scholarly journals Bioclimatic traits in statistical properties of daily photosynthetically active radiation

2020 ◽  
Author(s):  
Estefanía Muñoz ◽  
Andrés Ochoa
Keyword(s):  
Spectral Band ◽  
Distribution Functions ◽  
Dry Forest ◽  
Spectral Irradiance ◽  
High Dispersion ◽  
Data Set ◽  
Tropical Regions ◽  
Clear Sky ◽  
Life Zone ◽  
Low Dispersion

Abstract. In this paper, we present a methodology to analyze the stochastic component of daily solar radiation at the earth's surface in the photosynthetically active spectral band. Extraterrestrial solar spectral irradiance from the SOLID project and in situ observed PAR from the FLUXNET data set are used to calculate daily time series of the clearness and clear-sky indices for 28 FLUXNET sites around the world for 1978–2014. We found that the shape of the probability distribution functions of the clearness and clear-sky indices exhibit a spatial pattern related to the Köppen climate classification and the Holdridge life zones. According to the Köppen classification, oceanic, humid continental, and Mediterranean climates show bimodal distributions; semi-arid, temperate, subtropical, and desert climates show unimodal distributions with high dispersion; and tropical climates show unimodal distributions with low dispersion. Moreover, according to the Holdridge triangle, sites with bimodal distributions are concentrated in moist and wet forest life zones located in boreal and cool temperate regions and sub-humid and humid provinces. Unimodal distributions with high dispersion are concentrated in the moist forest life zone in subtropical and tropical regions and humid province; and unimodal distributions with low dispersion are concentrated in dry forest, very dry forest, and thorn woodland in tropical and subtropical regions between arid and subhumid humidity provinces.

scholarly journals Evaluation of the MOZAIC Capacitive Hygrometer during the airborne field study CIRRUS-III

2015 ◽  
Vol 8 (3) ◽  
pp. 1233-1243 ◽  
Author(s):  
P. Neis ◽  
H. G. J. Smit ◽  
M. Krämer ◽  
N. Spelten ◽  
A. Petzold
Keyword(s):  
Ambient Temperature ◽  
Field Study ◽  
Laser System ◽  
Distribution Functions ◽  
Tunable Diode Laser ◽  
Data Set ◽  
Clear Sky ◽  
Operation Conditions ◽  
Open Path ◽  
Passenger Aircraft

Abstract. The MOZAIC Capacitive Hygrometer (MCH) is usually operated aboard passenger aircraft in the framework of MOZAIC (Measurement of Ozone by Airbus In-Service Aircraft) for measuring atmospheric relative humidity (RH). In order to evaluate the performance of the MCH, the instrument was operated aboard a Learjet 35A research aircraft as part of the CIRRUS-III field study together with a closed-cell Lyman-α fluorescence hygrometer (Fast in situ Stratospheric Hygrometer, or FISH) and an open-path tunable diode laser system (Open-path Jülich Stratospheric TDL ExpeRiment, or OJSTER) for water vapour measurement. After reducing the CIRRUS-III data set to data corresponding to MOZAIC aircraft operation conditions, the 1 Hz RH data cross correlation between the MCH and reference instruments FISH (clear sky) and OJSTER (in-cirrus) yielded a remarkably good agreement of R2 = 0.92 and slope m = 1.02 and provided a MCH uncertainty of 5% RH. Probability distribution functions of RH deduced from the MCH and reference instruments agreed well between 10 and 70% RH with respect to liquid water in the ambient temperature range of ca. −70 to −40 °C. The use of MCH data is limited to sensor temperatures above the calibration limit of Tsensor = −40 °C (corresponds to ambient temperature of Tambient = −70 °C at typical cruising speed of long-haul passenger aircraft). Good performance of the MCH for clear sky as well as for in-cirrus conditions demonstrated the sensor robustness also for operation inside ice clouds.

scholarly journals Evaluation of the MOZAIC Capacitive Hygrometer during the airborne field study CIRRUS-III

2014 ◽  
Vol 7 (9) ◽  
pp. 9803-9838 ◽  
Author(s):  
P. Neis ◽  
H. G. J. Smit ◽  
M. Krämer ◽  
N. Spelten ◽  
A. Petzold
Keyword(s):  
Field Study ◽  
Laser System ◽  
Distribution Functions ◽  
Tunable Diode Laser ◽  
Data Set ◽  
Ice Clouds ◽  
Clear Sky ◽  
Closed Cell ◽  
Passenger Aircraft ◽  
Good Agreement

