A first assessment of the Sentinel-2 Level 1-C cloud mask product to support informed surface analyses

Abstract Cloud detection in optical remote sensing images is a crucial problem because undetected clouds can produce misleading results in the analyses of surface and atmospheric parameters. Sentinel-2 provides high spatial resolution satellite data distributed with associated cloud masks. In this paper, we evaluate the ability of Sentinel-2 Level-1C cloud mask products to discriminate clouds over a variety of biogeographic scenarios and in different cloudiness conditions. Reference cloud masks for the identification of misdetection were generated by applying a local thresholding method that analyses Sentinel-2 Band 2 (0.490 μm) and Band 10 (1.375 μm) separately; histogram-based thresholds were locally tuned by checking the single bands and the natural color composite (B4B3B2); in doubtful cases, NDVI and DEM were also analyzed to refine the masks; the B2B11B12 composite was used to separate snow. The analysis of the cloud classification errors obtained for our test sites allowed us to get important inferences of general value. The L1C cloud mask generally underestimated the presence of clouds (average Omission Error, OE, 37.4%); this error increased (OE > 50%) for imagery containing opaque clouds with a large transitional zone (between the cloud core and clear areas) and cirrus clouds, fragmentation emerged as a major source of omission errors (R2 0.73). Overestimation was prevalently found in the presence of holes inside the main cloud bodies. Two extreme environments were particularly critical for the L1C cloud mask product. Detection over Amazonian rainforests was highly inefficient (OE > 70%) due to the presence of complex cloudiness and high water vapor content. On the other hand, Alpine orography under dry atmosphere created false cirrus clouds. Altogether, cirrus detection was the most inefficient. According to our results, Sentinel-2 L1C users should take some simple precautions while waiting for ESA improved cloud detection products

Geoelectrical Surveys for Characterization of the Coastal Saltwater Intrusion in Metapontum Forest Reserve (Southern Italy)

A geoelectrical survey was carried out in the Metapontum Forest Reserve located along the Ionian coast of the Basilicata region (Southern Italy). In this work we used the method of two-dimensional electrical resistivity tomography for obtaining high-resolution electrical images in the investigated site. In particular, three electrical resistivity tomography, all orthogonal to the coastline, in the investigated area were carried out. To complete and integrate the geophysical data, soil and groundwater samplings, seventeen and five, respectively, were analyzed using chemical physical techniques. Geoelectrical survey, supported by laboratory analysis of soil and water samples have revealed the presence of a process of saltwater in coastal Forest Reserve of Metapontum, which have caused the decline of the existing pine forest with the consequent erosion and desertification problems. The results have disclosed the way to identify and discriminate large areas affected by intensive soil salinization and high resolution electrical images of the subsurface electrical resistivity plays a key role in delineating the saltwater intrusion front in coastal areas. Furthermore, our integrated study represents a contribution to the future programs for the protection, planning, and management of the terrestrial and marine resources in this coastal area

Integrated Indicators for the Estimation of Vulnerability to Land Degradation

In this chapter we approach the assessment of the vulnerability to land degradation of a typical Mediterranean environment using a modified version of the ESA model. This approach combines analyses of the socio-economic component with analyses of the vegetation trends. According to the standard ESA strategy, different indicators representing the impact of agricultural and grazing activities are used. The main feature of these indicators is that they are census-based and consequently suitable only for the analysis at municipal scale. Therefore we have also elaborated a mechanization index (proxy for soil compaction induced by agricultural machineries) that uses land cover and morphological data [36], enabling high spatial resolution and faster rate of update. The indicators related to the anthropic impact are integrated into an overall Land Management Index (LMI) and in each area it is possible to enhance the main contributing factors to highlight the prevailing forces that drive human-induced degradation processes. In order to include vegetation in the vulnerability map we analyze satellite vegetation index NDVI (Normalized Difference Vegetation Index) which is recognized as ideal tool for monitoring long term trends of degradation phenomena and assessing different values of severity of the concerned processes [37,38]. The final result of our analyses is an integrated vulnerability map of the investigated region, accounting for management and vegetation factors, which allows us to identify priority sites where restoration/rehabilitation interventions are urgent. The adopted procedure can be easily applied to geographic contexts characterized by high complexity in terms of land cover type and economic vocation (intensive agriculture, grazing, industrial activities) thus enabling an early detection of the areas most vulnerable to land degradation

Investigating climate variability and long-term vegetation activity across heterogeneous Basilicata agroecosystems

The Basilicata region summarizes many basic features of the biogeographic complexity characterizing Mediterranean countries. The intricate geomorphology and the long history of human management generated the current landscapes, which include both high-value ecosystems and areas prone to desertification. Preserving goods and services provided by such composite land cover mosaics poses many problems due to the interference/overlap of diverse natural and anthropic factors which make the correct selection of relevant parameters and the interpretation of observational data rather difficult. Here, we study interconnections between local climate and vegetation activity by correlating parameters characterizing the interannual statistics of the NDVI (Normalized Difference Vegetation Index), derived from satellite data, with a recently devised multivariate statistical index of meteoclimatic variability. We used a 15-year sequence of remote images concerning a set of plots located around meteorological ground stations of the central-eastern part of the region to pick up spatial structures in the vegetation–climate relationships. Our analyses were able to correlate spatial heterogeneity to variations in water exchanges between vegetation and atmosphere. This study represents a first step to improve the description of relevant processes to protect natural habitats and quality agriculture, therefore combating land degradation and climate change detrimental effects

