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Albedo time series of the European Alps based on NOAA AVHRR data (1985 - 2012)

Applicant Wunderle Stefan
Number 132172
Funding scheme Project funding (Div. I-III)
Research institution Geographisches Institut Universität Bern
Institution of higher education University of Berne - BE
Main discipline Climatology. Atmospherical Chemistry, Aeronomy
Start/End 01.02.2012 - 31.01.2016
Approved amount 238'281.00
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Keywords (8)

Broad band albedo; NOAA-AVHRR; climate change; land use change; European Alps; broadband albedo; regional climate model; snow coverage

Lay Summary (English)

Lead
Lay summary
The Alpine climate has changed during the last decades, resulting in a shift of vegetation zones, changes in vegetation phase and function concurring with changes of the duration and distribution of snow coverage. There is clear evidence that these changes in land coverage will influence the albedo. Albedo is one dominant factor of the radiation balance controlling the amount of reflected or absorbed radiation.Up to now, global and regional climate models mostly apply background albedo maps (albedo of the snow-free land surface) based on land use classifications. These maps typically provide a mean annual background albedo for each climate model grid cell. In some models, a climatological mean annual cycle is considered in addition to this. However, possible albedo feedbacks which could be important during extreme periods such as the summer of 2003 are basically neglected.The principal item of the proposed project is the statistical analysis of the albedo time series, which will bring new insights on albedo changes of the Alps during the last 25 years. The project focuses on the derivation of broadband albedo based on our archived satellite data of the NOAA series and aims at addressing the following scientific questions: -Does the albedo of the European Alps show significant changes during the last 25 years?-Are the changes of albedo in distinct elevation zones caused by temperature increase (snow cover duration) or land use changes (socio-economic reasons)?-Is there a clear difference between North-South and East-West Alps?-What are the potential improvements of regional climate models when their current albedo (diagnostic and prognostic) formulations are compared to a 25 year long satellite albedo dataset.A homogenous and consistent albedo data set with a high spatial (1.1km2) and temporal (10-days) resolution based on data of the Advanced Very High Resolution Radiometer (AVHRR) on board of the NOAA-satellites will be generated. The broadband albedo will be derived for the years 1985 until 2012 using processing software developed to take into account the special conditions (topography, cloud coverage) of the Alps. Thus, for the first time albedo changes of all elevation zones and regions of the Alps will be analyzed on their trends and variability.
Direct link to Lay Summary Last update: 21.02.2013

Responsible applicant and co-applicants

Employees

Name Institute

Publications

Publication
Albedo climatology for European land surfaces retrieved from AVHRR data (1990-2014) and its spatial and temporal analysis from green-up to vegetation senescence.
Sütterlin Melanie, Stöckli Reto, Schaaf Crystal, Wunderle Stefan (2016), Albedo climatology for European land surfaces retrieved from AVHRR data (1990-2014) and its spatial and temporal analysis from green-up to vegetation senescence., in Journal of Geophysical Research: Atmospheres, 121(14), 8156-8171.
Albedo and reflectance anisotropy retrieval from AVHRR operated onboard NOAA and MetOp satellites: Algorithm performance and accuracy assessment for Europe
Sütterlin M. Schaaf C. B. Stöckli R. Sun Q. Hüsler F. Neuhaus C. & Wunderle S (2015), Albedo and reflectance anisotropy retrieval from AVHRR operated onboard NOAA and MetOp satellites: Algorithm performance and accuracy assessment for Europe, in Remote Sensing of Environment, 168, 163-176.

Collaboration

Group / person Country
Types of collaboration
Schneehydrologie / WSL-SLF Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
MODIS Science Team/ Boston University, Department of Geography United States of America (North America)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Exchange of personnel

Scientific events

Active participation

Title Type of contribution Title of article or contribution Date Place Persons involved
EUMETSAT Meteorological Conference Talk given at a conference Towards a European surface albedo climatology 21.11.2014 Geneva, Switzerland Stöckli Reto; Sütterlin Melanie; Wunderle Stefan;


