Search

The atmosphere of Mars presents a strong response to aerosol radiative forcing compared to that of the Earth, thus atmospheric models should have accurate radiative transfer algorithms for the simulation of temperatures and circulation. In this work, we evaluate the radiative effects of dust aerosol calculated by different radiative transfer schemes and the influence of dust properties in these calculations. Two‐stream solutions were compared with multistream discrete ordinate methods. Fluxes and heating rates were evaluated for a variety of atmospheric conditions, including dust storms. The results show that in low‐to‐medium dust opacity scenarios, the highly efficient two‐stream methods provide accurate estimations, with heating rate errors of less than 2 K/sol. These errors increase with opacity, when differences of 20 K/sol are reached, which may be relevant in the simulations of temperature fields and atmospheric circulation under regional and global dust storm conditions. In such cases, the use of four‐stream or higher order methods may be required, although accuracy improvements for eight‐ or higher‐stream schemes were negligible. The influence of dust particle properties in aerosol radiative forcing estimations is mainly due to the particle size, where variations of 20% of the effective radius resulted in differences of 5 K/sol; the shape of the particles showed a minor impact, with differences of <2 K/sol. The results of this study contribute to quantification of the uncertainties in current Mars climate models and may help modellers to select the appropriate approach depending on the scenario. Plain Language Summary: The thin atmosphere of Mars has a strong response to the effects of dust aerosol compared to that of the Earth. The radiative heating and cooling due to dust affect the temperatures and drive the Martian climate at all spatial scales. In addition, remote sensing retrievals and studies of climate and weather on Mars depend on precise calculations of these quantities. The "two‐stream" method for calculating the energy budget and temperature variations is widely used, although it presents some limitations in modeling dust interactions with solar radiation. In this work, we compare radiative estimations of this method with results obtained by more accurate, but time consuming, algorithms. The comparison results show a good agreement when there is low to medium amount of lofted dust. As the atmospheric dust loading increases, such as in the case of regular Mars dust storms, more complex methods may be required. Regarding the influence of dust particle properties in these calculations, the uncertainties associated with the size of the particles introduce meaningful differences at high altitudes. The results of this study contribute to quantification of the uncertainties in Mars climate models and may help modellers to select the appropriate method depending on the scenario. Key Points: We study the accuracy and performance of radiative transfer schemes of Mars' atmosphere and the impact of dust aerosol particle propertiesTwo‐stream approximations provide accurate radiative flux and heating rate estimates in low and medium opacity scenariosIn high opacity cases and dust storms, four‐stream methods may be recommended. Accuracy improvements from higher‐order methods are negligible [ABSTRACT FROM AUTHOR]

NASA's Mars 2020 (M2020) rover mission includes a suite of sensors to monitor current environmental conditions near the surface of Mars and to constrain bulk aerosol properties from changes in atmospheric radiation at the surface. The Mars Environmental Dynamics Analyzer (MEDA) consists of a set of meteorological sensors including wind sensor, a barometer, a relative humidity sensor, a set of 5 thermocouples to measure atmospheric temperature at ∼1.5 m and ∼0.5 m above the surface, a set of thermopiles to characterize the thermal IR brightness temperatures of the surface and the lower atmosphere. MEDA adds a radiation and dust sensor to monitor the optical atmospheric properties that can be used to infer bulk aerosol physical properties such as particle size distribution, non-sphericity, and concentration. The MEDA package and its scientific purpose are described in this document as well as how it responded to the calibration tests and how it helps prepare for the human exploration of Mars. A comparison is also presented to previous environmental monitoring payloads landed on Mars on the Viking, Pathfinder, Phoenix, MSL, and InSight spacecraft. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Geophysical Research. Planets is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Purpose: Whether prognostic awareness benefits terminally ill cancer patients' psychological-existential well-being and quality of life (QOL) is unclear because of lack of well-controlled longitudinal studies. This study longitudinally evaluated the associations of accurate prognostic awareness and prognostic acceptance with psychological distress, existential suffering, and QOL while comprehensively controlling for confounders in Taiwanese terminally ill cancer patients' last year of life.Patients and Methods: A convenience sample of 325 cancer patients was followed until death. Psychological distress and existential suffering were assessed by severe anxiety and depressive symptoms and high self-perceived sense of burden to others, respectively. Dichotomized and continuous (QOL) outcome variables were evaluated by multivariate logistic and linear regression modeling with the generalized estimating equation, respectively.Results: Accurate prognostic awareness was not associated with the likelihood of severe anxiety or depressive symptoms but significantly increased the likelihood of high self-perceived sense of burden to others and was associated with poorer QOL in participants' last year of life. Participants who knew and highly accepted their prognosis were significantly less likely to experience severe anxiety symptoms than those who were unaware of or knew their prognosis but had difficulty accepting it.Conclusion: Knowing one's poor prognosis and confronting one's impending death without full acceptance and adequate professional psycho-spiritual support may harm more than benefit terminally ill cancer patients' psychological state, existential well-being, and QOL. These findings highlight the importance of tailoring psycho-spiritual support to cancer patients' psychological and existential needs when prognostic information is disclosed. [ABSTRACT FROM AUTHOR]

Objective Adequate knowledge of prognosis is a prerequisite for planning appropriate end-of-life (EOL) care. However, questions remain about whether the association between prognostic understanding and EOL-care intensity reflects terminally ill cancer patients' preferences for EOL care. This study investigated the associations between accurate prognostic understanding and EOL-care preferences, and identified correlates of accurate prognostic understanding. Methods A cross-sectional survey of 2452 terminally ill cancer patients from 23 hospitals throughout Taiwan. Results Nearly half the participants (49.80%) accurately understood their prognosis. These patients were significantly more likely to prefer comfort-oriented care as their goal for EOL care, but less likely to prefer life-prolonging treatments. Accurately understanding prognosis decreased the likelihood of preferring intensive care unit care, cardiac pulmonary resuscitation, cardiac massage, intubation, and mechanical ventilation support, but increased preference for hospice care. Participants were significantly more likely to accurately understand their prognosis if they were male, younger, better educated, with a stronger preference for physicians to disclose their prognosis to them, and receiving care at a hospital accredited as a medical center and in northwest Taiwan. The likelihood of accurate prognostic understanding was lower for patients recently (≤12 months) diagnosed with cancers with better prognosis and hematologic malignancies than for lung cancer patients. Conclusions Accurately understanding prognosis is associated with fewer preferences for life-sustaining treatments and is correlated with both patient and institutional characteristics. Interventions should be developed to improve accurate prognostic understanding, thus facilitating informed EOL-care decisions that may limit the use of aggressive interventions. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]