The Emission Spectrum of the Hot Jupiter WASP-79b from HST/WFC3

Here we present a thermal emission spectrum of WASP-79b, obtained via Hubble Space Telescope Wide Field Camera 3 G141 observations as part of the PanCET program. As we did not observe the ingress or egress of WASP-79b’s secondary eclipse, we consider two scenarios: a fixed mid-eclipse time based on the expected occurrence time, and a mid-eclipse time as a free parameter. In both scenarios, we can measure thermal emission from WASP-79b from 1.1 to 1.7 μm at 2.4σ confidence consistent with a 1900 K brightness temperature for the planet. We combine our observations with Spitzer dayside photometry (3.6 and 4.5 μm) and compare these observations to a grid of atmospheric forward models that span a range of metallicities, carbon-to-oxygen ratios, and recirculation factors. Given the strength of the planetary emission and the precision of our measurements, we found a wide range of forward models to be consistent with our data. The best-match equilibrium model suggests that WASP-79b’s dayside has a solar metallicity and carbon-to-oxygen ratio, alongside a recirculation factor of 0.75. Models including significant H− opacity provide the best match to WASP-79b’s emission spectrum near 1.58 μm. However, models featuring high-temperature cloud species—formed via vigorous vertical mixing and low sedimentation efficiencies—with little day-to-night energy transport also match WASP-79b’s emission spectrum. Given the broad range of equilibrium chemistry, disequilibrium chemistry, and cloudy atmospheric models consistent with our observations of WASP-79b’s dayside emission, further observations will be necessary to constrain WASP-79b’s dayside atmospheric properties.

Wind Speed Analysis of Hurricane Sandy

The database of the HWind project sponsored by the National Oceanic and Atmospheric Administration (NOAA) for hurricanes between 1994 and 2013 is analysed. This is the first objective of the current research. Among these hurricanes, Hurricane Sandy was selected for a detailed study due to the number of files available and its social relevance, with this being the second objective of this study. Robust wind speed statistics showed a sharp increase in wind speed, around 6 m s−1 at the initial stage as Category 1, and a linear progression of its interquartile range, which increased at a rate of 0.54 m s−1 per day. Wind speed distributions were initially right-skewed. However, they evolved to nearly symmetrical or even left-skewed distributions. Robust kurtosis was similar to that of the Gaussian distribution. Due to the noticeable fraction of wind speed intermediate values, the Laplace distribution was used, its scale parameter increasing slightly during the hurricane’s lifecycle. The key features of the current study were the surface and recirculation factor calculation. The surface area with a category equal to, or higher than, a tropical storm was calculated and assumed to be circular. Its radius increased linearly up to 600 km. Finally, parcel trajectories were spirals in the lower atmosphere but loops in the mid-troposphere due to wind translation and rotation. The recirculation factor varied, reaching values close to 0.9 and revealing atmospheric stratification.

Sensitivity of CO2 and CH4 Annual Cycles to Different Meteorological Variables at a Rural Site in Northern Spain

The focus of the current paper is to explore the influence of meteorological variables on atmospheric CO2 and CH4 mean annual cycles at a rural site. Four variables were investigated: boundary layer height, recirculation factor, trajectory direction, and wind speed modelled at the altitude of the site. Boundary layer height and wind speed were provided by the METeorological data EXplorer (METEX) model. Recirculation factor and trajectory direction were obtained from calculations based on this trajectory model, and a nonparametric procedure was used to obtain a smooth evolution. The main results are higher concentrations obtained during the night, attributed to lower dispersion in this period. The smoothed values of the boundary layer height reached nearly 1200 m AGL during the day in August, and its low values caused high concentrations in spring. During the night, the recirculation factor and wind speed showed a sharp contrast between summer and winter. The average recirculation factor was low, 0.10, and average wind speed was 5.1 m·s−1. Trajectories were directionally distributed in four quadrants. Different tests were performed by selecting values of meteorological variables above or below certain thresholds. The influence of these variables reached values around 6.3 and 0.023 ppm for CO2 and CH4 average concentrations, respectively, during the day when the boundary layer was below 400 m. The main conclusion of this study is that the influence of meteorological variables should not be ignored. In particular, extremely low boundary layer heights may have noticeable effects on both gases.

MGT/HTFC Hybrid System Emulator Test Rig: Experimental Investigation on the Anodic Recirculation System

The Thermochemical Power Group (TPG) of the University of Genoa designed and installed a complete hybrid system emulator test rig equipped with a 100 kW recuperated micro gas turbine, a modular cathodic vessel located between recuperator outlet and combustor inlet, and an anodic recirculation system based on the coupling of a single stage ejector with an anodic vessel. The layout of the system was carefully designed, considering the coupling between a planar SOFC stack and the 100 kW commercial machine installed at TPG laboratory. A particular pressurized hybrid system was studied to define the anodic side properties in terms of mass flow rates, pressures, and temperatures. In this work, this experimental facility is used to analyze the anodic ejector performance from fluid dynamic and thermal points of view. The attention is mainly focused on the recirculation factor value in steady-state conditions. For this reason, a wide experimental campaign was carried out to measure the behavior of this property in different operative conditions with the objective to avoid carbon deposition in the anodic circuit, in the reformer, and in the fuel cell stack.

RECIRCULATION IN SHALLOW BAYS AND RIVERS

A theoretical model is presented to provide an approximation of the water and temperature recirculation in a shallow bay, lake or river, between the outlet and inlet canals of the cooling system for a power plant In particular, a temperature recirculation factor relating the outlet and inlet temperatures is derived.