Recently released Moderate-Resolution Imaging Spectroradiometer (MODIS) land surface temperature (LST) collection 6.1 (C6.1) products are useful for understanding ice–atmosphere interactions over East Antarctica, but their accuracy should be known prior to application. This study assessed Level 2 and Level 3 MODIS C6.1 LST products (MxD11_L2 and MxD11C1) in comparison with the radiance-derived in situ LSTs from 12 weather stations. Significant cloud-related issues were identified in both LST products. By utilizing a stricter filter based on automatic weather station cloud data, despite losing 29.4% of the data, accuracy of MODIS LST was greatly improved. The cloud-screened MODIS LST exhibited cold biases (−5.18 to −0.07°C, and root mean square errors from 2.37 to 6.28°C) than in situ LSTs at most stations, with smaller cold biases at inland stations, but larger ones at coastal regions and the edge of plateau. The accuracy was notably higher during warm periods (October–March) than during cold periods (April–September). The cloud-screened MODIS C6.1 LST did not show significant improvements over C5 (Collection 5) version across East Antarctica. Ice-crystal precipitation occurring during temperature inversions at the surface (Tair-Tsurface) played a crucial role in MODIS LST accuracy on inland plateau. In coastal regions, larger MODIS LST biases were observed when the original measurements were lower.

The absolute dating of mortar by accelerator mass spectrometry (AMS) has been the subject of renewed interest for several years. International intercomparison campaigns, called MODIS (MOrtar Dating Intercomparison Study), have been carried out. The first MODIS-1 campaign highlighted limitations in mortar dating, due to the similarity between the primary material to be dated (binder) and the contaminant (exogenous CaCO3). Methods have since emerged to overcome this problem and the need for a good preliminary characterization has been proven. The Laboratoire de Mesure du Carbone 14 (LMC14) took part in the second intercomparison campaign, MODIS2, by applying thermal decomposition increments to distinguish the carbonated binder, the organic matter contaminants (late in formation pyrogenic carbonate, LDH) and limestone. The LMC14 results on MODIS2 are quite conclusive on “pure” re-carbonated lime mortar binders containing little contaminant geological limestone but show their weaknesses for mortars heavily contaminated in Dolomites, which are difficult to discern from the binder. Recommendations for users of radiocarbon (14C) dating on mortar-based materials are made in the conclusion.

The dry lowlands of Ethiopia are seasonally affected by long periods of low rainfall and, coinciding with rainfall in the Amhara highlands, flood waters which flow onto the lowlands resulting in damage to landscapes and settlements. In an attempt to convert water from storm generated floods into productive use, this study proposes a methodology using remote sensing data and geographical information system tools to identify potential sites where flood spreading weirs may be installed and farming systems developed which produce food and fodder for poor rural communities. First, land use land cover maps for the study area were developed using Landsat-8 and MODIS temporal data. Sentinel-1 data at 10 and 20 m resolution on a 12-day basis were then used to determine flood prone areas. Slope and drainage maps were derived from Shuttle RADAR Topography Mission Digital Elevation Model at 90 m spatial resolution. Accuracy assessment using ground survey data showed that overall accuracies (correctness) of the land use/land cover classes were 86% with kappa 0.82. Coinciding with rainfall in the uplands, March and April are the months with flood events in the short growing season (belg) and June, July and August have flood events during the major (meher) season. In the Afar region, there is potentially >0.55 m ha land available for development using seasonal flood waters from belg or meher seasons. During the 4 years of monitoring (2015–2018), a minimum of 142,000 and 172,000 ha of land were flooded in the belg and meher seasons, respectively. The dominant flooded areas were found in slope classes of <2% with spatial coverage varying across the districts. We concluded that Afar has a huge potential for flood-based technology implementation and recommend further investigation into the investments needed to support new socio-economic opportunities and implications for the local agro-pastoral communities.

Recent greening of vegetation across the Arctic is associated with warming temperatures, hydrologic change and shorter snow-covered periods. Here we investigated trends for a subset of arctic vegetation on the island of Greenland. Vegetation in Greenland is unique due to its close proximity to the Greenland Ice Sheet and its proportionally large connection to the Greenlandic population through the hunting of grazing animals. The aim of this study was to determine whether or not longer snow-free periods (SFPs) were causing Greenlandic vegetation to dry out and become less productive. If vegetation was drying out, a subsequent aim of the study was to determine how widespread the drying was across Greenland. We utilized a 15-year time-series obtained by the MODerate Resolution Imaging Spectroradiometer (MODIS) to analyze the Greenland vegetation by deriving descriptors corresponding with the SFP, the number of cumulative growing degree-days and the time-integrated Normalized Difference Vegetation Index. While the productivity of most vegetated areas increased in response to longer growing periods, there were localized regions that exhibited signs consistent with the drying hypothesis. In these areas, vegetation productivity decreased in response to longer SFPs and more accumulated growing degree-days.

