scholarly journals Precipitation Intensity Changes in the Tropics from Observations and Models

2018 ◽  
Vol 31 (12) ◽  
pp. 4775-4790 ◽  
Author(s):  
Guojun Gu ◽  
Robert F. Adler
Keyword(s):  
Phase Shift ◽  
Precipitation Intensity ◽  
Decadal Shift ◽  
Spatial Features ◽  
External Forcings ◽  
Intensity Changes ◽  
Time Periods ◽  
The Tropics ◽  
Precipitation Changes ◽  
The Impact

Tropical (30°N–30°S) interdecadal precipitation changes and trends are explored for the satellite era using GPCP monthly analyses and CMIP5 outputs and focusing on precipitation intensity distributions represented by percentiles (Pct) and other parameters. Positive trends occur for the upper percentiles (Pct ≥ 70th), and become statistically significant for Pct ≥ 80th. Negative trends appear for the middle one-half percentiles (~20th–65th) and are statistically significant for the 20th–40th percentiles. As part of these trends there is a decadal shift around 1998, indicating the presence of an interdecadal [Pacific decadal oscillation (PDO)] signal. For the lower percentiles (Pct ≤ 10th), positive trends occur, although weakly. The AMIP-type simulations generally show similar trend results for their respective time periods. Precipitation intensity changes are further examined using four precipitation categories based on the climatological percentiles: Wet (Pct ≥ 70th), Intermediate (70th > Pct ≥ 30th), Dry (30th > Pct ≥ 5th), and No Rain (5th > Pct ≥ 0th). Epoch differences of occurrence frequency between 1988–97 and 1998–2015 have spatial features generally reflecting the combined effect of the PDO and external forcings, specifically the anthropogenic greenhouse gas (GHG)-related warming based on comparisons with both AMIP and CMIP results. Furthermore, precipitation intensity over Wet zones shows much stronger changes than mean precipitation including a more prominent change around 1998 associated with the PDO phase shift. Trends also appear in the sizes of Intermediate and Dry zones, especially over ocean. However, changes in the sizes of Wet and No Rain zones are generally weak. AMIP simulations reproduce these changes relatively well. Comparisons with the CMIP5 historical experiments further confirm that the observed changes and trends are a combination of the effect of the PDO phase shift and the impact of anthropogenic GHG-related warming.

Experimental Investigation of the Impact of Dual Time Periods on Crash Hazardous Location Identification

ICCTP 2011 ◽  
2011 ◽  
Author(s):  
Gilbert Leano ◽  
Wen Cheng ◽  
Xudong Jia ◽  
Lingqi Kong ◽  
Robert Brennan
Keyword(s):  
Experimental Investigation ◽  
Time Periods ◽  
Location Identification ◽  
The Impact

scholarly journals Representation of climate change consequences in British newspapers

2021 ◽  
pp. 026732312097872
Author(s):  
Maria Laura Ruiu
Keyword(s):  
Climate Change ◽  
Public Understanding ◽  
Left Group ◽  
Impact Of Climate Change ◽  
Human Control ◽  
Time Periods ◽  
The Impact

This article explores British newspaper descriptions of the impact of climate change across three time periods. It shows a reduction in representing the consequences of climate change as ‘out of human control’. It also shows a decrease in adopting alarming and uncertain descriptions within the centre-left group, whereas mocking the effects of climate change is a peculiarity of right-leaning narratives. The complexity of climate narratives produces a variety of representations of the consequences of climate change, which in turn might increase ‘uncertainty’ in public understanding of climate change.

A Contextual Evaluation of Composite Forecasts of Annual Earnings

2016 ◽  
Vol 19 (03) ◽  
pp. 1650014 ◽  
Author(s):  
Pieter T. Elgers ◽  
May H. Lo ◽  
Wenjuan Xie ◽  
Le Emily Xu
Keyword(s):  
Time Series ◽  
Firm Size ◽  
Predictive Accuracy ◽  
Relative Accuracy ◽  
Regulation Fair Disclosure ◽  
Fair Disclosure ◽  
Time Periods ◽  
Time Specific ◽  
Annual Earnings ◽  
The Impact

This study addresses the impact of firm- and time-specific attributes on the accuracy of composite forecasts of annual earnings, constructed from time-series, price-based, and analysts' forecasts. The attributes examined include firm size, analysts' coverage, and time periods pre-dating and following the implementation of regulation fair disclosure. Our results indicate that the relative accuracy of the composite forecasts is time-specific. In the pre-regulation fair disclosure period, composite forecasts significantly outperform each of the three individual forecast sources. Moreover, the extent of improvement in accuracy of composite forecasts is significantly higher for the smaller and lightly-covered firms. Collectively, these results suggest that the predictive accuracy of composite forecasts is contextual.

