Abstract We describe a time series of meteorological parameters and surface energy balance components of a seasonal snow cover from an automatic weather station (4863 m a.s.l., 32.28° N, 77.58° E), for a winter season from 1 December 2012 to 30 March 2013, located on a moraine close to the equilibrium line altitude of Chhota Shigri glacier, Himachal Pradesh, India. The analysis shows that for over 80% of the time in winter, the snow surface was at a cooling phase. During late winter however, the surface had some positive residual energy which induced some melt during peak hours of the day. The net all-wave radiation was mostly negative during winter because of the high reflective property of snow and reduced incoming longwave radiation due to low cloud. The sensible heat flux heats the surface at night and enhances the cooling during day. The latent heat flux is always negative, showing that the surface is losing mass through sublimation processes (−0.83 mm w.e./day). A correlation between the energy fluxes and temperature shows a distinct relationship between fluxes. A comparison between the two studies performed on- and off-glacier reveals a significant difference in some parameters. A higher value (−1.08 mm/day) of sublimation rate at 4863 m a.s.l. shows that a large amount of energy available at the surface was used in sublimation processes. A comparatively lower albedo, relative humidity and net longwave radiation and higher latent heat flux, wind speed and net shortwave radiation yield a distinctive surface energy balance, highlighting the need for a large number of stations at different zones to achieve a coherent picture of energy balance in the region.

Abstract During the period 28 February 2000–31 December 2013, the MODVOLC system ( http://modis.higp.hawaii.edu ) autonomously analysed almost 9 trillion (i.e. 9×10 12 ) pixels contained within almost 3 million MODIS images, searching for evidence of high-temperature thermal signatures associated with volcanic eruptions. Thermal unrest, mainly associated with active lava, be it in the form of flows, domes, lakes or confined to vents, was detected at 93 volcanoes during this period of time. The first part of this paper describes the physical basis and operational implementation of the MODVOLC algorithm. The second part presents data to detail the nature of the thermal emission from these 93 volcanoes over the past 14 years.

Abstract We describe a new volcanic hotspot detection system, named Middle InfraRed Observation of Volcanic Activity (MIROVA), based on the analysis of infrared data acquired by the Moderate Resolution Imaging Spectroradiometer sensor (MODIS). MIROVA uses the middle infrared radiation (MIR), measured by MODIS, in order to detect and measure the heat radiation deriving from volcanic activity. The algorithm combines spectral and spatial principles, allowing the detection of heat sources from 1 megawatt (MW) to more than 10 gigawatt (GW). This provides a unique opportunity to: (i) recognize small-scale variations in thermal output that may precede the onset of effusive activity; (ii) track the advance of large lava flows; (iii) estimate lava discharge rates; (iv) identify distinct effusive trends; and, lastly, (v) follow the cooling process of voluminous lava bodies for several months. Here we show the results obtained from data sets spanning 14 years recorded at the Stromboli and Mt Etna volcanoes, Italy, and we investigate the above aspects at these two persistently active volcanoes. Finally, we describe how the algorithm has been implemented within an operational near-real-time processing chain that enables the MIROVA system to provide data and infrared maps within 1–4 h of the satellite overpass.