Abstract. The MOZAIC Capacitive Hygrometer (MCH) is usually operated onboard of passenger aircraft in the framework of MOZAIC (Measurement of Ozone by AIRBUS In-Service Aircraft). In order to evaluate the performance of the MCH, it was operated aboard a Learjet 35A aircraft as part of the CIRRUS-III field study together with a closed-cell Lyman-α fluorescence hygrometer (FISH) and an open path tunable diode laser system (OJSTER) for water vapour measurement. After reducing the data set to MOZAIC-relevant conditions, the 1Hz relative humidity (RH) cross correlation between MCH and reference instruments FISH (clear sky) and OJSTER (in-cirrus) yielded a remarkably good agreement of R2 = 0.97 and slope m = 0.96 and provided the MCH uncertainty of 5% RH. Probability distribution functions of RH deduced from MCH and reference instruments agreed well over the entire range of observations. The main limitation for the use of MCH data is related to sensor temperatures below the calibration limit of Tsensor = −40 °C (corresponds to ambient temperature of Tambient = −70 °C at typical cruising speed of long-haul passenger aircraft), which causes a delay in the sensor's time response. Good performance of MCH for clear sky as well as for in-cirrus conditions demonstrated the sensor robustness also for operation inside ice clouds.

scholarly journals Do galactic bars depend on environment?: an information theoretic analysis of Galaxy Zoo 2

2020 ◽  
Vol 501 (1) ◽  
pp. 994-1001
Author(s):  
Suman Sarkar ◽  
Biswajit Pandey ◽  
Snehasish Bhattacharjee
Keyword(s):  
Spatial Distribution ◽  
Mutual Information ◽  
Local Density ◽  
Statistical Significance ◽  
Distribution Functions ◽  
Cumulative Distribution ◽  
Host Galaxy ◽  
Data Sets ◽  
Data Set ◽  
Information Theoretic

ABSTRACT We use an information theoretic framework to analyse data from the Galaxy Zoo 2 project and study if there are any statistically significant correlations between the presence of bars in spiral galaxies and their environment. We measure the mutual information between the barredness of galaxies and their environments in a volume limited sample (Mr ≤ −21) and compare it with the same in data sets where (i) the bar/unbar classifications are randomized and (ii) the spatial distribution of galaxies are shuffled on different length scales. We assess the statistical significance of the differences in the mutual information using a t-test and find that both randomization of morphological classifications and shuffling of spatial distribution do not alter the mutual information in a statistically significant way. The non-zero mutual information between the barredness and environment arises due to the finite and discrete nature of the data set that can be entirely explained by mock Poisson distributions. We also separately compare the cumulative distribution functions of the barred and unbarred galaxies as a function of their local density. Using a Kolmogorov–Smirnov test, we find that the null hypothesis cannot be rejected even at $75{{\ \rm per\ cent}}$ confidence level. Our analysis indicates that environments do not play a significant role in the formation of a bar, which is largely determined by the internal processes of the host galaxy.

Reliability-based covariate analysis for complex systems in heterogeneous environment: Case study of mining equipment

2018 ◽  
Vol 233 (4) ◽  
pp. 593-604
Author(s):  
Amin Moniri-Morad ◽  
Mohammad Pourgol-Mohammad ◽  
Hamid Aghababaei ◽  
Javad Sattarvand
Keyword(s):  
Complex Systems ◽  
Cox Regression ◽  
Reliability Evaluation ◽  
Distribution Functions ◽  
Heterogeneous Environment ◽  
Mining Equipment ◽  
Data Set ◽  
Explanatory Variables ◽  
The Impact

Operational heterogeneity and harsh environment lead to major variations in production system performance and safety. Traditional probabilistic model is dealt with time-to-event data analysis, which does not have the capability of quantifying and simulation of these types of complexities. This research proposes an integrated methodology for analyzing the impact of dominant explanatory variables on the complex system reliability. A flexible parametric proportional hazards model is developed by focusing on standard parametric Cox regression model for reliability evaluation in complex systems. To achieve this, natural cubic splines are utilized to create a smooth and flexible baseline hazards function where the standard parametric distribution functions do not fit into the failure data set. A real case study is considered to evaluate the reliability for multi-component mechanical systems such as mining equipment. Different operational and environmental explanatory variables are chosen for the analysis process. Research findings revealed that precise estimation of the baseline hazards function is a major part of the reliability evaluation in heterogeneous environment. It is concluded that an appropriate maintenance strategy potentially mitigate the equipment failure intensity.

scholarly journals Neighbourhood variation in the price of soda relative to milk and its association with neighbourhood socio-economic status and race