Self-organised

Title Date Place

Associated projects

Number Title Start Funding scheme
111894 Analysis of NOAA-AVHRR time series to investigate climate induced changes of vegetation in the Alps and surrounding landscapes 01.04.2006 Project funding (Div. I-III)
111894 Analysis of NOAA-AVHRR time series to investigate climate induced changes of vegetation in the Alps and surrounding landscapes 01.04.2006 Project funding (Div. I-III)

Abstract

The Alpine climate has changed during the last decades, resulting in a shift of vegetation zones (biogeographical changes: Beniston et al. 1997), changes in vegetation phase and function (e.g. phenological changes, Cleland et al. 2007) concurring with changes of the duration and distribution of snow coverage (Sturm et al. 2005). There is clear evidence that these changes in land coverage will influence the albedo. Albedo is one dominant factor of the radiation balance controlling the amount of reflected or absorbed radiation. Slight changes of the albedo can affect the terrestrial water and carbon exchanges (Betts et al. 2007, Randerson et al. 2006). Weather forecast and especially regional or global climate models rely on precise information of the albedo. Meteorological measurements of the incoming and outgoing radiation are precise but most of the measurement equipment is installed in accessible terrain and over grass surfaces. Due to the high spatial heterogeneity of land surface properties such albedo measurements are not scalable in space. Interpolation techniques between different point measurements generally show poor results, especially in mountaineous terrain. Satellite sensors on the other hand, offer continuous spatiotemporal coverage and are the only means to cover large regions in a spatially integrative manner. Satellite albedo, however, has to be retrieved indirectly by use of a complex set of algorithms and needs to be carefully validated with ground measurements. The vulnerability of the European Alps due to climate change is well documented and there is great effort to predict the changes in temperature, precipitation and land use change for the next 50 to 100 years. Up to now, global and regional climate models mostly apply background albedo maps (albedo of the snow-free land surface) based on land use classifications. These maps typically provide a mean annual background albedo for each climate model grid cell. In some models, a climatological mean annual cycle is considered in addition to this. However, possible albedo feedbacks which could be important during extreme periods such as the summer of 2003 are basically neglected. The comparison of the mean climate model background albedo to satellite products and the linkage between deficiencies in the albedo parameterization and climate model biases is a first important step towards an improved albedo description in climate models. The principal item of the proposed project is the statistical analysis of the albedo time series, which will bring new insights on albedo changes of the Alps during the last 25 years. The project focuses on the derivation of broadband albedo based on our archived satellite data of the NOAA series and aims at addressing the following scientific questions: -Does the albedo of the European Alps show significant changes during the last 25 years?-Are the changes of albedo in distinct elevation zones caused by temperature increase (? snow cover duration) or land use changes (socio-economic reasons)?-Is there a clear difference between North-South and East-West Alps?-What are the potential improvements of regional climate models when their current albedo (diagnostic and prognostic) formulations are compared to a 25 year long satellite albedo dataset.A homogenous and consistent albedo data set with a high spatial (1.1km2) and temporal (10-days) resolution based on data of the Advanced Very High Resolution Radiometer (AVHRR) on board of the NOAA-satellites will be generated. The broadband albedo will be derived for the years 1985 until 2012 using processing software developed to take into account the special conditions (topography, cloud coverage) of the Alps. Thus, for the first time albedo changes of all elevation zones and regions of the Alps will be analyzed on their trends and variability. The outcome will be analyzed taken into account land use changes (CORINE, Swiss area statistic) and the snow coverage (will be the outcome of our running Hyper-Swiss-Net project “snow and climate” funded by Swiss University Conference). Finally, the albedo dataset will be made available to the climate modeling community in order to improve current formulations of albedo in climate models.The Significance of this project is-to show for the first time the spatial and temporal distribution of albedo during the last 25 years.-important data set to serve as diagnostic boundary condition and validation tool for European regional climate models (RCM’s).-the result will help to answer the question: What are the contributions of the biophysical feedbacks of land cover and albedo changes over the Alps to the biogeochemical climatic effects of a predicted increase in CO2 storage.-contribution for an improved understanding and representations of albedo in regional climate models used to predict the future climate of the European Alps. Regional climate model predictions are the basis for climate change scenarios used in policy decisions for mitigation and adaptation of climate change.
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