Spectral Density of Polarimetric Variables Separating Biological Scatterers in the VAD Display

Abstract Echoes in clear air from two types of biological scatterers mixed within the resolution volumes over a large region, observed with S-band dual polarization radar, are presented. This case occurred in the evening of 7 September 2004, at the beginning of the fall migrating season of song birds (passerines). Polarimetric spectral analyses are used for distinguishing birds and insects in multimodal spectra. Spatial continuity of spectral peaks shows clear separation of insect (wind) speeds from bird speeds. Spectral densities of polarimetric variables exhibit vastly different values at speeds corresponding to insects than from those of birds, allowing the separation of the two scatterer types. Therefore, the statistics of the intrinsic polarimetric variables computed from spectral densities are unbiased and closer to the ensemble statistics of the echo type than the ones obtained with standard processing techniques. A novel display of the spectral densities versus azimuth, termed spectral velocity–azimuth display (SVAD), is constructed for easier viewing and interpretation of the velocity field. Analyses of the SVADs reveal the mean velocities and the directions of the two types of scatterers.

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Potential of spectroscopic analyses for non-destructive estimation of tea quality-related metabolites in fresh new leaves

Scientific Reports ◽

10.1038/s41598-021-83847-0 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Hiroto Yamashita ◽

Rei Sonobe ◽

Yuhei Hirono ◽

Akio Morita ◽

Takashi Ikka

Keyword(s):

Short Wave ◽

Machine Learning Algorithms ◽

Estimation Methods ◽

Chemical Information ◽

Tea Quality ◽

The Mean ◽

Processing Techniques ◽

Spectral Patterns ◽

Physical And Chemical ◽

Non Destructive

AbstractSpectroscopic sensing provides physical and chemical information in a non-destructive and rapid manner. To develop non-destructive estimation methods of tea quality-related metabolites in fresh leaves, we estimated the contents of free amino acids, catechins, and caffeine in fresh tea leaves using visible to short-wave infrared hyperspectral reflectance data and machine learning algorithms. We acquired these data from approximately 200 new leaves with various status and then constructed the regression model in the combination of six spectral patterns with pre-processing and five algorithms. In most phenotypes, the combination of de-trending pre-processing and Cubist algorithms was robustly selected as the best combination in each round over 100 repetitions that were evaluated based on the ratio of performance to deviation (RPD) values. The mean RPD values were ranged from 1.1 to 2.7 and most of them were above the acceptable or accurate threshold (RPD = 1.4 or 2.0, respectively). Data-based sensitivity analysis identified the important hyperspectral regions around 1500 and 2000 nm. Present spectroscopic approaches indicate that most tea quality-related metabolites can be estimated non-destructively, and pre-processing techniques help to improve its accuracy.

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Differences between Nonprecipitating Tropical and Trade Wind Marine Shallow Cumuli

Monthly Weather Review ◽

10.1175/mwr-d-15-0110.1 ◽

2016 ◽

Vol 144 (2) ◽

pp. 681-701 ◽

Cited By ~ 6

Author(s):

Virendra P. Ghate ◽

Mark A. Miller ◽

Ping Zhu

Keyword(s):

