scholarly journals Seasonal and diurnal variations in Martian surface ultraviolet irradiation: biological and chemical implications for the Martian regolith

2003 ◽  
Vol 2 (1) ◽  
pp. 21-34 ◽  
Author(s):  
M. R. Patel ◽  
A. Bérces ◽  
C. Kolb ◽  
H. Lammer ◽  
P. Rettberg ◽  
...  
Keyword(s):  
Oxidation Potential ◽  
Diurnal Variations ◽  
Martian Surface ◽  
Dose Rates ◽  
Uv Irradiance ◽  
Seasonal And Diurnal Variations ◽  
Phage T7 ◽  
Biological Interpretation ◽  
Uv Dose ◽  
Martian Regolith

The issue of the variation of the surface ultraviolet (UV) environment on Mars was investigated with particular emphasis being placed on the interpretation of data in a biological context. A UV model has been developed to yield the surface UV irradiance at any time and place over the Martian year. Seasonal and diurnal variations were calculated and dose rates evaluated. Biological interpretation of UV doses is performed through the calculation of DNA damage effects upon phage T7 and Uracil, used as examples for biological dosimeters. A solar UV ‘hotspot’ was revealed towards perihelion in the southern hemisphere, with a significant damaging effect upon these species. Diurnal profiles of UV irradiance are also seen to vary markedly between aphelion and perihelion. The effect of UV dose is also discussed in terms of the chemical environment of the Martian regolith, since UV irradiance can reach high enough levels so as to have a significant effect upon the soil chemistry. We show, by assuming that H2O is the main source of hydrogen in the Martian atmosphere, that the stoichiometrically desirable ratio of 2:1 for atmospheric H and O loss rates to space are not maintained and at present the ratio is about 20:1. A large planetary oxygen surface sink is therefore necessary, in contrast with escape to space. This surface oxygen sink has important implications for the oxidation potential and the toxicology of the Martian soil. UV-induced adsorption of {\rm O}_{2}^{-} super-radicals plays an important role in the oxidative environment of the Martian surface, and the biologically damaging areas found in this study are also shown to be regions of high subsurface oxidation. Furthermore, we briefly cover the astrobiological implications for landing sites that are planned for future Mars missions.

scholarly journals Comparison of OMI UV observations with ground-based measurements at high northern latitudes

2015 ◽  
Vol 15 (6) ◽  
pp. 8933-8981 ◽  
Author(s):  
G. Bernhard ◽  
A. Arola ◽  
A. Dahlback ◽  
V. Fioletov ◽  
A. Heikkilä ◽  
...  
Keyword(s):  
Surface Albedo ◽  
Additional Data ◽  
The Arctic ◽  
Ozone Monitoring Instrument ◽  
Dose Rates ◽  
Northern Latitudes ◽  
Uv Irradiance ◽  
Data Products ◽  
Ozone Monitoring ◽  
Uv Dose

Abstract. The Dutch-Finnish Ozone Monitoring Instrument (OMI) on board NASA's Aura spacecraft provides estimates of erythemal (sunburning) ultraviolet (UV) dose rates and erythemal daily doses. These data were compared with ground-based measurements at 13 stations located throughout the Arctic and Scandinavia from 60 to 83° N. The study corroborates results from earlier work, but is based on a longer time series (eight vs. two years) and considers additional data products, such as the erythemal dose rate at the time of the satellite overpass. Furthermore, systematic errors in satellite UV data resulting from inaccuracies in the surface albedo climatology used in the OMI UV algorithm are systematically assessed. At times when the surface albedo is correctly known, OMI data typically exceed ground-based measurements by 0–11%. When the OMI albedo climatology exceeds the actual albedo, OMI data may be biased high by as much as 55%. In turn, when the OMI albedo climatology is too low, OMI data can be biased low by up to 59%. Such large negative biases may occur when reflections from snow and ice, which increase downwelling UV irradiance, are misinterpreted as reflections from clouds, which decrease the UV flux at the surface. Results suggest that a better OMI albedo climatology would greatly improve the accuracy of OMI UV data products even if year-to-year differences of the actual albedo cannot be accounted for. A pathway for improving the OMI albedo climatology is discussed. Results also demonstrate that ground-based measurements from the center of Greenland, where high, homogenous surface albedo is observed year round, are ideally suited to detect systematic problems or temporal drifts in estimates of surface UV irradiance from space.