scholarly journals Evaluating the role of contracting and expanding rainforest in initiating cycles of speciation across the Isthmus of Panama

2012 ◽  
Vol 279 (1742) ◽  
pp. 3520-3526 ◽  
Author(s):  
Brian Tilston Smith ◽  
Amei Amei ◽  
John Klicka
Keyword(s):  
Bird Species ◽  
Tropical Regions ◽  
Isthmus Of Panama ◽  
Species Pairs ◽  
The Matrix ◽  
High Species Richness ◽  
The Rich ◽  
The Tropics ◽  
The Impact

Climatic and geological changes across time are presumed to have shaped the rich biodiversity of tropical regions. However, the impact climatic drying and subsequent tropical rainforest contraction had on speciation has been controversial because of inconsistent palaeoecological and genetic data. Despite the strong interest in examining the role of climatic change on speciation in the Neotropics there has been few comparative studies, particularly, those that include non-rainforest taxa. We used bird species that inhabit humid or dry habitats that dispersed across the Panamanian Isthmus to characterize temporal and spatial patterns of speciation across this barrier. Here, we show that these two assemblages of birds exhibit temporally different speciation time patterns that supports multiple cycles of speciation. Evidence for these cycles is further corroborated by the finding that both assemblages consist of ‘young’ and ‘old’ species, despite dry habitat species pairs being geographically more distant than pairs of humid habitat species. The matrix of humid and dry habitats in the tropics not only allows for the maintenance of high species richness, but additionally this study suggests that these environments may have promoted speciation. We conclude that differentially expanding and contracting distributions of dry and humid habitats was probably an important contributor to speciation in the tropics.

The Potential Applications of Raman Spectroscopy in Unravelling Complex Palaeowildfire Ecosystems

2021 ◽  
Author(s):  
Thomas Theurer ◽  
David Muirhead ◽  
David Jolley ◽  
Dmitri Mauquoy
Keyword(s):  
Raman Spectroscopy ◽  
Carbonaceous Material ◽  
Complex Interactions ◽  
Intensity Changes ◽  
Potential Applications ◽  
Ecosystem Studies ◽  
History Of ◽  
The Impact ◽  
Unique Relationship

<p>Raman spectroscopy represents a novel methodology of characterising plant-fire interactions through geological history, with enormous potential. Applications of Raman spectroscopy to charcoal have shown that this is an effective method of understanding intensity changes across palaeofire regimes. Such analyses have relied on the determination of appropriate Raman parameters, given their relationship with temperature of formation and microstructural changes in reference charcoals. Quantitative assessments of charcoal microstructure have also been successfully applied to the assessment of carbonaceous maturation under alternate thermal regimes, such as pyroclastic volcanism. Palaeowildfire systems in association with volcanism may present a complex history of thermal maturation, given interactions between detrital charcoals and volcanogenic deposition. However, whilst palaeofire and volcanic maturation of carbonaceous material are well understood individually, their interaction has yet to be characterised. Here we present the first analysis of palaeofire charcoals derived from volcanic ignition utilising Raman spectroscopy. Our results indicate that complex interactions between volcanism and palaeofire systems may be better understood by the characterisation of charcoal microstructure, alongside palaeobotanical and ecosystem studies. Understanding the unique relationship between wildfires and volcanism, and the impact that this has on the fossil record, may better assist our understanding of wildfire systems in deep history. Further still, this highlights the potential for better understanding the socioecological impacts of modern and future wildfire systems closely associated with volcanic centres. </p>

scholarly journals On what scales can GOSAT flux inversions constrain anomalies in terrestrial ecosystems?

