Dry Times Ahead

Previous research on the health and air quality impacts of wildfire smoke has largely focused on the impact of smoke on outdoor air quality; however, many people spend a majority of their time indoors. The quality of indoor air on smoke-impacted days is largely unknown. In this analysis, we use publicly available data from an existing large network of low-cost indoor and outdoor fine particulate matter (PM2.5) monitors to quantify the relationship between indoor and outdoor particulate air quality on smoke-impacted days in 2020 across the western United States (US). We also investigate possible regional and socioeconomic trends in this relationship for regions surrounding six major cities in the western US. We find indoor PM2.5 concentrations are 82% or 4.2 µg m−3 (median across all western US indoor monitors for the year 2020; interquartile range, IQR: 2.0–7.2 µg m−3) higher on smoke-impacted days compared to smoke-free days. Indoor/outdoor PM2.5 ratios show variability by region, particularly on smoke-free days. However, we find the ratio of indoor/outdoor PM2.5 is less than 1 (i.e. indoor concentrations lower than outdoor) at nearly all indoor-outdoor monitor pairs on smoke-impacted days. Although typically lower than outdoor concentrations on smoke-impacted days, we find that on heavily smoke-impacted days (outdoor PM2.5 > 55 µg m−3), indoor PM2.5 concentrations can exceed the 35 µg m−3 24 h outdoor standard set by the US Environmental Protection Agency. Further, total daily-mean indoor PM2.5 concentrations increase by 2.1 µg m−3 with every 10 µg m−3 increase in daily-mean outdoor PM2.5. (median of statistically significant linear regression slopes across all western US monitor pairs; IQR: 1.0–4.3 µg m−3) on smoke-impacted days. These results show that for indoor environments in the western US included in our analysis, remaining indoors during smoke events is currently an effective, but limited, strategy to reduce PM2.5 exposure.

The potato psyllid, Bactericera cockerelli (Sulc) (Hemiptera: Triozidae), is a vector of the bacterium “Candidatus Liberibacter solanacearum,” the putative causal agent of potato zebra chip disease that has seriously affected the potato industry in the Central and Southwestern United States for the past decade. The 2011 potato growing season saw the first report of zebra chip disease in Washington, Oregon, and Idaho; however, B. cockerelli has been recorded in this region every season at least for the past 7 yr. Studies were conducted to determine the relationship between psyllids collected from the Pacific Northwest potatoes in 2011 and those from the Southwestern and Central United States. High resolution melting analysis of the B. cockerelli mitochondrial Cytochrome C Oxidase subunit I-like gene was conducted on over 450 psyllids collected from numerous locations across the Central and Western United States. Results suggest that at least three potato psyllid haplotypes exist in the United States, correlating to the Central, Western, and Northwestern United States geographical regions. The high resolution melting analysis results were subsequently supported by DNA sequencing data.

Satellite imagery is commonly used to map surface water extents over time, but many approaches yield discontinuous records resulting from cloud obstruction or image archive gaps. We applied the Dynamic Surface Water Extent (DSWE) model to downscaled (250‐m) daily Moderate Resolution Imaging Spectroradiometer (MODIS) data in Google Earth Engine to generate monthly surface water maps for the conterminous United States (US) from 2003 through 2019. The aggregation of daily observations to monthly maps of maximum water extent produced records with diminished cloud and cloud shadow effects across most of the country. We used the continuous monthly record to analyze spatiotemporal surface water trends stratified within Environmental Protection Agency Ecoregions. Although not all ecoregion trends were significant (p < 0.05), results indicate that much of the western and eastern US underwent a decline in surface water over the 17‐year period, while many ecoregions in the Great Plains had positive trends. Trends were also generated from monthly streamgage discharge records and compared to surface water trends from the same ecoregion. These approaches agreed on the directionality of trend detected for 54 of 85 ecoregions, particularly across the Great Plains and portions of the western US, whereas trends were not congruent in select western deserts, the Great Lakes region, and the southeastern US. By describing the geographic distribution of surface water over time and comparing these records to instrumented discharge data across the conterminous US, our findings demonstrate the efficacy of using satellite imagery to monitor surface water dynamics and supplement traditional instrumented monitoring.

