A new satellite-based global climatology of dust aerosol optical depth

By mass, dust is the largest contributor to global aerosol burden, yet long-term observational records of dust, particularly over the ocean, are limited. Here, two nearly global observational datasets of dust aerosol optical depth τd are created primarily on the basis of optical measurements of the aerosol column from 1) the Moderate Resolution Imaging Spectroradiometer (MODIS) aboard the Terra satellite spanning from 2001 to 2018 and 2) the Advanced Very High Resolution Radiometer (AVHRR) from 1981 to 2018. The quality of the new data is assessed by comparison with existing dust datasets that are spatially more limited. Between 2001 and 2018, τd decreased over Asia and increased significantly over the Sahara, Middle East, and parts of eastern Europe, with the largest increase found over the Aral Sea where emissive playa surfaces have been exposed. These daily, observational, and nearly global records of dust will allow for improvement in understanding the role of dust in climate variability

Future changes in tropical cyclone activity in the North Indian Ocean projected by high-resolution MRI-AGCMs

Open Access at publisher's web site: http://www.springerlink.com/content/b682734237171631

The effects of air and lip-pressure variations on the motion of a clarinet reed within an artificial embouchure

To observe the influence of air and lip-pressure variations on reed motion, a blowing chamber containing an artificial-embouchure device was constructed into which a clarinet was inserted and sealed at the barrel joint. A DC light source was directed through the bell end of the clarinet into a photo transistor mounted near the mouthpiece. Light fluctuations produced by the reed's movement were converted to voltages and directed to an analog-to-digital converter unit interfaced with an Apple lie computer. In air-pressure experiments, lip pressure was held constant while air pressure was varied. In lip-pressure experiments, air pressure was held constant while lip pressure was varied. Intensities were measured on a sound-level meter and air-pressure was monitored via a U-tube water manometer connected to the chamber; thus, the reed's vibrational patterns were observed at specific air pressures, lip pressures, and itensities

Reconstructing Summer Upper-Level Flow In The Northern Rocky Mountains Using An Alpine Larch (Larix Lyallii) Tree-Ring Chronology

Mid-latitude mesoscale weather in the climatological summer is heavily influenced by fluctuations in synoptic-scale circulation patterns. Previous research has linked Arctic amplification to alterations in summer synoptic climatology, leading to more extreme weather events in the mid-latitudes. In this study we reconstruct seasonal (JJA) upper-level (500 hPa) atmospheric flow for four geographic locations in the mid-latitudes using an alpine larch (Larix lyallii Parl.) tree-ring chronology derived from western Montana. Our goal is to assess the long-term (400+ year) stability of upper-level flow to place the observed trends in a historical context. Spatial pattern correlations indicate that tree growth increases when meridional flow and zonal flow are strong west (r = 0.504, p = 0.001, n = 37) and north (r = 0.642, p < 0.001, n = 37) of the study site, respectively. Tree growth declines when meridional flow and zonal flow are strong east (r = -0.497, p = 0.001, n = 37) and south (r = -0.584, p < 0.001, n = 37) of the study site, respectively. Our 444-year climate reconstructions of 500 hPa flow show that ridging is becoming more intense in recent decades while troughs are declining in intensity

Conserved Non-Coding Element Derived Regulation of the Meis2.2 Homeobox Gene During Embryonic Development

The homeobox-containing Meis gene family includes at least four members that are expressed in spatially and temporally conserved fashion throughout development in all vertebrates examined thus far. Products of the Meis genes function as cofactors, interacting with other transcription factors and DNA to assist in the regulation of transcription. Most importantly, they appear to work with the Hox proteins as well as other homeobox genes’ products including Pbx proteins. At this time, little is known about the regulation of the Meis genes. Using phylogenetic footprinting to search for regulatory elements in association with the Meis family of homeobox-containing genes, we identified a highly conserved element located downstream of the Meis2 gene that we have called Meis2 Downstream Element 1 (m2de1). This putative enhancer is conserved in sequence and position across the genomes of all vertebrates examined. Furthermore, the m2de1 element contains several putative transcription factor binding sites. In this study, we have demonstrated the ability of m2de1 to drive reporter gene expression through microinjection derived transgenic analysis. Reporter gene expression was observed in the developing brain of zebrafish embryos in a manner consistent with endogenous Meis2 expression, potentially implicating the m2de1 element with cis-regulatory function

Tertius Romane: An Examination Of Muscovite Mystical Political Theology

The relationship between the Russian Orthodox Church and Russian state has received less than required academic attention. In the post-Soviet space, the Russian Church has again begun to interact with the Russian state. Through research of Russian primary sources including chronicles, vitae of princes, and various correspondence, this paper traces the origins of the relationship between Church and State and examines both the mystical and political theological actualities of such. This thesis demonstrates similarities, historical themes, and aspects of Church and State interactions through a comparison to Ernst Kantorowicz’s The King’s Two Bodies: A Study in Mediaeval Political Theology that can be applied to examine modern day Russian Church and State political theology

A high-resolution map of human evolutionary constraint using 29 mammals.

