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Träfflista för sökning "WFRF:(Ardö Jonas) srt2:(2015-2019)"

Sökning: WFRF:(Ardö Jonas) > (2015-2019)

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1.
  • Bodin, Theo, et al. (författare)
  • Annoyance, Sleep and Concentration Problems due to Combined Traffic Noise and the Benefit of Quiet Side.
  • 2015
  • Ingår i: International Journal of Environmental Research and Public Health. - : MDPI AG. - 1660-4601. ; 12:2, s. 1612-1628
  • Tidskriftsartikel (refereegranskat)abstract
    • Access to a quiet side in one's dwelling is thought to compensate for higher noise levels at the most exposed façade. It has also been indicated that noise from combined traffic sources causes more noise annoyance than equal average levels from either road traffic or railway noise separately.
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2.
  • Abdi, Abdulhakim, et al. (författare)
  • Evaluating Water Controls on Vegetation Growth in the Semi-Arid Sahel Using Field and Earth Observation Data
  • 2017
  • Ingår i: Remote Sensing. - : MDPI AG. - 2072-4292. ; 9:3
  • Tidskriftsartikel (refereegranskat)abstract
    • Water loss is a crucial factor for vegetation in the semi-arid Sahel region of Africa. Global satellite-driven estimates of plant CO2 uptake (gross primary productivity, GPP) have been found to not accurately account for Sahelian conditions, particularly the impact of canopy water stress. Here, we identify the main biophysical limitations that induce canopy water stress in Sahelian vegetation and evaluate the relationships between field data and Earth observation-derived spectral products for up-scaling GPP. We find that plant-available water and vapor pressure deficit together control the GPP of Sahelian vegetation through their impact on the greening and browning phases. Our results show that a multiple linear regression (MLR) GPP model that combines the enhanced vegetation index, land surface temperature, and the short-wave infrared reflectance (Band 7, 2105–2155 nm) of the moderate-resolution imaging spectroradiometer satellite sensor was able to explain between 88% and 96% of the variability of eddy covariance flux tower GPP at three Sahelian sites (overall = 89%). The MLR GPP model presented here is potentially scalable at a relatively high spatial and temporal resolution. Given the scarcity of field data on CO2 fluxes in the Sahel, this scalability is important due to the low number of flux towers in the region.
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3.
  • Abdi, Hakim, et al. (författare)
  • The El Niño – La Niña cycle and recent trends in supply and demand of net primary productivity in African drylands
  • 2016
  • Ingår i: Climatic Change. - : Springer Science and Business Media LLC. - 0165-0009 .- 1573-1480. ; 138:1, s. 111-125
  • Tidskriftsartikel (refereegranskat)abstract
    • Inter-annual climatic variability over a large portion of sub-Saharan Africa is under the influence of the El Niño-Southern Oscillation (ENSO). Extreme variability in climate is a threat to rural livelihoods in sub-Saharan Africa, yet the role of ENSO in the balance between supply and demand of net primary productivity (NPP) over this region is unclear. Here, we analyze the impact of ENSO on this balance in a spatially explicit framework using gridded population data from the WorldPop project, satellite-derived data on NPP supply, and statistical data from the United Nations. Our analyses demonstrate that between 2000 and 2013 fluctuations in the supply of NPP associated with moderate ENSO events average ± 2.8 g C m−2 yr.−1 across sub-Saharan drylands. The greatest sensitivity is in arid Southern Africa where a + 1 °C change in the Niño-3.4 sea surface temperature index is associated with a mean change in NPP supply of −6.6 g C m−2 yr.−1. Concurrently, the population-driven trend in NPP demand averages 3.5 g C m−2 yr.−1 over the entire region with densely populated urban areas exhibiting the highest mean demand for NPP. Our findings highlight the importance of accounting for the role ENSO plays in modulating the balance between supply and demand of NPP in sub-Saharan drylands. An important implication of these findings is that increase in NPP demand for socio-economic metabolism must be taken into account within the context of climate-modulated supply.
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4.
  • Ahlberg, Erik, et al. (författare)
  • "Vi klimatforskare stödjer Greta och skolungdomarna"
  • 2019
  • Ingår i: Dagens nyheter (DN debatt). - 1101-2447.
  • Tidskriftsartikel (populärvet., debatt m.m.)abstract
    • DN DEBATT 15/3. Sedan industrialiseringens början har vi använt omkring fyra femtedelar av den mängd fossilt kol som får förbrännas för att vi ska klara Parisavtalet. Vi har bara en femtedel kvar och det är bråttom att kraftigt reducera utsläppen. Det har Greta Thunberg och de strejkande ungdomarna förstått. Därför stödjer vi deras krav, skriver 270 klimatforskare.
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5.