Surface Fluxes ◽

Cloud Base ◽

Trade Wind ◽

Cumulus Clouds ◽

Wind Speeds ◽

Lower Cloud ◽

Observational Site ◽

Velocity Scale ◽

Atmospheric Radiation Measurement ◽

The Mean

Abstract Marine nonprecipitating cumulus topped boundary layers (CTBLs) observed in a tropical and in a trade wind region are contrasted based on their cloud macrophysical, dynamical, and radiative structures. Data from the Atmospheric Radiation Measurement (ARM) observational site previously operating at Manus Island, Papua New Guinea, and data collected during the deployment of ARM Mobile Facility at the island of Graciosa, in the Azores, were used in this study. The tropical marine CTBLs were deeper, had higher surface fluxes and boundary layer radiative cooling, but lower wind speeds compared to their trade wind counterparts. The radiative velocity scale was 50%–70% of the surface convective velocity scale at both locations, highlighting the prominent role played by radiation in maintaining turbulence in marine CTBLs. Despite greater thicknesses, the chord lengths of tropical cumuli were on average lower than those of trade wind cumuli, and as a result of lower cloud cover, the hourly averaged (cloudy and clear) liquid water paths of tropical cumuli were lower than the trade wind cumuli. At both locations ~70% of the cloudy profiles were updrafts, while the average amount of updrafts near cloud base stronger than 1 m s−1 was ~22% in tropical cumuli and ~12% in the trade wind cumuli. The mean in-cloud radar reflectivity within updrafts and mean updraft velocity was higher in tropical cumuli than the trade wind cumuli. Despite stronger vertical velocities and a higher number of strong updrafts, due to lower cloud fraction, the updraft mass flux was lower in the tropical cumuli compared to the trade wind cumuli. The observations suggest that the tropical and trade wind marine cumulus clouds differ significantly in their macrophysical and dynamical structures.

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Rapid coral mortality following unusually calm and hot conditions on Iriomote, Japan

F1000Research ◽

10.12688/f1000research.12660.2 ◽

2018 ◽

Vol 6 ◽

pp. 1728 ◽

Cited By ~ 2

Author(s):

Andrew H Baird ◽

Sally A. Keith ◽

Erika Woolsey ◽

Ryuta Yoshida ◽

Tohru Naruse

Keyword(s):

Water Movement ◽

Sea Surface ◽

Bleaching Event ◽

Coral Mortality ◽

Average Wind Speed ◽

Common Cause ◽

Wind Speeds ◽

Average Wind ◽

The Mean ◽

Low Wind Speeds

Coral bleaching can be induced by many different stressors, however, the most common cause of mass bleaching in the field is higher than average sea surface temperatures (SST). Here, we describe an unusual bleaching event that followed very calm sea conditions combined with higher than average SST. Patterns of mortality differed from typical bleaching in four ways: 1) mortality was very rapid; 2) a different suite of species were most affected; 3) tissue mortality in Acropora spp. was often restricted to the center of the colony; 4) the event occurred early in summer. The two weeks prior to the event included 8 days where the average wind speed was less than 3 ms-1. In addition, SSTs in the weeks preceding and during the event were 1.0-1.5°C higher than the mean for the last 30 years. We hypothesize that this unusual bleaching event was caused by anoxia resulting from a lack of water movement induced by low wind speeds combined with high SST.

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The Characteristics of West Season Wind and Wave as well as Their Impacts on Ferry Cruise in The Kalianget-Kangean Cruise Route, Madura, Indonesia

Pertanika Journal of Science and Technology ◽

10.47836/pjst.29.3.16 ◽

2021 ◽

Vol 29 (3) ◽

Author(s):

Viv Djanat Prasita ◽

Lukman Aulia Zati ◽

Supriyatno Widagdo

Keyword(s):

Wind Speed ◽

Wave Height ◽

The West ◽

Wind Speeds ◽

Wave Patterns ◽

Time Stamps ◽

The Mean ◽

Two Peaks ◽

The Impact ◽

Descriptive Statistical Analysis

The wind and wave conditions in the waters of the Kalianget-Kangean cruise route in the west season are relatively high so that these winds and waves can have a dangerous impact on that cruise route. The aim of this research was to analyze the characteristics of wind speed and wave height over a 10 year period (2008-2017), as well as to evaluate the weekly patterns for three months (December 2017-February 2018). These time stamps represent the west season in waters at Kalianget-Kangean route, and to identify the impact of winds and wave on this path. The method used in this research is descriptive statistical analysis to obtain the mean and maximum values of wind speed and wave height. Wind and wave patterns were analyzed by WRPlot and continued with mapping of wind and wave patterns in the waters of Kalianget-Kangean and its surroundings. The data used was obtained from the Meteorology, Climatology and Geophysics Agency. The results show wind and wave characteristics with two peaks formed regularly between 2008-2017, marking the west and east monsoons. In addition, the wind speed and wave height were generally below the danger threshold, ie <10 knots and <2 m, respectively. However, there are exceptions in the west season, especially at the peak in January, where the forces are strengthened with a steady blowing direction. The maximum wind speed reaches and wave height reaches 29 knots and 6.7 m, respectively. The weekly conditions for both parameters from December 2017 to February 2018 were relatively safe, for sailing. Moreover, January 23-29, 2018 featured extreme conditions estimated as dangerous for cruise due to the respective maximum values of 25 knots and 3.8 m recorded. The channel is comparably safe, except during the western season time in December, January, February, characterized by wind speeds and wave height exceeding 21 knots and 2.5 m, correspondingly.

