Bridging the gap between iLEAPS and GEWEX land-surface modelling

GEWEX-iLEAPS: Bridging the gap between the iLEAPS and GEWEX land-surface modelling communities – leaders Gordon Bonan & Joe Santanello (GEWEX)

Models of Earth’s weather and climate require fluxes of momentum, energy, and moisture across the land-atmosphere interface to solve the equations of atmospheric physics and dynamics. However, land models that provide the required surface fluxes differ between weather and climate models. This distinction among land models (and their development and application) is largely driven by the different science and research needs of the weather and climate communities.

Our understanding of Earth’s climate has progressed to the point that no credible modelling centre would develop a model without representation of the terrestrial biosphere, the interacting physical, chemical, and biological components of the Earth system, and human perturbations to the biosphere. A particular focus is the carbon cycle and its feedback with climate, but other biogeochemical cycles related to reactive gases and atmospheric chemistry are also important. In addition, changes in ecosystem state and biogeography in response to climate change or human activities drive changes in climate by altering energy, water, and biogeochemical cycles. Inclusion of these biotic and human processes is part of the evolution of models of Earth’s physical climate to Earth system models (ESM).

In contrast, numerical weather prediction (NWP) relies more heavily on accurate representation of the terrestrial hydrosphere, including the initialisation of soil moisture and snow, their time evolution, and their influence on and feedbacks with boundary layer processes. The carbon cycle and long-term biological processes are not necessary on these short time scales, and, as a result, the development and scope of land models for NWP has diverged over time from that of the climate community.

This distinction in the scientific scope of the land-atmosphere interface is embodied in two entities within the international scientific governing bodies. The Global Land Atmosphere System Study (GLASS) is a scientific panel of the Global Energy and Water EXchanges (GEWEX), a core project within the World Climate Research Programme (WCRP). Its focus has historically been diurnal to seasonal to annual hydrometeorological coupling between land and atmosphere. The Integrated Land Ecosystem – Atmosphere Processes Study (iLEAPS) is the land-atmosphere core project of the International Geosphere-Biosphere Programme (IGBP). The focus of iLEAPS has historically been biogeochemical processes that affect atmospheric chemistry and climate. As a result, GLASS and iLEAPS activities and associated land model intercomparison projects have typically proceeded in parallel as a function of their particular capabilities and applications.

Given the current and continued dissolution of traditional discipline boundaries driven by global environmental change research, it is now timely to survey the two communities to better understand their recent past, present, and future evolution in order to develop improved prediction models across scales.

Past and upcoming activities:

  • Joint iLEAPS-GEWEX Newsletter issue 12: “Bridging the gap between the iLEAPS and GEWEX land-surface modelling communities”
  • 2013: Planned publication based on the Newsletter contributions
  • October 2013, Helsinki University: “Future directions in land-surface and earth-system modeling” The University of Helsinki and Finnish Meteorological Organisation are organizing a workshop on the future of Land Surface / Earth System Modelling in Aug/Sep 2013 in Helsinki. The workshop has 50 k EUR for travel support and will include top people from major ESM consortia and major iLEAPS-GEWEX land-surface / ESM modellers to discuss gaps in knowledge and next steps forward. The Finnish Meteorological Organisation will provide 10-25 person-years per year for the next decade for ESM development which may be of great interest to all the participants. The meeting will also look at the GEWEX-iLEAPS collaboration and how it could contribute to ESM development.
  • Session “Bridging the gap in land-surface modeling” at iLEAPS Science Conference in May 2014, Nanjing University, China