Predicting Average Vehicle Speed in Two Lane Highways Considering Weather Condition and Traffic Characteristics

NASA Astrophysics Data System (ADS)

Mirbaha, Babak; Saffarzadeh, Mahmoud; AmirHossein Beheshty, Seyed; Aniran, MirMoosa; Yazdani, Mirbahador; Shirini, Bahram

2017-10-01

Analysis of vehicle speed with different weather condition and traffic characteristics is very effective in traffic planning. Since the weather condition and traffic characteristics vary every day, the prediction of average speed can be useful in traffic management plans. In this study, traffic and weather data for a two-lane highway located in Northwest of Iran were selected for analysis. After merging traffic and weather data, the linear regression model was calibrated for speed prediction using STATA12.1 Statistical and Data Analysis software. Variables like vehicle flow, percentage of heavy vehicles, vehicle flow in opposing lane, percentage of heavy vehicles in opposing lane, rainfall (mm), snowfall and maximum daily wind speed more than 13m/s were found to be significant variables in the model. Results showed that variables of vehicle flow and heavy vehicle percent acquired the positive coefficient that shows, by increasing these variables the average vehicle speed in every weather condition will also increase. Vehicle flow in opposing lane, percentage of heavy vehicle in opposing lane, rainfall amount (mm), snowfall and maximum daily wind speed more than 13m/s acquired the negative coefficient that shows by increasing these variables, the average vehicle speed will decrease.

Torrejon AB, Madrid, Spain. revised uniform summary of surface weather observations (RUSSWO). parts a-f. Final report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1978-10-03

This report is a six-part statistical summary of surface weather observations for Torrejon AB, Madrid Spain. It contains the following parts: (A) Weather Conditions; Atmospheric Phenomena; (B) Precipitation, Snowfall and Snow Depth (daily amounts and extreme values); (C) Surface winds; (D) Ceiling Versus Visibility; Sky Cover; (E) Psychrometric Summaries (daily maximum and minimum temperatures, extreme maximum and minimum temperatures, psychrometric summary of wet-bulb temperature depression versus dry-bulb temperature, means and standard deviations of dry-bulb, wet-bulb and dew-point temperatures and relative humidity); and (F) Pressure Summary (means, standard, deviations, and observation counts of station pressure and sea-level pressure). Data in thismore » report are presented in tabular form, in most cases in percentage frequency of occurrence or cumulative percentage frequency of occurrence tables.« less

Exploring the spatio-temporal relationship between two key aeroallergens and meteorological variables in the United Kingdom

NASA Astrophysics Data System (ADS)

Khwarahm, Nabaz; Dash, Jadunandan; Atkinson, Peter M.; Newnham, R. M.; Skjøth, C. A.; Adams-Groom, B.; Caulton, Eric; Head, K.

2014-05-01

Constructing accurate predictive models for grass and birch pollen in the air, the two most important aeroallergens, for areas with variable climate conditions such as the United Kingdom, require better understanding of the relationships between pollen count in the air and meteorological variables. Variations in daily birch and grass pollen counts and their relationship with daily meteorological variables were investigated for nine pollen monitoring sites for the period 2000-2010 in the United Kingdom. An active pollen count sampling method was employed at each of the monitoring stations to sample pollen from the atmosphere. The mechanism of this method is based on the volumetric spore traps of Hirst design (Hirst in Ann Appl Biol 39(2):257-265, 1952). The pollen season (start date, finish date) for grass and birch were determined using a first derivative method. Meteorological variables such as daily rainfall; maximum, minimum and average temperatures; cumulative sum of Sunshine duration; wind speed; and relative humidity were related to the grass and birch pollen counts for the pre-peak, post peak and the entire pollen season. The meteorological variables were correlated with the pollen count data for the following temporal supports: same-day, 1-day prior, 1-day mean prior, 3-day mean prior, 7-day mean prior. The direction of influence (positive/negative) of meteorological variables on pollen count varied for birch and grass, and also varied when the pollen season was treated as a whole season, or was segmented into the pre-peak and post-peak seasons. Maximum temperature, sunshine duration and rainfall were the most important variables influencing the count of grass pollen in the atmosphere. Both maximum temperature (pre-peak) and sunshine produced a strong positive correlation, and rain produced a strong negative correlation with grass pollen count in the air. Similarly, average temperature, wind speed and rainfall were the most important variables influencing the count of birch pollen in the air. Both wind speed and rain produced a negative correlation with birch pollen count in the air and average temperature produced a positive correlation.

Analysis on temporal and spatial distribution of reference evapotranspiration and its possible influencing factors in Yunnan Province

NASA Astrophysics Data System (ADS)

Li, Yashan; Nan, Lijun; Wang, Yanjun; Xu, Chengdong; Yang, Yunyuan; Cui, Changwei; Yang, Junmei; Guo, Yuan; Li, Miaorong

2018-04-01

This article was based on the climate data of 125 meteorological stations from 1982 to 2011 in Yunnan Province, the daily basis ET0 was calculated with Penman-Monteith equation recommended by FAO in 1998. Then the Kriging interpolation method and related methods of climate statistical diagnosis analysis were used to analyze the features. The main results showed that the highest value of annual ET0 of Yunnan Province was the joint parts of Dali, Lijiang and Chuxiong, and also the north of Chuxiong and Kunming, while the least value was the northeast and northwest of Yunnan Province. The ET0 was showed rising trend, the speed was about 5.9mm/10a, but the rising trend was not significant. The ET0 of spring was highest, and the ET0 of summer and autumn was taken the second place, the ET0 of winter was last. The ET0 of spring, summer, autumn, winter was account for 33.35 per cent, 28.91 per cent, 20.36, per cent, 17.39 per cent of annual ET0 respectively. The ET0 of May was highest and December was least in annual. ET0 was closely related to wind speed, relative humidity, hours of sunshine and the daily maximum temperature. The correlation between wind speed, hours of sunshine, the daily maximum temperature and ET0 was very significantly positive, while the correlation between relative humidity and ET0 was very significantly negative.

Applying stochastic small-scale damage functions to German winter storms

NASA Astrophysics Data System (ADS)

Prahl, B. F.; Rybski, D.; Kropp, J. P.; Burghoff, O.; Held, H.

2012-03-01

Analyzing insurance-loss data we derive stochastic storm-damage functions for residential buildings. On district level we fit power-law relations between daily loss and maximum wind speed, typically spanning more than 4 orders of magnitude. The estimated exponents for 439 German districts roughly range from 8 to 12. In addition, we find correlations among the parameters and socio-demographic data, which we employ in a simplified parametrization of the damage function with just 3 independent parameters for each district. A Monte Carlo method is used to generate loss estimates and confidence bounds of daily and annual storm damages in Germany. Our approach reproduces the annual progression of winter storm losses and enables to estimate daily losses over a wide range of magnitudes.

Anomalous meridional thermospheric neutral winds in the AE-E NATE data: Effects of the equatorial nighttime pressure bulge

NASA Technical Reports Server (NTRS)

Goembel, L.; Herrero, F. A.

1995-01-01

The work described here makes it possible to identify anomalous wind behavior such as the nighttime meridional wind abatements that occur at F-region heights. A new analysis technique uses a simple empirical wind model to simulate measurements of 'normal' winds (as measured by the Neutral Atmosphere and Temperature Experiment (NATE) that flew on the Atmosphere Explorer-E (AE-E)) to highlight anomalous wind measurements made by the satellite while in circular orbits at 270-290 km altitude. Our approach is based on the recognition that the 'in orbit' wind variation must show the combined effects of the diurnal wind variation as seen from the ground with the latitude variation of the satellite orbit. For the data period 77250-78035 examined thus far, the wind abatement always occurred with a corresponding pressure or temperature maximum, and was detected on 12 out of the 36 nights with data. This study has revealed that the wind abatement occur only during or shortly after increases in solar extreme ultraviolet (EUV) flux, as indicated by daily radio flux measurements. In the past, nighttime wind reversals at mid-latitudes have been associated with increased geomagnetic activity. This study indicates that intensified solar EUV heating may be responsible for anomalous thermospheric nighttime winds at mid-latitudes.

Flight thresholds and seasonal variations in flight activity of the light-brown apple moth, Epiphyas postvittana (Walk.) (Tortricidae), in Victoria, Australia.

PubMed

Danthanarayana, W

1976-12-01

The flight activity of Epiphyas postvittana was studied at two sites near Melbourne with the aid of suction traps, over a period of 4 years. Maximum numbers were found to fly during the period September to March with peak activity coinciding with the emergence of winter, spring and summer generation moths. E. postivittana is predominantly a nocturnal flier with maximum activity around 20.00-24.00 h. The lower temperature threshold of flight was 8-11°C. The upper temperature threshold varied from 20-21°C, 24-25°C and 27-28°C for the winter, spring and summer generation moths respectively. Flight was highly influenced by the prevailing wind. The lower wind speed threshold was 0.5-0.8 m -s and the upper wind speed threshold was 2.6-2.7 m -s . The relationship between wind speed and the amount of flight was non-linear, with the frequency of flights decreasing sharply with increasing wind speed. No flights occurred at wind speeds greater than 2.8 m -s . Variation in relative humidity had no influence on flight, but lack of rain favoured flight. The amount of flight activity and the amount of rainfall were negatively correlated; flights did not occur when the daily precipitation exceeded 32.5 mm, and with a precipitation exceeding 39 mm no flights could be expected. The value of these findings to pest control programmes is discussed.

Normal and Extreme Wind Conditions for Power at Coastal Locations in China

PubMed Central

Gao, Meng; Ning, Jicai; Wu, Xiaoqing

2015-01-01

In this paper, the normal and extreme wind conditions for power at 12 coastal locations along China’s coastline were investigated. For this purpose, the daily meteorological data measured at the standard 10-m height above ground for periods of 40–62 years are statistically analyzed. The East Asian Monsoon that affects almost China’s entire coastal region is considered as the leading factor determining wind energy resources. For most stations, the mean wind speed is higher in winter and lower in summer. Meanwhile, the wind direction analysis indicates that the prevalent winds in summer are southerly, while those in winter are northerly. The air densities at different coastal locations differ significantly, resulting in the difference in wind power density. The Weibull and lognormal distributions are applied to fit the yearly wind speeds. The lognormal distribution performs better than the Weibull distribution at 8 coastal stations according to two judgement criteria, the Kolmogorov–Smirnov test and absolute error (AE). Regarding the annual maximum extreme wind speed, the generalized extreme value (GEV) distribution performs better than the commonly-used Gumbel distribution. At these southeastern coastal locations, strong winds usually occur in typhoon season. These 4 coastal provinces, that is, Guangdong, Fujian, Hainan, and Zhejiang, which have abundant wind resources, are also prone to typhoon disasters. PMID:26313256

Normal and Extreme Wind Conditions for Power at Coastal Locations in China.

PubMed

Gao, Meng; Ning, Jicai; Wu, Xiaoqing

2015-01-01

In this paper, the normal and extreme wind conditions for power at 12 coastal locations along China's coastline were investigated. For this purpose, the daily meteorological data measured at the standard 10-m height above ground for periods of 40-62 years are statistically analyzed. The East Asian Monsoon that affects almost China's entire coastal region is considered as the leading factor determining wind energy resources. For most stations, the mean wind speed is higher in winter and lower in summer. Meanwhile, the wind direction analysis indicates that the prevalent winds in summer are southerly, while those in winter are northerly. The air densities at different coastal locations differ significantly, resulting in the difference in wind power density. The Weibull and lognormal distributions are applied to fit the yearly wind speeds. The lognormal distribution performs better than the Weibull distribution at 8 coastal stations according to two judgement criteria, the Kolmogorov-Smirnov test and absolute error (AE). Regarding the annual maximum extreme wind speed, the generalized extreme value (GEV) distribution performs better than the commonly-used Gumbel distribution. At these southeastern coastal locations, strong winds usually occur in typhoon season. These 4 coastal provinces, that is, Guangdong, Fujian, Hainan, and Zhejiang, which have abundant wind resources, are also prone to typhoon disasters.

Selected meteorological data for an arid site near Beatty, Nye County, Nevada, calendar years 1990 and 1991

USGS Publications Warehouse

Wood, James L.; Andraski, Brian J.

1995-01-01

Selected meteorological data were collected at a study site adjacent to a low-level radioactive-waste burial facility near Beatty, Nevada, for calendar years 1990 and 1991. Data were collected in support of ongoing studies to estimate the potential for downward movement of radionuclides into the unsaturated sediments beneath waste-burial trenches at the facility. The data include air temperature, relative humidity, vapor pressure, incident solar radiation, windspeed, wind direction, barometric pressure, and precipitation. The data are summarized in tables and graphs.Instrumentation used at the site is discussed. The discussion includes the type, reported accuracy, and mounting height of each sensor.In 1990, the average hourly air temperatures ranged from -16.2 degrees Celsius, in December, to 44.2 degrees Celsius, in July. Hourly averaged relative humidity ranged from 6 percent to more than 90 percent. Hourly vapor pressures ranged from 0.08 to 1.84 kilopascals. Daily maximum incident solar radiation values ranged from 192 to 1,028 watts per square meter. Daily mean windspeed ranged from less than 1 to 8.7 meters per second. Wind direction was primarily from the northwest in fall, winter, and spring and varied from southeast, southwest, or northwest during the summer. Hourly barometric pressures ranged from 99.47 to 103.12 kilopascals. Total precipitation for 1990 was 32.4 millimeters; almost 45 percent was in September.In 1991, the average hourly air temperatures ranged from -9.2 degrees Celsius, in January, to 43.7 degrees Celsius, in July. Hourly averaged relative humidity ranged from 3 percent to more than 95 percent. Hourly vapor pressures ranged from 0.07 to 2.22 kilopascals. Daily maximum incident solar radiation values ranged from 143 to 1,041 watts per square meter. Daily mean windspeed ranged from 1.2 to 8.4 meters per second. Wind direction was primarily from the northwest in fall, winter, and spring and varied from southeast, southwest, or northwest during the summer. Hourly barometric pressures ranged from 99.52 to 103.40 kilopascals. Total precipitation for 1991 was 103.6 millimeters; almost 60 percent was in March.

