Comparing atmosphere-land surface feedbacks from models within the tropics (CALM)
Lead Research Organisation:
University of Reading
Department Name: Meteorology
Abstract
Man-made transformations to the environment, and in particular the land surface, are having a large impact on the distribution (in both time and space) of rainfall, upon which all life is reliant. From global changes in the composition of the atmosphere, through the emission of greenhouse gases and aerosols, to more localised land use and land cover (LULC) changes due to an expanding population with an increasing ecological footprint, human activity has a considerable impact on the processes controlling rainfall. This is of particular importance for environmentally vulnerable regions such as many of those in the tropics. Here, widespread poverty, an extensive disease burden and pockets of political instability has resulted in a low resilience and limited adaptative capacity to climate related shocks and stresses. The CALM project has the overarching aims of: (i) furthering our understanding of how the interactions between tropical rainfall and the land surface are represented in the latest climate model simulations from the 5th Climate Modelling Intercomparison Project (CMIP5); and (ii) how these interactions relate to abrupt climate changes such as those which occurred over the Sahara thousands of years ago or, more recently, the prolonged Sahelian drought.
As recent climate disasters (such as flooding in Pakistan, heat waves in India and droughts in China) demonstrate, society is particularly vulnerable to extremes related to tropical rainfall. The overall objective of this project is to better understand both present day and future tropical rainfall variability and associated controlling processes. In particular, recent work has suggested that the atmosphere-land surface feedback is going to be increasing important for any possible abrupt climate changes, thus this project will focus on model simulations of this process over a location where such changes have already taken place. The research addresses the interconnected themes of water cycle drivers, the water cycle-human interface, society and the changing water cycle, and interactions between water at the land surface and in the sub-surface.
Land use (and related types of land cover) is rapidly changing, as an increasing population migrates to urban areas, large tracts of land are deforested, agriculture is intensified and increasing use is made of groundwater resources through irrigation. These changes influence the climate through the release of greenhouse gases and aerosols and by changing the flows of mass and energy from the surface to the atmosphere. Currently the climate influence of variations in concentrations of greenhouse gases and aerosols (induced by LULC change) is simulated for the past and projected into the future using bio-geochemical modelling, measurements of changes in atmospheric composition, or by building greenhouse gas emission scenarios driven by different future socio-economic changes. A recent project, CMIP5, has run a number of state-of-the-art climate models using various present-day and future emission scenarios of greenhouse gases, and therefore provides an unprecedented amount of simulated model data. This project aims to compare the data from all of these models, as well as observational, satellite-derived and blended observational-satellite data, to see how the interactions between rainfall and the land surface differs (or agrees) between the models and reality. By following a process-based methodology, which is already well established and widely used in other funded projects, the project will enable a better understanding of how present-day and future rainfall is associated with the surrounding environment.
As recent climate disasters (such as flooding in Pakistan, heat waves in India and droughts in China) demonstrate, society is particularly vulnerable to extremes related to tropical rainfall. The overall objective of this project is to better understand both present day and future tropical rainfall variability and associated controlling processes. In particular, recent work has suggested that the atmosphere-land surface feedback is going to be increasing important for any possible abrupt climate changes, thus this project will focus on model simulations of this process over a location where such changes have already taken place. The research addresses the interconnected themes of water cycle drivers, the water cycle-human interface, society and the changing water cycle, and interactions between water at the land surface and in the sub-surface.
Land use (and related types of land cover) is rapidly changing, as an increasing population migrates to urban areas, large tracts of land are deforested, agriculture is intensified and increasing use is made of groundwater resources through irrigation. These changes influence the climate through the release of greenhouse gases and aerosols and by changing the flows of mass and energy from the surface to the atmosphere. Currently the climate influence of variations in concentrations of greenhouse gases and aerosols (induced by LULC change) is simulated for the past and projected into the future using bio-geochemical modelling, measurements of changes in atmospheric composition, or by building greenhouse gas emission scenarios driven by different future socio-economic changes. A recent project, CMIP5, has run a number of state-of-the-art climate models using various present-day and future emission scenarios of greenhouse gases, and therefore provides an unprecedented amount of simulated model data. This project aims to compare the data from all of these models, as well as observational, satellite-derived and blended observational-satellite data, to see how the interactions between rainfall and the land surface differs (or agrees) between the models and reality. By following a process-based methodology, which is already well established and widely used in other funded projects, the project will enable a better understanding of how present-day and future rainfall is associated with the surrounding environment.
Planned Impact
The potential impact of this research is substantial, because many uncertainties remain over how the land surface influences tropical precipitation. The primary aim of this project is to improve our current level of understanding of how anthropogenic changes to the land surface contributes to trends and variability in tropical regions, which is crucial for society as this can have large economic, social and human impacts on individuals and society as a whole. Therefore the main beneficiaries will be intergovernmental, government, non-governmental stakeholders and policymakers and, eventually, individual farmers and people. The research outcomes will be of direct use in obtaining a better understanding of the impact of changes in precipitation patterns, and in particular the impact of changing the land surface, for the benefit of millions of people across the world. Ultimately, it will address the overall challenge of poverty reduction and continued development in the tropics.
