1,720,959 research outputs found
Global changes in daily precipitation since 1950
Get PDFUnderstanding long-term changes in global precipitation is vital due to its impact on human and natural ecosystems. However, in many regions, confidence in precipitation changes is low due to a lack of high quality observations resulting in uncertainty in precipitation changes. This thesis investigates changes in the entire distribution of precipitation since 1950 over global land areas using a newly developed dataset of daily observations ideal for investigating climatic changes globally.
The dataset developed in this thesis, Rainfall Estimates on a Gridded Network (REGEN), interpolates raw station-based daily precipitation records from multiple archives (including two of the largest) onto a 1 degree X 1 degree grid. The process of merging multiple station archives results in the highest station count (~135,000 stations) and the longest temporal record (1950-2013) of any existing global daily precipitation datasets, and is almost 30 years longer than the longest existing product. This thesis also demonstrates the importance of including observational uncertainties when developing such a dataset and intercomparing with existing products. The results presented in this thesis indicate that REGEN’s precipitation estimates are consistent with existing monthly and daily, global and regional datasets.
Changes in the entire distribution of daily precipitation are investigated alongside changes in the frequency and intensity of precipitation events at each grid box over land. In doing so this thesis highlights key relationships between frequency of wet-days (>= 1 mm), precipitation intensity (amount of precipitation per rainy day) and the daily precipitation distribution. We find that precipitation intensity and extremes have increased since 1950 across the majority of global land areas. Furthermore, continental-scale increases in the frequency of wet-days are observed across Asia and the US, and similar widespread increases in the precipitation intensity are observed across Europe and Australia.
The dataset and methods developed in this thesis enable many new avenues of research, such as model evaluation and investigation of processes behind the long term precipitation changes. Ultimately, this global analysis increases our understanding of past precipitation changes, in turn helping us adapt to precipitation changes in a warmer climate
Rainfall Estimates on a Gridded Network (REGEN) based on long-term station data V1.0
No full textA global land-based gridded dataset of daily precipitation at 1 degree X 1 degree resolution from 1950 to 2013. Two datasets are available under the REGEN moniker. This dataset interpolates only the long-term precipitation stations (stations with at least 40 complete years of data).
A second related dataset interpolates all stations available regardless of completeness of station timeseries. Besides the grid cell average precipitation amount per day (mm/day), the Yamamoto standard deviation per grid cell (mm/day), the kriging error per grid cell (%) and number of stations per grid cell variables are also included.
Currently, there are two major data archives of global in situ daily rainfall data: 1. The Global Historical Station Network (GHCN-Daily) hosted by National Oceanic and Atmospheric Administration (NOAA) and 2. The Deutscher Wetterdienst (DWD) Global Precipitation Climatology Centre (GPCC). These two data archives are combined along with additional station data acquired from other researchers. The merged archive is quality controlled and the flagged stations are removed to create a long term high quality archive of raw station data. This dataset uses ordinary block kriging to interpolate a long-term station subset of this high quality merged archive. The REGEN all station based dataset instead interpolates all stations in this high quality merged archive.
The output consists of a separate CF-compliant netcdf file for each year, each containing the four aforementioned variables. These values are available for global land areas with the exception of Antarctica. The time dimension of the netcdf ranges from 1950-01-01 to 2013-12-31. Each dataset (All station based and long-term station based) is in classic netcdf format and occupies around 350MB of disk space for each year with the combined total of all years being around 26GB. Besides these two netcdfs, two additional netcdfs containing a mask indicating the high data quality grid cells of each dataset (all station and long-term) are also available. These netcdf files have the same grid descriptions as the original data but contain only one timestep for the entire period.
This dataset was produced by Steefan Contractor of the ARC Centre of Excellence for Climate Systems Sciences, as part of a the research program "The role of land surface forcing and feedbacks for regional climate".Preferred citation:
Contractor, Stefan 2018. Rainfall Estimates on a Gridded Network based on long-term station data v1.0 NCI National Research Data Collection , doi:10.25914/5b9fa67fce5d6
Access to the data is via the NCI geonetwork record in related identifiers, details are also provided in the readme file
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Changes in observed daily precipitation over global land areas since 1950
Get PDFEstimates of observed long-term changes in daily precipitation globally have been limited due to availability of high-quality observations. In this study, a new gridded dataset of daily precipitation, called Rainfall Estimates on a Gridded Network (REGEN) V1–2019, was used to perform an assessment of the climatic changes in precipitation at each global land location (except Antarctica). This study investigates changes in the number of wet days (≥1 mm) and the entire distribution of daily wet- and all-day records, in addition to trends in annual and seasonal totals from daily records, between 1950 and 2016. The main finding of this study is that precipitation has intensified across a majority of land areas globally throughout the wet-day distribution. This means that when it rains, light, moderate, or heavy wet-day precipitation has become more intense across most of the globe. Widespread increases in the frequency of wet days are observed across Asia and the United States, and widespread increases in the precipitation intensity are observed across Europe and Australia. Based on a comparison of spatial pattern of changes in frequency, intensity, and the distribution of daily totals, we propose that changes in light and moderate precipitation are characterized by changes in precipitation frequency, whereas changes in extreme precipitation are primarily characterized by intensity changes. Based on the uncertainty estimates from REGEN, this study highlights all results in the context of grids with high-quality observations.This study was funded by Australian Research Council (ARC) Grant DP160103439. MGD received funding from ARC Grant DE150100456, and the Spanish Ministry for the Economy, Industry and Competitiveness Grant RYC-2017-22964. LVA was also funded by ARC Grant CE110001028. We are also grateful to the National Centers for Environmental Information (NCEI) and the Global Precipitation Climatology Centre (GPCC) for support during the production of REGEN.Peer ReviewedPostprint (published version
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
- …