Climate Extreme Events over Northern Eurasia in Changing Climate

NASA Astrophysics Data System (ADS)

Bulygina, O.; Korshunova, N. N.; Razuvaev, V. N.; Groisman, P. Y.

2014-12-01

During the period of widespread instrumental observations in Northern Eurasia, the annual surface air temperature has increased by 1.5°C. Close to the north in the Arctic Ocean, the late summer sea ice extent has decreased by 40% providing a near-infinite source of water vapor for the dry Arctic atmosphere in the early cold season months. The contemporary sea ice changes are especially visible in the Eastern Hemisphere All these factors affect the change extreme events. Daily and sub-daily data of 940 stations to analyze variations in the space time distribution of extreme temperatures, precipitation, and wind over Russia were used. Changing in number of days with thaw over Russia was described. The total seasonal numbers of days, when daily surface air temperatures (wind, precipitation) were found to be above (below) selected thresholds, were used as indices of climate extremes. Changing in difference between maximum and minimum temperature (DTR) may produce a variety of effects on biological systems. All values falling within the intervals ranged from the lowest percentile to the 5th percentile and from the 95th percentile to the highest percentile for the time period of interest were considered as daily extremes. The number of days, N, when daily temperatures (wind, precipitation, DTR) were within the above mentioned intervals, was determined for the seasons of each year. Linear trends in the number of days were calculated for each station and for quasi-homogeneous climatic regions. Regional analysis of extreme events was carried out using quasi-homogeneous climatic regions. Maps (climatology, trends) are presented mostly for visualization purposes. Differences in regional characteristics of extreme events are accounted for over a large extent of the Russian territory and variety of its physical and geographical conditions. The number of days with maximum temperatures higher than the 95% percentile has increased in most of Russia and decreased in Siberia in spring and autumn. Reducing the number of days with extremely low air temperatures dominated in all seasons. At the same time, the number of days with abnormally low air temperatures has increased in Middle Volga region and south of Western Siberia. In most parts of European Russia observed increase in the number of days with heavy snowfalls.

Selected meteorological and micrometeorological data for an arid site near Beatty, Nye County, Nevada, calendar year 1992

USGS Publications Warehouse

Wood, James L.

1996-01-01

il-heat-flux data were collected at a study site adjacent to a low-level radioactive-waste burial facility near Beatty, Nevada, for calendar year 1992. Data were collected in support of ongoing studies to estimate the potential for downward movement of radionuclides into the unsaturated sediments beneath waste-burial trenches at the arid facility. Data collected for the whole year include air temperature, relative humidity, vapor pressure, incident solar radiation, windspeed, wind direction, barometric pressure, and precipitation. Net radiation, soil temperature, and soil-heat flux data also were collected for part of the year. The data are summarized in tables and graphs.Instrumentation used at the site is discussed. The discussion includes the type, reported accuracy, and the mounting height of each sensor.During 1992, the hourly and 20-minute mean air temperatures ranged from -8.6 degrees Celsius, in January, to 42.3 degrees Celsius, in July. Hourly and 20-minute mean relative humidity ranged from 2 percent to 100 percent. Hourly and 20-minute mean vapor pressures ranged from 0.07 to 2.47 kilopascals. Daily maximum incident solar radiation values ranged from 115 to 1,021 watts per square meter. Daily maximum net radiation values ranged from 195 to 632 watts per square meter. Daily mean windspeed ranged from 0.6 to 8.1 meters per second. Wind direction was primarily from the northwest in fall, winter, and spring and was from the southeast, southwest, or northwest during the summer. Barometric pressures ranged from 100.16 kilopascals to 103.38 kilopascals. Total precipitation for 1992 was 165.3 millimeters, with more than 50 percent in February and March. Daily mean soil temperatures at a depth from 2 to 6 centimeters ranged from 10.7 to 39.1 degrees Celsius between June and October. Daily mean soil-heat flux at a dep*h of 8 centimeters ranged from -13.4 to 12.2 watts per square meter during the same period.

Mars climatology from viking 1 after 20 sols.

PubMed

Hess, S L; Henry, R M; Leovy, C B; Ryan, J A; Tillman, J E; Chamberlain, T E; Cole, H L; Dutton, R G; Greene, G C; Simon, W E; Mitchell, J L

1976-10-01

The results from the meteorology instruments on the Viking 1 lander are presented for the first 20 sols of operation. The daily patterns of temperature, wind, and pressure have been highly consistent during the period. Hence, these have been assembled into 20-sol composites and analyzed harmonically. Maximum temperature was 241.8 degrees K and minimum 187.2 degrees K. The composite wind vector has a mean diurnal magnitude of 2.4 meters per second with prevailing wind from the south and counterclockwise diurnal rotation. Pressure exhibits diurnal and semidiurnal oscillations. The diurnal is ascribed to a combination of effects, and the semidiurnal appears to be the solar semidiurnal tide. Similarities to Earth are discussed. A major finding is a continual secular decrease in diurnal mean pressure. This is ascribed to carbon dioxide deposition at the south polar cap.

Reliability Estimation of Parameters of Helical Wind Turbine with Vertical Axis

PubMed Central

Dumitrascu, Adela-Eliza; Lepadatescu, Badea; Dumitrascu, Dorin-Ion; Nedelcu, Anisor; Ciobanu, Doina Valentina

2015-01-01

Due to the prolonged use of wind turbines they must be characterized by high reliability. This can be achieved through a rigorous design, appropriate simulation and testing, and proper construction. The reliability prediction and analysis of these systems will lead to identifying the critical components, increasing the operating time, minimizing failure rate, and minimizing maintenance costs. To estimate the produced energy by the wind turbine, an evaluation approach based on the Monte Carlo simulation model is developed which enables us to estimate the probability of minimum and maximum parameters. In our simulation process we used triangular distributions. The analysis of simulation results has been focused on the interpretation of the relative frequency histograms and cumulative distribution curve (ogive diagram), which indicates the probability of obtaining the daily or annual energy output depending on wind speed. The experimental researches consist in estimation of the reliability and unreliability functions and hazard rate of the helical vertical axis wind turbine designed and patented to climatic conditions for Romanian regions. Also, the variation of power produced for different wind speeds, the Weibull distribution of wind probability, and the power generated were determined. The analysis of experimental results indicates that this type of wind turbine is efficient at low wind speed. PMID:26167524

Reliability Estimation of Parameters of Helical Wind Turbine with Vertical Axis.

PubMed

Dumitrascu, Adela-Eliza; Lepadatescu, Badea; Dumitrascu, Dorin-Ion; Nedelcu, Anisor; Ciobanu, Doina Valentina

2015-01-01

Due to the prolonged use of wind turbines they must be characterized by high reliability. This can be achieved through a rigorous design, appropriate simulation and testing, and proper construction. The reliability prediction and analysis of these systems will lead to identifying the critical components, increasing the operating time, minimizing failure rate, and minimizing maintenance costs. To estimate the produced energy by the wind turbine, an evaluation approach based on the Monte Carlo simulation model is developed which enables us to estimate the probability of minimum and maximum parameters. In our simulation process we used triangular distributions. The analysis of simulation results has been focused on the interpretation of the relative frequency histograms and cumulative distribution curve (ogive diagram), which indicates the probability of obtaining the daily or annual energy output depending on wind speed. The experimental researches consist in estimation of the reliability and unreliability functions and hazard rate of the helical vertical axis wind turbine designed and patented to climatic conditions for Romanian regions. Also, the variation of power produced for different wind speeds, the Weibull distribution of wind probability, and the power generated were determined. The analysis of experimental results indicates that this type of wind turbine is efficient at low wind speed.

Wind potential assessment in urban area of Surakarta city

NASA Astrophysics Data System (ADS)

Tjahjana, Dominicus Danardono Dwi Prija; Halomoan, Arnold Thamrin; Wibowo, Andreas; Himawanto, Dwi Aries; Wicaksono, Yoga Arob

2018-02-01

Wind energy is one of the promising energy resource in urban area that has not been deeply explored in Indonesia. Generally the wind velocity in Indonesia is relatively low, however on the roof top of the high rise building in urban area the wind velocity is high enough to be converted for supporting the energy needs of the building. In this research a feasibility study of wind energy in urban area of Surakarta was done. The analysis of the wind energy potential on the height of 50 m was done by using Weibull distribution. The wind data based on the daily wind speed taken from 2011-2015. From the result of the wind speed analysis, a wind map in Surakarta was developed for helping to determine the places that have good potential in wind energy. The result showed that in five years the city of Surakarta had mean energy density (ED) of 139.43 W/m2, yearly energy available (EI) of 1221.4 kWh/m2/year, the most frequent wind velocity (VFmax) of 4.79 m/s, and the velocity contributing the maximum energy (VEmax) of 6.97 m/s. The direction of the wind was mostly from south, with frequency of 38%. The south and west area of the city had higher wind velocity than the other parts of the city. Also in those areas there are many high rise buildings, which are appropriate for installation of small wind turbine on the roof top (building mounted wind turbine/ BMWT).

Validation of China-wide interpolated daily climate variables from 1960 to 2011

NASA Astrophysics Data System (ADS)

Yuan, Wenping; Xu, Bing; Chen, Zhuoqi; Xia, Jiangzhou; Xu, Wenfang; Chen, Yang; Wu, Xiaoxu; Fu, Yang

2015-02-01

Temporally and spatially continuous meteorological variables are increasingly in demand to support many different types of applications related to climate studies. Using measurements from 600 climate stations, a thin-plate spline method was applied to generate daily gridded climate datasets for mean air temperature, maximum temperature, minimum temperature, relative humidity, sunshine duration, wind speed, atmospheric pressure, and precipitation over China for the period 1961-2011. A comprehensive evaluation of interpolated climate was conducted at 150 independent validation sites. The results showed superior performance for most of the estimated variables. Except for wind speed, determination coefficients ( R 2) varied from 0.65 to 0.90, and interpolations showed high consistency with observations. Most of the estimated climate variables showed relatively consistent accuracy among all seasons according to the root mean square error, R 2, and relative predictive error. The interpolated data correctly predicted the occurrence of daily precipitation at validation sites with an accuracy of 83 %. Moreover, the interpolation data successfully explained the interannual variability trend for the eight meteorological variables at most validation sites. Consistent interannual variability trends were observed at 66-95 % of the sites for the eight meteorological variables. Accuracy in distinguishing extreme weather events differed substantially among the meteorological variables. The interpolated data identified extreme events for the three temperature variables, relative humidity, and sunshine duration with an accuracy ranging from 63 to 77 %. However, for wind speed, air pressure, and precipitation, the interpolation model correctly identified only 41, 48, and 58 % of extreme events, respectively. The validation indicates that the interpolations can be applied with high confidence for the three temperatures variables, as well as relative humidity and sunshine duration based on the performance of these variables in estimating daily variations, interannual variability, and extreme events. Although longitude, latitude, and elevation data are included in the model, additional information, such as topography and cloud cover, should be integrated into the interpolation algorithm to improve performance in estimating wind speed, atmospheric pressure, and precipitation.

Drivers of Intra-Summer Seasonality and Daily Variability of Coastal Low Cloudiness in California Subregions

NASA Astrophysics Data System (ADS)

Schwartz, R. E.; Iacobellis, S.; Gershunov, A.; Williams, P.; Cayan, D. R.

2014-12-01

Summertime low cloud intrusion into the terrestrial west coast of North America impacts human, ecological, and logistical systems. Over a broad region of the West Coast, summer (May - September) coastal low cloudiness (CLC) varies coherently on interannual to interdecadal timescales and has been found to be organized by North Pacific sea surface temperature. Broad-scale studies of low stratiform cloudiness over ocean basins also find that the season of maximum low stratus corresponds to the season of maximum lower tropospheric stability (LTS) or estimated inversion strength. We utilize a 18-summer record of CLC derived from NASA/NOAA Geostationary Operational Environmental Satellite (GOES) at 4km resolution over California (CA) to make a more nuanced spatial and temporal examination of intra-summer variability in CLC and its drivers. We find that uniform spatial coherency over CA is not apparent for intra-summer variability in CLC. On monthly to daily timescales, at least two distinct subregions of coastal California (CA) can be identified, where relationships between meteorology and stratus variability appear to change throughout summer in each subregion. While north of Point Conception and offshore the timing of maximum CLC is closely coincident with maximum LTS, in the Southern CA Bight and northern Baja region, maximum CLC occurs up to about a month before maximum LTS. It appears that summertime CLC in this southern region is not as strongly related as in the northern region to LTS. In particular, although the relationship is strong in May and June, starting in July the daily relationship between LTS and CLC in the south begins to deteriorate. Preliminary results indicate a moderate association between decreased CLC in the south and increased precipitable water content above 850 hPa on daily time scales beginning in July. Relationships between daily CLC variability and meteorological variables including winds, inland temperatures, relative humidity, and geopotential heights within and above the marine boundary layer are investigated and dissected by month, CA subregion, and cloud height. The rich spatial detail of the satellite derived CLC record is utilized to examine the propagation in time and space of CLC on synoptic scales within and among subregions.