Phenology is a key ecosystem process that reflects climate–vegetation functioning, and is an indicator of global environmental changes. Recently, it has been suggested that land-use change and timber extraction promote differences in forest phenology. We use remote-sensing data to describe regional leaf phenological patterns in combination with field data from 131 plots in old-growth and disturbed forests distributed over subtropical forests of Argentina (54–65°W). We assessed how climate is related to phenological patterns, and analysed how changes in forest structural characteristics such as stock of above-ground biomass relate to the observed phenological signals across the gradient. We found that the first three axes of a principal component analysis explained 85% of the variation in phenological metrics across subtropical forests, ordering plots mainly along indicators of seasonality and productivity. At the regional scale, the relative importance of forest biomass in explaining variation in phenological patterns was about 15%. Climate showed the highest relative importance, with temperature and rainfall explaining Enhanced Vegetation Index metrics related to seasonality and productivity patterns (27% and 47%, respectively). Within forest types, climate explains the major fraction of variation in phenological patterns, suggesting that forest function may be particularly sensitive to climate change. We found that forest biomass contributed to explaining a proportion of leaf phenological variation within three of the five forest types studied, and this may be related to changes in species composition, probably as a result of forest use.

An accurate radiocarbon (14C) dating of mortars requires adjusting the sample preparation procedure to each specific mortar composition. In order to follow the influence of mortar components and the preparation procedure on dating results, a mortar intercomparison study (MODIS) was undertaken by 10 organizations (institutes and laboratories) in the analyses of four different types of mortars (see in this issue Hajdas et al. 2017 and Hayen et al. 2017). This paper presents the preparation protocol DoM v.1 applied by the Poznań team, together with dating results on a set of mortar samples used for the of intercomparison. This procedure involved petrographic observations, SEM-EDS analyses, different mechanical-chemical preparation, a test of leaching reaction for available fractions, and finally 14C dating of chosen samples. The applied preparation allows one to obtain dry-sieved grain fractions and different fractions from suspension: grain fractions from suspension collected in different times of leaching, repeated suspension (different portions), as well as suspension collected at different times of sedimentation. The obtained results show the great importance of good sampling and the influence of sample preparation on 14C dating results.

Seven radiocarbon laboratories: Åbo/Aarhus, CIRCE, CIRCe, ETHZ, Poznań, RICH, and Milano-Bicocca performed separation of carbonaceous fractions suitable for 14C dating of four mortar samples selected for the MOrtar Dating Inter-comparison Study (MODIS). In addition, optically stimulated luminescence (OSL) analyses were completed by Milano-Bicocca and IRAMAT-CRP2A Bordeaux. Each laboratory performed separation according to laboratory protocol. Results of this first intercomparison show that even though consistent 14C ages were obtained by different laboratories, two mortars yielded ages different than expected from the archaeological context.

Closed basin playas are among the most sensitive hydrologic systems globally and are excellent indicators of current and past climatic variability. This variability can significantly impact hydrologic regimes and biotic communities, and is often expressed in lake-bed deposits and shoreline features. We analyzed two playa basins in western North America that lie to either side of the current divide between monsoon and westerly precipitation regimes. Using a 23-year sequence of Landsat images at a 16-day time step, we determined the playa inundation response to varying precipitation inputs. Our results show that a strongly contrasting lake-inundation response occurs in lake basins separated by only 200 km. The Animas/Lordsburg Basin shows a marked lake-area increase in response to winter precipitation events, while the more southerly Palomas Basin shows a stronger response to monsoonal and El Niño-type events. This sensitivity to different input sources over short distances may explain some of the apparent asynchronous behavior of playa response found in lake records. Comprehensive regional-scale inundation records could be used to understand the dynamics of playa inundation events and how these events are linked to atmospheric circulation, and possibly to understand the observed asynchronous behavior of lake basins during the late Pleistocene and Holocene.

Marine-terminating outlet glaciers discharge most of the Greenland ice sheet's mass through frontal ablation and meltwater runoff. While calving can be estimated by in situ and remote sensing observations, submarine melting and subglacial meltwater transport are more challenging to quantify. Here we investigate the subglacial hydrology of Rink Isbræ, a fast-flowing West Greenland tidewater glacier, using time-lapse photography, modeled runoff estimates and daily satellite imagery from 2007 to 2011. We find that sediment plumes appear episodically at four distinct locations across the terminus, and last between 2 h and 17 d. This suggests short-term variability in discharge and the existence of persistent pathways. The seasonal onset of sediment plumes occurs before supraglacial lake drainages, shortly after the onset of runoff, and only after the wintertime ice mélange has begun disintegrating. Plumes were also visible after the cessation of runoff (23 ± 5 d), which is indicative of subglacial storage. The lack of either a seasonal velocity change or a correspondence between meltwater availability and plume occurrence suggests that the subglacial system persists in a state of inefficient drainage. Subglacial hydrology at tidewater glaciers is of critical importance in understanding dynamics at the ice front.

