A new technique is presented for the simultaneous measurement of water vapor, liquid water, and water ice in clouds using spectral observations of scattered sunlight between 0.865 and 1.065 μm. A ...nonlinear least squares approach is used to fit the measurements with the absorption spectral signatures of the vapor, liquid, and solid phases of water. This allows for the retrieval of the total path‐integrated column abundances of vapor, liquid, and ice and directly yields the fractional absorption by all three phases of water within clouds at these wavelengths. Laboratory, ground‐based, and aircraft‐based observations are presented that illustrate the application of this technique and its comparison to other methods of measuring liquid water in widely varying conditions. The results suggest that the retrieval of liquid water is relatively insensitive to interference from other absorbers. The measurement of ice is less accurate and precise than that of liquid and is affected to some degree by the absorption of water vapor and liquid; uncertainty estimates are given. The method provides key information for radiative balance studies and has the potential to aid aviation safety. An extension of this technique to include scattered sunlight at longer wavelengths is likely to produce more accurate results and lower detection limits for both liquid and ice. Applying the technique to shorter wavelengths should allow for retrievals that are less sensitive to photon path distribution uncertainties.
The ability to retrieve key information about clouds from observations of atmospheric absorption by molecular oxygen along with the O
2
‐O
2
collision complex is examined. Specifically, the ...fractional absorption of scattered solar radiation in the oxygen A and B bands and the 477 nm O
2
‐O
2
absorption band at moderate resolution (0.5–6.0 nm) is shown to allow estimates to be made not only of cloud optical depth but also of cloud base and top heights from a down‐looking observing platform above cloud level. We first demonstrate through theoretical calculations that these cloud parameters can be accurately retrieved from measurements of fractional absorption at this moderate resolution and with no requirement of absolutely calibrated radiances. Further, it is shown that the addition of B band and O
2
‐O
2
absorption information to A band observations can decrease the uncertainty in these cloud parameter estimates by more than 50% (depending on the cloud's properties) compared to using A band information alone. The theoretical analysis is supported by sample, above‐cloud measurements of the oxygen A band fractional absorption associated with hurricane Michelle over the Gulf of Mexico. The experimental results are in excellent agreement with the cloud base and top heights inferred from cloud photographs and from dropsonde relative humidity data, demonstrating the capability of this approach for improved cloud remote sensing.
The ability to retrieve key information about clouds from observations of atmospheric absorption by molecular oxygen along with the O2‐O2 collision complex is examined. Specifically, the fractional ...absorption of scattered solar radiation in the oxygen A and B bands and the 477 nm O2‐O2 absorption band at moderate resolution (0.5–6.0 nm) is shown to allow estimates to be made not only of cloud optical depth but also of cloud base and top heights from a down‐looking observing platform above cloud level. We first demonstrate through theoretical calculations that these cloud parameters can be accurately retrieved from measurements of fractional absorption at this moderate resolution and with no requirement of absolutely calibrated radiances. Further, it is shown that the addition of B band and O2‐O2 absorption information to A band observations can decrease the uncertainty in these cloud parameter estimates by more than 50% (depending on the cloud's properties) compared to using A band information alone. The theoretical analysis is supported by sample, above‐cloud measurements of the oxygen A band fractional absorption associated with hurricane Michelle over the Gulf of Mexico. The experimental results are in excellent agreement with the cloud base and top heights inferred from cloud photographs and from dropsonde relative humidity data, demonstrating the capability of this approach for improved cloud remote sensing.
We report the results of a field experiment designed to study atmospheric water vapor absorption in the visible and near‐infrared spectral regions between 550 and 1000 nm. We carried out ...spectroscopic ground measurements of direct solar radiation under clear‐sky conditions in Boulder, Colorado. The data with a spectral resolution of approximately 1 nm were analyzed using the differential optical absorption spectroscopy (DOAS) technique in five different absorption bands of water vapor. We show that this technique can reveal the broadband effects of errors and inconsistencies in absorption spectra information for the water molecule. Retrievals of column tropospheric water vapor from the field spectra were compared to simultaneous independent estimates from Global Positioning System (GPS) data and radiosonde soundings. The data set is used to critically assess the widely used High‐Resolution Transmission Molecular Absorption Database (HITRAN) Rothman et al., 1998. The results indicate that line intensities in the 3ν + δ polyad centered at 820 nm are underestimated by 21% with respect to the strong 3ν polyad centered at 940 nm, while the 4ν polyad at 720 nm shows agreement within the measurement accuracy of 3%. Two weaker bands centered at 650 and 590 nm were found to be overestimated by about 8–10%. The effect of the proposed corrections on the absorption of incoming solar flux for a clear‐sky atmosphere is estimated to be 0.6 W/m2 for an overhead Sun.
