Science can explain
9 April, 2018, 12:00 am
ENHANCED weather activity with above average cloudiness, westerly wind bursts, rains, thunderstorms, low pressure systems and support for any existing cyclonic vortices towards further deepening, often leading to tropical cyclone activity, is characteristic during enhanced Madden Julian Oscillation (MJO).
An enhanced amplitude MJO wave is passing over the Pacific and has been responsible for the enhancement weather activity over Easter, leading to the Fiji and even Vanuatu Easter floods. The present activity over us and the region, which should last for another seven-10 days with much activity in an enhanced form, is also due to the influence of the MJO.
The MJO has led to the formation, dissipation, and then rejuvenation of Tropical Cyclone Iris, off the coast of Queensland which has now reached Category 2 status. TC Josie was also influenced by the MJO.
The South Pacific Convergence Zone (SPCZ) has been unusually active for the past few weeks and it is expected to remain so, as long as we are under the active phase of the MJO.
Activity is moving eastwards as the MJO propagates eastwards over the Central Pacific. It does not appear that we will have any tropical cyclone formation within the next five-seven days as the MJO pulse is rapidly moving away to the eastern Pacific, reducing its influence in the western tropics.
Any deepening of a low pressure or depression may not find any further help from the MJO as it is expected to track eastwards within the next five-seven days diminishing its likely impacts in the western Pacific.
Great care has to be taken before we excite the already traumatised public of our nation because of the Easter floods. Looking at the weather maps we do not note any major cyclonic motion at the low levels, neither major areas of low pressure or deep depressions.
The latest application that many people walk around with showing them the “wind flow patterns” is their mobile phone apps is just that. Tropical cyclones require more than closed wind circulations as the initial fields required to form into cyclones.
The entire globe is covered with lows and highs, and great care should be taken when people walk around with these very basic mundane applications to forecast the location and track of cyclones.
These applications were never meant to be tropical cyclone forecasting tools for starters and should not be used as such. The application shows users a “wind streamline analysis” only, which does not mean that you will be having a cyclone in the area of convergence shown on your phone app.
Atmospheric waves in our upper atmosphere moving from the west to east around planet Earth, with varying amplitudes and frequency in the form of troughs or ridges, helping with either cyclonic or anti-cyclonic vorticity advection to the lower surface levels, which either helps form, enhance or suppress surface high or low pressure. Thus, good or bad weather can be explained by these upper air waves.
The MJO is just one of the many contributing factors in weather forecasting, and not an exclusive factor or tool. The MJO is the largest element of the intra-seasonal (one-three month) variability in the tropical atmosphere. It was discovered in 1971 by Ronal Madden and Paul Julian of the American National Center for Atmospheric Research (NCAR).
Unlike a standing pattern like the El Nino/Southern Oscillation (ENSO), the MJO is a travelling pattern that propagates eastward at approximately 5 m/s through the atmosphere above the warm parts of the Indian Ocean and progresses towards the Pacific tropical oceans, over a 30-90 day period. This overall circulation pattern manifests itself most clearly as anomalous rainfall, wind bursts, enhanced convective activity and thunderstorms.
The MJO is the major fluctuation in tropical weather on a weekly to monthly timescale. It is not a day-to-day forecasting tool similar to a weather map. Nor would you note it in an upper air atmospheric weather chart analysis. These waves are hemispheric scale with varying amplitudes and frequency, and can only be delineated and understood using general circulation computer models.
The MJO is a large-scale coupling between atmospheric circulation and tropical deep convection. A synoptic meteorologist may use this information for him/her to understand whether we are in a suppressed or an enhanced phase which may have a bearing on weather forecasting.
It is sufficient to say the science of meteorology, weather and climate dynamics, including areas covered by the natural variability and change of climate; are all very complex subjects and not for the common lay person to understand and grasp by the use of a quick primer such as “Meteorology for Dummies 101”.
Experts spend their lifetime trying to come to depths of the subject, studying the complexity with which the atmospheric and oceanic sciences work and interplay with weather and climate issues on Earth to help mankind take preventative actions dealing with the extremes of weather and climate.
Globally, these are areas often most neglected by our people and leaders, who are fairly busy making generalised newspaper headlines, attributing outcomes of nature as belonging to some fixed reasons or changes in climate being attributed for some ills of nature.
Meteorological areas of weather and climate sciences needs to be fully supported by the state, including the secondary and tertiary education sectors, if we as a nation are to find a way out of the many vulnerable situations that we keep findings ourselves in this dynamic world of weather and climate impacts and issues.
Only science will show us a way out of the quagmire of the challenges nature has for humanity. Newspaper headlines by politicians will make them popular temporarily, but in the long run we have to “bite the bullet” and do the hard work required to build a scientific knowledge based society that can tackle the issues that nature will throw at us suddenly, when you least expect it.
I hope the recent Easter floods and the impacts it has had on our nation will provide some impetus for our leaders to support meteorological education in Fiji.
In this article, we note how little known factors such as the MJO factor can be of such importance in regulating, enhancing or suppressing our daily or weekly weather, which includes tropical cyclone activity, rains, winds and floods.
* Dr Sushil K Sharma is a World Meteorological Organisation accredited Class 1 professional meteorologist and is an associate professor of meteorology at the Fiji National University. The views expressed are the author’s and not of the FNU or this newspaper.