title: A novel moisture adjusted vegetation index (MAVI) to reduce background reflectance and topographical effects on LAI retrieval.
abstract: A new moisture adjusted vegetation index (MAVI) is proposed using the red, near infrared, and shortwave infrared (SWIR) reflectance in band-ratio form in this paper. The effectiveness of MAVI in retrieving leaf area index (LAI) is investigated using Landsat-5 data and field LAI measurements in two forest and two grassland areas. The ability of MAVI to retrieve forest LAI under different background conditions is further evaluated using canopy reflectance of Jack Pine and Black Spruce forests simulated by the 4-Scale model. Compared with several commonly used two-band vegetation index, such as normalized difference vegetation index, soil adjusted vegetation index, modified soil adjusted vegetation index, optimized soil adjusted vegetation index, MAVI is a better predictor of LAI, on average, which can explain 70% of variations of LAI in the four study areas. Similar to other SWIR-related three-band vegetation index, such as modified normalized difference vegetation index (MNDVI) and reduced simple ratio (RSR), MAVI is able to reduce the background reflectance effects on forest canopy LAI retrieval. MAVI is more suitable for retrieving LAI than RSR and MNDVI, because it avoids the difficulty in properly determining the maximum and minimum SWIR values required in RSR and MNDVI, which improves the robustness of MAVI in retrieving LAI of different land cover types. Moreover, MAVI is expressed as ratios between different spectral bands, greatly reducing the noise caused by topographical variations, which makes it more suitable for applications in mountainous area.
authors.affiliation: Department of Geography, Minjiang University, Fuzhou, China; International Institute for Earth System Sciences, Nanjing University, Nanjing, China.
authors.forename: Gaolong
authors.initials: G
authors.lastname: Zhu
authors.affiliation: International Institute for Earth System Sciences, Nanjing University, Nanjing, China; Institute for Climate and Global Change Research, Nanjing University, Nanjing, China.
authors.forename: Weimin
authors.initials: W
authors.lastname: Ju
authors.affiliation: International Institute for Earth System Sciences, Nanjing University, Nanjing, China; Department of Geography, University of Toronto, Toronto, Ontario, Canada.
authors.forename: J M
authors.initials: JM
authors.lastname: Chen
authors.affiliation: Jiangsu Key Laboratory of Agricultural Meteorology, College of Applied Meteorology, Nanjing University of Information Science and Technology, Nanjing, China.
authors.forename: Yibo
authors.initials: Y
authors.lastname: Liu
mesh_terms: D002681:China; D065928:Forests; D065948:Grassland; D018515:Plant Leaves / Q000737:chemistry*; D006109:Poaceae / Q000737:chemistry; D058998:Remote Sensing Technology; D063809:Satellite Imagery; D014197:Trees / Q000737:chemistry; D014867:Water / Q000737:chemistry*
chemical_list: D014867:Water