentally. The objective of this study is to validate the expected relationship of canopy water content with NDII by the standard LAI data product from MODIS; the quotient is the expected leaf water content which will vary by land-cover type. Maximum NDII for 2000-2007 was calculated from the MODIS standard surface reflectance data products and compared to maximum MODIS LAI for the same years. Mean leaf water content from MODIS was not significantly different from leaf data for most land cover types. However the large standard deviations indicated that canopy water content from NDII is not currently accurate for monitoring the incipient stages of plant water stress.

[1]  J. Peñuelas,et al.  Estimation of plant water concentration by the reflectance Water Index WI (R900/R970) , 1997 .

[2]  C. Tucker.  Remote sensing of leaf water content in the near infrared , 1980 .

[3]  M. Hardisky.  The Influence of Soil Salinity, Growth Form, and Leaf Moisture on-the Spectral Radiance of Spartina alterniflora Canopies , 2008 .

[4]  S. Ustin,et al.  Multi-temporal vegetation canopy water content retrieval and interpretation using artificial neural networks for the continental USA , 2008 .

[5]  A. Huete,et al.  Overview of the radiometric and biophysical performance of the MODIS vegetation indices , 2002 .

[6]  S. Running,et al.  Problems With Scaling Leap Water Relations To Regional Scales , 1990, 10th Annual International Symposium on Geoscience and Remote Sensing.

[7]  S. Tarantola,et al.  Designing a spectral index to estimate vegetation water content from remote sensing data: Part 2. Validation and applications , 2002 .

[8]  T. Jackson,et al.  Remote sensing of vegetation water content from equivalent water thickness using satellite imagery , 2008 .

[9]  D. Sims,et al.  Estimation of vegetation water content and photosynthetic tissue area from spectral reflectance: a comparison of indices based on liquid water and chlorophyll absorption features , 2003 .

[10]  S. Running,et al.  Global products of vegetation leaf area and fraction absorbed PAR from year one of MODIS data , 2002 .

[11]  Xianjun Hao,et al.  Sensitivity studies of the moisture effects on MODIS SWIR reflectance and vegetation water indices , 2008 .

[12]  Thomas J. Jackson,et al.  Vegetation water content during SMEX04 from ground data and Landsat 5 Thematic Mapper imagery , 2008 .

[13]  J. Townshend,et al.  Towards an operational MODIS continuous field of percent tree cover algorithm: examples using AVHRR and MODIS data , 2002 .

[14]  Alan H. Strahler,et al.  Global land cover mapping from MODIS: algorithms and early results , 2002 .

[15]  E. Raymond Hunt,et al.  Airborne remote sensing of canopy water thickness scaled from leaf spectrometer data , 1991 .

[16]  Shusen Wang,et al.  Remote sensing of grassland–shrubland vegetation water content in the shortwave domain , 2006 .

[17]  John J. Qu,et al.  Soil adjusted vegetation water content retrievals in grasslands , 2009 .

[18]  Roberta E. Martin,et al.  PROSPECT-4 and 5: Advances in the leaf optical properties model separating photosynthetic pigments , 2008 .

[19]  B. Rock,et al.  Detection of changes in leaf water content using Near- and Middle-Infrared reflectances , 1989 .

[20]  E. Raymond Hunt,et al.  Remote sensing of vegetation water content using shortwave infrared reflectances , 2007, SPIE Optical Engineering + Applications.

[21]  S. Ustin,et al.  Estimating Vegetation Water content with Hyperspectral data for different Canopy scenarios: Relationships between AVIRIS and MODIS Indexes , 2006 .

[22]  B. Gao.  NDWI—A normalized difference water index for remote sensing of vegetation liquid water from space , 1996 .

[23]  J. Dozier.  Spectral Signature of Alpine Snow Cover from the Landsat Thematic Mapper , 1989 .

[24]  Terry L. Sohl,et al.  Regional characterization of land cover using multiple sources of data , 1998 .

[25]  Martha C. Anderson,et al.  Vegetation water content mapping using Landsat data derived normalized difference water index for corn and soybeans , 2004 .

[26]  D. M. Gates,et al.  Spectral Properties of Plants , 1965 .

[27]  David Riaño,et al.  Water content estimation from hyperspectral images and MODIS indexes in Southeastern Arizona , 2008 .