Long term variability of B supergiant winds

NASA Technical Reports Server (NTRS)

Massa, Derck L.

1995-01-01

The object of this observing proposal was to sample wind variability in B supergiants on a daily basis over a period of several days in order to determine the time scale with which density variability occurs in their winds. Three stars were selected for this project: 69 Cyg (B0 Ib), HD 164402 (B0 Ib), and HD 47240 (B1 Ib). Three grey scale representations of the Si IV lambda lambda 1400 doublet in each star are attached. In these figures, time (in days) increases upward, and the wavelength (in terms of velocity relative to the rest wavelength of the violet component of the doublet) is the abscissa. The spectra are normalized by a minimum absorption (maximum flux) template, so that all changes appear as absorptions. As a result of these observations, we can now state with some certainty that typical B supergiants develop significant wind inhomogeneities with recurrence times of a few days, and that some of these events show signs of strong temporal coherence.

Estimating Planetary Boundary Layer Heights from NOAA Profiler Network Wind Profiler Data

NASA Technical Reports Server (NTRS)

Molod, Andrea M.; Salmun, H.; Dempsey, M

2015-01-01

An algorithm was developed to estimate planetary boundary layer (PBL) heights from hourly archived wind profiler data from the NOAA Profiler Network (NPN) sites located throughout the central United States. Unlike previous studies, the present algorithm has been applied to a long record of publicly available wind profiler signal backscatter data. Under clear conditions, summertime averaged hourly time series of PBL heights compare well with Richardson-number based estimates at the few NPN stations with hourly temperature measurements. Comparisons with clear sky reanalysis based estimates show that the wind profiler PBL heights are lower by approximately 250-500 m. The geographical distribution of daily maximum PBL heights corresponds well with the expected distribution based on patterns of surface temperature and soil moisture. Wind profiler PBL heights were also estimated under mostly cloudy conditions, and are generally higher than both the Richardson number based and reanalysis PBL heights, resulting in a smaller clear-cloudy condition difference. The algorithm presented here was shown to provide a reliable summertime climatology of daytime hourly PBL heights throughout the central United States.

Biophysics of Cold Adaptation and Acclimatization: Microbial Decomposition.

DTIC Science & Technology

1984-03-01

plant communities. Parameters such as temperature, precipitation and relative humidity, as they are related to winds and sea ice, interact to produce the...predictable pattern, 9 the occurrence of clouds, precipitation and heavy fogs build to a maximum as the number of daily sunshine hours increases. At 12...August 2, the sun finally sets for 1 hour and 25 minutes. Climatic records kept since 1934 show low precipitation levels with a 40 year mean of 11.5 cm/yr

Statistical inhomogeneity of dates of sudden stratospheric warmings in the wintertime northern hemisphere

NASA Astrophysics Data System (ADS)

Savenkova, E. N.; Gavrilov, N. M.; Pogoreltsev, A. I.; Manuilova, R. O.

2017-05-01

Using the data of meteorological information reanalysis, a statistical analysis of dates of the main sudden stratospheric warmings observed in 1958-2014 has been performed and their inhomogeneous distribution in winter months with maximums in the beginning of January, from the end of January to the beginning of February, and in the end of February has been shown. To explain these regularities, a climatological analysis of variations in the amplitudes and vertical components of Eliassen-Palm fluxes created by large-scale planetary waves (PWs), as well as of zonal-mean winds and deviations of temperature from their winter-average values in high northern latitudes at heights of up to 50 km from the surface has been carried out using the 20-year (1995-2014) collection of daily meteorological information from the UK Met Office database. During the aforementioned intervals of observing more frequent sudden stratospheric warmings, climatological maximums of temperature perturbations, local minimums of eastward winds, and local maximums of the amplitude and Eliassen-Palm fluxes of PWs with a zonal wavenumber of 1 in the high-latitude northern stratosphere were found. Distinctions between atmospheric characteristics averaged over two last decades have been revealed.

Wind effect on salt transport variability in the Bay of Bengal

NASA Astrophysics Data System (ADS)

Sandeep, K. K.; Pant, V.

2017-12-01

The Bay of Bengal (BoB) exhibits large spatial variability in sea surface salinity (SSS) pattern caused by its unique hydrological, meteorological and oceanographical characteristics. This SSS variability is largely controlled by the seasonally reversing monsoon winds and the associated currents. Further, the BoB receives substantial freshwater inputs through excess precipitation over evaporation and river discharge. Rivers like Ganges, Brahmaputra, Mahanadi, Krishna, Godavari, and Irawwady discharge annually a freshwater volume in range between 1.5 x 1012 and 1.83 x 1013 m3 into the bay. A major volume of this freshwater input to the bay occurs during the southwest monsoon (June-September) period. In the present study, a relative role of winds in the SSS variability in the bay is investigated by using an eddy-resolving three dimensional Regional Ocean Modeling System (ROMS) numerical model. The model is configured with realistic bathymetry, coastline of study region and forced with daily climatology of atmospheric variables. River discharges from the major rivers are distributed in the model grid points representing their respective geographic locations. Salt transport estimate from the model simulation for realistic case are compared with the standard reference datasets. Further, different experiments were carried out with idealized surface wind forcing representing the normal, low, high, and very high wind speed conditions in the bay while retaining the realistic daily varying directions for all the cases. The experimental simulations exhibit distinct dispersal patterns of the freshwater plume and SSS in different experiments in response to the idealized winds. Comparison of the meridional and zonal surface salt transport estimated for each experiment showed strong seasonality with varying magnitude in the bay with a maximum spatial and temporal variability in the western and northern parts of the BoB.

Downscaling wind and wavefields for 21st century coastal flood hazard projections in a region of complex terrain

USGS Publications Warehouse

O'Neill, Andrea; Erikson, Li; Barnard, Patrick

2017-01-01

While global climate models (GCMs) provide useful projections of near-surface wind vectors into the 21st century, resolution is not sufficient enough for use in regional wave modeling. Statistically downscaled GCM projections from Multivariate Adaptive Constructed Analogues provide daily averaged near-surface winds at an appropriate spatial resolution for wave modeling within the orographically complex region of San Francisco Bay, but greater resolution in time is needed to capture the peak of storm events. Short-duration high wind speeds, on the order of hours, are usually excluded in statistically downscaled climate models and are of key importance in wave and subsequent coastal flood modeling. Here we present a temporal downscaling approach, similar to constructed analogues, for near-surface winds suitable for use in local wave models and evaluate changes in wind and wave conditions for the 21st century. Reconstructed hindcast winds (1975–2004) recreate important extreme wind values within San Francisco Bay. A computationally efficient method for simulating wave heights over long time periods was used to screen for extreme events. Wave hindcasts show resultant maximum wave heights of 2.2 m possible within the Bay. Changes in extreme over-water wind speeds suggest contrasting trends within the different regions of San Francisco Bay, but 21th century projections show little change in the overall magnitude of extreme winds and locally generated waves.

Selected meteorological data for an arid site near Beatty, Nye County, Nevada, calendar year 1988

USGS Publications Warehouse

Wood, James L.; Hill, Kevin J.; Andraski, Brian J.

1992-01-01

Selected meteorological data were collected at a study site adjacent to a low-level radioactive-waste burial facility near Beatty/ Nevada, for calendar year 1988. Data were collected in support of ongoing studies to estimate the potential for downward movement of radionuclides into the unsaturated sediments beneath waste-burial trenches at the facility. The data include air temperature, relative humidity, vapor pressure, incident solar radiation, windspeed, wind direction, and precipitation. The data are summarized in tables and graphs.Instrumentation used at the site is discussed. The discussion includes the type, reported accuracy, and mounting height of each sensor.In 1988, the average hourly air temperatures ranged from -10.2 degrees Celsius, in December, to 45.3 degrees Celsius, in July. Hourly averaged relative humidity ranged from about 12 percent to over 80 percent. Hourly vapor pressures ranged from 0.09 to 2.22 kilopascals. Daily values for maximum incident solar radiation ranged from 63 to 1,064 watts per square meter. Daily mean windspeed ranged from 1.2 to 7.8 meters per second. Monthly wind-direction patterns are shown in a series of diagrams in which wind direction is summed over 10-degree arcs from hourly averaged data. Total precipitation for 1988 was 104.5 millimeters, with over 70 percent occurring from January through May.

A meteorologically-driven yield reduction model for spring and winter wheat

NASA Technical Reports Server (NTRS)

Ravet, F. W.; Cremins, W. J.; Taylor, T. W.; Ashburn, P.; Smika, D.; Aaronson, A. (Principal Investigator)

1983-01-01

A yield reduction model for spring and winter wheat was developed for large-area crop condition assessment. Reductions are expressed in percentage from a base yield and are calculated on a daily basis. The algorithm contains two integral components: a two-layer soil water budget model and a crop calendar routine. Yield reductions associated with hot, dry winds (Sukhovey) and soil moisture stress are determined. Input variables include evapotranspiration, maximum temperature and precipitation; subsequently crop-stage, available water holding percentage and stress duration are evaluated. No specific base yield is required and may be selected by the user; however, it may be generally characterized as the maximum likely to be produced commercially at a location.

Empirical Model for Evaluating PM10 Concentration Caused by River Dust Episodes

PubMed Central

Lin, Chao-Yuan; Chiang, Mon-Ling; Lin, Cheng-Yu

2016-01-01

Around the estuary of the Zhuo-Shui River in Taiwan, the waters recede during the winter, causing an increase in bare land area and exposing a large amount of fine earth and sand particles that were deposited on the riverbed. Observations at the site revealed that when northeastern monsoons blow over bare land without vegetation or water cover, the fine particles are readily lifted by the wind, forming river dust, which greatly endangers the health of nearby residents. Therefore, determining which factors affect river dust and constructing a model to predict river dust concentration are extremely important in the research and development of a prototype warning system for areas at risk of river dust emissions. In this study, the region around the estuary of the Zhuo-Shui River (from the Zi-Qiang Bridge to the Xi-Bin Bridge) was selected as the research area. Data from a nearby air quality monitoring station were used to screen for days with river dust episodes. The relationships between PM10 concentration and meteorological factors or bare land area were analyzed at different temporal scales to explore the factors that affect river dust emissions. Study results showed that no single factor alone had adequate power to explain daily average or daily maximum PM10 concentration. Stepwise regression analysis of multiple factors showed that the model could not effectively predict daily average PM10 concentration, but daily maximum PM10 concentration could be predicted by a combination of wind velocity, temperature, and bare land area; the coefficient of determination for this model was 0.67. It was inferred that river dust episodes are caused by the combined effect of multiple factors. In addition, research data also showed a time lag effect between meteorological factors and hourly PM10 concentration. This characteristic was applied to the construction of a prediction model, and can be used in an early warning system for local residents. PMID:27271642

Empirical Model for Evaluating PM10 Concentration Caused by River Dust Episodes.

PubMed

Lin, Chao-Yuan; Chiang, Mon-Ling; Lin, Cheng-Yu

2016-06-02

Around the estuary of the Zhuo-Shui River in Taiwan, the waters recede during the winter, causing an increase in bare land area and exposing a large amount of fine earth and sand particles that were deposited on the riverbed. Observations at the site revealed that when northeastern monsoons blow over bare land without vegetation or water cover, the fine particles are readily lifted by the wind, forming river dust, which greatly endangers the health of nearby residents. Therefore, determining which factors affect river dust and constructing a model to predict river dust concentration are extremely important in the research and development of a prototype warning system for areas at risk of river dust emissions. In this study, the region around the estuary of the Zhuo-Shui River (from the Zi-Qiang Bridge to the Xi-Bin Bridge) was selected as the research area. Data from a nearby air quality monitoring station were used to screen for days with river dust episodes. The relationships between PM10 concentration and meteorological factors or bare land area were analyzed at different temporal scales to explore the factors that affect river dust emissions. Study results showed that no single factor alone had adequate power to explain daily average or daily maximum PM10 concentration. Stepwise regression analysis of multiple factors showed that the model could not effectively predict daily average PM10 concentration, but daily maximum PM10 concentration could be predicted by a combination of wind velocity, temperature, and bare land area; the coefficient of determination for this model was 0.67. It was inferred that river dust episodes are caused by the combined effect of multiple factors. In addition, research data also showed a time lag effect between meteorological factors and hourly PM10 concentration. This characteristic was applied to the construction of a prediction model, and can be used in an early warning system for local residents.

Spatial and temporal evolution of climatic factors and its impacts on potential evapotranspiration in Loess Plateau of Northern Shaanxi, China.