scholarly journals Comparison of OMI UV observations with ground-based measurements at high northern latitudes

2015 ◽  
Vol 15 (13) ◽  
pp. 7391-7412 ◽  
Author(s):  
G. Bernhard ◽  
A. Arola ◽  
A. Dahlback ◽  
V. Fioletov ◽  
A. Heikkilä ◽  
...  
Keyword(s):  
Surface Albedo ◽  
Additional Data ◽  
The Arctic ◽  
Ozone Monitoring Instrument ◽  
Dose Rates ◽  
Northern Latitudes ◽  
Uv Irradiance ◽  
Data Products ◽  
Ozone Monitoring ◽  
Uv Dose

Abstract. The Dutch–Finnish Ozone Monitoring Instrument (OMI) on board NASA's Aura spacecraft provides estimates of erythemal (sunburning) ultraviolet (UV) dose rates and erythemal daily doses. These data were compared with ground-based measurements at 13 stations located throughout the Arctic and Scandinavia from 60 to 83° N. The study corroborates results from earlier work, but is based on a longer time series (8 versus 2 years) and considers additional data products, such as the erythemal dose rate at the time of the satellite overpass. Furthermore, systematic errors in satellite UV data resulting from inaccuracies in the surface albedo climatology used in the OMI UV algorithm are systematically assessed. At times when the surface albedo is correctly known, OMI data typically exceed ground-based measurements by 0–11 %. When the OMI albedo climatology exceeds the actual albedo, OMI data may be biased high by as much as 55 %. In turn, when the OMI albedo climatology is too low, OMI data can be biased low by up to 59 %. Such large negative biases may occur when reflections from snow and ice, which increase downwelling UV irradiance, are misinterpreted as reflections from clouds, which decrease the UV flux at the surface. Results suggest that a better OMI albedo climatology would greatly improve the accuracy of OMI UV data products even if year-to-year differences of the actual albedo cannot be accounted for. A pathway for improving the OMI albedo climatology is discussed. Results also demonstrate that ground-based measurements from the center of Greenland, where high, homogenous surface albedo is observed year round, are ideally suited to detect systematic problems or temporal drifts in estimates of surface UV irradiance from space.

scholarly journals Solar UV Irradiance Measurements at Four Sites in Tibet

1970 ◽  
Vol 8 (3) ◽  
pp. 75-86 ◽  
Author(s):  
Norsang Gelsor ◽  
Nima Pingcuo ◽  
Tsoja Wangmu ◽  
Berit Kjeldstad ◽  
Yi-Chun Chen ◽  
...  
Keyword(s):  
Dose Rates ◽  
Clear Sky ◽  
Data Analyses ◽  
Uv Irradiance ◽  
Eastern Tibet ◽  
Solar Uv ◽  
Solar Uv Irradiance ◽  
Uv Dose ◽  
Summer Time ◽  
Solar Ultraviolet

