scholarly journals Effects of flux variation on the surface temperatures of Earth-analog circumbinary planets

2020 ◽  
Vol 499 (1) ◽  
pp. 1506-1521
Author(s):  
S Karthik Yadavalli ◽  
Billy Quarles ◽  
Gongjie Li ◽  
Nader Haghighipour
Keyword(s):  
Differential Evolution ◽  
Surface Temperature ◽  
Binary Star ◽  
Balance Model ◽  
Flux Variation ◽  
Short Term ◽  
Dynamical Mass ◽  
Single Star ◽  
Hypothetical System ◽  
Circumbinary Planets

ABSTRACT The Kepler Space telescope has uncovered around thirteen circumbinary planets (CBPs) that orbit a pair of stars and experience two sources of stellar flux. We characterize the top-of-atmosphere flux and surface temperature evolution in relation to the orbital short-term dynamics between the central binary star and an Earth-analog CBP. We compare the differential evolution of an Earth-analog CBP’s flux and surface temperature with that of an equivalent single-star (ESS) system to uncover the degree by which the potential habitability of the planet could vary. For a Sun-like primary, we find that the flux variation over a single planetary orbit is greatest when the dynamical mass ratio is $\sim$0.3 for a G-K spectral binary. Using a latitudinal energy balance model, we show that the ice-albedo feedback plays a substantial role in (Earth-analog) CBP habitability due to the interplay between flux redistribution (via obliquity) and changes in the total flux (via binary gyration). We examine the differential evolution of flux and surface temperature for Earth-like analogs of the habitable zone CBPs (4 Kepler and 1 hypothetical system) and find that these analogs are typically warmer than their ESS counterparts.

scholarly journals Surface flux patterns on planets in circumbinary systems and potential for photosynthesis

2014 ◽  
Vol 14 (3) ◽  
pp. 465-478 ◽  
Author(s):  
Duncan H. Forgan ◽  
Alexander Mead ◽  
Charles S. Cockell ◽  
John A. Raven
Keyword(s):  
Binary Star ◽  
Surface Flux ◽  
Close Binary ◽  
Mass Motion ◽  
Single Star ◽  
Photosynthetic Organisms ◽  
Spatial And Temporal Distributions ◽  
Close Binary Star ◽  
Binary Star System ◽  
Circumbinary Planets

AbstractRecently, the Kepler Space Telescope has detected several planets in orbit around a close binary star system. These so-called circumbinary planets will experience non-trivial spatial and temporal distributions of radiative flux on their surfaces, with features not seen in their single-star orbiting counterparts. Earth-like circumbinary planets inhabited by photosynthetic organisms will be forced to adapt to these unusual flux patterns. We map the flux received by putative Earth-like planets (as a function of surface latitude/longitude and time) orbiting the binary star systems Kepler-16 and Kepler-47, two star systems which already boast circumbinary exoplanet detections. The longitudinal and latitudinal distribution of flux is sensitive to the centre-of-mass motion of the binary, and the relative orbital phases of the binary and planet. Total eclipses of the secondary by the primary, as well as partial eclipses of the primary by the secondary add an extra forcing term to the system. We also find that the patterns of darkness on the surface are equally unique. Beyond the planet's polar circles, the surface spends a significantly longer time in darkness than latitudes around the equator, due to the stars’ motions delaying the first sunrise of spring (or hastening the last sunset of autumn). In the case of Kepler-47, we also find a weak longitudinal dependence for darkness, but this effect tends to average out if considered over many orbits. In the light of these flux and darkness patterns, we consider and discuss the prospects and challenges for photosynthetic organisms, using terrestrial analogues as a guide.

scholarly journals Birth environment of circumbinary planets: are there circumbinary planets on inclined orbits?