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On the wind resource in Algeria: Probability distributions evaluation

Proceedings of the Institution of Mechanical Engineers Part A Journal of Power and Energy ◽

10.1177/0957650920975883 ◽

2020 ◽

pp. 095765092097588

Author(s):

Houdayfa Ounis ◽

Nawel Aries

Keyword(s):

Wind Speed ◽

Probability Distribution ◽

Probability Distributions ◽

Resource Assessment ◽

Descriptive Statistics ◽

The Other ◽

Wind Speeds ◽

Wind Resource Assessment ◽

The Mean ◽

Wind Resource

The present study aims to present a contribution to the wind resource assessment in Algeria using ERA-Interim reanalysis. Firstly, the ERA-Interim reanalysis 10 m wind speed data are considered for the elaboration of the mean annual 10 m wind speed map for a period starting from 01-01-2000 to 31-12-2017. Moreover, the present study intends to highlight the importance of the descriptive statistics other than the mean in wind resource assessment. On the other hand, this study aims also to select the proper probability distribution for the wind resource assessment in Algeria. Therefore, nine probability distributions were considered, namely: Weibull, Gamma, Inverse Gaussian, Log Normal, Gumbel, Generalized Extreme Value (GEV), Nakagami, Generalized Logistic and Pearson III. Furthermore, in combination with the distribution, three parameter estimation methods were considered, namely, Method of Moment, Maximum Likelihood Method and L-Moment Method. The study showed that Algeria has several wind behaviours due to the diversified topographic, geographic and climatic properties. Moreover, the annual mean 10 m wind speed map showed that the wind speed varies from 2.3 to 5.3 m/s, where 73% of the wind speeds are above 3 m/s. The map also showed that the Algerian Sahara is windiest region, while, the northern fringe envelopes the lowest wind speeds. In addition, it has been shown that the study of the mean wind speeds for the evaluation of the wind potential alone is not enough, and other descriptive statistics must be considered. On the other hand, among the nine considered distribution, it appears that the GEV is the most appropriate probability distribution. Whereas, the Weibull distribution showed its performance only in regions with high wind speeds, which, implies that this probability distribution should not be generalized in the study of the wind speed in Algeria.

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Evaluation of the Ocean Surface Wind Speed Change following the Super Typhoon from Space-Borne GNSS-Reflectometry

Remote Sensing ◽

10.3390/rs12122034 ◽

2020 ◽

Vol 12 (12) ◽

pp. 2034 ◽

Cited By ~ 2

Author(s):

Hongsu Liu ◽

Shuanggen Jin ◽

Qingyun Yan

Keyword(s):

Wind Speed ◽

Correlation Coefficient ◽

Surface Wind ◽

Ocean Surface ◽

Surface Wind Speed ◽

Wind Speeds ◽

Mean Error ◽

Super Typhoon ◽

The Mean ◽

Ocean Surface Wind

Ocean surface wind speed is an essential parameter for typhoon monitoring and forecasting. However, traditional satellite and buoy observations are difficult to monitor the typhoon due to high cost and low temporal-spatial resolution. With the development of spaceborne GNSS-R technology, the cyclone global navigation satellite system (CYGNSS) with eight satellites in low-earth orbit provides an opportunity to measure the ocean surface wind speed of typhoons. Though observations are made at the extremely efficient spatial and temporal resolution, its accuracy and reliability are unclear in an actual super typhoon case. In this study, the wind speed variations over the life cycle of the 2018 Typhoon Mangkhut from CYGNSS observations were evaluated and compared with European Centre for Medium-Range Weather Forecasts (ECMWF) Re-Analysis-5 (ERA-5). The results show that the overall root-mean-square error (RMSE) of CYGNSS versus ECMWF was 4.12 m/s, the mean error was 1.36 m/s, and the correlation coefficient was 0.96. For wind speeds lower and greater than 15 m/s, the RMSE of CYGNSS versus ECMWF were 1.02 and 4.36 m/s, the mean errors were 0.05 and 1.61 m/s, the correlation coefficients were 0.91 and 0.90, and the average relative errors were 9.8% and 11.6%, respectively. When the typhoon reached a strong typhoon or super typhoon, the RMSE of CYGNSS with respect to ERA-5 from ECMWF was 5.07 m/s; the mean error was 3.57 m/s; the correlation coefficient was 0.52 and the average relative error was 11.0%. The CYGNSS estimation had higher precision for wind speeds below 15 m/s, but degraded when the wind speed was above 15 m/s.

