The low energy neutral atom imagers on Mars Express and IMAGE have revealed that the neutral atom populations in interplanetary space come from a variety of sources and challenge our current understanding of heliospheric physics. For example, both in cruise phase and at Mars, the neutral particle instrument NPD on Mars Express observed “unexplained neutral beams” unrelated to Mars which appear to be either of heliospheric or solar wind origin. Likewise, the NPI instrument on Mars Express has revealed streams of neutral atoms with different properties than those observed by NPD. Independently, IMAGE/LENA has reported neutral atom observations that may be interpreted as a “secondary stream” having different characteristics and flowing from a higher ecliptic longitude than the nominal upstream direction. Both sets of observations do not appear to fit in easily with the neutral atom environment from 1.0 to 1.57 AU as it is currently understood. In this paper, we examine some highly suggestive similarities in the IMAGE/LENA and Mars Express/ASPERA-3/NPI data to try to determine potential origins for the observed signal. 相似文献
Densities derived from accelerometer measurements on the CHAMP satellite near 400 km are used to statistically establish characteristics of large-scale (>1000 km) traveling atmospheric disturbances (TADs). Only TADs that at least propagate from the auroral zone to the equator are analyzed here, and a total of 21 identifiable events are found over the years 2001–2007. The average speed of all TADs, regardless of local time, is 646 ± 122 ms−1. The average speeds on the dayside and nightside are 595 ± 127 ms−1 and 685 ± 106 ms−1, respectively, i.e., the speed appears to be 10% higher on average on the nightside. On six occasions TADs were only detected on the night side; however, TADs on the dayside often appear more distinctly in the data. Moreover, contrary to some theoretical expectations, dayside TADs do not dissipate more readily than night side TADs, although much less are detected between 8–20 solar local time. No clear dependence of TAD amplitude or phase speed with respect to Kp, or rate of increase of Kp, is found. 相似文献
Halocarbons, such as CFC-11, CFC-12 and HCFC-22, are important trace gases in the atmosphere through their role as greenhouse gases and their influence on stratospheric ozone chemistry. This paper focuses on an initial study using integration of spectral radiance measurements from a spaceborne limb sounding Fourier Transform Spectrometer (FTS) to retrieve these compounds in the upper troposphere and lower stratosphere (UTLS). The instrument employed in this study is the Michelson Interferometer for Passive Atmospheric Sounding onboard ENVISAT (MIPAS-E) which obtains spectral data in the altitude range of 6–68 km at an unapodized spectral resolution of 0.025 cm−1. We have used optimal estimation techniques to retrieve vertical information for these compounds using a radiometric approach.
It is shown that significant retrieval information is obtained at up to five measured levels in the UTLS for CFC-11, up to six for CFC-12 and up to two levels for HCFC-22. An initial error analysis indicates significant sensitivity of our retrievals to variability in operationally retrieved pressure and temperature data. For each halocarbon, gain, offset and spectroscopic uncertainties generally each contribute less than 10% to the total error. Finally, tracer correlations are used to compare the datasets to equivalent relationships derived here from version 2 ATMOS data with very good agreements for CFC-12 but with more variability in the CFC-11 comparisons. 相似文献
The “information age” has produced tools capable of supporting a variety of employment and business models that previously were infeasible. Convergence of socio-economic factors, workforce composition, accelerating product obsolescence and technological advances has created an unparalleled need and fertile opportunity to redefine the workforce model. These new technological capabilities alone are insufficient to reinvent the business models. Management must, through vision and solid commitment at all hierarchical levels, migrate values, reinvent precepts, coalesce processes, and redefine workforce models to remain financially viable in the emerging compressed timelines. The tools are at hand; economic realities make corporate change a financial requirement, and the changing values, goals, and social composition of the workforce apply pressure to create a new network centric workforce model. These converging pressures make rethinking the corporation viable and necessary. How rapidly these changes occur will be determined now by old-fashioned rates of human/corporate acceptance of change. Compression of the market timeline may force significant, perhaps unrecoverable fallout among those companies that are slow to take up this challenge 相似文献
The first unambiguous identification of ammonia in the upper atmosphere of Jupiter has been obtained from the observation of individual NH3 bands in an IUE high resolution spectrum in the 2100–2400 Å spectral range. The variation with wavelength of the strengths of these NH3 bands implies that the NH3 abundance has to be strongly reduced by photolysis in the upper jovian atmosphere. Preliminary analysis by means of scattering models shows that the ammonia mixing ratio cannot be constant with altitude. The mixing ratio NH3/H2 ranges from 5 10?8 to 5 10?7 at the 250 mb pressure level, and decreases as P or P2 toward higher altitudes. 相似文献
The influence of isolation and confinement on social support and depressed mood was examined in a study of 235 men and women who spent a year at McMurdo Station in Antarctica, and a study of 77 men and women who spent a year at the Amundson-Scott South Pole Station. Although availability of support remained unchanged, there was a significant decrease in reported satisfaction with support obtained, as well as a significant increase in depressed mood. Satisfaction with support was inversely associated with depressed mood at the beginning and end of isolation and confinement. At the end of winter, this association varied by source of support. High levels of tension-anxiety, depression and anger preceded an increase in advice seeking, but high levels of advice seeking also preceded an increase in tension-anxiety and depression. Results suggest a significant erosion of social support under conditions of prolonged isolation and confinement, leading to an increase in depressed mood. 相似文献