Confusing the Definition (part 1): Misunderstood Monsoons

Heavy rain? It must be the monsoon. Or is it? (photo: Mathew Reeve)

Heavy rain? It must be the monsoon. Or is it? (photo: Mathew Reeve)

Before we can investigate the presence or absence of some attribute…. or before we can rank objects or measure them in terms of some variable, we must form the concept of the variable (Lazarfeld and Barton, 1951)

Scientific research is based around definitions. We use definable concepts in our scientific questions, our project proposals, and our research design. We need definitions so that scientists can communicate together and with society. Without robust definitions, research can easily ramble off in irrelevant directions.

When we talk to family and friends about seasons like winter and summer, there is an underlying understanding of what we are talking about. Despite the fact that we ‘agree’ on these definitions, there are tell-tale signs of disagreements that may seem meaningless past a discussion over coffee or tea. For example, you may have discussed with others about when spring starts. Some people say its starts on the 1st March, or the Spring Equinox, whilst others say it starts when the daffodils bloom. Farmers may be more interested in temperatures and say that spring starts after the last frost (for example see this news article). The Norwegian scientific community follow the same thought process and say that spring has started when the daily temperatures stay above 0 degrees Celsius.  In some parts of North America, the Groundhog decides when spring will start. These disagreements may seem frivolous, but I think most would agree that if we want to give people any information about the conditions in spring time in the future then it should be based on a definition that the audience can relate to. The need for a definition as a framework around the concept is crucial for the success of communication.

For most of us, the concept of the monsoon may seem easily definable. The monsoon starts with the sudden transition from hot and dry to warm and very wet. People are happy about this rain, since it brings life to the land and food on the plate. Millions of people depend on this rainfall every year. For research to be successfully communicated to these vulnerable communities or their politicians, then we need to define the monsoon very clearly. The problem is that it is not defined clearly. The monsoon definition is a highly disputed issue and still today the community of monsoon researchers has yet to find an accord.

A fish-eye view of heavy rain (photo: Mathew Reeve)

A fish-eye view of heavy rain (photo: Mathew Reeve)

The monsoon has been defined in relation to many different parameters in the past. Some people use rainfall to define it. Some people use wind direction, outgoing long-wave radiation (which can measure the height of clouds), temperature, or humidity. The confusion doesn’t stop there, because we need to apply different thresholds to the different parameters to identify the monsoon start and end. People can’t agree on that either.

Millions of people in South East Asia rely on the monsoonal rains for their livelihoods and food supply. The timing of the onset is extremely important with regards to the success of the season’s crop production. I find it surprising that there is no agreement on how to define the monsoon as described here:

[…] the monsoon-research community has not yet reached a consensus on a unified definition of monsoon rainy season (Wang and Ho, 2002)

[…] there is not a universally accepted method […]to be used as each definition has its own merits in capturing some characteristics associated with monsoon. (Zhang, 2010)

[…] there exist no widely accepted definitions of these monsoon transitions (Fasullo and Webster, 2002)

There are a multitude of definitions out there; each using different datasets, parameters and thresholds by which to declare the monsoon onset and withdrawal. Despite this overwhelming acceptance that there is no agreement, more definitions keep being published. In 1977 Michael Glantz and Richard Katz asked when is a drought a drought? Here I would like to ask, when is a monsoon a monsoon?

The crux of the problem is that the monsoon is strongly associated with rainfall, whereas in reality (or traditionally) the monsoon was related to wind direction. Let us illustrate this with some quotes:

Lay people […] equate the summer monsoon with increased rain. However, the start or finish of the rainy season may differ significantly from the changes in the prevailing surface winds (Ramage, 1995)

‘Monsun’ (Malayan ‘musim’, the ‘hippalos’ of the Greeks) is derived from the Arabic word ‘mausim’ […] The word has been applied to the seasons at which certain winds prevail, which are, besides, named from places lying in the direction from whence they come; thus, for instance, there is the ‘mausim’ of Aden, of Guzerat, Malabar, etc (von Humboldt, 1848)

This confusion would be less problematic if the reversal of wind direction was highly correlated or closely related with the start and end of the monsoonal rains. It wouldn’t matter if we were telling people about the monsoon start according to a wind or rain definition since they both started at the same time. This is the case in some regions, but absolutely not everywhere. In Bangladesh, the rain increases dramatically in April/May, up to 2 months before the large-scale monsoon circulation begins in earnest.

Just as people define spring differently, people also define the monsoon differently. In our research we have seen several different definitions in Bangladesh. Some people even define the monsoon according to when the frogs start singing. In some parts of Thailand, the ants seem to be the most competent at forecasting the monsoon.

So we have seen that defining the monsoon isn’t as easy as we may first expect. Differences in our definitions of spring seem frivolous, but when it comes to the monsoon it is more serious. This is because a delay in the monsoon start may mean the difference between a successful or a failed rice season. The monsoon used to be related to wind and now rainfall seems most important amongst many other parameters. It is so important to define this properly if we are to succeed in communicating research to society in general. In the next snack I will look into the origins of this confusion, and suggest one solution, which may help the situation.


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Mathew Stiller-Reeve

I am a postdoc researcher at Uni Research Climate and the Bjerknes Centre for Climate Research. I research the monsoon in Bangladesh and I am the founder of ClimateSnack; an community that hopes to give all young and early career climate scientists an opportunity to practice and improve their scientific communication skills.

Latest posts by Mathew Stiller-Reeve (see all)

  • Nice one, Mathew!
    Maybe you could qualify “Without robust definitions, research can easily ramble off in irrelevant directions.” a bit more. “Irrelevant” appears to be a value judgement, thus it comes down to whose values one refers to. Do science and society at large have to always agree on their values? Weren’t there scientific inventions that seemed useless/irrelevant at the time which are now seen as extremely valuable? Scientists should listen to the needs of society, yes, but aren’t there many other examples where scientists informed society, which lead to a change in perceptions thereafter? I guess a continuous dialogue and iterations over time can lead to a reshaping of our definitions/perceptions.

    • Thanks Thomas, you make some great points! I completely agree that ‘Irrelevant’ is a value judgement. When I wrote this I was thinking in terms of applied science that aims to be used in specific applications. In this type of applied research, I think you can and must make judgement calls. This is why we need to have evaluation of climate adaptation projects that aim to improve the lives or situations of specific communities/stakeholders/clients/users. In this sense scientists should listen to the needs of society preferably, as you say, through an iterative dialogue. On the other hand, the ‘purer’ form of science can possibly inform society, but thats not it’s main aim initially. Its main aim is to advance science and knowledge.

      I think there are two (of possibly many) different objectives or goals: One is for our science to specifically inform society (basically providing a ‘climate service’) and the other is for our science to advance our research field. Each are equally important, but I think it is vital that these goals are properly integrated in our research planning and then consciously and concisely communicated with our results.

      I am actually taking up this issue in the next snack about the ‘confusing the definition’. I think monsoon research projects need to be clearer about which goal they are aiming for before they start. Since monsoon meteorology has such a huge potential benefit to society, it is so important not to confuse.

      ‘Irrelevant’ is a value judgement, but in some applications, the relevancy of science needs to be judged.

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