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Evacuee Perception of Geophysical Hazards for Hurricane Irma

Weather Climate and Society ◽

10.1175/wcas-d-18-0019.1 ◽

2019 ◽

Vol 11 (1) ◽

pp. 217-227 ◽

Cited By ~ 5

Author(s):

Jason Senkbeil ◽

Jennifer Collins ◽

Jacob Reed

Keyword(s):

Wind Speed ◽

Storm Surge ◽

Wind Speeds ◽

Wind Gusts ◽

Different Types ◽

High Concern ◽

Rest Areas ◽

The Mean ◽

Atlantic Hurricanes ◽

Hurricane Irma

Abstract Hurricane Irma was one of the strongest Atlantic hurricanes in history before landfall and caused a large evacuation. A total of 155 evacuees at interstate rest areas were asked to rank their concern about damage at their residence for six different geophysical hurricane hazards. Additionally, they were asked about their perceived maximum wind speeds (PMWS) and the wind speeds at which they thought damage would occur (DW) at their residence. These wind speeds were then compared to the actual peak wind gusts (APG) nearest to each resident’s location. Results show a significantly greater concern for wind and storm size, compared to other hazards (tornadoes, rainfall/flooding, storm surge, falling trees). The mean PMWS of evacuees was greater than the mean APG, suggesting widespread misperception of wind speeds. Furthermore, the mean APG was less than the mean DW, and the mean PMWS was also higher than the DW. Additional tests found no significant differences in wind perception between residents with previous storm experiences and no experience, and no significant differences between those who resided in mandatory evacuation zip codes and those who did not. These results suggest that wind speed risk is poorly understood, even though it is a high concern for evacuees from hurricanes. The communication of wind speed risk in forecasts should possibly be modified by placing greater emphasis on postlandfall impacts, wind speed decay after landfall, and wind speeds that cause damage to different types of residences.

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Winds near the Surface of Waves: Observations and Modeling

Journal of Physical Oceanography ◽

10.1175/jpo-d-17-0009.1 ◽

2018 ◽

Vol 48 (5) ◽

pp. 1079-1088 ◽

Cited By ~ 10

Author(s):

Alexander V. Babanin ◽

Jason McConochie ◽

Dmitry Chalikov

Keyword(s):

Boundary Layer ◽

Wind Wave ◽

Wave Boundary Layer ◽

Wind Speeds ◽

Vertical Profiling ◽

The Mean ◽

Flux Layer ◽

Logarithmic Layer ◽

Wave Boundary ◽

Lake George

AbstractThe concept of a constant-flux layer is usually employed for vertical profiling of the wind measured at some elevation near the ocean surface. The surface waves, however, modify the balance of turbulent stresses very near the surface, and therefore such extrapolations can introduce significant biases. This is particularly true for buoy measurements in extreme conditions, when the anemometer mast is within the wave boundary layer (WBL) or even below the wave crests. In this paper, field data and a WBL model are used to investigate such biases. It is shown that near the surface the turbulent stresses are less than those obtained by extrapolation using the logarithmic-layer assumption, and the mean wind speeds very near the surface, based on Lake George field observations, are up to 5% larger. The behavior is then simulated by means of a WBL model coupled with nonlinear waves, which confirmed the observations and revealed further details of complex behaviors at the wind-wave boundary layer.

