Much research and speculation exists about the meteorological and climatological impacts of biomass burning in the Maritime Continent (MC) of Indonesia and Malaysia, particularly during El Nino ...events. However, the MC hosts some of the world's most complicated meteorology, and we wish to understand how tropical phenomena at a range of scales influence observed burning activity. Using Moderate Resolution Imaging Spectroradiometer (MODIS) derived active fire hotspot patterns coupled with aerosol data assimilation products, satellite based precipitation, and meteorological indices, the meteorological context of observed fire prevalence and smoke optical depth in the MC are examined. Relationships of burning and smoke transport to such meteorological and climatic factors as the interannual El Nino-Southern Oscillation (ENSO), El Nino Modoki, Indian Ocean Dipole (IOD), the seasonal migration of the Intertropical Convergence Zone, the 30-90 day Madden Julian Oscillation (MJO), tropical waves, tropical cyclone activity, and diurnal convection were investigated. A conceptual model of how all of the differing meteorological scales affect fire activity is presented. Each island and its internal geography have different sensitivities to these factors which are likely relatable to precipitation patterns and land use practices. At the broadest scales as previously reported, we corroborate ENSO is indeed the largest factor. However, burning is also enhanced by periods of El Nino Modoki. Conversely, IOD influences are unclear. While interannual phenomena correlate to total seasonal burning, the MJO largely controls when visible burning occurs. High frequency phenomena which are poorly constrained in models such as diurnal convection and tropical cyclone activity also have an impact which cannot be ignored. Finally, we emphasize that these phenomena not only influence burning, but also the observability of burning, further complicating our ability to assign reasonable emissions.
The ionic nature of a functionalized protic ionic liquid cannot be rationalized simply through the differences in aqueous proton dissociation constants between the acid precursor and the conjugate ...acid of the base precursor. The extent of proton transfer,
i.e.
the equilibrium ionicity, of a tertiary ammonium acetate protic ionic liquid can be significantly increased by introducing an hydroxyl functional group on the cation, compared to the alkyl or amino-functionalized analogues. This increase in apparent ionic nature correlates well with variations in solvent-solute and solvent-solvent interaction parameters, as well as with physicochemical properties such as viscosity.
Ionicity of protic ionic liquids are significantly affected by additional functionality, thereby influencing solvation properties.
The sensitivity of ionic liquids (ILs) to water affects their physical and chemical properties, even at relatively low concentrations, yet the structural thermodynamics of protic IL– (PIL−) water ...systems at low water concentrations still remains unclear. Using the rigorous Kirkwood–Buff theory of solutions, which can quantify the interactions between species in IL–water systems solely from thermodynamic data, we have shown the following: (1) Between analogous protic and aprotic ILs (AILs), the AIL cholinium bis(trifluoromethanesulfonyl)imide (ChNTf2) shows stronger interactions with water at low water concentrations, with the analogous PIL N,N-dimethylethanolammonium bis(trifluoromethanesulfonyl)imide (DMEtANTf2) having stronger water–ion interactions at higher water contents, despite water–ion interactions weakening with increasing water content in both systems. (2) Water has little effect on the average ion–ion interactions in both protic and aprotic ILs, aside from the AIL ChNTf2, which shows a strengthening of ion–ion interactions with increasing water content. (3) Self-association of water in both PIL–water systems leading to the presence of large aggregates of water in IL-rich compositions has been inferred. Water–water interactions in DMEtANTf2 were found to be similar to those of dialkylimidazolium AILs, whereas these interactions were much larger in the PIL N,N-dimethylethanolammonium propionate (DMEtAPr), attributed to the change in anion–water interactions.
