EGU2020-4240, updated on 12 Jun 2020
EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

What we talk about when we talk about seasonality?

Ola Kwiecien1,2
Ola Kwiecien
  • 1Ruhr-University Bochum, Sediments & Isotope Geology, Geosciences, Bochum, Germany (
  • 2Northumbria University, Geography & Environmental Sciences, Newcastle, UK (

The concept of seasonal changes is traditionally understood as a consecutive follow-up of four seasons, spring, summer, autumn, and winter (in the mid-latitudes); or wet/ dry season alteration (in low latitudes). Intuitively, the term ‘seasonality’ usually refers to temperature or moisture gradients throughout a year. These gradients determine the composition and dynamics of natural ecosystems and agricultural strategies; as such seasonality is a key parameter when describing modern and past climatic and environmental conditions. Consequently, changes in seasonality are often called for as the ultimate driving force of observed changes, but there is more to them than meets the eye. Most importantly there is an essential and often overlooked aspect of external, orbitally-driven seasonality, and internal, regional-to-local responses to these changes.

What does ‘increased’ or ‘decreased’ seasonality actually mean? Can we quantify this change? And is the amplitude all that matters? What about temporal distribution? Does temperature and precipitation always respond symmetrically and harmonically? My contribution is aimed at raising awareness, caution and precision when referring to seasonality changes. Come to my poster and let’s discuss it!

How to cite: Kwiecien, O.: What we talk about when we talk about seasonality? , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-4240,, 2020

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Presentation version 2 – uploaded on 01 May 2020
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  • CC1: Comment on EGU2020-4240, Mengmeng Liu, 03 May 2020

    Hello, we are in the same session and I'm interested in your seasonality presentation. May I ask if the accumulated warmth (GDD) has a linear relationship with the accumulated insolation during a certain period at a given site? And at that place, if I use GDD0, is there an insolation value that corresponds to 0 °C? These are something I thought about a few months ago and I just see your presentation. I would appreciate it very much if you have interest in discussing these!

    • AC1: Reply to CC1, Ola Kwiecien, 04 May 2020

      Hello Mengmeng, thank you for asking - this is exactely the type of question I was hoping to get. Having said that, I admit that I do not really know the answer. But I am more than happy to discuss it. I am working mostly (but not exclusively) with inorganic proxies and until now I did not pay much attention to GDD. I imagine that theoretically the realation might be close to linear, but practically I think it will be dependant on the regional factors, formost the altitude and land cover. Incorporating GDD into my conceptual sketch is a very good excercise! Actually I think that it is not only temperature but also the lenght of the day (sunlight), both controlled by insolation that might matter for organic world. Any ideas on that?


      • CC2: Reply to AC1, Mengmeng Liu, 04 May 2020

        Hi Ola, thank you very much for replying! I'm trying to figure out what insolation value corresponds to 0 °C at a given site, then I'm allowed to compare the accumulated insolation during the period to the accumulated warmth above 0 °C (GDD0). 

Presentation version 1 – uploaded on 01 May 2020 , no comments