  • Ahmed, Mohamed, et al. (författare)
  • Dynamic response of NDVI to soil moisture variations during different hydrological regimes in the Sahel region
  • 2017
  • Ingår i: International Journal of Remote Sensing. - : Informa UK Limited. - 1366-5901 .- 0143-1161. ; 38:19, s. 5408-5429
  • Tidskriftsartikel (refereegranskat)abstract
    • Over the last few decades, the African Sahel has become thefocus of many studies regarding vegetation dynamics and theirrelationships with climate and people. This is because rainfalllimits the production of biomass in the region, a resource onwhich people are directly dependent for their livelihoods. In thisstudy, we utilized a remote-sensing approach to answering thefollowing two questions: (1) how does the dynamic relationshipbetween soil moisture and plant growth vary across hydrologi-cal regimes, and (2) are vegetation-type-dependent responsesto soil moisture availability detectable from satellite imagery? Inorder to answer these questions, we studied the relationshipbetween monthly modelled soil moisture as an indicator forwater availability and the remotely sensed normalized differ-ence vegetation index (NDVI) as a proxy for vegetation growthbetween a“recovery rainfall period”(1982 to 1997) and a“stable rainfall period”(1998 to 2013), at different time lagsacross the Sahel region. Using windowed cross-correlation, wefind a strong significant positive relationship between NDVI andsoil moisture at a concurrent time and at NDVI lagging behindsoil moisture by 1 month for grassland, cropland, and decid-uous shrubland vegetation–the dominant vegetation classes inthe Sahel. South of the Sahel (the Sudanian and Guinean areas),wefind longer optimal lags (soil moisture lagged by 1–3 months) in association with mixed forest and deciduousshrubland. Wefind no major significant change in optimal lagbetween the recovery and stable periods in the Sahelian region;however, in the Sudanian and Guinean areas, we observe atrend towards shorter time lags. This change in optimal lagsuggests a vegetation change, which may be a response to aclimatic shift or land-use change. This approach of identifyingspatiotemporal trends in optimal lag correlations between mod-elled soil moisture and NDVI could prove to be a useful tool formapping vegetation change and ecosystem behaviour, in turnhelping inform climate change mitigation approaches and agri-cultural planning
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6.
  • Ardö, Jonas (författare)
  • Comparison between remote sensing and a dynamic vegetation model for estimating terrestrial primary production of Africa
  • 2015
  • Ingår i: Carbon Balance and Management. - : Springer Science and Business Media LLC. - 1750-0680. ; 10
  • Tidskriftsartikel (refereegranskat)abstract
    • Africa is an important part of the global carbon cycle. It is also a continent facing potential problems due to increasing resource demand in combination with climate change-induced changes in resource supply. Quantifying the pools and fluxes constituting the terrestrial African carbon cycle is a challenge, because of uncertainties in meteorological driver data, lack of validation data, and potentially uncertain representation of important processes in major ecosystems. In this paper, terrestrial primary production estimates derived from remote sensing and a dynamic vegetation model are compared and quantified for major African land cover types.
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7.
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8.
  • Ardö, Jonas, et al. (författare)
  • Meteorological measurements in Demokeya, North Kordofan : a contribution to climate change research
  • 2015
  • Ingår i: Sudan Academy of Sciences Journal-Special Issue (Climate Change). - 1816-8272. ; 11, s. 118-127
  • Tidskriftsartikel (refereegranskat)abstract
    • Studies of climatic change and adaptation to climate change can include a wide range of methodologies and approaches. As one of such approaches, we here present meteorological measurement data from a site in the Demokeya experimental forest outside El Obeid in North Kordofan State of Sudan. We hope this descriptive note can inform about the available meteorological data, as well as to promote and support the use of these data from Demokeya experimental forest in studies related to climate change and their role for agriculture and forestry.
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9.
  • Ardö, Jonas, et al. (författare)
  • MODIS EVI-based net primary production in the Sahel 2000–2014
  • 2018
  • Ingår i: International Journal of Applied Earth Observation and Geoinformation. - : Elsevier BV. - 1569-8432. ; 65, s. 35-45
  • Tidskriftsartikel (refereegranskat)abstract
    • Africa is facing resource problems due to increasing demand combined with potential climate-induced changes in supply. Here we aim to quantify resources in terms of net primary production (NPP [g C m−2 yr−1]) of vegetation in the Sahel region for 2000–2014.Using time series of the enhanced vegetation index (EVI) from MODIS, NPP was estimated for the Sahel region with a 500 × 500 m spatial resolution and 8-day temporal resolution. The estimates were based on local eddy covariance flux measurements from six sites in the Sahel region and the carbon use efficiency originating from a dynamic vegetation model.No significant NPP change was found for the Sahel as a region but, for sub-regions, significant changes, both increasing and decreasing, were observed. Substantial uncertainties related to NPP estimates and the small availability of evaluation data makes verification difficult. The simplicity of the methodology used, dependent on earth observation only, is considered an advantage.
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10.
  • Ardö, Jonas (författare)
  • Soil carbon sequestration and climate change in semi-arid Sudan
  • 2015
  • Ingår i: Sudan Academy of Sciences Journal-Special Issue (Climate Change). - 1816-8272. ; 11, s. 140-163
  • Tidskriftsartikel (refereegranskat)abstract
    • Climate change poses risk for natural and human systems in Africa. Increasing temperatures and changes in precipitation patterns is likely to affect agriculture, pastoralism and forestry. Mitigation of increasing atmospheric concentration of CO2 through soil carbon sequestration in semi-arid ecosystems may be beneficial to soil properties and cultivation. This paper describes and discusses soil carbon sequestration in relation to climate change in semi-arid regions, with special attention to the Sudan. It is anticipated that adaptation to climate changes is a more reasonable way to cope with future climate change than mitigation through soil carbon sequestration, especially for low emitting countries in Africa such as the Sudan.
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