2019 ◽  
Author(s):  
Brendan Byrne ◽  
Dylan B. A. Jones ◽  
Kimberly Strong ◽  
Saroja M. Polavarapu ◽  
Anna B. Harper ◽  
...  
Keyword(s):  
Spatial Scales ◽  
Net Ecosystem Exchange ◽  
Terrestrial Ecosystems ◽  
Atmospheric Co2 ◽  
Strong Correlations ◽  
Climate Anomalies ◽  
Temperature And Precipitation ◽  
The Tropics ◽  
Emergent Constraint ◽  
The Impact

Abstract. Interannual variations in temperature and precipitation impact the carbon balance of terrestrial ecosystems, leaving an imprint in atmospheric CO2. Quantifying the impact of climate anomalies on the net ecosystem exchange (NEE) of terrestrial ecosystems can provide a constraint to evaluate terrestrial biosphere models against, and may provide an emergent constraint on the response of terrestrial ecosystems to climate change. We investigate the spatial scales over which interannual variability in NEE can be constrained using atmospheric CO2 observations from the Greenhouse Gases Observing Satellite (GOSAT). NEE anomalies are calculated by performing a series of inversion analyses using the GEOS-Chem model to assimilate GOSAT observations. Monthly NEE anomalies are compared to proxies, variables which are associated with anomalies in the terrestrial carbon cycle, and to upscaled NEE estimates from FLUXCOM. Strong agreement is found in the timing of anomalies in the GOSAT flux inversions with soil temperature and FLUXCOM. Strong correlations are obtained (P  RNINO3.4) in the tropics on continental and larger scales, and in the northern extratropics on sub-continental scales during the summer (R2 ≥ 0.49). These results, in addition to a series of observing system simulation experiments that were conducted, provide evidence that GOSAT flux inversions can isolate anomalies in NEE on continental and larger scales. However, in both the tropics and northern extratropics, the agreement between the inversions and the proxies/FLUXCOM is sensitive to the flux inversion configuration. Our results suggest that regional scales are likely the minimum scales that can be resolved in the tropics using GOSAT observations, but obtaining robust NEE anomaly estimates on these scales may be difficult.

scholarly journals The Impact Of Defeasance On Bond Prices

2011 ◽  
Vol 4 (3) ◽  
pp. 15
Author(s):  
James A. Seifert ◽  
David E. Mielke
Keyword(s):  
Financial Markets ◽  
Corporate Debt ◽  
Bond Prices ◽  
Price Changes ◽  
Before And After ◽  
Time Periods ◽  
Changes In Risk ◽  
The Impact

This study reports on the financial markets reaction to the defeasance of corporate debt and whether the market perceives a changes in risk as a result of this activity. The prices of seventeen bonds both before and after defeasance were analyzed using t-tests to determine if any significant price changes related to the act of defeasance occurred between these two time periods. Contrary to what might be expected no significant differences were found.

scholarly journals Wording of Daily Diary Questions Matters: An Investigation of the Effect of Daily Diary Instructional Phrases on Respondents’ Recall Time frames (Preprint)

2019 ◽  
Author(s):  
Arthur A. Stone ◽  
Cheng K. Fred Wen ◽  
Stefan Schneider ◽  
Doerte U. Junghaenel
Keyword(s):  
Medical Science ◽  
Daily Diary ◽  
Time Frame ◽  
Affective States ◽  
Diverse Range ◽  
Daily Experience ◽  
Time Periods ◽  
Waking Up ◽  
Time Frames ◽  
The Impact

BACKGROUND Daily diaries are extensively used for examining participants' daily experience in behavioral and medical science. Whether participants recall their experiences within the time frames prescribed by task has received little attention. OBJECTIVE The objectives of this study are to describe survey respondents' self-reported recall timeframe and to evaluate the impact of different daily diary items on respondents reported affective states. METHODS In this study, 577 participants completed a mood survey with one of four time frame instructions: 1) today, 2) since waking up today, 3) during the last 24 hours, or 4) in the last day. They were also asked to indicate the time periods they considered when answering these items and to recall the instructional phrases associated with the items. RESULTS Almost all participants in the "Today" (97%) and "Since waking up today" (94%)" conditions reported using time periods consistent with our expectations, while a lower proportion was observed in the "during the last 24 hours" (69%) condition. A diverse range of responses was observed in the "In the last day" condition. Furthermore, the instructions influenced the levels of some self-reported affects, although exploratory analyses were not able to identify the mechanism underlying this finding. CONCLUSIONS Overall, these results indicate that "Today" and "Since waking up today" are the most effective instructional phrases for inquiring about daily experience and that investigators should use caution when using the other two instructional phrases.

scholarly journals 154. Antibiotic Use During Three Separate Waves of the COVID-19 Pandemic at a Large Academic Medical Center in Detroit, MI