PubMed

Li, C; Wu, P T; Li, X L; Zhou, T W; Sun, S K; Wang, Y B; Luan, X B; Yu, X

2017-07-01

Agriculture is very sensitive to climate change, and correct forecasting of climate change is a great help to accurate allocation of irrigation water. The use of irrigation water is influenced by crop water demand and precipitation. Potential evapotranspiration (ET 0 ) is a measure of the ability of the atmosphere to remove water from the surface through the processes of evaporation and transpiration, assuming no control on water supply. It plays an important role in assessing crop water requirements, regional dry-wet conditions, and other factors of water resource management. This study analyzed the spatial and temporal evolution processes and characteristics of major meteorological parameters at 10 stations in the Loess Plateau of northern Shaanxi (LPNS). By using the Mann-Kendall trend test with trend-free pre-whitening and the ArcGIS platform, the potential evapotranspiration of each station was quantified by using the Penman-Monteith equation, and the effects of climatic factors on potential evapotranspiration were assessed by analyzing the contribution rate and sensitivity of the climatic factors. The results showed that the climate in LPNS has become warmer and drier. In terms of the sensitivity of ET 0 to the variation of each climatic factor in LPNS, relative humidity (0.65) had the highest sensitivity, followed by daily maximum temperature, wind speed, sunshine hours, and daily minimum temperature (-0.05). In terms of the contribution rate of each factor to ET 0 , daily maximum temperature (5.16%) had the highest value, followed by daily minimum temperature, sunshine hours, relative humidity, and wind speed (1.14%). This study provides a reference for the management of agricultural water resources and for countermeasures to climate change. According to the climate change and the characteristics of the study area, farmers in the region should increase irrigation to guarantee crop water demand. Copyright © 2017. Published by Elsevier B.V.

Gamma-radiation monitoring in post-tectonic biotitic granites at Celorico da Beira

NASA Astrophysics Data System (ADS)

Domingos, Filipa; Barbosa, Susana; Pereira, Alcides; Neves, Luís

2017-04-01

Despite its obvious relevance, the effect of meteorological variables such as temperature, pressure, wind, rainfall and particularly humidity on the temporal variability of natural radiation is complex and still not fully understood. Moreover, the nature of their influence with increasing depth is also poorly understood. Thereby, two boreholes were set 3 m apart in the region of Celorico da Beira within post-tectonic biotitic granites of the Beiras Batolith. Continuous measurements were obtained with identical gamma-ray scintillometers deployed at depths of 1 and 6 m during a 6 month period in the years of 2014 and 2015. Temperature, relative humidity, pressure, rainfall, wind speed and direction were measured at the site, as well as temperature and relative humidity inside the boreholes, with the aim of assessing the influence of meteorological parameters on the temporal variability of gamma radiation at two distinct depths. Both time series display a complex temporal structure including multiyear, seasonal and daily variability. At 1 m depth, a daily periodicity on the gamma ray counts time series was noticed with daily maxima occurring most frequently from 8 to 12 p.m. and daily minima between 8 and 12 a.m.. At 6 m depth, maximum and minimum daily means occurred with approximately a 10 h lag from the above. Gamma radiation data exhibited fairly strong correlations with temperature and relative humidity, however, varying with depth. Gamma radiation counts increased with increasing temperature and decreasing relative humidity at 1 m depth, while at a 6 m depth the opposite was recorded, with counts increasing with relative humidity and decreasing with temperature. Wind speed was shown to be inversely related with counts at 6 m depth, while positively correlated at 1 m depth. Pressure and rainfall had minor effects on both short-term and long-term gamma radiation counts.

Long-term Measurements of Summer-time Ozone at the Walnut Grove Tower - Understanding Trends in the Boundary Layer

NASA Astrophysics Data System (ADS)

Mahmud, A.; Di, P.; Mims, D.; Avise, J.; DaMassa, J.; Kaduwela, A. P.

2015-12-01

The California Air Resources Board (CARB) has been monitoring boundary layer ozone at the Walnut Grove Tower (WGT) since 1996 for investigating regional transport and vertical profile. Walnut Grove is located between Sacramento and Stockton, CA in the Sacramento - San Joaquin Delta. Sampling inlets are positioned at 30-ft, 400-ft, 800-ft, 1200-ft and 1600-ft levels of the 2000-ft tower, which is one of the tallest monitoring towers in the Western US. Ozone, ambient temperature, wind speed, and wind direction are simultaneously measured at each level, and reported as hourly averages. The current study included analyses of available ozone and corresponding meteorological data for the months of June - September from 1996 - 2014 with objectives to: 1) explore trends and inter-annual variability of ozone, 2) examine any correlations between ozone and meteorological parameters, 3) understand interactions of ozone measured at various levels, and 4) assess how well a regulatory state-of-the-science air quality model such as the Community Multi-scale Air Quality Model (CMAQ) captures observation. Daily 1-hr maximum ozone has been consistently decreasing during the 1996 - 2014 period at a rate of ~1 ppb per year. This indicates that CARB's measures to control ambient ozone have been effective over the past years. Evolution of the vertical profile throughout the day shows that ozone is fairly homogeneously mixed between 1 - 5 pm, when mixing height typically reaches the maximum. Ozone at 30-ft shows the greatest variability because of its proximity to the ground and emissions sources - rises faster during morning hours (7 - 10 am) and declines more rapidly during evening hours (7 - 10 pm) compared to other levels. Air masses reaching the tower are predominantly southwesterly (247 - 257 deg.) at the bottom, and southwesterly to slightly northwesterly (254 - 302 deg.) at top levels. Daily 1-hr maximum ozone was negatively correlated with wind speed (i.e. ozone was high under low wind condition) and positively correlated with ambient temperature (i.e. ozone was high under high temperature condition) during ~40% and ~50% of the time, respectively. A modeling exercise for Jun - Sep of 2012 shows that CMAQ captures the observed evolution and vertical mixing of ozone throughout the day quite well in the boundary layer.

Temporal and spatial variation of maximum wind speed days during the past 20 years in major cities of Xinjiang

NASA Astrophysics Data System (ADS)

Baidourela, Aliya; Jing, Zhen; Zhayimu, Kahaer; Abulaiti, Adili; Ubuli, Hakezi

2018-04-01

Wind erosion and sandstorms occur in the neighborhood of exposed dust sources. Wind erosion and desertification increase the frequency of dust storms, deteriorate air quality, and damage the ecological environment and agricultural production. The Xinjiang region has a relatively fragile ecological environment. Therefore, the study of the characteristics of maximum wind speed and wind direction in this region is of great significance to disaster prevention and mitigation, the management of activated dunes, and the sustainable development of the region. Based on the latest data of 71 sites in Xinjiang, this study explores the temporal evolution and spatial distribution of maximum wind speed in Xinjiang from 1993 to 2013, and highlights the distribution of annual and monthly maximum wind speed and the characteristics of wind direction in Xinjiang. Between 1993 and 2013, Ulugchat County exhibited the highest number of days with the maximum wind speed (> 17 m/s), while Wutian exhibited the lowest number. In Xinjiang, 1999 showed the highest number of maximum wind speed days (257 days), while 2013 showed the lowest number (69 days). Spring and summer wind speeds were greater than those in autumn and winter. There were obvious differences in the direction of maximum wind speed in major cities and counties of Xinjiang. East of the Tianshan Mountains, maximum wind speeds are mainly directed southeast and northeast. North and south of the Tianshan Mountains, they are mainly directed northwest and northeast, while west of the Tianshan Mountains, they are mainly directed southeast and northwest.

Selected meteorological data for an arid site near Beatty, Nye County, Nevada, calendar year 1989

USGS Publications Warehouse

Wood, J.L.; Andraski, Brian J.

1992-01-01

Selected meteorological data were collected at a study site adjacent to a low-level radioactive-waste burial facility near Beatty, Nevada, for calendar year 1989. Data were collected in support of ongoing studies to estimate the potential for downward movement of radionuclides into the unsaturated sediments beneath waste-burial trenches at the facility. The data include air temperature, relative humidity, vapor pressure, incident solar radiation, windspeed, wind direction, and precipitation. The data are summarized in tables and graphs.Instrumentation used at the site is discussed. The discussion includes the type, reported accuracy, and mounting height of each sensor.In 1989, the hourly averaged air temperature ranged from -14.5 degrees Celsius, in February, to 46.0 degrees Celsius, in July. Hourly averaged relative humidity ranged from less than 12 percent to over 80 percent. Hourly vapor pressures ranged from 0.06 to 1.71 kilopascals. Daily maximum incident solar radiation values ranged from 149 to 1,084 watts per square meter. Daily mean windspeed ranged from less than 1 to 8.6 meters per second. Monthly wind direction patterns are shown in a series of diagrams in which wind direction is summed over 10-degree arcs from hourly averaged data. Wind direction was primarily from the northwest in fall, winter, and spring and varied from southeast, southwest, or northwest during the summer. Total precipitation for 1989 was 14.0 millimeters, with almost 90 percent occurring from January through May.

Empirical predictive models of daily relativistic electron flux at geostationary orbit: Multiple regression analysis

DOE PAGES

Simms, Laura E.; Engebretson, Mark J.; Pilipenko, Viacheslav; ...

2016-04-07

The daily maximum relativistic electron flux at geostationary orbit can be predicted well with a set of daily averaged predictor variables including previous day's flux, seed electron flux, solar wind velocity and number density, AE index, IMF Bz, Dst, and ULF and VLF wave power. As predictor variables are intercorrelated, we used multiple regression analyses to determine which are the most predictive of flux when other variables are controlled. Empirical models produced from regressions of flux on measured predictors from 1 day previous were reasonably effective at predicting novel observations. Adding previous flux to the parameter set improves the predictionmore » of the peak of the increases but delays its anticipation of an event. Previous day's solar wind number density and velocity, AE index, and ULF wave activity are the most significant explanatory variables; however, the AE index, measuring substorm processes, shows a negative correlation with flux when other parameters are controlled. This may be due to the triggering of electromagnetic ion cyclotron waves by substorms that cause electron precipitation. VLF waves show lower, but significant, influence. The combined effect of ULF and VLF waves shows a synergistic interaction, where each increases the influence of the other on flux enhancement. Correlations between observations and predictions for this 1 day lag model ranged from 0.71 to 0.89 (average: 0.78). Furthermore, a path analysis of correlations between predictors suggests that solar wind and IMF parameters affect flux through intermediate processes such as ring current ( Dst), AE, and wave activity.« less

Empirical predictive models of daily relativistic electron flux at geostationary orbit: Multiple regression analysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Simms, Laura E.; Engebretson, Mark J.; Pilipenko, Viacheslav

The daily maximum relativistic electron flux at geostationary orbit can be predicted well with a set of daily averaged predictor variables including previous day's flux, seed electron flux, solar wind velocity and number density, AE index, IMF Bz, Dst, and ULF and VLF wave power. As predictor variables are intercorrelated, we used multiple regression analyses to determine which are the most predictive of flux when other variables are controlled. Empirical models produced from regressions of flux on measured predictors from 1 day previous were reasonably effective at predicting novel observations. Adding previous flux to the parameter set improves the predictionmore » of the peak of the increases but delays its anticipation of an event. Previous day's solar wind number density and velocity, AE index, and ULF wave activity are the most significant explanatory variables; however, the AE index, measuring substorm processes, shows a negative correlation with flux when other parameters are controlled. This may be due to the triggering of electromagnetic ion cyclotron waves by substorms that cause electron precipitation. VLF waves show lower, but significant, influence. The combined effect of ULF and VLF waves shows a synergistic interaction, where each increases the influence of the other on flux enhancement. Correlations between observations and predictions for this 1 day lag model ranged from 0.71 to 0.89 (average: 0.78). Furthermore, a path analysis of correlations between predictors suggests that solar wind and IMF parameters affect flux through intermediate processes such as ring current ( Dst), AE, and wave activity.« less

Predicting tropical cyclone intensity using satellite measured equivalent blackbody temperatures of cloud tops. [regression analysis

NASA Technical Reports Server (NTRS)

Gentry, R. C.; Rodgers, E.; Steranka, J.; Shenk, W. E.

1978-01-01

A regression technique was developed to forecast 24 hour changes of the maximum winds for weak (maximum winds less than or equal to 65 Kt) and strong (maximum winds greater than 65 Kt) tropical cyclones by utilizing satellite measured equivalent blackbody temperatures around the storm alone and together with the changes in maximum winds during the preceding 24 hours and the current maximum winds. Independent testing of these regression equations shows that the mean errors made by the equations are lower than the errors in forecasts made by the peristence techniques.