Three great moisture anomalies were observed during the twentieth century over the western United States: a pluvial from 1905 to 1917, the Dust Bowl drought (1929–40), and the Southwestern drought of 1946–56. A composite analysis of the concurrent Pacific sea surface temperature (SST) field is used to infer the atmospheric circulation that may have been associated with these objectively defined decadal dry and wet periods. The early-twentieth-century pluvial occurred during a 13-yr SST regime with unusually cold water in the northern and northwestern North Pacific and in the eastern North Pacific. This pattern would favor a “Pineapple Express–like” mean storm track into the west. Warm ENSO-like conditions also observed during the pluvial would have favored an enhanced subtropical jet stream into the southwestern United States. The 11-yr Dust Bowl drought occurred during a poorly defined Pacific SST regime, although unusually cold water was present in the far western North Pacific. Weak warm SST conditions were also noted in the extreme northeastern North Pacific. This cold west–warm east SST pattern, although weak for the full 11-yr interval, may have contributed to positive atmospheric geopotential heights over the western and central United States during the Dust Bowl drought. Cooler SSTs in the eastern equatorial Pacific during some of the Dust Bowl years (e.g., 1934, 1935, 1938, and 1939) suggest a possible La Niña influence. La Niña conditions definitely seemed to have contributed to the 1950s drought, but the most anomalous SSTs for the 11-yr average were observed in the west-central North Pacific. The overall Pacific SST field during the 1946–56 drought was consistent with the cool phase of the Pacific decadal oscillation, and the warm SSTs in the west-central North Pacific would have favored a trough over the central North Pacific and a ridge over western North America in the upper-tropospheric flow.

The western United States is known for its water shortages due to large seasonal and inter-annual variability of precipitation as well as increasing demand. Climate change will impact the availability of water in the western United States through the modification of precipitation characteristics. Satellite data presents the opportunity to study these changes at a fine, continuous spatial resolution—particularly in places where no traditional ground observations exist. Utilizing the Tropical Rainfall Measuring Mission (TRMM) 3B42 version 7 precipitation data, this study examines the spatio-temporal changes in precipitation characteristics over the western United States between 1998 and 2015, and their connections with the atmospheric total column water vapor and the El Niño Southern Oscillation during the winter season. The results show that precipitation frequency in the western United States has been decreasing in general, precipitation totals and mean daily intensity are increasing in northwestern United States, but decreasing in the southwest United States during the 18 years of the study time period. Additionally, results show a strong relationship between total column water vapor and the precipitation characteristics, specifically in the southwestern United States.

Increases in burned area across the western United States (US) since the mid‐1980s have been widely documented and linked partially to climate factors, yet evaluations of trends in fire severity are lacking. Here we evaluate fire severity trends and their interannual relationships to climate for western US forests from 1985 to 2017. Significant increases in annual area burned at high severity (AABhs) were observed across most ecoregions, with an overall eightfold increase in AABhs across western US forests. The relationships we identified between the annual fire severity metrics and climate, as well as the observed and projected trend toward warmer and drier fire seasons, suggest that climate change will contribute to increased fire severity in future decades where fuels remain abundant. The growing prevalence of high‐severity fire in western US forests has important implications to forest ecosystems, including an increased probability of fire‐catalyzed conversions from forest to alternative vegetation types.

Various magnitude scales commonly used and the interrelationships among them are reviewed. It is shown that problems exist with all of the magnitude scales being used in the United States. When using regional catalogs, for example, it is often necessary to determine how the reported magnitudes were determined. Often such information is not available, although the potential errors are quite large. Both the MS and the mb scales were designed to be universal scales. However, both MS and mb magnitudes are often determined beyond the applicable range of the equations used to define the two scales. Furthermore, the MS magnitudes are not generally available for moderate to small earthquakes in most earthquake catalogs. The mb magnitudes are more generally available than MS values; however, there is also much greater variation in the way mb is determined. In particular, a significant change in the mb scale occurred in the early 1960’s when the World‐Wide Standard Seismograph Network (WWSSN) was established. This change in instrumentation used to determine mb values had a significant effect on estimated magnitudes (post‐1960 values are lower) and the saturation level of the mb scale. The older, longer‐period instruments recorded larger mb magnitudes than can be recorded with the WWSSN instruments. In addition, great care must be taken when selecting the mb magnitudes of western U.S. earthquakes, because the values are often in considerable error owing to the fact that they were determined at distances less than 25° and were not properly corrected for attenuation in the upper mantle, or asthenosphere. The seismic body wave magnitude mb of an earthquake is strongly affected by regional variations in the Q structure, composition, and physical state within the earth. Therefore because of differences in attenuation of P waves between the western and eastern United States, a problem arises when comparing mb values for the two regions. A regional mb magnitude bias exists which, depending on where the earthquake occurs and where the P waves are recorded, can lead to magnitude errors as large as ⅓ unit. There is also a significant difference between mb and ML values for earthquakes in the western United States. An empirical link between the mb of an eastern U.S. earthquake and the ML of an equivalent western earthquake is given by ML = 0.57 + 0.92(mb)east. This result is important when comparing ground motion between the two regions and for choosing a set of real western U.S. earthquake records to represent eastern earthquakes.