2021 ◽  
Vol 8 (Supplement_1) ◽  
pp. S188-S189
Author(s):  
Deepika Sivakumar ◽  
Shelbye R Herbin ◽  
Raymond Yost ◽  
Marco R Scipione
Keyword(s):  
Retrospective Review ◽  
Bacterial Pneumonia ◽  
Medical Center ◽  
Academic Medical Center ◽  
Antibiotic Use ◽  
Percent Change ◽  
Academic Medical ◽  
Days Of Therapy ◽  
Time Periods ◽  
The Impact

Abstract Background Inpatient antibiotic use early on in the COVID-19 pandemic may have increased due to the inability to distinguish between bacterial and COVID-19 pneumonia. The purpose of this study was to determine the impact of COVID-19 on antimicrobial usage during three separate waves of the COVID-19 pandemic. Methods We conducted a retrospective review of patients admitted to Detroit Medical Center between 3/10/19 to 4/24/21. Median days of therapy per 1000 adjusted patient days (DOT/1000 pt days) was evaluated for all administered antibiotics included in our pneumonia guidelines during 4 separate time periods: pre-COVID (3/3/19-4/27/19); 1st wave (3/8/20-5/2/20); 2nd wave (12/6/21-1/30/21); and 3rd wave (3/7/21-4/24/21). Antibiotics included in our pneumonia guidelines include: amoxicillin, azithromycin, aztreonam, ceftriaxone, cefepime, ciprofloxacin, doxycycline, linezolid, meropenem, moxifloxacin, piperacillin-tazobactam, tobramycin, and vancomycin. The percent change in antibiotic use between the separate time periods was also evaluated. Results An increase in antibiotics was seen during the 1st wave compared to the pre-COVID period (2639 [IQR 2339-3439] DOT/1000 pt days vs. 2432 [IQR 2291-2499] DOT/1000 pt days, p=0.08). This corresponded to an increase of 8.5% during the 1st wave. This increase did not persist during the 2nd and 3rd waves of the pandemic, and the use decreased by 8% and 16%, respectively, compared to the pre-COVID period. There was an increased use of ceftriaxone (+6.5%, p=0.23), doxycycline (+46%, p=0.13), linezolid (+61%, p=0.014), cefepime (+50%, p=0.001), and meropenem (+29%, p=0.25) during the 1st wave compared to the pre-COVID period. Linezolid (+39%, p=0.013), cefepime (+47%, p=0.08) and tobramycin (+47%, p=0.05) use remained high during the 3rd wave compared to the pre-COVID period, but the use was lower when compared to the 1st and 2nd waves. Figure 1. Antibiotic Use 01/2019 to 04/2019 Conclusion Antibiotics used to treat bacterial pneumonia during the 1st wave of the pandemic increased and there was a shift to broader spectrum agents during that period. The increased use was not sustained during the 2nd and 3rd waves of the pandemic, possibly due to the increased awareness of the differences between patients who present with COVID-19 pneumonia and bacterial pneumonia. Disclosures All Authors: No reported disclosures

scholarly journals Land–atmosphere interactions in the tropics

2019 ◽  
Author(s):  
Pierre Gentine ◽  
Adam Massmann ◽  
Benjamin R. Lintner ◽  
Sayed Hamed Alemohammad ◽  
Rong Fu ◽  
...  
Keyword(s):  
Land Surface ◽  
Deep Convection ◽  
Lower Troposphere ◽  
Surface Fluxes ◽  
Surface Radiation ◽  
Spatial And Temporal Scales ◽  
Wide Range ◽  
Shallow Clouds ◽  
The Tropics ◽  
The Impact

Abstract. The continental tropics play a leading role in the terrestrial water and carbon cycles. Land–atmosphere interactions are integral in the regulation of surface energy, water and carbon fluxes across multiple spatial and temporal scales over tropical continents. We review here some of the important characteristics of tropical continental climates and how land–atmosphere interactions regulate them. Along with a wide range of climates, the tropics manifest a diverse array of land–atmosphere interactions. Broadly speaking, in tropical rainforests, light and energy are typically more limiting than precipitation and water supply for photosynthesis and evapotranspiration; whereas in savanna and semi-arid regions water is the critical regulator of surface fluxes and land–atmosphere interactions. We discuss the impact of the land surface, how it affects shallow clouds and how these clouds can feedback to the surface by modulating surface radiation. Some results from recent research suggest that shallow clouds may be especially critical to land–atmosphere interactions as these regulate the energy budget and moisture transport to the lower troposphere, which in turn affects deep convection. On the other hand, the impact of land surface conditions on deep convection appear to occur over larger, non-local, scales and might be critically affected by transitional regions between the climatologically dry and wet tropics.

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