We present solar ultraviolet (UV) irradiance measurements at four sites in Tibet (Lhasa, Linzhi, Nagqu, and Tingri) for the period between July 2008 and September 2010. Erythemal UV dose rates and irradiances of solar UVA, UVB for all four sites are presented. Days with clear sky cloud transmittance (CLT) larger than 100% are particularly selected and analyzed for the four sites. Comparisons between the four sites are also carried out, and the clear-sky data analyses for the summer time show that Tingri (near Mt. Everest) has the highest UV irradiance, Lhasa the second highest, while Nagchu (Northen Tibet) and Linzhi (Eastern Tibet) have a bit lower values. Tingri has the strongest UV level among the four sites around the year, mainly due to increased albedo caused by snow-covered surroundings. UV data for Lhasa for the period from 2004 to 2010 are also analyzed, showing that the UV instantaneous irradiance trend for the recent six-year period is stable. However, the number of clear-sky days in Lhasa has increased over the recent six years, causing an increase in the yearly-integrated total UV irradiance. DOI: http://dx.doi.org/10.3126/jie.v8i3.5934 JIE 2011; 8(3): 75-86

scholarly journals Seasonal and diurnal variations of black carbon and organic carbon aerosols in Bangkok

2011 ◽  
Vol 116 (D15) ◽  
Author(s):  
L. K. Sahu ◽  
Y. Kondo ◽  
Y. Miyazaki ◽  
Prapat Pongkiatkul ◽  
N. T. Kim Oanh
Keyword(s):  
Organic Carbon ◽  
Black Carbon ◽  
Diurnal Variations ◽  
Seasonal And Diurnal Variations ◽  
Carbon Aerosols

scholarly journals Mars Global Ionosphere-Thermosphere Model: Solar cycle, seasonal, and diurnal variations of the Mars upper atmosphere

2015 ◽  
Vol 120 (2) ◽  
pp. 311-342 ◽  
Author(s):  
S. W. Bougher ◽  
D. Pawlowski ◽  
J. M. Bell ◽  
S. Nelli ◽  
T. McDunn ◽  
...  
Keyword(s):  
Solar Cycle ◽  
Diurnal Variations ◽  
Upper Atmosphere ◽  
Seasonal And Diurnal Variations

scholarly journals Seasonal and diurnal variations in moisture, heat and CO2 fluxes over a typical steppe prairie in Inner Mongolia, China

2009 ◽  
Vol 13 (7) ◽  
pp. 987-998 ◽  
Author(s):  
Z. Gao ◽  
D. H. Lenschow ◽  
Z. He ◽  
M. Zhou
Keyword(s):  
Inner Mongolia ◽  
Surface Albedo ◽  
Sensible Heat Flux ◽  
Experimental Period ◽  
Diurnal Variations ◽  
Heat Fluxes ◽  
Co2 Fluxes ◽  
Sensible Heat ◽  
Eddy Covariance Method ◽  
Seasonal And Diurnal Variations

Abstract. In order to examine energy partitioning and CO2 exchange over a steppe prairie in Inner Mongolia, China, fluxes of moisture, heat and CO2 in the surface layer from June 2007 through June 2008 were calculated using the eddy covariance method. The study site was homogenous and approximately 1500 m×1500 m in size. Seasonal and diurnal variations in radiation components, energy components and CO2 fluxes are examined. Results show that all four radiation components changed seasonally, resulting in a seasonal variation in net radiation. The radiation components also changed diurnally. Winter surface albedo was higher than summer surface albedo because during winter the snow-covered surface increased the surface albedo. The seasonal variations in both sensible heat and CO2 fluxes were stronger than those of latent heat and soil heat fluxes. Sensible heat flux was the main consumer of available energy for the entire experimental period. The energy imbalance problem was encountered and the causes are analyzed.

scholarly journals Seismic investigations of the Martian near-surface at the InSight landing site

2020 ◽  
Author(s):  
Cedric Schmelzbach ◽  
Nienke Brinkman ◽  
David Sollberger ◽  
Sharon Kedar ◽  
Matthias Grott ◽  
...  
Keyword(s):  
Deep Structure ◽  
Landing Site ◽  
P Wave ◽  
Mission Design ◽  
Normal Operation ◽  
Seismic Signals ◽  
Martian Surface ◽  
Broadband Seismometer ◽  
Near Surface ◽  
Martian Regolith