Development of a guideline on vegetation area to reduce the risk of weed pollinosis in Korea

NASA Astrophysics Data System (ADS)

Rang Kim, Kyu; Lee, Hye-Rim; Kim, Mijin; Baek, Won-ki; Oh, Jae-Won; Choi, Young-Jean; Jung, Hyun-Sook

2013-04-01

Allergenic pollens are influenced by the environmental conditions so that the daily number of pollens varies by temperature, humidity, wind speed, etc. The relationship between the daily pollens and meteorological conditions were determined and utilized to forecast daily risk level of pollen allergy in Korea. Another important factor for the daily risk level of pollens is the vegetation area of the allergenic plants. In this study, the relationship between the area and pollen concentration was identified for two major weed species: Ragweed and Japanese Hop. It was then utilized to determine the upper limit of vegetation area to confine the risk level to a certain degree in the field. Three sites with different levels of pollen concentration were selected among twelve pollen observation sites in Korea based on the historical observation of the weed pollens. The vegetation area of the two weed species within four square kilometers at each site was surveyed. The maximum daily pollen concentration was highly correlated with the vegetation area and it was selected as a dependent variable for the regression equations, which were used as the guideline for vegetation area. According to the guideline, to limit the maximum daily pollen concentration under the moderate risk level or less than 50 pollen grains per cubic meter for Ragweed, the vegetation area should remain less than 0.6% of the ground area. For the moderate risk of Japanese Hop, pollen grains should be limited less than 100 and the area be less than 0.4%.

Low-level nocturnal wind maximum over the Central Amazon Basin

NASA Technical Reports Server (NTRS)

Greco, Steven; Ulanski, Stanley; Garstang, Michael; Houston, Samuel

1992-01-01

A low-level nocturnal wind maximum is shown to exist over extensive and nearly undisturbed rainforest near the central Amazon city of Manaus. Meteorological data indicate the presence of this nocturnal wind maximum during both the wet and dry seasons of the Central Amazon Basin. Daytime wind speeds which are characteristically 3-7 m/s between 300 and 1000 m increase to 10-15 m/s shortly after sunset. The wind-speed maximum is reached in the early evening, with wind speeds remaining high until several hours after sunrise. The nocturnal wind maximum is closely linked to a strong low-level inversion formed by radiational cooling of the rainforest canopy. Surface and low-level pressure gradients between the undisturbed forest and the large Amazon river system and the city of Manaus are shown to be responsible for much of the nocturnal wind increase. The pressure gradients are interpreted as a function of the thermal differences between undisturbed forest and the river/city. The importance of both the frictional decoupling and the horizontal pressure gradient suggest that the nocturnal wind maximum does not occur uniformly over all Amazonia. Low-level winds are thought to be pervasive under clear skies and strong surface cooling and that, in many places (i.e., near rivers), local pressure gradients enhance the low-level nocturnal winds.

Solar energy potential in the United Arab Emirates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Khalil, A.; Alnajjar, A.

1995-12-31

In the present study, the global, direct and diffuse components of solar radiation as well as temperature, relative humidity and wind speed have been continuously monitored and analyzed on hourly, daily and monthly basis. Experimental data is compared to the predictions of different theoretical models as functions of declination and hour angles. Correlations are obtained describing the variation of hourly, daily and monthly averages of total and diffuse solar radiation using polynomial expressions. Empirical correlations describing the dependence of the daily average diffuse to total radiation ratio on the clearness index are also obtained. Data of daily diffuse to totalmore » radiation ratio is compared to correlations obtained by other investigators. The comparison shows a reasonable agreement with some scatter due to the seasonal dependence of the correlation. Comparison of calculations with experimental measurements under clear sky conditions show excellent agreement with a maximum error of 8%. The measured ratio of hourly to daily insolation is in excellent agreement with the model of Hottel which is expressed as a function of the clearness index, hour and the sunset hour angles.« less

Evaluation de l'impact du vent et des manoeuvres hydrauliques sur le calcul des apports naturels par bilan hydrique pour un reservoir hydroelectrique

NASA Astrophysics Data System (ADS)

Roy, Mathieu

Natural inflow is an important data for a water resource manager. In fact, Hydro-Quebec uses historical natural inflow data to perform a daily prediction of the amount of water that will be received in each of its hydroelectric reservoirs. This prediction allows the establishment of reservoir operating rules in order to optimize hydropower without compromising the safety of hydraulic structures. To obtain an accurate prediction, it follows that the system's input needs to be very well known. However, it can be very difficult to accurately measure the natural supply of a set of regulated reservoirs. Therefore, Hydro-Quebec uses an indirect method of calculation. This method consists of evaluating the reservoir's inflow using the water balance equation. Yet, this equation is not immune to errors and uncertainties. Water level measurement is an important input in order to compute the water balance equation. However, several sources of uncertainty including the effect of wind and hydraulic maneuvers can affect the readings of limnimetric gages. Fluctuations in water level caused by these effects carry over in the water balance equation. Consequently, natural inflow's signal may become noisy and affected by external errors. The main objective of this report is to evaluate the uncertainty caused by the effects of wind and hydraulic maneuvers on water balance equation. To this end, hydrodynamic models of reservoirs Outardes 4 and Gouin were prepared. According to the literature review, wind effects can be studied either by an unsteady state approach or by assuming steady state approach. Unsteady state simulation of wind effects on reservoir Gouin and Outardes 4 were performed by hydrodynamic modelling. Consideration of an unsteady state implies that the wind conditions vary throughout the simulation. This feature allows taking into account temporal effect of wind duration. In addition, it also allows the consideration of inertial forces such as seiches which are caused by wind conditions that can vary abruptly. Once the models were calibrated, unsteady state simulations were conducted in closed system where unsteady observed winds were the only forces included. From the simulated water levels obtained at each gage, water balance equation was calculated to determine the daily uncertainty of natural inflow in unsteady conditions. At Outardes 4, a maximum uncertainty of 20 m3/s was estimated during the month of October 2010. On the other hand, at the Gouin reservoir, a maximum uncertainty of 340m3/s was estimated during the month of July 2012. Steady state modelling is another approach to evaluate wind effect uncertainty in the water balance equation. This type of approach consists of assuming that the water level is instantly tilted under the influence of wind. Hence, temporal effect of wind duration and seiches cannot be taken into account. However, the advantage of steady state modelling is that it's better suited than unsteady state modelling to evaluate wind uncertainty in real time. Two steady state modelling methods were experimented to estimate water level difference between gages in function of wind characteristics: hydrodynamic modelling and non-parametric regression. It has been found that non-parametric models are more efficient when it comes to estimate water level differences between gages. However, the use of hydrodynamic model demonstrated that to study wind uncertainty in the water balance equation, it is preferable to assess wind responses individually at each gage instead of using water level differences. Finally, a combination method of water level gages observations has been developed. It allows reducing wind/hydraulic maneuvers impacts on the water balance equation. This method, which is applicable in real time, consists of assigning a variable weight at each limnimetric gages. In other words, the weights automatically adjust in order to minimize steady state modeled wind responses. The estimation of hydraulic maneuvers has also been included in the gage weight adjustment. It has been found that this new combination method allows the correction of noisy natural inflow signal under wind and hydraulic maneuvers effects. However, some fluctuations persist which reflects the complexity of correcting these effects on a real time based daily water balance equation. (Abstract shortened by UMI.).

Variability of ionospheric TEC during solar and geomagnetic minima (2008 and 2009): external high speed stream drivers

NASA Astrophysics Data System (ADS)

Verkhoglyadova, O. P.; Tsurutani, B. T.; Mannucci, A. J.; Mlynczak, M. G.; Hunt, L. A.; Runge, T.

2013-02-01

We study solar wind-ionosphere coupling through the late declining phase/solar minimum and geomagnetic minimum phases during the last solar cycle (SC23) - 2008 and 2009. This interval was characterized by sequences of high-speed solar wind streams (HSSs). The concomitant geomagnetic response was moderate geomagnetic storms and high-intensity, long-duration continuous auroral activity (HILDCAA) events. The JPL Global Ionospheric Map (GIM) software and the GPS total electron content (TEC) database were used to calculate the vertical TEC (VTEC) and estimate daily averaged values in separate latitude and local time ranges. Our results show distinct low- and mid-latitude VTEC responses to HSSs during this interval, with the low-latitude daytime daily averaged values increasing by up to 33 TECU (annual average of ~20 TECU) near local noon (12:00 to 14:00 LT) in 2008. In 2009 during the minimum geomagnetic activity (MGA) interval, the response to HSSs was a maximum of ~30 TECU increases with a slightly lower average value than in 2008. There was a weak nighttime ionospheric response to the HSSs. A well-studied solar cycle declining phase interval, 10-22 October 2003, was analyzed for comparative purposes, with daytime low-latitude VTEC peak values of up to ~58 TECU (event average of ~55 TECU). The ionospheric VTEC changes during 2008-2009 were similar but ~60% less intense on average. There is an evidence of correlations of filtered daily averaged VTEC data with Ap index and solar wind speed. We use the infrared NO and CO2 emission data obtained with SABER on TIMED as a proxy for the radiation balance of the thermosphere. It is shown that infrared emissions increase during HSS events possibly due to increased energy input into the auroral region associated with HILDCAAs. The 2008-2009 HSS intervals were ~85% less intense than the 2003 early declining phase event, with annual averages of daily infrared NO emission power of ~ 3.3 × 1010 W and 2.7 × 1010 W in 2008 and 2009, respectively. The roles of disturbance dynamos caused by high-latitude winds (due to particle precipitation and Joule heating in the auroral zones) and of prompt penetrating electric fields (PPEFs) in the solar wind-ionosphere coupling during these intervals are discussed. A correlation between geoeffective interplanetary electric field components and HSS intervals is shown. Both PPEF and disturbance dynamo mechanisms could play important roles in solar wind-ionosphere coupling during prolonged (up to days) external driving within HILDCAA intervals.

Distribution of the near-inertial kinetic energy inside mesoscale eddies: Observations in the Gulf of Mexico

NASA Astrophysics Data System (ADS)

Ixetl Garcia Gomez, Beatriz; Pallas Sanz, Enric; Candela Perez, Julio

2017-04-01

The near-inertial oscillations (NIOs), generated by the wind stress on the surface mixed layer, are the inertia gravity waves with the lowest frequency and the highest kinetic energy. NIOs are important because they drive vertical mixing in the interior ocean during wave breaking events. Although the interaction between NIOs and mesoscale eddies has been reported by several authors, these studies are mostly analytical and numerical, and only few observational studies have attempted to show the differences in near-inertial kinetic energy (KEi) between anticyclonic and cyclonic eddies. In this work the spatial structure of the KEi inside the mesoscale eddies is computed using daily satellite altimetry and observations of horizontal velocity from 23 moorings equipped with acoustic Doppler current profilers in the western Gulf of Mexico. Consistent to theory, the obtained four-year KEi-composites show two times more KEi inside the anticyclonic eddies than inside the cyclonic ones. The vertical and horizontal cross-sections of the KEi-composites show that the KEi is mainly located near to the surface of the cyclonic eddies (positive vorticity), whereas the KEi in anticyclonic eddies (negative vorticity) is maximum in the eddy's center near to the base of the eddy where the NIOs become more inertial, are trapped, and amplified. The mean vertical profiles show that the cyclonic eddies present a maximum of KEi near to the surface at 50, while the maximum of KEi in the anticyclonic eddies occurs between 900 and 1100 m. Inside anticyclonic eddies another two relative maximums are observed, one in the mixed layer and the second at 300 m. In contrast, the mean profile of KEi outside the mesoscale eddies has the maximum value at the surface ( 50 m), with high values of KEi in the first 200 m and negligible energy beneath that depth. A different mean distribution of the KEi is observed depending on the type of wind generator: tropical storms or unidirectional wind.

Retrieving air humidity, global solar radiation, and reference evapotranspiration from daily temperatures: development and validation of new methods for Mexico. Part III: reference evapotranspiration

NASA Astrophysics Data System (ADS)

Lobit, P.; Gómez Tagle, A.; Bautista, F.; Lhomme, J. P.

2017-07-01

We evaluated two methods to estimate evapotranspiration (ETo) from minimal weather records (daily maximum and minimum temperatures) in Mexico: a modified reduced set FAO-Penman-Monteith method (Allen et al. 1998, Rome, Italy) and the Hargreaves and Samani (Appl Eng Agric 1(2): 96-99, 1985) method. In the reduced set method, the FAO-Penman-Monteith equation was applied with vapor pressure and radiation estimated from temperature data using two new models (see first and second articles in this series): mean temperature as the average of maximum and minimum temperature corrected for a constant bias and constant wind speed. The Hargreaves-Samani method combines two empirical relationships: one between diurnal temperature range ΔT and shortwave radiation Rs, and another one between average temperature and the ratio ETo/Rs: both relationships were evaluated and calibrated for Mexico. After performing a sensitivity analysis to evaluate the impact of different approximations on the estimation of Rs and ETo, several model combinations were tested to predict ETo from daily maximum and minimum temperature alone. The quality of fit of these models was evaluated on 786 weather stations covering most of the territory of Mexico. The best method was found to be a combination of the FAO-Penman-Monteith reduced set equation with the new radiation estimation and vapor pressure model. As an alternative, a recalibration of the Hargreaves-Samani equation is proposed.

Session A-14: Variability of Storm Tracks Storm Tracks and Unseasonable Temperatures in Europe in December 2001

NASA Technical Reports Server (NTRS)

Przybylak, R.; Ardizzone, J.; Atlas, R.; Koslowsky, D.; Otterman, J.; Rogers, J.; Starr, D.; Atlas, Robert (Technical Monitor)

2002-01-01

In December 2001, a series of cyclonic centers progressed rapidly into Europe from the west and north. The cyclones moved in generally similar directions, along paths separated by few hundreds of kilometers. The advancing cyclones brought the usual sequence of changing wind directions and produced some high speed wind events. We investigate the wind patterns for this month based on analyses derived the Special Sensor Microwave/Imager observations and NCEP analyses. Whereas southwesterlies from the North Atlantic produced moderate temperatures early in the month, strong northerlies and northwesterlies (up to 15 m/s on 20-22 December) produced a drop in daily minimum and maximum temperatures of 18.8 C and 9.9 C, respectively, over a 4 day period (to -18.8 C and -6.8 C, respectively, on December 23 in Torun, Poland). Such low values in December are unprecedented in recent decades, though not for January or February.