2016 ◽  
Vol 19 (18) ◽  
pp. 3386-3396 ◽  
Author(s):  
David M Kern ◽  
Amy H Auchincloss ◽  
Lance S Ballester ◽  
Lucy F Robinson
Keyword(s):  
Economic Status ◽  
Hierarchical Regression ◽  
High Dispersion ◽  
Hispanic Population ◽  
Data Set ◽  
Census Block Group ◽  
Socio Economic Status ◽  
The Usa ◽  
Soda Consumption ◽  
Block Groups

AbstractObjectiveSoda consumption is high in the USA, especially among minorities and individuals of lower socio-economic status (SES); this may be due to its affordable price in relation to healthier alternatives. The objective of the present study was to examine geospatial variation in price of milk and soda, and the price of milk relative to soda, by neighbourhood SES and proportion of Hispanic and black individuals.DesignRetailer soda and milk prices (n 2987; Information Resources, Inc. Academic Data Set 2004–2011) were linked to census block group sociodemographic characteristics (American Community Survey 2005–2009). Linear hierarchical regression models were used to adjust for confounders.SettingLarge chain supermarkets and superstores (n 1743) in forty-one states and 1694 block groups (USA).ResultsFor equivalent fluid ounces, price of soda on average was 62 % lower than milk ($US 0·23 v. $US 0·63 per serving) and there was high dispersion in milk price across geographic areas. After adjustment for confounding, neighbourhoods with a higher concentration of black and Hispanic individuals tended to have lower soda prices and higher milk prices (−$US 0·001 and +$US 0·007 in price per serving, respectively, for a one quintile increase in black/Hispanic population), while soda and milk both became less expensive as SES decreased (–$US 0·002 and −$US 0·015 in serving price per one sd decrease in SES index, respectively).ConclusionsNeighbourhoods with a higher concentration of blacks and Hispanics may be at greater risk of higher soda consumption due to more affordable prices, in absolute terms and relative to the price of milk.

scholarly journals Spectral albedo of seasonal snow during intensive melt period at Sodankylä, beyond the Arctic Circle

2013 ◽  
Vol 13 (7) ◽  
pp. 3793-3810 ◽  
Author(s):  
O. Meinander ◽  
S. Kazadzis ◽  
A. Arola ◽  
A. Riihelä ◽  
P. Räisänen ◽  
...  
Keyword(s):  
Spectral Irradiance ◽  
The Arctic ◽  
Visible Range ◽  
Air Masses ◽  
Clear Sky ◽  
Effective Grain Size ◽  
European Arctic ◽  
Small Absorption ◽  
High Concentrations ◽  
Double Monochromator

Abstract. We have measured spectral albedo, as well as ancillary parameters, of seasonal European Arctic snow at Sodankylä, Finland (67°22' N, 26°39' E). The springtime intensive melt period was observed during the Snow Reflectance Transition Experiment (SNORTEX) in April 2009. The upwelling and downwelling spectral irradiance, measured at 290–550 nm with a double monochromator spectroradiometer, revealed albedo values of ~0.5–0.7 for the ultraviolet and visible range, both under clear sky and variable cloudiness. During the most intensive snowmelt period of four days, albedo decreased from 0.65 to 0.45 at 330 nm, and from 0.72 to 0.53 at 450 nm. In the literature, the UV and VIS albedo for clean snow are ~0.97–0.99, consistent with the extremely small absorption coefficient of ice in this spectral region. Our low albedo values were supported by two independent simultaneous broadband albedo measurements, and simulated albedo data. We explain the low albedo values to be due to (i) large snow grain sizes up to ~3 mm in diameter; (ii) meltwater surrounding the grains and increasing the effective grain size; (iii) absorption caused by impurities in the snow, with concentration of elemental carbon (black carbon) in snow of 87 ppb, and organic carbon 2894 ppb, at the time of albedo measurements. The high concentrations of carbon, detected by the thermal–optical method, were due to air masses originating from the Kola Peninsula, Russia, where mining and refining industries are located.

scholarly journals Availability of anions in the growth medium to roots of an actively growing plant.

1975 ◽  
Vol 23 (2) ◽  
pp. 131-138
Author(s):  
H. Van Keulen ◽  
N.G. Seligman ◽  
J. Goudriaan
Keyword(s):  
Root System ◽  
Growth Medium ◽  
Mass Flow ◽  
Dispersion Coefficient ◽  
Anion Transport ◽  
Root Density ◽  
High Dispersion ◽  
Rooting Zone ◽  
Speed Up ◽  
Low Dispersion