2020 ◽  
Vol 493 (2) ◽  
pp. 1907-1912 ◽  
Author(s):  
Chuan-Tao Ma ◽  
Yan-Xiang Gong ◽  
Xiao-Mei Wu ◽  
Jianghui Ji
Keyword(s):  
Binary Star ◽  
Outer Region ◽  
Close Binary ◽  
Close Binaries ◽  
Occurrence Rate ◽  
Single Star ◽  
Orbital Inclination ◽  
Close Encounters ◽  
Birth Environment ◽  
Circumbinary Planets

ABSTRACT The distribution of the orbital inclination angles of circumbinary planets (CBPs) is an important scientific issue, and it is of great significance for estimating the occurrence rate of CBPs and studying their formation and evolution. Although the CBPs currently discovered by the transit method are nearly coplanar, the true distribution of the inclinations of CBPs is still unknown. Previous research on CBPs has mostly regarded them as isolated binary-planet systems, without considering the birth environment of their host binaries. It is generally believed that almost all stars are born in clusters. Therefore, it is necessary to consider the effects of the close encounters of stars on CBP systems. In this paper, we discuss how the close encounters of fly-by stars affect the inclinations of CBPs. Based on extensive numerical simulations, we have found that CBPs in a close binary with a spacing of ∼0.2 au are almost unaffected by fly-by stars. Their orbits remain coplanar. However, when the spacing of the binary stars is greater than 1 au, two to three fly-bys of an intruding star can excite a considerable inclination, even for a CBP near the unstable boundary of the binary. For CBPs in the outer region, the fly-by of a single star can excite an inclination to more than 5°. In particular, CBPs in near polar or retrograde orbits can naturally form through binary–star encounters. If close binaries are born in open clusters, our simulations suggest that there may be high-inclination CBPs in binaries with a spacing >1 au.

scholarly journals Applying the METRo model for road-condition forecasting in Norway 

2021 ◽  
Author(s):  
Stephanie Mayer ◽  
Fabio Andrade ◽  
Torge Lorenz ◽  
Luciano de Lima ◽  
Anthony Hovenburg ◽  
...  
Keyword(s):  
Surface Temperature ◽  
Heat Dissipation ◽  
Road Traffic ◽  
Weather Forecast ◽  
Road Surface ◽  
Balance Model ◽  
Weather Station ◽  
The Road ◽  
Road Surface Temperature ◽  
Road Condition

<p>According to the 14<sup>th</sup> Annual Road Safety Performance Index Report by the European Transport Safety Council, annually more than 100,000 accidents occur on European roads, of which 22,660 people lost their lives in 2019. The factors contributing to road traffic accidents are commonly grouped into three categories: environment, vehicle or driver. The European accident research and safety report 2013 by Volvo states in about 30% of accidents contributing factors could be attributed to weather and environment leading for example to unexpected changes in road friction, such as black ice. In this work, we are developing a solution to forecast road conditions in Norway by applying the <em>Model of the Environment and Temperature of Roads – METRo</em>, which is a surface energy balance model to predict the road surface temperature. In addition, METRo includes modules for water accumulation at the surface (liquid and frozen) and vertical heat dissipation (Crevier and Delage, 2001). The road condition is forecasted for a given pair of latitude, longitude and desired forecast time. Data from the closest road weather station and postprocessed weather forecast are used to initialize METRo and provide boundary conditions to the road weather forecast. The weather forecasts are obtained from the THREDDS service and the road weather station data from the FROST service, both provided by MET Norway. We develop algorithms to obtain the data from these services, process them to match the METRo model input requirements and send them to METRo’s pre-processing algorithms, which combine observations and forecast data to initialize the model. In a case study, we will compare short-term METRo forecasts with observations obtained by road weather stations and with observations retrieved by car-mounted environmental sensors (e.g., road surface temperature). This work is part of the project <em>AutonoWeather - Enabling autonomous driving in winter conditions through optimized road weather interpretation and forecast</em> financed by the Research Council of Norway in 2020. </p>

scholarly journals Near–surface air temperature and snow skin temperature comparison from CREST-SAFE station data with MODIS land surface temperature data