Impacts of Industrial Wind Turbine Noise on Sleep Quality: Results From a Field Study of Rural Residents in Ontario, Canada.

PubMed

Lane, James D; Bigelow, Philip L; Majowicz, Shannon E; McColl, R Stephen

2016-07-01

The objectives of this study were to determine whether grid-connected industrial wind turbines (IWTs) are a risk factor for poor sleep quality, and if IWT noise is associated with sleep parameters in rural Ontarians. A daily sleep diary and actigraphy-derived measures of sleep were obtained from 12 participants from an IWT community and 10 participants from a comparison community with no wind power installations. The equivalent and maximum sound pressure levels within the bedroom were also assessed. No statistically significant differences were observed between IWT residents and non-IWT residents for any of the parameters measured in this study. Actigraphy and sleep diaries are feasible tools to understand the impact of IWTs on the quality of sleep for nearby residents. Further studies with larger sample sizes should be conducted to determine whether the lack of statistical significance observed here is a result of sample size, or reflects a true lack of association.

Large-scale kinetic energy spectra from Eulerian analysis of EOLE wind data

NASA Technical Reports Server (NTRS)

Desbois, M.

1975-01-01

A data set of 56,000 winds determined from the horizontal displacements of EOLE balloons at the 200 mb level in the Southern Hemisphere during the period October 1971-February 1972 is utilized for the computation of planetary- and synoptic-scale kinetic energy space spectra. However, the random distribution of measurements in space and time presents some problems for the spectral analysis. Two different approaches are used, i.e., a harmonic analysis of daily wind values at equi-distant points obtained by space-time interpolation of the data, and a correlation method using the direct measurements. Both methods give similar results for small wavenumbers, but the second is more accurate for higher wavenumbers (k above or equal to 10). The spectra show a maximum at wavenumbers 5 and 6 due to baroclinic instability and then decrease for high wavenumbers up to wavenumber 35 (which is the limit of the analysis), according to the inverse power law k to the negative p, with p close to 3.

Selected meteorological data for an arid site near Beatty, Nye County, Nevada, calendar year 1987

USGS Publications Warehouse

Wood, James L.; Fischer, Jeffrey M.

1992-01-01

Selected meteorological data were collected at a study site adjacent to a low-level radioactive-waste burial facility near Beatty, Nevada, for calendar year 1987. Data were collected in support of an ongoing study to estimate the potential for downward movement of radionuclides into the unsaturated sediments beneath waste-burial trenches at the facility. The data include air temperature, relative humidity, vapor pressure, incident solar radiation, windspeed, wind direction, and precipitation. The data are summarized in tables and graphs A discussion of the instrumentation used at the site is presented. Included in the discussion are the type of sensors, their reported accuracy, and mounting height of each sensor.In 1987, the average hourly air temperatures ranged from -7.6 degrees Celsius, in December, to 43.1 degrees Celsius, in July. Hourly averaged relative humidity ranged from about 12 percent to over 80 percent. Hourly vapor pressures ranged from 0.12 to 1.77 kilopascals. Daily values for maximum incident solar radiation ranged from 118 to 1,067 watts per square meter. Daily mean windspeed ranged from 1.4 to 9.4 meters per second. Monthly wind-direction patterns are shown in a series of diagrams in which wind direction is summed over 10-degree arcs from hourly averaged data. Total precipitation for 1987 was 136.4 millimeters, more than 75 percent occurring during January-April and November-December.

Supporting data for hydrologic studies in San Francisco Bay, California; meteorological measurements at the Port of Redwood City during 1992-1994

USGS Publications Warehouse

Schemel, Laurence E.

1995-01-01

Meteorological data were collected during 1992-94 at the Port of Redwood City, California, to support hydrologic studies in southern San Francisco Bay. The meteorological variables that were measured were air temperature, atmospheric pressure, quantum flux (insolation), and four parameters of wind speed and direction: scalar mean horizontal wind speed, (vector) resultant horizontal wind speed, resultant wind direction, and standard deviation of the wind direction. Hourly mean values based on measurements at five-minute intervals were logged at the site, then transferred to a portable computer monthly. Daily mean values were computed for temperature, insolation, pressure, and scalar wind speed. Hourly- mean and daily-mean values are presented in time- series plots and daily variability and seasonal and annual cycles are described. All data are provided in ASCII files on an IBM-formatted disk. Observations of temperature and wind speed at the Port of Redwood City were compared with measurements made at the San Francisco International Airport. Most daily mean values for temperature agreed within one- to two-tenths of a degree Celsius between the two locations. Daily mean wind speeds at the Port of Redwood City were typically half the values at the San Francisco International Airport. During summers, the differences resulted from stronger wind speeds at the San Francisco International Airport occurring over longer periods of each day. A comparison of hourly wind speeds at the Palo Alto Municipal Airport with those at the Port of Redwood City showed that values were similar in magnitude.

Do Weather Phenomena Have Any Influence on the Occurrence of Spontaneous Pneumothorax?

PubMed

Vodička, Josef; Vejvodová, Šárka; Šmíd, David; Fichtl, Jakub; Špidlen, Vladimír; Kormunda, Stanislav; Hostýnek, Jiří; Moláček, Jiří

2016-05-01

The objective of this study was to assess the impact of weather phenomena on the occurrence of spontaneous pneumothorax (SP) in the Plzeň region (Czech Republic). A retrospective analysis of 450 cases of SP in 394 patients between 1991 and 2013. We observed changes in average daily values of atmospheric pressure, air temperature and daily maximum wind gust for each day of that period and their effect on the development of SP. The risk of developing SP is 1.41 times higher (P=.0017) with air pressure changes of more than±6.1hPa. When the absolute value of the air temperature changes by more than±0.9°C, the risk of developing SP is 1.55 times higher (P=.0002). When the wind speed difference over the 5 days prior to onset of SP is less than 13m/sec, then the risk of SP is 2.16 times higher (P=.0004). If the pressure difference is greater than±6.1hPa and the temperature difference is greater than±0.9°C or the wind speed difference during the 5 days prior to onset of SP is less than 10.7m/s, the risk of SP is 2.04 times higher (P≤.0001). Changes in atmospheric pressure, air temperature and wind speed are undoubtedly involved in the development of SP, but don't seem to be the only factors causing rupture of blebs or emphysematous bullae. Copyright © 2015 SEPAR. Published by Elsevier Espana. All rights reserved.

An assessment of wind energy potential in Iberia under climate change

NASA Astrophysics Data System (ADS)

Liberato, Margarida L. R.; Santos, João A.; Rochinha, Carlos; Reyers, Mark; Pinto, Joaquim G.

2015-04-01

Wind energy potential in Iberia is assessed for recent-past (1961-2000) and future (2041-2070) climates. For recent-past, a COSMO-CLM simulation driven by ERA-40 is used. COSMO-CLM simulations driven by ECHAM5 following the A1B scenario are used for future projections. A 2 MW rated power wind turbine is selected. Mean potentials, inter-annual variability and irregularity are discussed on annual/seasonal scales and on a grid resolution of 20 km. For detailed regional assessments eight target sites are considered. For recent-past conditions, the highest daily mean potentials are found in winter over northern and eastern Iberia, particularly on high-elevation or coastal regions. In northwestern Iberia, daily potentials frequently reach maximum wind energy output (50 MWh day-1), particularly in winter. Southern Andalucía reveals high potentials throughout the year, whereas the Ebro valley and central-western coast show high potentials in summer. The irregularity in annual potentials is moderate (<15% of mean output), but exacerbated in winter (40%). Climate change projections show significant decreases over most of Iberia (<2 MWh day-1). The strong enhancement of autumn potentials in Southern Andalucía is noteworthy (>2 MWh day-1). The northward displacement of North Atlantic westerly winds (autumn-spring) and the strengthening of easterly flows (summer) are key drivers of future projections. Santos, J.A.; Rochinha, C.; Liberato, M.L.R.; Reyers, M.; Pinto, J.G. (2015) Projected changes in wind energy potentials over Iberia. Renewable Energy, 75, 1: 68-80. doi: 10.1016/j.renene.2014.09.026 Acknowledgements: This work was partially supported by FEDER (Fundo Europeu de Desenvolvimento Regional) funds through the COMPETE (Programa Operacional Factores de Competitividade) and by national funds through FCT (Fundação para a Ciência e a Tecnologia, Portugal) under project STORMEx FCOMP-01-0124-FEDER-019524 (PTDC/AAC-CLI/121339/2010).

Extreme value modeling for the analysis and prediction of time series of extreme tropospheric ozone levels: a case study.

PubMed

Escarela, Gabriel

2012-06-01

The occurrence of high concentrations of tropospheric ozone is considered as one of the most important issues of air management programs. The prediction of dangerous ozone levels for the public health and the environment, along with the assessment of air quality control programs aimed at reducing their severity, is of considerable interest to the scientific community and to policy makers. The chemical mechanisms of tropospheric ozone formation are complex, and highly variable meteorological conditions contribute additionally to difficulties in accurate study and prediction of high levels of ozone. Statistical methods offer an effective approach to understand the problem and eventually improve the ability to predict maximum levels of ozone. In this paper an extreme value model is developed to study data sets that consist of periodically collected maxima of tropospheric ozone concentrations and meteorological variables. The methods are applied to daily tropospheric ozone maxima in Guadalajara City, Mexico, for the period January 1997 to December 2006. The model adjusts the daily rate of change in ozone for concurrent impacts of seasonality and present and past meteorological conditions, which include surface temperature, wind speed, wind direction, relative humidity, and ozone. The results indicate that trend, annual effects, and key meteorological variables along with some interactions explain the variation in daily ozone maxima. Prediction performance assessments yield reasonably good results.

Meteoalarm severe wind gust thresholds from uniform periods in ECA&D

NASA Astrophysics Data System (ADS)

Wijnant, I. L.

2010-09-01

The main aim of our work is to propose new thresholds for Meteoalarm severe weather warnings which are based on the local climate, specifically for the severe wind gust warnings because the variability of these thresholds is currently rather extreme and unrealistic. In order to achieve this we added validated wind data to the database of the European Climate Assessment and Database project (ECA&D) and analysed them. We also developed wind related indices for ECA&D in order to facilitate further research. Since 2007 most of the severe weather warnings issued by the National Weather Services in Europe can be found on one website: www.meteoalarm.eu. For the 30 participating countries colour codes (yellow, orange, red) are presented on a map of Europe to reflect the severity of the weather event and its possible impact. The thresholds used for these colour codes obviously depend on the type of severe weather, but should also reflect local climate (for example: identical heat waves will have a more significant impact in Sweden than in Spain). The current Meteoalarm guideline is to issue second level warnings (orange) 1-30 times a year and third level warnings (red) less than once a year (being the total number of warnings from a specific country for all of the different sorts of severe weather events in that year). There is no similar guideline for specific sorts of severe weather events and participating countries choose their own thresholds. As a result we see unrealistic differences in the frequency and thresholds of the warnings for neighbouring countries. New thresholds based on return values would reflect the local climate of each country and give a more uniform indication of the social impact. Additionally, without uniform definitions of severe weather it remains difficult to determine if severe weather in Europe is changing. ECA&D receives long series of daily data from 62 countries throughout Europe and the Mediterranean. So far we have 7 countries that provide us with wind data. Quality control and homogeneity tests are conducted on all data before analysis is carried out. For wind data the standard ECA&D homogeneity tests (SNHT, Pettitt, Buishand and Von Neuman Ratio) are performed on the wind gust factor (the ratio of the maximum daily gust to the daily average wind speed) and a relatively new test (Petrovic's ReDistribution Method) on wind direction data. For the Dutch data we compared the results of the homogeneity tests with the available meta-data. Inhomogeneous series are not corrected but the older part (before the most recent break) is excluded from further analysis.

Human-biometeorological assessment of increasing summertime extreme heat events in Shanghai, China during 1973-2015

NASA Astrophysics Data System (ADS)

Kong, Qinqin; Ge, Quansheng; Xi, Jianchao; Zheng, Jingyun

2017-11-01

Summertime extreme heat events, defined by the Universal Thermal Climate Index (UTCI), have shown increasing trends in Shanghai from 1973 to 2015. There is a clear shift to higher temperatures for the daily maximum UTCI values, and the number of days with daily maximum UTCI exceeding 38 °C significantly increased by 4.34 days/10a. An upward trend of 3.67 days/10a was detected for the number of hot days which also displays an abrupt increase around 1998. Both the frequency and total duration of heat waves have significantly increased by 0.77 times/10a and 3.51 days/10a respectively. Their inter-decadal variations indicate a three-part division of the study period showing more and more heat waves and longer total duration, which are 1.0 times/a and 4.13 days/a for 1973-1987, 1.71 times/a and 7.64 days/a for 1988-2001, and 3.57 times/a and 16.0 days/a for 2002-2015. In addition to that are more occurrences of long-lasting heat waves. Compared with the UTCI, air temperature-based definitions have indicated substantially higher increases in extreme heat events, especially for hot nights. The relatively low humidity and strong wind speeds in the twenty-first century are considered to be responsible for this difference. Our study provides a more in-depth case to monitor extreme heat events under the combining effects of air temperature, humidity, wind speeds, total cloud cover, etc. and can support studies over other regions.

