Improvement in Weather forecasting
Source: By Amitabh Sinha: The Indian Express
Until not very long ago, India’s Met department seemed to exist mainly to provide rainfall forecasts during the monsoon season, or to tell the maximum and minimum temperatures in the four metropolises.
While the department was doing a lot of other valuable work as well, that did not seem to be of much relevance to the general public. Weather services were not a sought-after commodity — and even when available, were not taken very seriously.
This situation has changed dramatically over the last decade or so — on both the demand and the supply sides. There is huge demand for, and interest in, weather-related information, even among the general public. And the amount of information that the India Meteorological Department (IMD) puts out every day about not just rainfall but all kinds of weather events, is enormous.
The trust in weather forecasts has increased significantly, thanks to improvements in accuracy. But the demand for even more accurate and specific predictions continues to grow, particularly in light of the increasing instances of extreme weather events being triggered by climate change, and the disasters that they sometimes turn into.
To serve this growing need, the government is learnt to be planning a major upgrade of the IMD’s existing capabilities.
Why the government said no
Steady improvement
Upgradation of weather forecasting infrastructure, technologies, and skills are an ongoing exercise. A major push came in the form of the Monsoon Mission in 2012, aimed at improving the long-range monsoon forecasts that are crucial for the government’s economic planning. Thereafter, several other initiatives were launched to improve the observation network, install high-performance computing systems, deploy sophisticated instruments like Doppler radars, and develop better computer simulation models.
As a result, IMD now has a vastly improved monitoring and observation network, much more data and enhanced computing power. This has enabled IMD to provide significantly better weather forecasts, and offer much more public-oriented information — such as near-real-time forecasts and heat wave warnings.
The big turnaround in the public perception of weather forecasts came with IMD’s successes in predicting cyclones. Timely and accurate forecasts of cyclones, starting with Phailin in October 2013, led to the establishment of a reliable response and evacuation mechanism, because of which the loss of human lives, earlier in the hundreds, came down to very few or none at all.
The success of the cyclone early warning system brought a lot of credibility to the IMD. Its long-range monsoon forecasts too, have also been right almost every time over the last decade. However, making precise forecasts for hyper-local events, like a short burst of heavy rain in a particular part of a city, have been a challenge, and so have predictions of extreme events, which are increasing due to climate change. It is here that the IMD needs to further improve its capabilities.
An uncertain science
Over the last decade, even as the IMD has enhanced its forecasting skills and capabilities, climate change has made weather patterns more erratic. In general, forecasting weather in the tropics is more challenging than in areas that are farther from the equator, because of greater variability in weather phenomena. Also, it is relatively easy to predict large systems like the monsoon or a cyclone that are spread over large geographical areas. A spread-out heat wave is easier to forecast than a localised cloudburst event. Similarly, routine cyclic events are relatively easier to forecast than sudden, unexpected events.
The science of weather forecasting has inherent uncertainties. The more precise a forecast — in terms of the spatial spread or time-window for the event — the greater the uncertainty. Also, the earlier the forecast, the less precise it is likely to be.
It is for this reason that while the forecast for the four-month monsoon season over the country as a whole has been generally correct over the last decade, regional and monthly predictions have been far less accurate.
As another example, IMD has a 97-99 per cent probability of detecting a heat wave at least 24 hours in advance; this probability for a heavy rainfall event is less than 80 per cent.
Extreme weather events are even more difficult to predict. Events expected to happen only once in 50 or 100 years do not get captured easily by the models. Such events are now happening with alarming regularity, often triggering disasters like the deadly landslides in Kerala last month.
Need for precision
IMD currently has the ability to forecast weather events over a 12 km x 12 km area. This grid is larger than most Indian cities — which means that the likelihood of rainfall in a city can be forecast, but it cannot be specified where in the city it would rain.
The IMD has been trying out experimental forecasts for 3 km x 3 km grids, but the eventual objective is to get hyper-local forecasts for 1 km x 1 km areas. Such forecasts can be extremely helpful — not just for people to plan their activities but also in creating early warning systems for disasters.
Previous upgrades at the IMD have focused mainly on infrastructure enhancement. Some infrastructure upgradation is required even now — for example, in the installation of ocean observation systems and in high-resolution earth observation satellites. Also, the eastern and northeastern regions of the country do not have optimum coverage of Doppler radars.
But the big breakthrough is required in developing India-specific weather models that are able to understand and simulate Indian conditions more accurately.
With the climate change-induced unpredictability in weather systems, global models like the ones in use currently have their limitations. Developing such customised models is one of the main objectives of the planned upgrade, for which intensive research and development and regional assessments of climate change would be required.