Wildfires correlate with reductions in aboveground tree carbon stocks and sequestration capacity on forest land in the Western United States

P-wave tomography of the western United States: Insight into the Yellowstone hotspot and the Juan de Fuca slab

Extensive, severe wildfires, and wildfire‐induced smoke occurred across the western and central United States since August 2020. Wildfires resulting in the loss of habitats and emission of particulate matter and volatile organic compounds pose serious threatens to wildlife and human populations, especially for avian species, the respiratory system of which are sensitive to air pollutions. At the same time, the extreme weather (e.g., snowstorms) in late summer may also impact bird migration by cutting off their food supply and promoting their migration before they were physiologically ready. In this study, we investigated the environmental drivers of massive bird die‐offs by combining socioecological earth observations data sets with citizen science observations. We employed the geographically weighted regression models to quantitatively evaluate the effects of different environmental and climatic drivers, including wildfire, air quality, extreme weather, drought, and land cover types, on the spatial pattern of migratory bird mortality across the western and central US during August‐September 2020. We found that these drivers affected the death of migratory birds in different ways, among which air quality and distance to wildfire were two major drivers. Additionally, there were more bird mortality events found in urban areas and close to wildfire in early August. However, fewer bird deaths were detected closer to wildfires in California in late August and September. Our findings highlight the important impact of extreme weather and natural disasters on bird biology, survival, and migration, which can provide significant insights into bird biodiversity, conservation, and ecosystem sustainability.

Predicting baseflow recession characteristics at ungauged stream locations using a physical and machine learning approach

Research Article| October 01, 1942 Progress report of seismological work by the United States Coast and Geodetic Survey in the western United States during 1941* Franklin P. Ulrich Franklin P. Ulrich Search for other works by this author on: GSW Google Scholar Author and Article Information Franklin P. Ulrich Publisher: Seismological Society of America First Online: 03 Mar 2017 Online Issn: 1943-3573 Print Issn: 0037-1106 Copyright © 1942, by the Seismological Society of America Bulletin of the Seismological Society of America (1942) 32 (4): 283–296. https://doi.org/10.1785/BSSA0320040283 Article history First Online: 03 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Franklin P. Ulrich; Progress report of seismological work by the United States Coast and Geodetic Survey in the western United States during 1941. Bulletin of the Seismological Society of America 1942;; 32 (4): 283–296. doi: https://doi.org/10.1785/BSSA0320040283 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyBulletin of the Seismological Society of America Search Advanced Search This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Other| January 01, 1948 Progress report of seismological work by the United States Coast and Geodetic Survey in the Western United States during 1946* Franklin P. Ulrich Franklin P. Ulrich Search for other works by this author on: GSW Google Scholar Author and Article Information Franklin P. Ulrich Publisher: Seismological Society of America First Online: 03 Mar 2017 Online Issn: 1943-3573 Print Issn: 0037-1106 Copyright © 1948, by the Seismological Society of America Bulletin of the Seismological Society of America (1948) 38 (1): 55–67. https://doi.org/10.1785/BSSA0380010055 Article history First Online: 03 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Franklin P. Ulrich; Progress report of seismological work by the United States Coast and Geodetic Survey in the Western United States during 1946. Bulletin of the Seismological Society of America 1948;; 38 (1): 55–67. doi: https://doi.org/10.1785/BSSA0380010055 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyBulletin of the Seismological Society of America Search Advanced Search This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Predictors of not pursuing infertility treatment after an infertility diagnosis: examination of a prospective U.S. cohort

Trends in Plasma Exchange Use in Optic Neuritis Hospitalizations in the United States