The comparison of related genomes has emerged as a powerful lens for genome interpretation. Here we report the sequencing and comparative analysis of 29 eutherian genomes. We confirm that at least 5.5% of the human genome has undergone purifying selection, and locate constrained elements covering ∼4.2% of the genome. We use evolutionary signatures and comparisons with experimental data sets to suggest candidate functions for ∼60% of constrained bases. These elements reveal a small number of new coding exons, candidate stop codon readthrough events and over 10,000 regions of overlapping synonymous constraint within protein-coding exons. We find 220 candidate RNA structural families, and nearly a million elements overlapping potential promoter, enhancer and insulator regions. We report specific amino acid residues that have undergone positive selection, 280,000 non-coding elements exapted from mobile elements and more than 1,000 primate- and human-accelerated elements. Overlap with disease-associated variants indicates that our findings will be relevant for studies of human biology, health and disease

Dominant role of greenhouse-gas forcing in the recovery of Sahel rainfall

Sahelian summer rainfall, controlled by the West African monsoon, exhibited large-amplitude multidecadal variability during the twentieth century. Particularly important was the severe drought of the 1970s and 1980s, which had widespread impacts1–6. Research into the causes of this drought has identified anthropogenic aerosol forcing3,4,7 and changes in sea surface temperatures (SSTs; refs 1,2,6,8–11) as the most important drivers. Since the 1980s, there has been some recovery of Sahel rainfall amounts2–6,11–14, although not to the pre-drought levels of the 1940s and 1950s. Here we report on experiments with the atmospheric component of a state-of-the-art global climate model to identify the causes of this recovery. Our results suggest that the direct influence of higher levels of greenhouse gases in the atmosphere was the main cause, with an additional role for changes in anthropogenic aerosol precursor emissions. We find that recent changes in SSTs, although substantial, did not have a significant impact on the recovery. The simulated response to anthropogenic greenhouse-gas and aerosol forcing is consistent with a multivariate fingerprint of the observed recovery, raising confidence in our findings. Although robust predictions are not yet possible, our results suggest that the recent recovery in Sahel rainfall amounts is most likely to be sustained or amplified in the near term

Seasonal forecasts of North Atlantic tropical cyclone activity in the North American Multi-Model Ensemble

The North American Multi-Model Ensemble (NMME)-Phase II models are evaluated in terms of their retrospective seasonal forecast skill of the North Atlantic (NA) tropical cyclone (TC) activity, with a focus on TC frequency. The TC identification and tracking algorithm is modified to accommodate model data at daily resolution. It is also applied to three reanalysis products at the spatial and temporal resolution of the NMME-Phase II ensemble to allow for a more objective estimation of forecast skill. When used with the reanalysis data, the TC tracking generates realistic climatological distributions of the NA TC formation and tracks, and represents the interannual variability of the NA TC frequency quite well. Forecasts with the multi-model ensemble (MME) when initialized in April and later tend to have skill in predicting the NA seasonal TC counts (and TC days). At longer leads, the skill is low or marginal, although one of the models produces skillful forecasts when initialized as early as January and February. At short lead times, while demonstrating the highest skill levels the MME also tends to significantly outperform the individual models and attain skill comparable to the reanalysis. In addition, the short-lead MME forecasts are quite reliable. At regional scales, the skill is rather limited and mostly present in the western tropical NA and the Caribbean Sea. It is found that the overall MME forecast skill is limited by poor representation of the low-frequency variability in the predicted TC frequency, and large fluctuations in skill on decadal time scales. Addressing these deficiencies is thought to increase the value of the NMME ensemble in providing operational guidance

Aerosols implicated as a prime driver of twentieth-century North Atlantic climate variability

Systematic climate shifts have been linked to multidecadal variability in observed sea surface temperatures in the North Atlantic Ocean1. These links are extensive, influencing a range of climate processes such as hurricane activity2 and African Sahel3, 4, 5 and Amazonian5 droughts. The variability is distinct from historical global-mean temperature changes and is commonly attributed to natural ocean oscillations6, 7, 8, 9, 10. A number of studies have provided evidence that aerosols can influence long-term changes in sea surface temperatures11, 12, but climate models have so far failed to reproduce these interactions6, 9 and the role of aerosols in decadal variability remains unclear. Here we use a state-of-the-art Earth system climate model to show that aerosol emissions and periods of volcanic activity explain 76 per cent of the simulated multidecadal variance in detrended 1860–2005 North Atlantic sea surface temperatures. After 1950, simulated variability is within observational estimates; our estimates for 1910–1940 capture twice the warming of previous generation models but do not explain the entire observed trend. Other processes, such as ocean circulation, may also have contributed to variability in the early twentieth century. Mechanistically, we find that inclusion of aerosol–cloud microphysical effects, which were included in few previous multimodel ensembles, dominates the magnitude (80 per cent) and the spatial pattern of the total surface aerosol forcing in the North Atlantic. Our findings suggest that anthropogenic aerosol emissions influenced a range of societally important historical climate events such as peaks in hurricane activity and Sahel drought. Decadal-scale model predictions of regional Atlantic climate will probably be improved by incorporating aerosol–cloud microphysical interactions and estimates of future concentrations of aerosols, emissions of which are directly addressable by policy actions