Abstract
An early warning of crop losses in response to weather fluctuations helps farmers, governments, traders, and policy makers better monitor global food supply and demand and identifies nations in need of aid. This paper discusses the utility of vegetation health (VH) indices, derived from the advance very high-resolution radiometer (AVHRR) and visible infrared imaging radiometer suite (VIIRS), as a proxy for modeling Australian wheat from the National Oceanic and Atmospheric Administration (NOAA) operational afternoon polar-orbiting satellites. These models are used to assess wheat production and to provide an early warning of drought-related losses. The NOAA AVHRR- and VIIRS-based VH indices were used to model wheat yield in Australia. A strong correlation (≥0.7) between wheat yield and VH indices was found during the critical reproductive stage of development (enhanced crops sensitivity to weather), which starts 2 to 3 weeks before and ends 2 to 3 weeks after wheat heading. The results of modeling and independent testing proved that the VH indices (especially those estimating thermal and health conditions) are a good proxy providing 1 to 2 months before harvest yield prediction (with 3% to 6% error). With the new generation of NOAA-20 operational polar-orbiting satellites, launched in November 2017, the VH method will be improved considerably both in an advanced crop/pasture prediction, spatial resolution, and accuracy.
Highlights
Among the major world grain producing countries, Australia is a modest contributor (1.3%) to total global production, ranking ninth with slightly over 32 million tons of grain collected on average annually during 1993 to 2013.1 Australia is among the world’s largest grain exporting nations (USA, Russia, European Union, and Canada), ranking fifth in wheat exported annually since the 1980s.2,3 Most of the Australian wheat that is sold overseas is produced in western and southern Australia
normalized difference vegetation index (NDVI) and brightness temperature (BT) data were composited over a 7-day period, processed to remove shortand long-term noise, special climatology was calculated, and the data were converted to three vegetation health indices (VHI).[9,10,12,13]
NDVI application has expanded with the launch of National Oceanic and Atmospheric Administration (NOAA)-7 afternoon operational polar-orbiting satellite with advance very high-resolution radiometer (AVHRR) sensor on board
Summary
Among the major world grain producing countries, Australia is a modest contributor (1.3%) to total global production, ranking ninth with slightly over 32 million tons of grain collected on average annually during 1993 to 2013.1 Australia is among the world’s largest grain exporting nations (USA, Russia, European Union, and Canada), ranking fifth in wheat exported annually (contributing 4% to 8% to global grain in trade) since the 1980s.2,3 Most of the Australian wheat that is sold overseas is produced in western and southern Australia. High-resolution operational satellite data, used before in other grain producing countries, were tested in Australia for modeling wheat yield and assessment of model-based yield prediction in advance of harvest. These results are discussed in the paper. In situ data were presented by mean Australia wheat production [P, tons (t)] and area [A, hectares (ha)] from 1961 to 2014.1 The principals of data aggregation were the following: P and A were collected from the reports of farms growing wheat at the end of each agricultural year and aggregated to the Australia total country level. NDVI and BT data were composited over a 7-day period, processed to remove shortand long-term noise, special climatology was calculated, and the data were converted to three vegetation health indices (VHI).[9,10,12,13]
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