The wider scientific community (including climate scientists, land use and land cover specialists, impact modellers and climate model developers), will all be beneficially impacted by the outcomes of the proposed research (see Academic beneficiaries for details). In addition to the academic community, this research will beneficially impact several institutions, including:
1. UK and International Governments - Both attribution and prediction of regional climate change over the tropics are relevant to a variety of governmental departments and ministries. In the UK, these include the Department for International Development (DFID), the Department for Energy and Climate Change (DECC), and the Department for Environment, Food and Rural Affairs (DEFRA). Thus this project will contribute to improvements in the science, that the above ministries and departments will in turn translate into impacts on the ground, through their regional partnerships.
2. Living with Environmental Change (LWEC) Partnership, which is a group of 22 UK public sector funders and users of environmental research within the UK, including the different research councils and central government departments. LWEC has the aim of providing decision makers with the best information for the management and protection of vital ecosystems, strengthening the evidence base for policy and addressing the uncertainties that remain about the impacts of climate change. In addressing the proposed objectives, this project will have direct relevance to the various policymakers included in this partnership.
The wider scientific community (including climate scientists, land use and land cover specialists, impact modellers and climate model developers), will all be beneficially impacted by the outcomes of the proposed research (see Academic beneficiaries for details). In addition to the academic community, this research will beneficially impact several institutions, including:
1. UK and International Governments - Both attribution and prediction of regional climate change over the tropics are relevant to a variety of governmental departments and ministries. In the UK, these include the Department for International Development (DFID), the Department for Energy and Climate Change (DECC), and the Department for Environment, Food and Rural Affairs (DEFRA). Thus this project will contribute to improvements in the science, that the above ministries and departments will in turn translate into impacts on the ground, through their regional partnerships.
2. Living with Environmental Change (LWEC) Partnership, which is a group of 22 UK public sector funders and users of environmental research within the UK, including the different research councils and central government departments. LWEC has the aim of providing decision makers with the best information for the management and protection of vital ecosystems, strengthening the evidence base for policy and addressing the uncertainties that remain about the impacts of climate change. In addressing the proposed objectives, this project will have direct relevance to the various policymakers included in this partnership.
Organisations
Publications
Hegerl G
(2015)
Challenges in Quantifying Changes in the Global Water Cycle
in Bulletin of the American Meteorological Society
Maidment R
(2014)
The 30 year TAMSAT African Rainfall Climatology And Time series (TARCAT) data set
in Journal of Geophysical Research: Atmospheres
Maidment R
(2013)
Evaluation of satellite-based and model re-analysis rainfall estimates for Uganda Evaluation of rainfall estimates for Uganda
in Meteorological Applications
Tarnavsky E
(2014)
Extension of the TAMSAT Satellite-Based Rainfall Monitoring over Africa and from 1983 to Present
in Journal of Applied Meteorology and Climatology
Williams C
(2012)
Diagnosing atmosphere-land feedbacks in CMIP5 climate models
in Environmental Research Letters
Description | Human-made transformations to the environment, and in particular the land surface, are having a large impact on the distribution (in both time and space) of rainfall, upon which all life is reliant. Feedback loops involving the land surface and the atmosphere can potentially amplify climate change regionally and it is therefore vital that such processes are correctly represented within detailed computer simulations, the only means of predicting future changes in the regional water cycle. In the CALM project we have quantified these key links between daily precipitation, soil moisture and temperature in the latest climate simulations (CMIP5) and evaluated these against observationally-based datasets. No evidence for positive (amplifying) feedback was identified at the daily-scale although models appear to overestimate the lag between precipitation and soil moisture compared to observationally-based reanalysis simulations. The following mechanisms was proposed: precipitation leads to increased soil moisture which cools temperature over the next few days and reduces the occurrence of precipitation afterwards - a negative feedback. This work is being extended to establish at what time-scale positive feedback becomes important. |
Exploitation Route | The research is useful for the Met Office and other modelling centres in evaluating the realism of their computer simulations and products. The work is also of importance in informing government departments and non-govenment organisations into the importance of processes governing regional climate change. This work has been widely disseminated internationally at the European Geophysical Union conferences in 2012 and 2013 (both poster and oral presentations) and at focused meetings aimed at researchers and Met Office scientists. This work has also been disseminated at stakeholder meetings, aimed at government departments (DFID), the insurance industry (Zurich) and non-government organisations (Oxfam). |
Sectors | Communities and Social Services/Policy Environment |
URL | http://www.met.rdg.ac.uk/~charlie/ |
Description | Results have been disseminated at the EGU conference to a general academic audience and at focused CMIP5 workshops which included policy users. PI Allan has included outputs in public engagement activities (public talks). The results of this work were cited in the IPCC AR5 report (Chapter 9, Flato et al. 2013). |
