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Papers by Thomas Theis Nielsen

General rights Copyright and moral rights for the publications made accessible in the public port... more General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights. • Users may download and print one copy of any publication from the public portal for the purpose of private study or research. • You may not further distribute the material or use it for any profit-making activity or commercial gain. • You may freely distribute the URL identifying the publication in the public portal. Alle rettigheder forbeholdes centret (CLF). Mekanisk eller fotografisk gengivelse af denne REPORT eller dele heraf er uden instituttets skriftlige samtykke forbudt ifølge gaeldende dansk lov om ophavsret. Undtaget herfra er uddrag til anmeldelser.

The map of the Operational Plan for the Coastal Front, from Poland 1970 forms the basis for this ... more The map of the Operational Plan for the Coastal Front, from Poland 1970 forms the basis for this paper. The map portraits the blueprint of the combined operational war plans for the Polish military in the late 1960’s and 70’s. It details the offensive against NATO countries and their forces in Northern Europe. As such, this map is clearly designed as an operational map produced to outline and regulate, not just the actual plan of the offensive, but also to produce a narrative about the Polish army as capable of undertaking such a massive enterprise. We argue, with a point of departure in this particular map, that the regional, operational scale of military maps can be understood as performative maps, outlining not just plans and structuring space, but often also narratives.

Coordinating Lead Authors: Uriel Safriel, Zafar Adeel Lead Authors: David Niemeijer, Juan Puigdef... more Coordinating Lead Authors: Uriel Safriel, Zafar Adeel Lead Authors: David Niemeijer, Juan Puigdefabregas, Robin White, Rattan Lal, Mark Winslow, Juliane Ziedler, Stephen Prince, Emma Archer, Caroline King Contributing Authors: Barry Shapiro, Konrad Wessels, Thomas Nielsen, Boris Portnov, Inbal Reshef, Jillian Thonell, Esther Lachman, Douglas McNab Review Editors: Mohammed El-Kassas, Exequiel Ezcurra

Geografisk Tidsskrift-Danish Journal of Geography, 1997

Geografisk Tidsskrift-Danish Journal of Geography, 2006

Abstract Geografisk Tidsskrift, Danish Journal of Geography 106(1):87–102, 2006 The AVHRR (Advanc... more Abstract Geografisk Tidsskrift, Danish Journal of Geography 106(1):87–102, 2006 The AVHRR (Advanced Very High Resolution Radiometer) 8 km resolution Pathfinder NDVI (Normalized Difference vegetation Index) 10-day composite data set has been used for numerous local and global scale vegetation time series studies during recent decades. The dataset is a result of considerable processing and resampling from the original 1 km resolution AVHRR LAC (Local Area Coverage) data and combined with inappropriate sensor band design for vegetation monitoring these factors potentially introduce noise in the Pathfinder NDVI. The quality of the Pathfinder data has been difficult to assess but the recent release of SPOT-4 Vegetation (VGT) 10-day composite (S10) NDVI data is considered to be an improvement on the AVHRR data and offers the first possibility for a correct analysis/evaluation of the Pathfinder data.—In this study, three years of AVHRR Pathfinder and resampled SPOT-4 VGT (1998–2000) data has been evaluated/analysed using an ortho-regression analysis on 10-day, monthly and annual integrated values. Annual integrated values of AVHRR Pathfinder and SPOT-4 VGT data can be characterized by a linear relationship and correlate well on a continental scale. However the dynamic range of the SPOT-4 VGT NDVI is higher than the AVHRR Pathfinder NDVI. Analysis of individual IGBP biomes shows biome specific differences; evergreen broadleaf forest characterized by lower r values and highest RMSE values and normalized RMSE values indicate largest divergence for the shrubland biome. When performing the analysis on monthly maximum composites and 10-day composite data, intra-annual variations appear. Analyses of 10-day data also show a linear relationship between the NDVI of the two composite products; the relationship being characterized by lower r values and higher RMSE's. Monthly and 10-day maximum composites reveal intra-annual variations in the correlation between the SPOT-4 VGT and AVHRR Pathfinder data. This is attributed to different cloud masking algorithms; the SPOT-4 VGT cloud screening algorithm being insufficient thereby suppressing the rainy season ND VI. However, the correspondence between the SPOT-4 VGT and A VHRR PAL data is considerably better for a transect analysis covering an area not severely influenced by clouds when compared to the continental scale analysis. This suggests that the major part of the noise found in the continental scale SPOT-4 VGT NDVI and AVHRR PAL NDVI analyses can be attributed the different cloud masking algorithms and is to a lesser degree a consequence of the AVHRR PAL NDVI resampling. It is concluded that the quality of the AVHRR NDVI PAL is adequate for time series continental scale vegetation analysis despite the resampling scheme.