2015 ◽  
Vol 12 (8) ◽  
pp. 7665-7687 ◽  
Author(s):  
C. L. Pérez Díaz ◽  
T. Lakhankar ◽  
P. Romanov ◽  
J. Muñoz ◽  
R. Khanbilvardi ◽  
...  
Keyword(s):  
Surface Temperature ◽  
Skin Temperature ◽  
Air Temperature ◽  
Land Surface Temperature ◽  
Land Surface ◽  
Hydrological Cycle ◽  
Critical Role ◽  
Surface Air Temperature ◽  
Balance Model ◽  
Near Surface

Abstract. Land Surface Temperature (LST) is a key variable (commonly studied to understand the hydrological cycle) that helps drive the energy balance and water exchange between the Earth's surface and its atmosphere. One observable constituent of much importance in the land surface water balance model is snow. Snow cover plays a critical role in the regional to global scale hydrological cycle because rain-on-snow with warm air temperatures accelerates rapid snow-melt, which is responsible for the majority of the spring floods. Accurate information on near-surface air temperature (T-air) and snow skin temperature (T-skin) helps us comprehend the energy and water balances in the Earth's hydrological cycle. T-skin is critical in estimating latent and sensible heat fluxes over snow covered areas because incoming and outgoing radiation fluxes from the snow mass and the air temperature above make it different from the average snowpack temperature. This study investigates the correlation between MODerate resolution Imaging Spectroradiometer (MODIS) LST data and observed T-air and T-skin data from NOAA-CREST-Snow Analysis and Field Experiment (CREST-SAFE) for the winters of 2013 and 2014. LST satellite validation is imperative because high-latitude regions are significantly affected by climate warming and there is a need to aid existing meteorological station networks with the spatially continuous measurements provided by satellites. Results indicate that near-surface air temperature correlates better than snow skin temperature with MODIS LST data. Additional findings show that there is a negative trend demonstrating that the air minus snow skin temperature difference is inversely proportional to cloud cover. To a lesser extent, it will be examined whether the surface properties at the site are representative for the LST properties within the instrument field of view.

scholarly journals Evaluation of alternative formulae for calculation of surface temperature in snowmelt models using frequency analysis of temperature observations

2009 ◽  
Vol 6 (3) ◽  
pp. 3863-3890 ◽  
Author(s):  
C. H. Luce ◽  
D. G. Tarboton
Keyword(s):  
Time Series ◽  
Energy Balance ◽  
Surface Temperature ◽  
Energy Flux ◽  
Frequency Analysis ◽  
Energy Content ◽  
Balance Model ◽  
Snow Surface ◽  
Fourier Frequency ◽  
Snow Surface Temperature

Abstract. The snow surface temperature is an important quantity in the snow energy balance, since it modulates the exchange of energy between the surface and the atmosphere as well as the conduction of energy into the snowpack. It is therefore important to correctly model snow surface temperatures in energy balance snowmelt models. This paper focuses on the relationship between snow surface temperature and conductive energy fluxed that drive the energy balance of a snowpack. Time series of snow temperature at the surface and through the snowpack were measured to examine energy conduction in a snowpack. Based on these measurements we calculated the snowpack energy content and conductive energy flux at the snow surface. We then used these estimates of conductive energy flux to evaluate formulae for the calculation of the conductive flux at the snow surface based on surface temperature time series. We use a method based on Fourier frequency analysis to estimate snow thermal properties. Among the formulae evaluated, we found that a modified force-restore formula, based on the superimposition of the force-restore equation capturing diurnal fluctuations on a gradually changing temperature gradient, had the best agreement with observations of heat conduction. This formula is suggested for the parameterization of snow surface temperature in a full snowpack energy balance model.

Sign in / Sign up

Export Citation Format

Share Document