Investigating the relationship between weather and violence in Baltimore, Maryland, USA.

PubMed

Michel, Samuel J; Wang, Han; Selvarajah, Shalini; Canner, Joseph K; Murrill, Matthew; Chi, Albert; Efron, David T; Schneider, Eric B

2016-01-01

It is a common refrain at major urban trauma centers that caseloads increase in the heat of the summer. Several previous studies supported this assertion, finding trauma admissions and crime to correlate positively with temperature. We examined links between weather and violence in Baltimore, MD, through trauma presentation to Johns Hopkins Hospital and crime reports filed with the Baltimore Police Department. Crime data were obtained from the Baltimore City Police Department from January 1, 2008 to March 31, 2013. Trauma data were obtained from a prospectively collected registry of all trauma patients presenting to Johns Hopkins Hospital from January 1, 2007 to March 31, 2013. Weather data were obtained from the National Climatic Data Center. Correlation coefficients were calculated and negative binomial regression was used to elucidate the independent associations of weather and temporal variables with the trauma and crime data. When adjusting for temporal and meteorological factors, maximum daily temperature was positively associated with total trauma, intentional injury, and gunshot wounds presenting to Johns Hopkins Hospital along with total crime, violent crime, and homicides in Baltimore City. Associations of average wind speed, daily precipitation, and daily snowfall with trauma and crime were far weaker and, when significant, nearly universally negative. Maximum daily temperature is the most important weather factor associated with violence and trauma in our study period and location. Our findings suggest potential implications for hospital staffing to be explored in future studies. Copyright © 2015 Elsevier Ltd. All rights reserved.

Influence of wind on daily airborne pollen counts in Catalonia (NE Iberian Peninsula)

NASA Astrophysics Data System (ADS)

tareq Majeed, Husam; Periago, Cristina; Alarcón, Marta; De Linares, Concepción; Belmonte, Jordina

2016-04-01

The aim of this study is to analize the influence of wind (speed and direction) on the daily airborne pollen counts recorded in Catalonia (NE Iberian Peninsula) of 21 pollen taxa recorded at 6 aerobiological stations: Barcelona, Bellaterra, Girona, Lleida Manresa, and Tarragona for the period 2004-2014. The taxa studied are Alnus, Betula, Castanea, Cupressaceae, Fagus, Fraxinus, Olea, Pinus, Platanus, total Quercus, Quercus deciduous type, Quercus evergreen type, Ulmus, Corylus, Pistacia, Artemisia, Chenopodiaceae/Amaranthaceae, Plantago, Poaceae, Polygonaceae, and Urticaceae. The mean daily wind direction was divided into 8 sectors: N, NE, E, SE, S, SW, W and NW. For each sector, the correlation between the daily pollen concentrations and wind speed using Spearman's rank correlation coefficient was computed and compared with the wind rose charts. The results showed that Tarragona was the station with more significant correlations followed by Bellaterra, Lleida and Manresa. On the other hand, Artemisia was the most correlated taxon with mainly negative values, and Fagus was the least. The W wind direction showed the largest number of significant correlations, mostly positive, while the N direction was the least and negatively correlated.

Recent increase in maximum temperature at the tropical treeline of North America

NASA Astrophysics Data System (ADS)

Biondi, F.

2009-12-01

There are only a handful of weather stations above 3000 m in the entire American Cordillera, from Alaska to Tierra del Fuego. I present a surface instrumental record of high elevation (treeline) ecoclimatic variables for the tropics of North America. Besides its high elevation (3760 m) and tropical (19.5°N) features, this site is also located in the North American Monsoon System, making the data relevant to a broad suite of environmental issues. Automated half-hour data collected on Nevado de Colima, Mexico, from 2001 to 2009 show an increase in maximum temperature during the dry winter season, while incoming solar radiation remained stationary. Since minimum temperature did not increase as much, the daily range of air temperature has expanded over time. At this elevation, with average daily barometric pressure of 655 ± 1.4 hPa, maximum temperatures reflect the annual and daily energy cycle because of the dominant role of ground heating caused by incoming shortwave radiation. In fact, spring is the warmest season in this area, as it is followed by pronounced cooling during the summer monsoon because of increased cloudiness. The observed warming is associated with reduced wind speed, especially around solar noon, and is therefore most likely driven by reduced atmospheric flow, suggesting that the energy and water balance of high elevation tropical ecosystems are changing in unexpected ways. Further measurements and regional modeling experiments are therefore needed, given the staggering consequences this could have for any resource managers and policy makers concerned with trans-boundary (Mexico-US) terrestrial, coastal, and oceanic issues.

Evaluation of sediment transport at a fetch-limited beach from spring to neap tide

NASA Astrophysics Data System (ADS)

Carrasco, Ana Rita; Ferreira, Óscar; Matias, Ana; Freire, Paula; Alveirinho Dias, João.

2010-05-01

Sediment transport studies are useful tools for the determination of sediment budgets, important in the definition of management policies, in particular in environments not fully understood like fetch-limited beaches. Only a few studies have been made with respect to these beaches, and research efforts need to be continued to correctly quantify the main factors governing morphological changes. The present study provides new insights on sediment transport at a fetch-limited backbarrier beach located at the Peninsula do Ancão (Ria Formosa, South of Portugal). The field site extends over ~150 m and includes a sandy beach with a low and narrow reflective morphology, and an external sand bank at the seaward edge of the sub-aerial beach profile. Fluorescent tracers were used to measure the short-term sediment transport (rates and directions) from spring to neap tides, for fair-weather conditions. The experiment was set at two beach morphologies: beach face and sand bank. Tracer was released on 20th March 2008 at both sites, and sampling was conducted at low tide, each 24h, during 7 days. In situ fluorescent tracer detection was performed with UV light. Currents were obtained with a portable single-axis electromagnetic current meter located at the beach face, and an Aquadopp Profiler located at the sand bank. Local waves were obtained by numerical modelling for the study area, based on prevailing winds (measured by a nearby meteorological station), and using available bathymetric surveys. Tracer trends, tidal currents, wind conditions and waves were integrative in order to determine to which forcing mechanism the beach morphology was more responsive. Daily wind intensities were, in average, close to 5 m/s, and maximum estimated significant wave height (Hs) did not exceed 0.045 m. Daily mean wave period ranged from 0.5 s to 0.7 s. The maximum tidal range was 2.8 m. Currents were of higher magnitude at the sand bank than at the beach face, with the maximum during ebb tide (0.50 m/s). At the beach face, maximum velocities are very similar for both ebb and flood tide, with a maximum of 0.26 m/s. Tracer displacement was greater at the beach face, indicating that this is the most active part of the profile during the experiment. At the sand bank, tracer dispersion was greater, but tracer advection was shorter. Tracer isopachs illustrate a relatively independency of both analysed morphologies, without significant exchange across the profile. At both morphologies, the residual transport is dominated by the longshore component, and mostly directed towards the ebb. Ebb directed transport agrees with ebb dominance on tidal currents at this location. Results suggest a tidal and current dominance. Tidal range assumes particular importance at beach face.

Supporting data for hydrologic studies in San Francisco Bay, California : meteorological measurements at the Port of Redwood City during 1998-2001

USGS Publications Warehouse

Schemel, Laurence E.

2002-01-01

Meteorological data were collected during 1998-2001 at the Port of Redwood City, California, to support hydrologic studies in South San Francisco Bay. The measured meteorological variables were air temperature, atmospheric pressure, quantum flux (insolation), and four parameters of wind speed and direction: scalar mean horizontal wind speed, (vector) resultant horizontal wind speed, resultant wind direction, and standard deviation of the wind direction. Hourly mean values based on measurements at five-minute intervals were logged at the site. Daily mean values were computed for temperature, infolation, pressure, and scalar wind speed. Daily mean values for 1998-2001 are described in this report, and a short record of hourly mean values is compared to data from another near-by station. Data (hourly and daily mean) from the entire period of record (starting in April 1992) and reports describing data prior to 1998 are provided.

Influence of main forcing affecting the Tagus turbid plume under high river discharges using MODIS imagery

PubMed Central

Gómez-Gesteira, M.; Mendes, R.; deCastro, M.; Vaz, N.; Dias, J. M.

2017-01-01

The role of river discharge, wind and tide on the extension and variability of the Tagus River plume was analyzed from 2003 to 2015. This study was performed combining daily images obtained from the Moderate Resolution Imaging Spectroradiometer (MODIS) sensor located onboard the Aqua and Terra satellites. Composites were generated by averaging pixels with the same forcing conditions. River discharge shows a strong relation with the extension of the Tagus plume. The plume grows with the increasing river discharge and express a two day lag caused by the long residence time of water within the estuary. The Tagus turbid plume was found to be smaller under northerly and easterly winds, than under southerly and westerly winds. It is suggested that upwelling favoring winds provoke the offshore movement of the plume material with a rapidly decrease in turbidity values whereas downwelling favoring winds retain plume material in the north coast close to the Tagus mouth. Eastern cross-shore (oceanward) winds spread the plume seaward and to the north following the coast geometry, whereas western cross-shore (landward) winds keep the plume material in both alongshore directions occupying a large part of the area enclosed by the bay. Low tides produce larger and more turbid plumes than high tides. In terms of fortnightly periodicity, the maximum plume extension corresponding to the highest turbidity is observed during and after spring tides. Minimum plume extension associated with the lowest turbidity occurs during and after neap tides. PMID:29073209

Influence of main forcing affecting the Tagus turbid plume under high river discharges using MODIS imagery.

PubMed

Fernández-Nóvoa, D; Gómez-Gesteira, M; Mendes, R; deCastro, M; Vaz, N; Dias, J M

2017-01-01

The role of river discharge, wind and tide on the extension and variability of the Tagus River plume was analyzed from 2003 to 2015. This study was performed combining daily images obtained from the Moderate Resolution Imaging Spectroradiometer (MODIS) sensor located onboard the Aqua and Terra satellites. Composites were generated by averaging pixels with the same forcing conditions. River discharge shows a strong relation with the extension of the Tagus plume. The plume grows with the increasing river discharge and express a two day lag caused by the long residence time of water within the estuary. The Tagus turbid plume was found to be smaller under northerly and easterly winds, than under southerly and westerly winds. It is suggested that upwelling favoring winds provoke the offshore movement of the plume material with a rapidly decrease in turbidity values whereas downwelling favoring winds retain plume material in the north coast close to the Tagus mouth. Eastern cross-shore (oceanward) winds spread the plume seaward and to the north following the coast geometry, whereas western cross-shore (landward) winds keep the plume material in both alongshore directions occupying a large part of the area enclosed by the bay. Low tides produce larger and more turbid plumes than high tides. In terms of fortnightly periodicity, the maximum plume extension corresponding to the highest turbidity is observed during and after spring tides. Minimum plume extension associated with the lowest turbidity occurs during and after neap tides.

The temporal and spatial distribution characteristics of air pollution index and meteorological elements in Beijing, Tianjin and Shijiazhuang, China.

PubMed

Huading, Shi; Critto, Andrea; Torresan, Silvia; Qingxian, Gao

2018-06-13

With the rapid economic development and the continuous population growth, several important cities in China suffer serious air pollution, especially in the Beijing-Tianjin-Hebei economic developing area. Based on the daily air pollution index (API) and surface meteorological elements in Beijing, Tianjin and Shijiazhuang from 2001 to 2010, the relationships between API and meteorological elements were analyzed. The statistical analysis focused on the relationships at seasonal and monthly average scales, on different air pollution grades and air pollution processes. The results revealed that the air pollution conditions in the three areas gradually improved from 2001 to 2010, especially during summer; and the worst conditions in air quality were recorded in Beijing in spring due to the influences of dust, while in Tianjin and Shijiazhuang in winter due to household heating. Meteorological elements exhibited different influences on air pollution, showing similar relationships between API in monthly averages and four meteorological elements (i.e., the average, maximum and minimum temperatures, maximum air pressure, vapor pressure, and maximum wind speed); while the relationships on a seasonal average scale demonstrated significant differences. Compared with seasonal and monthly average scales of API, the relation coefficients based on different air pollution grades were significatively lower; while the relationship between API and meteorological elements based on air pollution process reduced the smoothing effect due to the average processing of seasonal and monthly API and improved the accuracy of the results based on different air pollution grades. Finally, statistical analysis of the distribution of pollution days in different wind directions indicated the directions of extreme and maximum wind speeds that mainly influence air pollution; representing a valuable information that could support the definition of air pollution control strategies through the identification of the regions (and the located emission sources) where to focus the implementation of emission reduction actions. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Minimisation of the LCOE for the hybrid power supply system with the lead-acid battery

NASA Astrophysics Data System (ADS)

Kasprzyk, Leszek; Tomczewski, Andrzej; Bednarek, Karol; Bugała, Artur

2017-10-01

The paper presents the methodology of minimisation of the unit cost of production of energy generated in the hybrid system compatible with the lead-acid battery, and used to power a load with the known daily load curve. For this purpose, the objective function in the form of the LCOE and the genetic algorithm method were used. Simulation tests for three types of load with set daily load characteristics were performed. By taking advantage of the legal regulations applicable in the territory of Poland, regarding the energy storing in the power system, the optimal structure of the prosumer solar-wind system including the lead-acid battery, which meets the condition of maximum rated power, was established. An assumption was made that the whole solar energy supplied to the load would be generated in the optimised system.