Analysis of anion transport to the root of an actively growing plant with a normally dense root system showed that virtually the whole of the anion store in the rooting zone is available to the plant within a few days at the most. Transport by diffusion only is enough to account for most of the depletion, but mass flow will speed up the process. The effect of mass flow will be considerable in soils with a high dispersion coefficient (loess), but very small in soils with a low dispersion coefficient (clay and sand). A rule is proposed to determine whether a given root density is sufficient to supply the nitrogen and water needs of the plant by diffusion only. (Abstract retrieved from CAB Abstracts by CABI’s permission)

scholarly journals Transformation of circular random variables based on circular distribution functions

Filomat ◽  
2018 ◽  
Vol 32 (17) ◽  
pp. 5931-5947
Author(s):  
Hatami Mojtaba ◽  
Alamatsaz Hossein
Keyword(s):  
Distribution Function ◽  
Random Variables ◽  
Real Data ◽  
Random Variable ◽  
Distribution Functions ◽  
Likelihood Method ◽  
Circular Distribution ◽  
Data Set ◽  
Trigonometric Moments ◽  
Von Mises

In this paper, we propose a new transformation of circular random variables based on circular distribution functions, which we shall call inverse distribution function (id f ) transformation. We show that M?bius transformation is a special case of our id f transformation. Very general results are provided for the properties of the proposed family of id f transformations, including their trigonometric moments, maximum entropy, random variate generation, finite mixture and modality properties. In particular, we shall focus our attention on a subfamily of the general family when id f transformation is based on the cardioid circular distribution function. Modality and shape properties are investigated for this subfamily. In addition, we obtain further statistical properties for the resulting distribution by applying the id f transformation to a random variable following a von Mises distribution. In fact, we shall introduce the Cardioid-von Mises (CvM) distribution and estimate its parameters by the maximum likelihood method. Finally, an application of CvM family and its inferential methods are illustrated using a real data set containing times of gun crimes in Pittsburgh, Pennsylvania.

scholarly journals Quantifying uncertainties of climate signals in chemistry climate models related to the 11-year solar cycle – Part 1: Annual mean response in heating rates, temperature, and ozone

2020 ◽  
Vol 20 (11) ◽  
pp. 6991-7019
Author(s):  
Markus Kunze ◽  
Tim Kruschke ◽  
Ulrike Langematz ◽  
Miriam Sinnhuber ◽  
Thomas Reddmann ◽  
...  
Keyword(s):  
Atmospheric Chemistry ◽  
Solar Minimum ◽  
Climate Model ◽  
Solar Maximum ◽  
Sunspot Cycle ◽  
Spectral Irradiance ◽  
Data Sets ◽  
Reference Spectrum ◽  
Heating Rates ◽  
Data Set

Abstract. Variations in the solar spectral irradiance (SSI) with the 11-year sunspot cycle have been shown to have a significant impact on temperatures and the mixing ratios of atmospheric constituents in the stratosphere and mesosphere. Uncertainties in modelling the effects of SSI variations arise from uncertainties in the empirical models reconstructing the prescribed SSI data set as well as from uncertainties in the chemistry–climate model (CCM) formulation. In this study CCM simulations with the ECHAM/MESSy Atmospheric Chemistry (EMAC) model and the Community Earth System Model 1 (CESM1)–Whole Atmosphere Chemistry Climate Model (WACCM) have been performed to quantify the uncertainties of the solar responses in chemistry and dynamics that are due to the usage of five different SSI data sets or the two CCMs. We apply a two-way analysis of variance (ANOVA) to separate the influence of the SSI data sets and the CCMs on the variability of the solar response in shortwave heating rates, temperature, and ozone. The solar response is derived from climatological differences of time slice simulations prescribing SSI for the solar maximum in 1989 and near the solar minimum in 1994. The SSI values for the solar maximum of each SSI data set are created by adding the SSI differences between November 1994 and November 1989 to a common SSI reference spectrum for near-solar-minimum conditions based on ATLAS-3 (Atmospheric Laboratory of Applications and Science-3). The ANOVA identifies the SSI data set with the strongest influence on the variability of the solar response in shortwave heating rates in the upper mesosphere and in the upper stratosphere–lower mesosphere. The strongest influence on the variability of the solar response in ozone and temperature is identified in the upper stratosphere–lower mesosphere. However, in the region of the largest ozone mixing ratio, in the stratosphere from 50 to 10 hPa, the SSI data sets do not contribute much to the variability of the solar response when the Spectral And Total Irradiance REconstructions-T (SATIRE-T) SSI data set is omitted. The largest influence of the CCMs on variability of the solar responses can be identified in the upper mesosphere. The solar response in the lower stratosphere also depends on the CCM used, especially in the tropics and northern hemispheric subtropics and mid-latitudes, where the model dynamics modulate the solar responses. Apart from the upper mesosphere, there are also regions where the largest fraction of the variability of the solar response is explained by randomness, especially for the solar response in temperature.

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