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How far will medium term weather forecasts improve assessment of risks? - ES0101

Description
There is potential for medium term weather forecasts to be made available to the farming community. It seems likely that such information will greatly improve the accuracy with which farmers can obtain site and season specific fertiliser recommendations using models such as SUNDIAL (1,2). The extent of potential benefits must be quantified to allow MAFF to assess the emphasis that should be given to medium term forecasts in future funding. The purpose of the proposed project is to quantify the potential of medium term forecasts to improve the accuracy of fertiliser recommendation and assessment of the risks of loss to the environment and reduced crop nitrogen uptake. This 12 month project will compare results obtained assuming (1) no access to weather forecasts (weather obtained as is currently practised in SUNDIAL-FRS using the sectioning method) (2) access to weather forecasts with 100% accuracy (hypothetical weather forecasts obtained using the weather generator ETCETERA3), and (3) access to weather forecasts with reduced accuracy (for example, introduced as a variation about the mean over a range of timescales). Simulations will be run using the SUNDIAL model on sandy, loam and clay soils with a winter cereal (winter wheat), a spring cereal (spring wheat), a leaky crop (potatoes) and a high residue input crop (winter oilseed rape). Weather conditions will be selected that typify wet/warm, wet/cool, dry/warm, dry/cool and average weather conditions at different times of the year. The fertiliser recommendations obtained using no forecast, forecast with 100% accuracy and reduced accuracy forecast will be compared. The forecasts will project over a range of durations (e.g. 3 weeks, 2 months to harvest). The comparison will investigate the confidence intervals for predicted crop nitrogen uptake, leaching and gaseous emissions, so quantifying the assessment of risks associated with each type of weather data. The results will be expressed in terms of potential economic saving in nitrogen attributable to the use of medium term forecasts in nitrogen fertiliser recommendation systems, and the risk of reduced crop yield. The accuracy in forecasts needed to produce a given improvement in fertiliser recommendations will be quantified.
Objective
The objectives of the proposed project are as follows:

01. Construct hypothetical weather data sets for the known period (used in the retrospective simulation) and the unknown period (used in the predictive simulation) for all combinations of dry to wet and cool to warm weather at different times of the year. The unknown period datasets will assume (1) no access to weather forecasts (weather obtained, as is currently practised in SUNDIAL-FRS, using the sectioning method), (2) access to weather forecasts with 100% accuracy (hypothetical weather forecasts obtained using the weather generator ETCETERA), and (3) access to weather forecasts with reduced accuracy (for example, introduced as a variation about the mean over a range of timescales).

02. Construct SUNDIAL set up files on sand, loam and clay soils for different combinations of winter cereals, spring cereals, leaky crops and high residue crops.

03. Run SUNDIAL simulations for all combinations of soils, crops and weather conditions assuming no access to weather forecasts and access to weather forecasts with 100% and reduced accuracy.

04. Investigate changes in the confidence intervals and potential economic gain associated with crop nitrogen uptake, leaching losses, gaseous emissions, and possible reduction in crop yield.
Project Documents
• Final Report : How far will medium term weather forecasts improve assessment of risks?   (1288k)
Time-Scale and Cost
From: 2001

To: 2002

Cost: £58,309
Contractor / Funded Organisations
Rothamsted Research (BBSRC)
Keywords
Climate and Weather              
Environmental Protection              
Sustainable Production              
Weather