Human Ecology, 2000

The temporal and spatial distribution of fires for an area in east-central Senegal was determined... more The temporal and spatial distribution of fires for an area in east-central Senegal was determined on the basis of multi-temporal NOAA AVHRR satellite images. Three years of data (1990–1992) were analyzed defining the boundary between two different fire regimes: very few and scattered fires to the north with the majority of fires south of the boundary. This boundary was stable

The process of becoming a geographer is by no means simple and incorporates huge amounts of disci... more The process of becoming a geographer is by no means simple and incorporates huge amounts of disciplinary embodiment. This paper provides an example of how this is enacted by exploring the perceptions of fieldwork within the education of Danish geographers. Firstly, the history of education of Danish geographers is unfolded. Secondly, it is shown that despite quite different organisational structures, in terms of the way that fieldwork is introduced and the educational structure in general; only little variations in learning objectives can be identified between the three Danish universities that educate geographers. Thirdly, based on an empirical study of Danish university geographers, we find three different perceptions of fieldwork as a learning methodology: fieldwork as an outdoor laboratory, fieldwork as sensuous realisation and fieldwork as a meta-theoretical practice. The results show that these three perceptions are not allocated to different academics or traditions, meaning that the individual researcher often encompasses more than one view of fieldwork either in relation to his or her own research or in relation to the education of future geographers. The categories of fieldwork presented, therefore, do not support the often claimed dichotomy between physical and human geography. Instead, the openness of geography as a synthesis discipline is found.

On the Frontiers of Climate and Environmental Change, 2013

This chapter compares the impact of land use changes in two municipalities. We look at the long-t... more This chapter compares the impact of land use changes in two municipalities. We look at the long-term changes regarding the expansion of acacia production and the effects of tropical storms. Due to households experiencing significant economic gains after only a few years, both primary forest and agricultural land are being replaced with acacia tree plantations. The downside to this is an increasing social inequality, which follows in the wake of both government decree support given to monoculture promotion, and the influences of market forces. We observe signs of social differentiation, where poor households end up serving as casual labour for the richer families on their acacia plantations. In addition, the poor can be rendered even more vulnerable after becoming labourers for the richer families, because they may no longer have an alternative source of income, yet they still face the risk of an increasing frequency of typhoon exposure.

Renewable and Sustainable Energy Reviews, 2010

Geografisk Tidsskrift-Danish Journal of Geography, 2014

ABSTRACT Vegetation dynamics of the West African Sahel has attracted great scientific interest ov... more ABSTRACT Vegetation dynamics of the West African Sahel has attracted great scientific interest over the last 40 years because of the dramatic inter-decadal variability observed in the resource base of the region directly impacting on the livelihoods of the West African population. From farmers to pastoralists, agro-pastoralists and forest-users, all depend on the availability of vegetation resources and are affected by fluctuations in the available vegetation resource. Vegetation dynamics are controlled by both natural and human factors, including climate change and variability, increased concentration of CO2 in the atmosphere, grazing pressure, bush fires and agricultural expansion or contraction. The use of satellite data in combination with field data played a major role in the monitoring of vegetation dynamics and land use in the Sahel, since the mega drought of the 1970s and the 1980s. This paper briefly reviews the advance of satellite-based monitoring of vegetation dynamics over these 40 years. We discuss the promises of current and likely future data sources and analysis tools, as well as the need to strengthen in situ data collection to support and validate satellite-based vegetation and land use monitoring and modelling.

Geografisk Tidsskrift-Danish Journal of Geography, 2003

ABSTRACT

Remote Sensing of Environment, 2009

data is available from 1981 to present time. The global coverage 8 km resolution 15-day composite... more data is available from 1981 to present time. The global coverage 8 km resolution 15-day composite data set has been used for numerous local to global scale vegetation time series studies during recent years. Several aspects however potentially introduce noise in the NDVI data set due to the AVHRR sensor design and data processing. More recent NDVI data sets from both Terra MODIS and SPOT VGT data are considered an improvement over AVHRR and these products in theory provide a possibility to evaluate the accuracy of GIMMS NDVI time series trend analysis for the overlapping period of available data. In this study the accuracy of the GIMMS NDVI time series trend analysis is evaluated by comparison with the 1 km resolution Terra MODIS (MOD13A2) 16-day composite NDVI data, the SPOT Vegetation (VGT) 10-day composite (S10) NDVI data and in situ measurements of a test site in Dahra, Senegal. Linear least squares regression trend analysis on eight years of GIMMS annual average NDVI (2000-2007) has been compared to Terra MODIS (1 km and 8 km resampled) and SPOT VGT NDVI data 1 km (2000-2007). The three data products do not exhibit identical patterns of NDVI trends. SPOT VGT NDVI data are characterised by higher positive regression slopes over the 8-year period as compared to Terra MODIS and AVHRR GIMMS NDVI data, possibly caused by a change in channels 1 and 2 spectral response functions from SPOT VGT1 to SPOT VGT2 in 2003. Trend analysis of AVHRR GIMMS NDVI exhibits a regression slope range in better agreement with Terra MODIS NDVI for semi-arid areas. However, GIMMS NDVI shows a tendency towards higher positive regression slope values than Terra MODIS in more humid areas. Validation of the different NDVI data products against continuous in situ NDVI measurements for the period 2002-2007 in the semi-arid Senegal revealed a good agreement between in situ measurements and all satellite based NDVI products. Using Terra MODIS NDVI as a reference, it is concluded that AVHRR GIMMS coarse resolution NDVI data set is well-suited for long term vegetation studies of the Sahel-Sudanian areas receiving b 1000 mm rainfall, whereas interpretation of GIMMS NDVI trends in more humid areas of the Sudanian-Guinean zones should be done with certain reservations.