A billion years ago, two black holes spiraled together, forming a new black hole. They produced gravitational waves that reached Earth on September 14, 2015, where they were measured during the first ...observing run of the Advanced LIGO detectors. This signal marked the birth of gravitational-wave astronomy, which provides a unique way to study black holes and neutron stars. The Advanced LIGO and Advanced Virgo detectors have now completed their third observing run, the latest in a series of runs, each more sensitive (and with higher detection rates) than the last. Here, we present the third Gravitational-Wave Transient Catalog (GWTC-3), which describes discoveries made up to the end of the third run.GWTC-3 contains 90 gravitational-wave candidates—35 more than the previous catalog—with better-than-even odds of being real signals. The catalog is an unprecedented census of merging black holes and neutron stars. We now have observations of binary neutron stars, binary black holes, and neutron star–black hole binaries. These cover a diverse range of masses, from neutron stars as light as 1.2 solar masses to remnant black holes exceeding 100 solar masses, and include ambiguous objects that straddle the expected divide between neutron stars and black holes.This paper details the latest results from the third observing run, from detector status and data-quality checks, to searches for signals and source-property inferences. GWTC-3 observations and associated data enable studies of compact astrophysical objects, the nature of gravity, and the history of the Universe. However, many puzzles and open questions remain to be addressed by future observing runs, which promise to yield hundreds more binary detections and possibly entirely new types of gravitational-wave sources.
We report on the population properties of 76 compact binary mergers detected with gravitational waves below a false alarm rate of 1 per year through GWTC-3. The catalog contains three classes of ...binary mergers: BBH, BNS, and NSBH mergers. We infer the BNS merger rate to be between 10 $\rm{Gpc^{-3} yr^{-1}}$ and 1700 $\rm{Gpc^{-3} yr^{-1}}$ and the NSBH merger rate to be between 7.8 $\rm{Gpc^{-3}\, yr^{-1}}$ and 140 $\rm{Gpc^{-3} yr^{-1}}$ , assuming a constant rate density versus comoving volume and taking the union of 90% credible intervals for methods used in this work. Accounting for the BBH merger rate to evolve with redshift, we find the BBH merger rate to be between 17.9 $\rm{Gpc^{-3}\, yr^{-1}}$ and 44 $\rm{Gpc^{-3}\, yr^{-1}}$ at a fiducial redshift (z=0.2). We obtain a broad neutron star mass distribution extending from $1.2^{+0.1}_{-0.2} M_\odot$ to $2.0^{+0.3}_{-0.3} M_\odot$. We can confidently identify a rapid decrease in merger rate versus component mass between neutron star-like masses and black-hole-like masses, but there is no evidence that the merger rate increases again before 10 $M_\odot$. We also find the BBH mass distribution has localized over- and under-densities relative to a power law distribution. While we continue to find the mass distribution of a binary's more massive component strongly decreases as a function of primary mass, we observe no evidence of a strongly suppressed merger rate above $\sim 60 M_\odot$. The rate of BBH mergers is observed to increase with redshift at a rate proportional to $(1+z)^{\kappa}$ with $\kappa = 2.9^{+1.7}_{-1.8}$ for $z\lesssim 1$. Observed black hole spins are small, with half of spin magnitudes below $\chi_i \simeq 0.25$. We observe evidence of negative aligned spins in the population, and an increase in spin magnitude for systems with more unequal mass ratio.
We present results of an all-sky search for continuous gravitational waves which can be produced by spinning neutron stars with an asymmetry around their rotation axis, using data from the third ...observing run of the Advanced LIGO and Advanced Virgo detectors. Four different analysis methods are used to search in a gravitational-wave frequency band from 10 to 2048 Hz and a first frequency derivative from $-10^{-8}$ to $10^{-9}$ Hz/s. No statistically-significant periodic gravitational-wave signal is observed by any of the four searches. As a result, upper limits on the gravitational-wave strain amplitude $h_0$ are calculated. The best upper limits are obtained in the frequency range of 100 to 200 Hz and they are ${\sim}1.1\times10^{-25}$ at 95\% confidence-level. The minimum upper limit of $1.10\times10^{-25}$ is achieved at a frequency 111.5 Hz. We also place constraints on the rates and abundances of nearby planetary- and asteroid-mass primordial black holes that could give rise to continuous gravitational-wave signals.