The availability of spatial data sourced from either field-derived or satellite-based systems has created new opportunities to estimate and/or monitor changes in carbon sequestration rates, climate change impacts or the potential habitat alterations occurring across large landscapes. However, an effort to create models is not standardized, in part, due to different needs and data sources available for the models. For example, data may have different spatial resolutions with varying degrees of complexity in regards to inputs and statistical methods. This study determines effects of 20, 15, 10, five and one km sampling resolutions on detection of changes in net primary productivity (NPP), occupancy selection criteria for areas to be included in the sample and identification of significant variables impacting NPP in Indonesia forests. Production forest designated for selective harvest was used to define the sampling areas. Variances explained by predictive models were similar across cell sizes although relative importance of variables was different. Partial dependence plots were used to search for potential thresholds or tipping points of NPP change as affected by an independent variable such as minimum daytime temperature. Applying different cell occupancy selection rules significantly changed the overall distribution of NPP values. The magnitude of those changes within a cell size varied with changes in cell size. The mean estimated NPP for production forests across Indonesia differed significantly at every sampling resolution and occupancy selection criteria. Lows ranged from 1.107 to 1.121 kg C m−2 yr−1 for the 1-km cell size for the three occupancy selection criteria with highs ranging from 1.245 to 1.189 kg C m−2 yr−1 for the 20-km cell size. The difference in NPP values between these two cell sizes for the three occupancy selection criteria extrapolates to a range in annual biomass of 132 × 106 to 66 × 106 t for the total area of production forests in Indonesia.

Of the more than twenty historically active volcanoes in Antarctica and the sub-Antarctic region only two, to our knowledge, host any ground-based monitoring instruments. Moreover, because of their remoteness, most of the volcanoes are seldom visited, thus relegating the monitoring of volcanism in this region almost entirely to satellites. In this study, high temporal resolution satellite data from the Hawaii Institute of Geophysics and Planetology's MODVOLC system using MODIS (Moderate Resolution Imaging Spectroradiometer) are complemented with high spatial resolution data (ASTER, or Advanced Spaceborne Thermal Emission and Reflection Radiometer, and similar sensors) to document volcanic activity throughout the region during the period 2000–10. Five volcanoes were observed in eruption (Mount Erebus, Mount Belinda, Mount Michael, Heard Island and McDonald Island), which were predominantly low-level and effusive in nature. Mount Belinda produced tephra, building a cinder cone in addition to an extensive lava field. Five volcanoes exhibited detectable thermal, and presumed fumarolic, activity (Deception, Zavodovski, Candlemas, Bristol, and Bellingshausen islands). A minor eruption reported at Marion Island was not detected in our survey due to its small size. This study also discovered a new active vent on Mount Michael, tracked dramatic vent enlargement on Heard Island, and provides an improved picture of the morphology of some of the volcanoes.

Carbon-based forest conservation requires the establishment of ‘reference emission levels’ against which to measure a country or region's progress in reducing their carbon emissions. In East Africa, landscape-scale estimates of carbon fluxes are uncertain and factors such as deforestation poorly resolved due to a lack of data. In this study, trends in vegetation cover and carbon for East Africa were quantified using moderate-resolution imaging spectroradiometer (MODIS) land cover grids from 2002 to 2008 (500-m spatial resolution), in combination with a regional carbon look-up table. The inclusion of data on rainfall and the distribution of protected areas helped to gauge impacts on vegetation burning (assessed using 1-km spatial resolution MODIS active fire data) and biome trends. Between 2002 and 2008, the spatial extents of forests, woodlands and scrublands decreased considerably and East Africa experienced a net carbon loss of 494 megatonnes (Mt). Most countries in the area were sources of carbon emissions, except for Tanzania and Malawi, where the areal increase of savannah and woodlands counterbalanced carbon emissions from deforestation. Both Malawi and Tanzania contain large areas of planted forest. Vegetation burning was correlated with rainfall (forest only) and differed depending on land management. Freely available global earth observation products have provided ways to achieve rapid assessment and monitoring of carbon change hotspots at the landscape scale.

A scheme for the detection of fog and low stratus over land during daytime based on data of the MODIS (Moderate Resolution Imaging Spectroradiometer) instrument is presented. The method is based on an initial threshold test procedure in the MODIS solar bands 1–7 (0.62–2.155 μm). Fog and low stratus detection generally relies on the definition of minimum and maximum fog and low stratus properties, which are converted to spectral thresholds by means of radiative transfer calculations (RTC). Extended sensitivity studies reveal that thresholds mainly depend on the solar zenith angle and, hence, illumination-dependent threshold functions are developed. Areas covered by snow, ice and mid-/high-level clouds as well as bright/hazy land surfaces are omitted from the initial classification result by means of a subsequent cloud-top height test based on MODIS IR band 31 (at 12 μm) and a NIR/VIS ratio test. The validation of the final fog and low stratus mask generally shows a satisfactory performance of the scheme. Validation problems occur due to the late overpass time of the TERRA platform and the time lag between SYNOP and satellite observations. Apparent misclassifications are mainly found at the edge of the fog layers, probably due to over-or underestimation of fog and low stratus cover in the transition zone from fog to haze.