| 1. |
- Tranvik, Lars J., et al.
(författare)
-
Lakes and reservoirs as regulators of carbon cycling and climate
- 2009
-
Ingår i: Limnology and Oceanography. - : Wiley. - 0024-3590 .- 1939-5590. ; 54:6:2, s. 2298-2314
-
Forskningsöversikt (refereegranskat)abstract
- We explore the role of lakes in carbon cycling and global climate, examine the mechanisms influencing carbon pools and transformations in lakes, and discuss how the metabolism of carbon in the inland waters is likely to change in response to climate. Furthermore, we project changes as global climate change in the abundance and spatial distribution of lakes in the biosphere, and we revise the estimate for the global extent of carbon transformation in inland waters. This synthesis demonstrates that the global annual emissions of carbon dioxide from inland waters to the atmosphere are similar in magnitude to the carbon dioxide uptake by the oceans and that the global burial of organic carbon in inland water sediments exceeds organic carbon sequestration on the ocean floor. The role of inland waters in global carbon cycling and climate forcing may be changed by human activities, including construction of impoundments, which accumulate large amounts of carbon in sediments and emit large amounts of methane to the atmosphere. Methane emissions are also expected from lakes on melting permafrost. The synthesis presented here indicates that (1) inland waters constitute a significant component of the global carbon cycle, (2) their contribution to this cycle has significantly changed as a result of human activities, and (3) they will continue to change in response to future climate change causing decreased as well as increased abundance of lakes as well as increases in the number of aquatic impoundments.
|
|
| 2. |
- Kutser, Tiit, et al.
(författare)
-
Estimating lake carbon fractions from remote sensing data
- 2015
-
Ingår i: Remote Sensing of Environment. - : Elsevier BV. - 0034-4257 .- 1879-0704. ; 157, s. 138-146
-
Tidskriftsartikel (refereegranskat)abstract
- Issues like monitoring lake water quality, studying the role of lakes in the global carbon cycle or the response of lakes to global change require data more frequently and/or over much larger areas than the in situ water quality monitoring networks can provide. The aim of our study was to investigate whether it is feasible to estimate different lake carbon fractions (CDOM, DOC, TOC, DIC, TIC and pCO(2)) from space using sensors like OLCI on future Sentinel 3. In situ measurements were carried out in eight measuring stations in two Swedish lakes within 2 days of MERIS overpass. The results suggest that the MERIS CDOM product was not suitable for estimating CDOM in lakes Malaren and Tamnaren and was not a good proxy for mapping lake DOC and TOC from space. However, a simple green to red band ratio and some other MERIS products like the total absorption coefficient, turbidity index, suspended matter and chlorophyll-a were correlated with different carbon fractions and could potentially be used as proxies to map these lake carbon fractions (CDOM, DOC, TOC, DIC, TIC and pCO2) from space. (C) 2014 Elsevier Inc All rights reserved.
|
|
| 3. |
- Kutser, Tiit, et al.
(författare)
-
Variations in colored dissolved organic matter between boreal lakes studied by satellite remote sensing
- 2009
-
Ingår i: Journal of Applied Remote Sensing. - : SPIE-Intl Soc Optical Eng. - 1931-3195. ; 3, s. 033538-
-
Tidskriftsartikel (refereegranskat)abstract
- Therehave been major improvements in our understanding of the roleof lakes and impoundments in global carbon cycle. Estimating thetrue role of lakes as sentinels, regulators and integrators ofclimate change requires analyzing carbon content of vast number oflakes. This is not realistic without using remote sensing methods.There are no satellite sensors at the moment that providefull global coverage and at the same time have spatialand radiometric resolutions suitable for lake color dissolved organic matter(CDOM) mapping. Therefore, the global study has to be performedusing more sensitive sensors to create regional lake CDOM statisticsfor as many sites as possible and extrapolating the resultson global lake map that can be created from lesssensitive sensor data with full global coverage (Landsat). As afirst step towards the global lake carbon mapping we showthat the Advanced Land Imager (ALI) allows to study regionalvariations in lake CDOM content and consequently estimate closely correlatedDOC (dissolved organic carbon) and CO2 saturation values. The resultsshow also that there may be regional differences in lakeCDOM content even if the study sites are geographically relativelyclose to each other and occupying zones with similar landcover and annual runoff. In one occasion the difference canbe explained with human impact that has caused acidification oflakes but the other occasion needs further studies.
|
|
| 4. |
- Verpoorter, Charles, et al.
(författare)
-
A global inventory of lakes based on high-resolution satellite imagery
- 2014
-
Ingår i: Geophysical Research Letters. - 0094-8276 .- 1944-8007. ; 41:18, s. 6396-6402
-
Tidskriftsartikel (refereegranskat)abstract
- An accurate description of the abundance and size distribution of lakes is critical to quantifying limnetic contributions to the global carbon cycle. However, estimates of global lake abundance are poorly constrained. We used high-resolution satellite imagery to produce a GLObal WAter BOdies database (GLOWABO), comprising all lakes greater than 0.002 km(2). GLOWABO contains geographic and morphometric information for similar to 117 million lakes with a combined surface area of about 5 x 106 km(2), which is 3.7% of the Earth's nonglaciated land area. Large and intermediate-sized lakes dominate the total lake surface area. Overall, lakes are less abundant but cover a greater total surface area relative to previous estimates based on statistical extrapolations. The GLOWABO allows for the global-scale evaluation of fundamental limnological problems, providing a foundation for improved quantification of limnetic contributions to the biogeochemical processes at large scales.
|
|
| 5. |
- Verpoorter, Charles, et al.
(författare)
-
Automated mapping of water bodies using Landsat multispectral data
- 2012
-
Ingår i: Limnology and Oceanography. - : Wiley. - 1541-5856. ; 10, s. 1037-1050
-
Tidskriftsartikel (refereegranskat)abstract
- The assessment of the role of lakes and impoundments at regional and global scales, e.g., in biogeochemical cycles, requires good estimates of the areal extent and shape of water bodies. Upscaling to large regions, except in limited areas where precise maps are available, so far depends on statistical estimates of the number and size of lakes, which explains why estimates are poor. We present an automated procedure that allows mapping of the actual number, size, and distribution of lakes at large scale. Landsat 7 Enhanced Thematic Mapper Plus (ETM +) mosaics from the GeoCover Circa 2000 dataset covering the Earth land surfaces with 14.25 m spatial resolution were used as input data. We developed an approach called GWEM (GeoCoverTM Water bodies Extraction Method) that combines remote sensing and GIS to extract water bodies and study their abundance and morphometry. All water bodies greater than 0.0002 km2 were taken into account as lakes. The accuracy of the method was tested on Sweden, where detailed maps of lakes, based on in situ data and orthophotos, exist for the whole country. The proposed method produced accurate results. The largest sources of errors are shadows of mountains and clouds, since the GeoCover mosaics are not absolutely cloud free.
|
|