<p>The InSight ultra-sensitive broadband seismometer package (SEIS) was installed on the Martian surface with the goal to study the seismicity on Mars and the deep interior of the Planet. A second surface-based instrument, the heat flow and physical properties package HP<sup>3</sup>, was placed on the Martian ground about 1.1 m away from SEIS. HP<sup>3</sup> includes a self-hammering probe called the ‘mole’ to measure the heat coming from Mars' interior at shallow depth to reveal the planet's thermal history. While SEIS was designed to study the deep structure of Mars, seismic signals such as the hammering ‘noise’ as well as ambient and other instrument-generated vibrations allow us to investigate the shallow subsurface. The resultant near-surface elastic property models provide additional information to interpret the SEIS data and allow extracting unique geotechnical information on the Martian regolith.</p><p>The seismic signals recorded during HP<sup>3</sup> mole operations provide information about the mole attitude and health as well as shed light on the near-surface, despite the fact that the HP<sup>3 </sup>mole continues to have difficulty penetrating below 40 cm (one mole length). The seismic investigation of the HP<sup>3</sup> hammering signals, however, was not originally planned during mission design and hence faced several technical challenges. For example, the anti-aliasing filters of the seismic-data acquisition chain were adapted when recording the mole hammering to allow recovering information above the nominal Nyquist frequency. In addition, the independently operating SEIS, HP<sup>3</sup> and lander clocks had to be correlated more frequently than in normal operation to enable high-precision timing.</p><p>To date, the analysis of the hammering signals allowed us to constrain the bulk P-wave velocity of the volume between the mole tip and SEIS (top 30 cm) to around 120 m/s. This low velocity value is compatible with laboratory tests performed on Martian regolith analogs with a density of around 1500 kg/m<sup>3</sup>. Furthermore, the SEIS leveling system resonances, seismic recordings of atmospheric pressure signals, HP<sup>3</sup> housekeeping data, and imagery provide additional constraints to establish a first seismic model of the shallow (topmost meters) subsurface at the landing site.</p>

scholarly journals Methanogenic Archaea Can Produce Methane in Deliquescence-Driven Mars Analog Environments

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Deborah Maus ◽  
Jacob Heinz ◽  
Janosch Schirmack ◽  
Alessandro Airo ◽  
Samuel P. Kounaves ◽  
...  
Keyword(s):  
Metabolic Activity ◽  
Methanogenic Archaea ◽  
Dynamic Environments ◽  
Martian Surface ◽  
Near Surface ◽  
Methanosarcina Mazei ◽  
Mars Analog ◽  
Recurring Slope Lineae ◽  
Martian Regolith ◽  
First Time

AbstractThe current understanding of the Martian surface indicates that briny environments at the near-surface are temporarily possible, e.g. in the case of the presumably deliquescence-driven Recurring Slope Lineae (RSL). However, whether such dynamic environments are habitable for terrestrial organisms remains poorly understood. This hypothesis was tested by developing a Closed Deliquescence System (CDS) consisting of a mixture of desiccated Martian Regolith Analog (MRA) substrate, salts, and microbial cells, which over the course of days became wetted through deliquescence. The methane produced via metabolic activity for three methanogenic archaea: Methanosarcina mazei, M. barkeri and M. soligelidi, was measured after exposing them to three different MRA substrates using either NaCl or NaClO4 as a hygroscopic salt. Our experiments showed that (1) M. soligelidi rapidly produced methane at 4 °C, (2) M. barkeri produced methane at 28 °C though not at 4 °C, (3) M. mazei was not metabolically reactivated through deliquescence, (4) none of the species produced methane in the presence of perchlorate, and (5) all species were metabolically most active in the phyllosilicate-containing MRA. These results emphasize the importance of the substrate, microbial species, salt, and temperature used in the experiments. Furthermore, we show here for the first time that water provided by deliquescence alone is sufficient to rehydrate methanogenic archaea and to reactivate their metabolism under conditions roughly analogous to the near-subsurface Martian environment.

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