First Year Of Impact | 2013 |
Sector | Communities and Social Services/Policy,Environment |
Impact Types | Policy & public services |
Description | NERC Highlights Topics - SMURPHS |
Amount | £3,008,179 (GBP) |
Funding ID | NE/N006054/1 |
Organisation | Natural Environment Research Council |
Sector | Public |
Country | United Kingdom |
Start | 12/2015 |
End | 11/2019 |
Description | 2013 How confident are we in the response of the global water cycle to climate change? Royal Society: Next Steps in Climate Change |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | Yes |
Type Of Presentation | Keynote/Invited Speaker |
Geographic Reach | International |
Primary Audience | Professional Practitioners |
Results and Impact | An invited talk was presented to researchers and professional practitioners including policymakers. This generated questions and discussion. Ideas for future ;projects were discussed and followed up. |
Year(s) Of Engagement Activity | 2013 |
URL | https://www.youtube.com/watch?v=r5OQaz6bsaE |
Description | 2017/02 - Media comment on article about Atmospheric Rivers |
Form Of Engagement Activity | A press release, press conference or response to a media enquiry/interview |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Media (as a channel to the public) |
Results and Impact | I provided expertise and comment to a reporter from the International Business Times about the effect of Atmospheric Rivers on extreme rainfall and winds. This was also picked up by the techtimes.com and themarshalltown.com. |
Year(s) Of Engagement Activity | 2017 |
URL | http://www.ibtimes.co.uk/atmospheric-rivers-snake-through-most-dangerous-extreme-storms-1607545 |
Description | 201703 - BLOG: Changing wet and dry seasons blog |
Form Of Engagement Activity | Engagement focused website, blog or social media channel |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Public/other audiences |
Results and Impact | A climate blog on latest scientific understanding of how tropical wet and dry seasons are changing. This was picked up and posted by the Walker Institute. |
Year(s) Of Engagement Activity | 2017 |
URL | http://www.walker.ac.uk/news-events/changing-wet-and-dry-seasons/ |
Description | Comparing atmosphere-land surface feedbacks from models within the tropics |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Type Of Presentation | Keynote/Invited Speaker |
Geographic Reach | National |
Primary Audience | Professional Practitioners |
Results and Impact | An invited talk was presented at the CMIP5 Science Review (Shenai, Reading) in which initial results from analysis of the new state of the art climate model simulations were discussed. We disseminated new results on coupling between soil moisture, rainfall and temperature simulated by the climate models, of importance for land surface feedbacks which play a substantial role in determining future regional climate projections over land. Not aware of any so far. |
Year(s) Of Engagement Activity | 2012 |
Description | Diagnosing atmosphere-land feedbacks in CMIP5 climate models |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Professional Practitioners |
Results and Impact | Human-made transformations to the environment, and in particular the land surface, are having a large impact on the distribution (in both time and space) of rainfall, upon which all life is reliant. Focusing on precipitation, soil moisture and near-surface temperature, we compare data from Phase 5 of the Climate Modelling Intercomparison Project (CMIP5), as well as blended observational-satellite data, to see how the interaction between rainfall and the land surface differs (or agrees) between the models and reality, at daily timescales. As expected, the results suggest a strong positive relationship between precipitation and soil moisture when precipitation leads and is concurrent with soil moisture estimates, for the tropics as a whole. Conversely a negative relationship is shown when soil moisture leads rainfall by a day or more. A weak positive relationship between precipitation and temperature is shown when either leads by one day, whereas a weak negative relationship is shown over the same time period between soil moisture and temperature. Temporally, in terms of lag and lead relationships, the models appear to be in agreement on the overall patterns of correlation between rainfall and soil moisture. However, in terms of spatial patterns, a comparison of these relationships across all available models reveals considerable variability in the ability of the models to reproduce the correlations between precipitation and soil moisture. There is also a difference in the timings of the correlations, with some models showing the highest positive correlations when precipitation leads soil moisture by one day. Finally, the results suggest that there are 'hotspots' of high linear gradients between precipitation and soil moisture, corresponding to regions experiencing heavy rainfall. These results point to an inability of the CMIP5 models to simulate a positive feedback between soil moisture and precipitation at daily timescales. A prestigious oral presentation was made by the project scientist, Dr Charles Williams, at the European Geosciences Union (EGU) international conference in Vienna. This was an ideal opportunity for disseminating the results of the project, including new i |
Year(s) Of Engagement Activity | 2013 |
Description | EGU 2012: Comparing atmosphere-land surface feedbacks from models within the tropics (CALM) |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Type Of Presentation | Paper Presentation |
Geographic Reach | International |
Primary Audience | Professional Practitioners |
Results and Impact | Initial results from the comparison of land-atmosphere coupling simulated by state of the art CMIP5 climate models was presented at the EGU international conference in Vienna. Discussion with academics generated more interest. |
Year(s) Of Engagement Activity | 2012 |
URL | http://presentations.copernicus.org/EGU2012-10406_presentation.pdf |