Updating data dmi
The new setup is comprised of two existing models, which are run multiple times to produce a so-called ensemble forecast--essentially lots of slightly different individual weather forecasts that can all be analysed all at once.
This produces an ensemble of possible weather scenarios for a certain location at a certain time in the future, which the forecasters then use to calculate the probability of heavy rain or bright sunshine, for example.
Weather forecasting agencies around the world are constantly developing new systems to produce ever more accurate forecasts, capable of capturing fast moving, often chaotic and localised weather events.
But this means bigger models and even bigger computing capacity.
Yang’s priority was to run a bigger model without increasing the amount of computing power beyond DMI’s current capacity.
Yang says several countries outside of the Nordics have also expressed interest in the new system.“We hope that with the operational launch we’ll make a strong case,” he says.The previous system produced meteorological data for every 5.5 square kilometres.Yang and his colleagues at DMI are now experimenting with even smaller scales, down to as little as 300 metres.This, he says, in combination with more frequent updates, will provide an almost continuous local forecast that will allow DMI to improve their predictions of chaotic and often highly localised extreme weather events more precisely, such as cloud bursts—severe storms that can develop quickly with little advance warning.Other countries are watching to see how much of an improvement the new setup offers.The new system has been running alongside DMI’s regular forecasts for Denmark and the Faeroe Islands, since September 2016.During this time it has convincingly outperformed the existing system, producing an hourly updated forecast and predicting weather conditions at a much finer scale than previously, says Yang.“So far it has performed consistently better than the existing systems,” he says.It runs on a 2.5 square kilometres resolution and is updated every hour.It produces a 24-member ensemble forecast, which means 24 possible scenarios for the weather over the next 2 days.The new model system DMI switched over to The Continuous Mesoscale Ensemble Prediction System (COMEPS) at midnight on June 15th.It is based on two existing forecast systems known as HARMONIE and HIRLAM.