Evaluating the impact of agriculture on albedo using Sentinel-2 data in southern Sweden

英语. The climate impact of food production plays a big part in the anthropogenic climate impact. Mitigation strategies from this sector are hence of great importance. One area which mainly has been used to calculate climate impact is albedo, the overall reflectance of incoming radiation in all directions. Albedo has been measured for a long time and is vital when calculating the energy balance of an area or biome. It is mainly measured and calculated with the MODIS satellites with a 500 m resolution. This study aims to use the Sentinel-2 spectral instrument with a 10 m resolution to measure the albedo of individual crops effectively. The result shows that the method used to calculate albedo from the Sentinel-2 instrument effectively follows changes in albedo equal to MODIS, for example, changes in seasons over a year. Which means that Sentinel-2 has great potential in being used to give more detailed data with less disturbing factors such as built-up areas, water or other crops within the same pixel. This study also shows differences in albedo between crops, crops and bare soil, and between normal years and years with droughts.

英语. The climate change induced by human sources is vast, and when implementing mitigation strategies, it is important to do this where it has the greatest impact. One of the biggest climate impacts from human sources is from agricultural land. As much as 26% of the greenhouse gas (GHG) emissions from humans originate from agriculture at present time. One way in which the impact from different land covers, including agricultural land, is evaluated is through the use of satellite remote sensing data. When analysing climate impact through remote sensing one important variable is albedo, which is the ratio of reflected long- and short-wave radiation at the earth's surface. Albedo is at the present time most commonly derived from the MODIS-satellite instrument, which has a resolution down to 500m. This project investigated the use of a Sentinel-2 satellite instrument which has a resolution down to 10m. This would mean that land areas could be analysed with more details, for example analysing different crops climate impact. The method used a narrow-to-broadband calculation of the different wavelengths to calculate the surface albedo from the Sentinel-2 data and compare the results with the MODIS data. Followed by testing the albedo calculations from the Sentinel-2 data on six different crops and bare soil in an area in southwestern Skåne in Sweden. The results show that it would be viable to use Sentinel-2 data to analyse surface albedo. It proved to be much easier to exclude land cover which is not needed, for example in this study built-up areas, water, and crops on nearby fields were excluded. All of which would be an issue to exclude in a coarser dataset, e.g., the MODIS data. The data also show significant differences between the crops analysed and between crops and bare soil. Future research should focus on further evaluating the albedo calculations based on the Sentinel-2 instrument.