Exploring the Use of Sentinel-2 Data to Monitor Heterogeneous Effects of Contextual Drought and Heatwaves on Mediterranean Forests

The use of satellite data to detect forest areas impacted by extreme events, such as droughts, heatwaves, or fires is largely documented, however, the use of these data to identify the heterogeneity of the forests’ response to determine fine scale spatially irregular damage is less explored. This paper evaluates the health status of forests in southern Italy affected by adverse climate conditions during the hot and dry summer of 2017, using Sentinel-2 images (10m) and in situ data. Our analysis shows that the post-event—NDVI (Normalized Difference Vegetation Index) decrease, observed in five experimental sites, well accounts for the heterogeneity of the local response to the climate event evaluated in situ through the Mannerucci and the Raunkiaer methods. As a result, Sentinel-2 data can be effectively integrated with biological information from field surveys to introduce continuity in the estimation of climate change impacts even in very heterogeneous areas whose details could not be captured by lower resolution observations. This integration appears to be a successful strategy in the study of the relationships between the climate and forests from a dynamical perspective

L’industrializzazione dell’agricoltura nella Piana del Sele: una prospettiva geografica basata sull’Urban Atlas Copernicus

Il contributo nasce da un approccio interdisciplinare allo studio delle tra-sformazioni territoriali: ne sono autori, infatti, geografi, fisici e ingegneri ambientali esperti di telerilevamento. L’obiettivo è quello di studiare la recente espansione del capitalismo agricolo in una regione strategica per l’economia del Mezzogiorno: la Piana del Sele. In pochi anni, questo territorio a forte vocazione agri-cola ha conosciuto una drastica alterazione della copertura del suolo, che, se nel 2012 registrava un sostanziale equilibrio tra seminativi e serre, nel 2018, in appena sei anni, ha visto una crescita ponderosa delle serre a scapito proprio dei seminativi. È questa la conseguen-za dell’espansione della cosiddetta “quarta gamma” nel mercato or-tofrutticolo - esplosa anche in Italia nelle ultime due decadi – ovvero la produzione in serra di prodotti freschi, lavati e pronti al consumo. Si tratta di un fenomeno che, oltre alla valenza commerciale, ha dei riverberi geo-economici, sociali e ambientali di prim’ordine. In primo luogo, la penetrazione nei mercati locali dei grandi capitalisti agricoli; in secondo luogo, la riduzione della capacità degli ecosistemi di assi-curare beni e servizi; in terzo luogo, il depauperamento del paesaggio e il potenziale aumento del rischio idrogeologico. La metodologia d’indagine prevede l’analisi dei cambiamenti del-la land cover nei comuni di Battipaglia e Bellizzi, nella provincia di Salerno, nel segmento temporale 2012-2018 attraverso l’Urban Atlas Copernicus, realizzato utilizzando dati satellitari ad altissima risolu-zione. Attraverso il software InVEST, ai cambiamenti osservati è stata abbinata la quantificazione della perdita generata dalla riduzione dei beni e servizi ecosistemici.ritorial transformations: in fact, its authors are geographers, physicists and environmental engineers who are experts in remote sensing. The aim is to study the recent expansion of agricultural capitalism in a strategic region for the economy of the South: the Sele Plain. In just a few years, this territory with a strong agricultural vocation has experienced a drastic alteration of the land cover: in 2012 there was a substantial bal-ance between arable land and greenhouses, but in 2018, in just six years, there was a substantial growth of greenhouses own detriment of arable land. This is the consequence of the expansion of the so-called “fourth range” in the fruit and vegetable market - which has also grown up in Italy in the last two decades - or rather the greenhouse production of fresh, washed and ready-to-eat products. It is a phenomenon which, in addition to its commercial value, has first-rate geo-economic, social and environmental effects. First, the penetration of local markets by large ag-ricultural capitalists; secondly, the reduction of the ability of ecosystems to provide goods and services; thirdly, the depletion of the landscape and the potential increase in hydrogeological risk. The survey methodology involves the analysis of land cover changes in the municipalities of Battipaglia and Bellizzi, in the province of Salerno, in the 2012-2018 time span through the Urban Atlas Copernicus, created using very high resolution satellite data. Through the InVEST software, the observed changes were combined with the quantification of the loss generated by the reduction of the ecosystem goods and services

Editorial for the Special Issue “Advances of Remote Sensing in the Analysis of the Spatial and Temporal Variability of Land Surface”

Land systems have taken a central role in major environmental/climatic issues of the Anthropocene, as they are the result of interacting natural and anthropic processes that are crucial for life on Earth [...

Radium concentration and magnetic susceptibility measurements for characterizing soils devoted to cereal cultivation

In order to characterize soil samples collected in two different agricultural areas of Potenza suburbs (Southern Italy) devoted to durum wheat cultivation, we used the combination of two techniques: magnetic susceptibility measurements and effective radium concentration obtained from radon emanation. Magnetic susceptibility measurements are generally used as a proxy method for monitoring heavy metals in soil. Radium concentration and radon exhalation rate from soil are used for characterizing different soils. First results suggest that effective radium concentrations in soils can be helpful for the interpretation of magnetic susceptibility field surveys