27.03.2018
The new open-access article "Progress in subseasonal to seasonal prediction through a joint weather and climate community effort" describes how weather and climate scientists work together to improve forecasts for weeks and months ahead. The paper was published in “Nature Partner Journals – Climate and Atmospheric Science”. The authors are Annarita Mariotti, Director of the NOAA MAPP Program, as well as Paolo Ruti and Michel Rixen, who coordinate research for the World Weather Research Programme and World Climate Research Programme, respectively.
A schematic illustrating the role of different parts of the Earth’s climate system (atmosphere, purple; land surface, green; ocean, blue) as sources of S2S predictability (vertical axis). For short lead times, knowing the initial state of the atmosphere counts the most. At 2-week to 4-week lead times, knowledge of the land surface is also needed. Forecasting more than 30 days ahead typically requires knowledge of the ocean, such as the sea surface temperature variations linked to El Niño.
Quelle: Mariotti, Ruti, Rixen: Progress in subseasonal to seasonal prediction through a joint weather and climate community effort: npj Climate and Atmospheric Science 1, 2018 (NOAA CPO graphic adapted from original by Paul Dirmeyer, GMU/COLA)
In their article, the authors put a spotlight on research for predictions that lie in between weather and climate forecasts, that is, which look several weeks to months ahead. They start by explaining how, historically, weather and climate research have developed, and specialized, separately from another due to different mechanisms at play at these different time scales. The weather research community has been using ever-increasing model resolution and computing power to predict the weather yet one more day in advance. As the diagram above illustrates, weather researchers and modelers focus foremost on atmospheric processes when wanting to improve the predictions of weather up to a week ahead.
The climate science community on the other hand has been considering more and more components of the planet’s physical climate system within increasingly complex “Earth System Models”. This reflects an increasing understanding of the importance which interactions between these components hold for climate predictions.
In between these two domains, interest in forecasts weeks or months ahead is steadily increasing. For example, wind farm operators may seek estimates of power output for the next weeks and months. Farmers may be interested whether conditions in a few weeks’ or months’ time will favor early or late harvests. Countless other application areas exist, for example around water management, tourism, or fisheries.
In their now-published summary paper, Mariotti, Ruti and Rixen explain in detail how scientists lay the basis for improved forecasts weeks to months ahead. One key to such “sub-seasonal to seasonal predictions” are interactions between the atmosphere and other, more slowly-evolving components of the Earth system. Representing these correctly will require the fusion of techniques from both weather and climate science.
The article also describes institutional and organizational efforts which facilitate research in the above directions – such as the international “Subseasonal-to-Seasonal Prediction Project” (S2S) and NOAA Research’s “MAPP Subseasonal to Seasonal (S2S) Prediction Task Force”, co-supported by the National Weather Service and other agencies with interests spanning the weather-climate timescales.
Annarita Mariotti, Paolo M. Ruti, Michel Rixen: Progress in subseasonal to seasonal prediction through a joint weather and climate community effort. npj Climate and Atmospheric Science 1, Article number: 4 (2018) - doi:10.1038/s41612-018-0014-z (Article is licensed under a Creative Commons Attribution 4.0 International License)
Read this and more at the website of the World Climate Research Programme
Read the article at npj Climate and Atmospheric Science at the website of nature.com
