Recent calculations of the Martian obliquity suggest that it varies chaotically on timescales longer than about 107 years and varies between about 0 and 60°. We examine the seasonal water behavior at obliquities between 40 and 60°. Up to several tens of centimeters of water may sublime from the polar caps each year, and possibly move to the equator, where it is more stable. CO2 frost and CO2‐H2O clathrate hydrate are stable in the polar deposits below a few tens of meters depth, so that the polar cap could contain a significant CO2 reservoir. If CO2 is present, it could be left over from the early history of Mars; also, it could be released into the atmosphere during periods of high obliquity, causing occasional periods of more‐clement climate.

There is a pressing need to verify air pollutant and greenhouse gas emissions from anthropogenic fossil energy sources to enforce current and future regulations. We demonstrate the feasibility of using simultaneous remote sensing observations of column abundances of CO 2 , CO, and NO 2 to inform and verify emission inventories. We report, to our knowledge, the first ever simultaneous column enhancements in CO 2 (3-10 ppm) and NO 2 (1-3 Dobson Units), and evidence of δ 13 CO 2 depletion in an urban region with two large coal-fired power plants with distinct scrubbing technologies that have resulted in ΔNO x /ΔCO 2 emission ratios that differ by a factor of two. Ground-based total atmospheric column trace gas abundances change synchronously and correlate well with simultaneous in situ point measurements during plume interceptions. Emission ratios of ΔNO x /ΔCO 2 and ΔSO 2 /ΔCO 2 derived from in situ atmospheric observations agree with those reported by instack monitors. Forward simulations using in-stack emissions agree with remote column CO 2 and NO 2 plume observations after fine scale adjustments. Both observed and simulated column ΔNO 2 /ΔCO 2 ratios indicate that a large fraction (70-75%) of the region is polluted. We demonstrate that the column emission ratios of ΔNO 2 /ΔCO 2 can resolve changes from day-to-day variation in sources with distinct emission factors (clean and dirty power plants, urban, and fires). We apportion these sources by using NO 2 , SO 2 , and CO as signatures. Our high-frequency remote sensing observations of CO 2 and coemitted pollutants offer promise for the verification of power plant emission factors and abatement technologies from ground and space.air pollution | greenhouse gases | climate change T race gas [nitrogen oxides (NO x ), sulfur dioxide (SO 2 ), and carbon monoxide (CO)] and carbon dioxide (CO 2 ) emissions from anthropogenic fossil energy production are major contributors to air pollution and global warming. Under the Clean Air Act, in the United States these emissions are considered a threat to public health and welfare and are regulated by the Environmental Protection Agency (EPA). Although reporting requirements for air pollutants are well established, they are still under development for CO 2 . Reported inventories of CO 2 and pollutant gases are calculated for specific activities using emission factors that depend on fuel composition, combustion efficiency, and scrubbing methods. These bottom-up inventories are subject to significant uncertainties and manipulations (1). Alternatively, atmospheric observations offer an independent top-down method to verify emissions of pollutant trace gases that have low atmospheric background levels and exhibit large and distinct increases near various combustion sources. For example, satellite observations of NO 2 have been used to evaluate regional and local emissions (2), but they are only useful for trend analysis, because their large observational footprint can underestimate NO 2 . In contrast, background levels of CO 2 are hi...

Globally, patents on several well established biologic agents used to treat rheumatic diseases have already or will expire over the next few years, allowing for the availability of subsequent entry biologics (SEBs or biosimilars). The objective of this study was to identify gaps in knowledge and attitudes towards SEBs among Canadian rheumatologists. Eighty-one rheumatologists completed the survey and were included in the analysis (22 % of the 369 who were contacted). We found that one third of physicians (31 %) were familiar with SEBs and that physicians with greater than 20 years of practice were significantly more likely to be familiar or very familiar with SEBs compared to respondents with less than 10 years or 10-20 years of experience (OR 11.1, 95 % CI: 2.1-55.5, p = 0.004 and OR 4.5, 95 % CI: 1.2-16.2, p = 0.023, respectively). A third (32 %) of physicians agreed or strongly agreed that they would be comfortable with indication extrapolation. Most respondents (88 %) would feel concerned or very concerned if a pharmacist had the ability to substitute a biologic drug for an SEB without the physician's approval. This survey was the first study that evaluated the position of rheumatologists on key areas surrounding SEBs from a nationwide Canadian perspective. Current physician attitudes and perceptions of SEBs can inform future educational initiatives and highlight important issues for payers, policy makers, and other stakeholders.

We model the heat transfer by radiation and conduction in the top few millimeters of a planetary surface to determine the magnitude of near‐surface (≈100 μm) thermal gradients and their effects on mid‐infrared emission spectra for a number of planetary environments. The model is one‐dimensional and uses a finite difference scheme for ≈10‐μm layers. Calculations are performed for samples heated at the base and from above by sunlight. Our results indicate that near‐surface radiative cooling creates significant thermal gradients in the top few hundred microns of surfaces in which radiation is an important heat transfer mechanism. The effect is maximized in evacuated, underdense particulate media with sufficiently high temperatures. Near‐surface thermal gradients will be significant in fine‐grained particulate surfaces on the Moon (40–60 K/100 μm) and Mercury (≈80 K/100 μm), increasing spectral contrast and creating emission maxima in the transparent regions of the spectra. They will be of lesser importance on the surface of Mars, with a maximum value of around 5 K/100 μm in areas of low thermal inertia, and will be negligible on planets with more substantial atmospheres (<1 K/100 μm). We conclude that the effects that thermal gradients have on mid‐IR emission spectra are predictable and do not negate the utility of emission spectroscopy for remote determination of planetary surface composition.

Global land mapping of satellite-observed CO2 total columns using spatio-Global land mapping of satellite-observed CO2 total columns using spatiotemporal geostatistics temporal geostatistics