The structure of Mars lower atmosphere from Mars Express Radio Science (MaRS) occultation measurements
JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS
Authors: Tellmann, Silvia; Paetzold, Martin; Haeusler, Bernd; Hinson, D. P.; Tyler, G. Leonard
Abstract
The Mars Express Radio Science Experiment (MaRS) investigates the lower and middle atmosphere of Mars between the surface and about 40 km with a very high vertical resolution. More than 600 profiles of temperature, pressure, and neutral number density were retrieved between 2004 and 2011 covering four Martian years (MYs 27-30). Radio occultation experiments provide the unique possibility to retrieve geopotential height information to supplement temperature values. The temperature field in the northern winter hemisphere displays strong temperature inversions indicating a pronounced polar warming in the northern polar night (MY 27). The temperature and geopotential fields imply the presence of a strong zonal jet, with peak wind speeds of more than 170 m/s at an altitude of about 30 km ( 15 Pa) and a latitude of 60-65 degrees N. The longitudinal temperature and geopotential fields in the southern winter of Martian year 30 at latitudes between 49 degrees and 69 degrees S are dominated by a stationary zonal wave s = 1 structure in the lower atmosphere. Associated meridional wind fields retrieved by assuming geostrophic balance have amplitudes up to 12 m/s at the 200 Pa level. An investigation of small-scale atmospheric waves reveals enhanced gravity wave activity in the daytime atmosphere above elevated terrain and in the winter extratropics. Radio occultation experiments also provide unique insight into the structure of the planetary boundary layer. The deepest convective boundary layers, up to 10 km, are found over elevated terrain. Citation: Tellmann, S., M. Patzold, B. Hausler, D. P. Hinson, and G. L. Tyler (2013), The structure of Mars lower atmosphere from Mars Express Radio Science (MaRS) occultation measurements, J. Geophys. Res. Planets, 118, 306-320, doi:10.1002/jgre.20058.
Comparison of the methane production potential and biodegradability of kitchen waste from different sources under mesophilic and thermophilic conditions
WATER SCIENCE AND TECHNOLOGY
Authors: Yang, Ziyi; Wang, Wen; Zhang, Shuyu; Ma, Zonghu; Anwar, Naveed; Liu, Guangqing; Zhang, Ruihong
Abstract
The methane production potential of kitchen waste (KW) obtained from different sources was compared through mesophilic and thermophilic anaerobic digestion. The methane yields (MYs) obtained with the same KW sample under different temperatures were similar, whereas the MYs obtained with different samples differed significantly. The highest MY obtained in S7 was 54%-60% higher than the lowest MY in S3. The modified Gompertz model was utilized to simulate the methane production process. The maximum production rate of methane under thermophilic conditions was 2%-86% higher than that under mesophilic conditions. The characteristics of different KW samples were studied. In the distribution of total chemical oxygen demand, the diversity of organic compounds of KW was the most dominant factor that affected the potential MYs of KW. The effect of the C/N and C/P ratios or the concentration of metal ions was insignificant. Two typical methods to calculate the theoretical MY (TMY) were compared, the organic composition method can simulate methane production more precisely than the elemental analysis method. Significant linear correlations were found between TMYorg and MYs under mesophilic and thermophilic conditions. The organic composition method can thus be utilized as a fast technique to predict the methane production potential of KW.