A recent field-intensive program in Shark Bay, Western Australia provides new multi-scale perspectives on the world's most extensive modern stromatolite system. Mapping revealed a unique geographic ...distribution of morphologically distinct stromatolite structures, many of them previously undocumented. These distinctive structures combined with characteristic shelf physiography define eight 'Stromatolite Provinces'. Morphological and molecular studies of microbial mat composition resulted in a revised growth model where coccoid cyanobacteria predominate in mat communities forming lithified discrete stromatolite buildups. This contradicts traditional views that stromatolites with the best lamination in Hamelin Pool are formed by filamentous cyanobacterial mats. Finally, analysis of internal fabrics of stromatolites revealed pervasive precipitation of microcrystalline carbonate (i.e. micrite) in microbial mats forming framework and cement that may be analogous to the micritic microstructures typical of Precambrian stromatolites. These discoveries represent fundamental advances in our knowledge of the Shark Bay microbial system, laying a foundation for detailed studies of stromatolite morphogenesis that will advance our understanding of benthic ecosystems on the early Earth.
ABSTRACT We present a deep centimeter-wavelength catalog of the Orion Nebula Cluster (ONC), based on a 30 hr single-pointing observation with the Karl G. Jansky Very Large Array in its ...high-resolution A-configuration using two 1 GHz bands centered at 4.7 and 7.3 GHz. A total of 556 compact sources were detected in a map with a nominal rms noise of 3 Jy bm−1, limited by complex source structure and the primary beam response. Compared to previous catalogs, our detections increase the sample of known compact radio sources in the ONC by more than a factor of seven. The new data show complex emission on a wide range of spatial scales. Following a preliminary correction for the wideband primary-beam response, we determine radio spectral indices for 170 sources whose index uncertainties are less than 0.5. We compare the radio to the X-ray and near-infrared point-source populations, noting similarities and differences.
Seven and a half years (June 2006 to November 2013) of Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) aerosol and cloud layer products are compared with collocated Ozone Monitoring ...Instrument (OMI) aerosol index (AI) data and Aqua Moderate Resolution Imaging Spectroradiometer (MODIS) cloud products in order to investigate variability in estimates of biannual and monthly above-cloud aerosol (ACA) events globally. The active- (CALIOP) and passive-based (OMI-MODIS) techniques have their advantages and caveats for ACA detection, and thus both are used to derive a thorough and robust comparison of daytime cloudy-sky ACA distribution and climatology. For the first time, baseline above-cloud aerosol optical depth (ACAOD) and AI thresholds are derived and examined (AI = 1.0, ACAOD = 0.015) for each sensor. Both OMI-MODIS and CALIOP-based daytime spatial distributions of ACA events show similar patterns during both study periods (December–May) and (June–November). Divergence exists in some regions, however, such as Southeast Asia during June through November, where daytime cloudy-sky ACA frequencies of up to 10 % are found from CALIOP yet are non-existent from the OMI-based method. Conversely, annual cloudy-sky ACA frequencies of 20–30 % are reported over northern Africa from the OMI-based method yet are largely undetected by the CALIOP-based method. Using a collocated OMI-MODIS-CALIOP data set, our study suggests that the cloudy-sky ACA frequency differences between the OMI-MODIS- and CALIOP-based methods are mostly due to differences in cloud detection capability between MODIS and CALIOP as well as QA flags used. An increasing interannual variability of ∼ 0.3–0.4 % per year (since 2009) in global monthly cloudy-sky ACA daytime frequency of occurrence is found using the OMI-MODIS-based method. Yet, CALIOP-based global daytime ACA frequencies exhibit a near-zero interannual variability. Further analysis suggests that the OMI-derived interannual variability in cloudy-sky ACA frequency may be affected by OMI row anomalies in later years. A few regions are found to have increasing slopes in interannual variability in cloudy-sky ACA frequency, including the Middle East and India. Regions with slightly negative slopes of the interannual variability in cloudy-sky ACA frequencies are found over South America and China, while remaining regions in the study show nearly zero change in ACA frequencies over time. The interannual variability in ACA frequency is not, however, statistically significant on both global and regional scales, given the relatively limited sample sizes. A longer data record of ACA events is needed in order to establish significant trends of ACA frequency regionally and globally.
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