Nuclear reactors are uniquely powerful, abundant, and flavor-pure sources of antineutrinos that continue to play a vital role in the US neutrino physics program. The US reactor antineutrino physics ...community is a diverse interest group encompassing many detection technologies and many particle physics topics, including Standard Model and short-baseline oscillations, BSM physics searches, and reactor flux and spectrum modeling. The community's aims offer strong complimentary with numerous aspects of the wider US neutrino program and have direct relevance to most of the topical sub-groups composing the Snowmass 2021 Neutrino Frontier. Reactor neutrino experiments also have a direct societal impact and have become a strong workforce and technology development pipeline for DOE National Laboratories and universities. This white paper, prepared as a submission to the Snowmass 2021 community organizing exercise, will survey the state of the reactor antineutrino physics field and summarize the ways in which current and future reactor antineutrino experiments can play a critical role in advancing the field of particle physics in the next decade.
We report the identification and nucleotide sequence analysis of a cryptic plasmid pMIDG2830 from the Gram-negative bacterium
Neisseria flavescens. The largest open reading frame encodes a protein ...similar to the replication protein, RepA, found in pAB49 from
Acinetobacter baumannii and pNI10 from
Pseudomonas. Modified by the incorporation of a kanamycin resistance cassette, the plasmid can be stably maintained in
Escherichia coli and
Neisseria meningitidis, and can be used as a shuttle plasmid in meningococcal research.
The cow rumen is adapted for the breakdown of plant material into energy and nutrients, a task largely performed by enzymes encoded by the rumen microbiome. Here we present 913 draft bacterial and ...archaeal genomes assembled from over 800 Gb of rumen metagenomic sequence data derived from 43 Scottish cattle, using both metagenomic binning and Hi-C-based proximity-guided assembly. Most of these genomes represent previously unsequenced strains and species. The draft genomes contain over 69,000 proteins predicted to be involved in carbohydrate metabolism, over 90% of which do not have a good match in public databases. Inclusion of the 913 genomes presented here improves metagenomic read classification by sevenfold against our own data, and by fivefold against other publicly available rumen datasets. Thus, our dataset substantially improves the coverage of rumen microbial genomes in the public databases and represents a valuable resource for biomass-degrading enzyme discovery and studies of the rumen microbiome.
Background. Necrotizing enterocolitis (NEC) is a devastating inflammatory bowel disease of premature infants speculatively associated with infection. Suspected NEC can be indistinguishable from ...sepsis, and in established cases an infant may die within hours of diagnosis. Present treatment is supportive. A means of presymptomatic diagnosis is urgently needed. We aimed to identify microbial signatures in the gastrointestinal microbiota preceding NEC diagnosis in premature infants. Methods. Fecal samples and clinical data were collected from a 2-year cohort of 369 premature neonates. Next-generation sequencing of 16S ribosomal RNA gene regions was used to characterize the microbiota of prediagnosis fecal samples from 12 neonates with NEC, 8 with suspected NEC, and 44 controls. Logistic regression was used to determine clinical characteristics and operational taxonomic units (OTUs) discriminating cases from controls. Samples were cultured and isolates identified using matrix-assisted laser desorption/ionization–time of flight. Clostridial isolates were typed and toxin genes detected. Results. A clostridial OTU was overabundant in prediagnosis samples from infants with established NEC (P = .006). Culture confirmed the presence of Clostridium perfringens type A. Fluorescent amplified fragment-length polymorphism typing established that no isolates were identical. Prediagnosis samples from NEC infants not carrying profuse C. perfringens revealed an overabundance of a Klebsiella OTU (P = .049). Prolonged continuous positive airway pressure (CPAP) therapy with supplemental oxygen was also associated with increased NEC risk. Conclusions. Two fecal microbiota signatures (Clostridium and Klebsiella OTUs) and need for prolonged CPAP oxygen signal increased risk of NEC in presymptomatic infants. These biomarkers will assist development of a screening tool to allow very early diagnosis of NEC.
Evidence suggests deep stratospheric intrusions can elevate western US surface ozone to unhealthy levels during spring. These intrusions can be classified as 'exceptional events', which are not ...counted towards non-attainment determinations. Understanding the factors driving the year-to-year variability of these intrusions is thus relevant for effective implementation of the US ozone air quality standard. Here we use observations and model simulations to link these events to modes of climate variability. We show more frequent late spring stratospheric intrusions when the polar jet meanders towards the western United States, such as occurs following strong La Niña winters (Niño3.4<-1.0 °C). While El Niño leads to enhancements of upper tropospheric ozone, we find this influence does not reach surface air. Fewer and weaker intrusion events follow in the two springs after the 1991 volcanic eruption of Mt. Pinatubo. The linkage between La Niña and western US stratospheric intrusions can be exploited to provide a few months of lead time during which preparations could be made to deploy targeted measurements aimed at identifying these exceptional events.
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