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Quantification of NOX Emissions Based on Car MAX-DOAS Measurements over Beijing and Impacts of Wind Field

10.5194/egusphere-egu2020-12459 ◽

2020 ◽

Author(s):

Xinghong Cheng

Keyword(s):

Spatial Distribution ◽

Wind Speed ◽

Wind Field ◽

Meteorological Condition ◽

Emission Rates ◽

Wind Fields ◽

Vertical Column ◽

Wind Speeds ◽

South Central ◽

The Mean

We carried out 14 days of Car MAX-DOAS experiments on the 6th Ring Rd of Beijing in January, September and October, 2014. The tropospheric vertical column densities (VCD) of NO2 are retrieved and used to estimate the emissions of NOx. The offline LAPS-WRF-CMAQ model system is used to simulate wind fields by assimilation of observational data and calculate the NO2 to NOx concentration ratios. The NOX emissions in Beijing for different seasons derived from Car MAX-DOAS measurements are compared with the multi-resolution emission inventory in China for 2012 (MEIC 2012), and impacts of wind field on estimated emissions and its uncertainties are also investigated. Results show that the NO2 VCD is higher in January than other two months and it is typically larger at the southern parts of the 6th Ring Road than the northern parts of it. Wind field has obvious impacts on the spatial distribution of NO2 VCD, and the mean NO2 VCD with south wind at most sampling points along the 6th Ring Rd is higher than north wind. The journey-to-journey variation pattern of estimated NOX emissions rates (ENOX) is consistent with that of the NO2 VCD, and ENOX is mainly determined by the NO2 VCD. In addition, the journey-to-journey ENOX in the same month is different and it is affected by wind speed, the ratio of NO2 and NOx concentration and the decay rate of NOX from the emission sources to measured positions under different meteorological condition. The ENOX ranges between 6.46&#215;1025 and 50.05&#215;1025 molec s-1. The averaged ENOX during every journey in January, September and October are respectively 35.87&#215;1025, 20.34&#215;1025, 8.96&#215;1025 molec s-1. The estimated ENOX after removing the simulated error of wind speed and observed deviation of NO2 VCD are found to be mostly closer to the MEIC 2012, but sometimes ENOX is lower or higher and it indicates that the MEIC 2012 might be overestimate or underestimate the true emissions. The estimated ENOX on January 27 and September 19 are obviously higher than other journeys in the same month because the mean NO2 VCD and Leighton ratio during these two periods are larger, and corresponding wind speeds are smaller. Additionally, because south wind may affect the spatial distribution of mean NO2 VCD in Beijing which is downwind of south-central&#160;regions of Hebei province with high source emission rates, the uncertainty of the estimated ENOX with south wind will be increased.

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Extrapolation Problem for Continuous Time Periodically Correlated Isotropic Random Fields

Bulletin of Mathematical Sciences and Applications ◽

10.18052/www.scipress.com/bmsa.19.1 ◽

2017 ◽

Vol 19 ◽

pp. 1-23

Author(s):

Iryna Golichenko ◽

Oleksand Masyutka ◽

Mikhail Moklyachuk

Keyword(s):

Random Field ◽

Spectral Characteristics ◽

Mean Square ◽

Spectral Densities ◽

Optimal Linear ◽

Extrapolation Problem ◽

Time Argument ◽

The Mean ◽

Mean Square Errors ◽

Isotropic Random

The problem of optimal linear estimation of functionals depending on the unknown values of a random fieldζ(t,x), which is mean-square continuous periodically correlated with respect to time argumenttє R and isotropic on the unit sphere Sn with respect to spatial argumentxєSn. Estimates are based on observations of the fieldζ(t,x) +Θ(t,x) at points (t,x) :t< 0;xєSn, whereΘ(t,x) is an uncorrelated withζ(t,x) random field, which is mean-square continuous periodically correlated with respect to time argumenttє R and isotropic on the sphereSnwith respect to spatial argumentxєSn. Formulas for calculating the mean square errors and the spectral characteristics of the optimal linear estimate of functionals are derived in the case of spectral certainty where the spectral densities of the fields are exactly known. Formulas that determine the least favourable spectral densities and the minimax (robust) spectral characteristics are proposed in the case where the spectral densities are not exactly known while a class of admissible spectral densities is given.

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