The analysis and kinetic energy balance of an upper-level wind maximum during intense convection

NASA Technical Reports Server (NTRS)

Fuelberg, H. E.; Jedlovec, G. J.

1982-01-01

The purpose of this paper is to analyze the formation and maintenance of the upper-level wind maximum which formed between 1800 and 2100 GMT, April 10, 1979, during the AVE-SESAME I period, when intense storms and tornadoes were experienced (the Red River Valley tornado outbreak). Radiosonde stations participating in AVE-SESAME I are plotted (centered on Oklahoma). National Meteorological Center radar summaries near the times of maximum convective activity are mapped, and height and isotach plots are given, where the formation of an upper-level wind maximum over Oklahoma is the most significant feature at 300 mb. The energy balance of the storm region is seen to change dramatically as the wind maximum forms. During much of its lifetime, the upper-level wind maximum is maintained by ageostrophic flow that produces cross-contour generation of kinetic energy and by the upward transport of midtropospheric energy. Two possible mechanisms for the ageostrophic flow are considered.

Investigation of Kelvin wave periods during Hai-Tang typhoon using Empirical Mode Decomposition

NASA Astrophysics Data System (ADS)

Kishore, P.; Jayalakshmi, J.; Lin, Pay-Liam; Velicogna, Isabella; Sutterley, Tyler C.; Ciracì, Enrico; Mohajerani, Yara; Kumar, S. Balaji

2017-11-01

Equatorial Kelvin waves (KWs) are fundamental components of the tropical climate system. In this study, we investigate Kelvin waves (KWs) during the Hai-Tang typhoon of 2005 using Empirical Mode Decomposition (EMD) of regional precipitation, zonal and meridional winds. For the analysis, we use daily precipitation datasets from the Global Precipitation Climatology Project (GPCP) and wind datasets from the European Centre for Medium-Range Weather Forecasts (ECMWF) Interim Re-analysis (ERA-Interim). As an additional measurement, we use in-situ precipitation datasets from rain-gauges over the Taiwan region. The maximum accumulated precipitation was approximately 2400 mm during the period July 17-21, 2005 over the southwestern region of Taiwan. The spectral analysis using the wind speed at 950 hPa found in the 2nd, 3rd, and 4th intrinsic mode functions (IMFs) reveals prevailing Kelvin wave periods of ∼3 days, ∼4-6 days, and ∼6-10 days, respectively. From our analysis of precipitation datasets, we found the Kelvin waves oscillated with periods between ∼8 and 20 days.

Intermediate photovoltaic system application experiment operational performance report. Volume 6: Beverly High School, Beverly, Mass.

NASA Astrophysics Data System (ADS)

1982-03-01

Performance data are given for the month of February, 1982 for a photovoltaic power supply at a Massachusetts high school. Data given include: monthly and daily electrical energy yield; monthly and daily insolation; monthly and daily array efficiency; energy production as a function of power level, voltage, cell temperature, and hour of day; insolation as a function of hour of the day; input, output and efficiency for each of two power conditioning units and for the total power conditioning system; energy supplied to the load by the photovoltaic system and by the grid; photovoltaic system efficiency; dollar value of the energy supplied by the photovoltaic system; capacity factor; daily photovoltaic energy to load; daily system availability and hours of daylight; heating and cooling degree days; hourly cell temperature, ambient temperature, wind speed, and insolation; average monthly wind speed; wind direction distribution; and daily data acquisition mode and recording interval plot.

Determination of the wind power systems load to achieve operation in the maximum energy area

NASA Astrophysics Data System (ADS)

Chioncel, C. P.; Tirian, G. O.; Spunei, E.; Gillich, N.

2018-01-01

This paper analyses the operation of the wind turbine, WT, in the maximum power point, MPP, by linking the load of the Permanent Magnet Synchronous Generator, PMSG, with the wind speed value. The load control methods at wind power systems aiming an optimum performance in terms of energy are based on the fact that the energy captured by the wind turbine significantly depends on the mechanical angular speed of the wind turbine. The presented control method consists in determining the optimal mechanical angular speed, ωOPTIM, using an auxiliary low power wind turbine, WTAUX, operating without load, at maximum angular velocity, ωMAX. The method relies on the fact that the ratio ωOPTIM/ωMAX has a constant value for a given wind turbine and does not depend on the time variation of the wind speed values.

Influence of Sub-Daily Variation on Multi-Fractal Detrended Fluctuation Analysis of Wind Speed Time Series

PubMed Central

Li, Weinan; Kong, Yanjun; Cong, Xiangyu

2016-01-01

Using multi-fractal detrended fluctuation analysis (MF-DFA), the scaling features of wind speed time series (WSTS) could be explored. In this paper, we discuss the influence of sub-daily variation, which is a natural feature of wind, in MF-DFA of WSTS. First, the choice of the lower bound of the segment length, a significant parameter of MF-DFA, was studied. The results of expanding the lower bound into sub-daily scope shows that an abrupt declination and discrepancy of scaling exponents is caused by the inability to keep the whole diel process of wind in one single segment. Additionally, the specific value, which is effected by the sub-daily feature of local meteo-climatic, might be different. Second, the intra-day temporal order of wind was shuffled to determine the impact of diel variation on scaling exponents of MF-DFA. The results illustrate that disregarding diel variation leads to errors in scaling. We propose that during the MF-DFA of WSTS, the segment length should be longer than 1 day and the diel variation of wind should be maintained to avoid abnormal phenomena and discrepancy in scaling exponents. PMID:26741491

Mechanistic Drifting Forecast Model for A Small Semi-Submersible Drifter Under Tide-Wind-Wave Conditions

NASA Astrophysics Data System (ADS)

Zhang, Wei-Na; Huang, Hui-ming; Wang, Yi-gang; Chen, Da-ke; Zhang, lin

2018-03-01

Understanding the drifting motion of a small semi-submersible drifter is of vital importance regarding monitoring surface currents and the floating pollutants in coastal regions. This work addresses this issue by establishing a mechanistic drifting forecast model based on kinetic analysis. Taking tide-wind-wave into consideration, the forecast model is validated against in situ drifting experiment in the Radial Sand Ridges. Model results show good performance with respect to the measured drifting features, characterized by migrating back and forth twice a day with daily downwind displacements. Trajectory models are used to evaluate the influence of the individual hydrodynamic forcing. The tidal current is the fundamental dynamic condition in the Radial Sand Ridges and has the greatest impact on the drifting distance. However, it loses its leading position in the field of the daily displacement of the used drifter. The simulations reveal that different hydrodynamic forces dominate the daily displacement of the used drifter at different wind scales. The wave-induced mass transport has the greatest influence on the daily displacement at Beaufort wind scale 5-6; while wind drag contributes mostly at wind scale 2-4.

Effects on surface meteorological parameters and radiation levels of a heavy dust storm occurred in Central Arabian Peninsula

NASA Astrophysics Data System (ADS)

Maghrabi, A. H.; Al-Dosari, A. F.

2016-12-01

On 24 April 2015 a severe dust storm event arrived at Riyadh causing various problems. The quantitative impact of this dusty event on solar ultraviolet radiation UVA and UVB, global solar radiation component, downward and outgoing long-wave radiation, and some meteorological variables, was investigated and presented. The results showed significant changes in all of these parameters due to this event. Shortly after the storm arrived, UVA, UVB, global radiation, and air temperature rapidly decrease by 83%, 86%, 57.5%, and 9.4%, respectively. Atmospheric pressure increased by 4 mbar, relative humidly increased from 8% to 16%, and wind direction became northerly with wind speed increasing to a maximum of 6.3 m/s. Outgoing long-wave radiation decreased by 19 W/m2 and downward long-wave radiation increased by 41 W/m2. The dust storm caused the atmosphere to emit radiation that resembled that of a black body. The daily average of the atmospheric pressure showed no changes compared to a non-dusty day. Apart from the relative humidity (which increased by about 32%), the remainder of the variables have shown significant reduction, with different magnitudes, in their daily values due to the dust event compared to the values of a non-disturbed reference day. For instance, the daily mean values of the UVA radiation, air temperature, and outgoing long-wave radiation, decreased in the dusty day by 15.6%, 30.8% and 11.4%, respectively, as compared to the clear day.

The inducement of planetary boundary layer mass convergence associated with varying vorticity beneath tropospheric wind maximum

NASA Technical Reports Server (NTRS)

Johnson, D. R.

1984-01-01

The effects of the vorticity distribution are applied to study planetary boundary layer mass convergence beneath free tropospheric wind maximum. For given forcing by viscous and pressure gradient forces beneath a wind maximum, boundary layer cross stream mass transport is increased by anticyclonic vorticity on the right flank and decreased by cyclonic vorticity on the left flank. Such frictionally forced mass transport induces boundary layer mass convergence beneath the relative wind maximum. This result is related to the empirical rule that the most intense convection and severe weather frequently develop beneath the 500 mb zero relative vorticity isopleth.

Laboratory Study of Topographic Effects on the Near-surface Tornado Flow Field

NASA Astrophysics Data System (ADS)

Razavi, Alireza; Sarkar, Partha P.

2018-03-01

To study topographic effects on the near-surface tornado flow field, the Iowa State University tornado simulator was used to simulate a translating tornado passing over three different two-dimensional topographies: a ridge, an escarpment and a valley. The effect of the translation speed on maximum horizontal wind speeds is observed for translation speeds of 0.15 and 0.50 m s^{-1} , with the lower value resulting in a larger maximum horizontal wind speed. The tornado translation over the three topographies with respect to flat terrain is assessed for changes in: (a) the maximum horizontal wind speeds in terms of the flow-amplification factor; (b) the maximum aerodynamic drag in terms of the tornado speed-up ratio; (c) the maximum duration of exposure at any location to high wind speeds of a specific range in terms of the exposure amplification factor. Results show that both the maximum wind amplification factor of 14%, as well as the maximum speed-up ratio of 14%, occur on the ridge. For all topographies, the increase in aerodynamic drag is observed to be maximized for low-rise buildings, which illustrates the importance of the vertical profiles of the horizontal wind speed near the ground. The maximum exposure amplification factors, estimated for the range of wind speeds corresponding to the EF2 (50-60 m s^{-1} ) and EF3 (61-75 m s^{-1}) scales, are 86 and 110% for the ridge, 4 and 60% for the escarpment and - 6 and 47% for the valley, respectively.

Solar Rotational Periodicities and the Semiannual Variation in the Solar Wind, Radiation Belt, and Aurora

NASA Technical Reports Server (NTRS)

Emery, Barbara A.; Richardson, Ian G.; Evans, David S.; Rich, Frederick J.; Wilson, Gordon R.

2011-01-01

The behavior of a number of solar wind, radiation belt, auroral and geomagnetic parameters is examined during the recent extended solar minimum and previous solar cycles, covering the period from January 1972 to July 2010. This period includes most of the solar minimum between Cycles 23 and 24, which was more extended than recent solar minima, with historically low values of most of these parameters in 2009. Solar rotational periodicities from S to 27 days were found from daily averages over 81 days for the parameters. There were very strong 9-day periodicities in many variables in 2005 -2008, triggered by recurring corotating high-speed streams (HSS). All rotational amplitudes were relatively large in the descending and early minimum phases of the solar cycle, when HSS are the predominant solar wind structures. There were minima in the amplitudes of all solar rotational periodicities near the end of each solar minimum, as well as at the start of the reversal of the solar magnetic field polarity at solar maximum (approx.1980, approx.1990, and approx. 2001) when the occurrence frequency of HSS is relatively low. Semiannual equinoctial periodicities, which were relatively strong in the 1995-1997 solar minimum, were found to be primarily the result of the changing amplitudes of the 13.5- and 27-day periodicities, where 13.5-day amplitudes were better correlated with heliospheric daily observations and 27-day amplitudes correlated better with Earth-based daily observations. The equinoctial rotational amplitudes of the Earth-based parameters were probably enhanced by a combination of the Russell-McPherron effect and a reduction in the solar wind-magnetosphere coupling efficiency during solstices. The rotational amplitudes were cross-correlated with each other, where the 27 -day amplitudes showed some of the weakest cross-correlations. The rotational amplitudes of the > 2 MeV radiation belt electron number fluxes were progressively weaker from 27- to 5-day periods, showing that processes in the magnetosphere act as a low-pass filter between the solar wind and the radiation belt. The A(sub p)/K(sub p) magnetic currents observed at subauroral latitudes are sensitive to proton auroral precipitation, especially for 9-day and shorter periods, while the A(sub p)/K(sub p) currents are governed by electron auroral precipitation for 13.5- and 27-day periodicities.

Airborne fungal spores of Alternaria, meteorological parameters and predicting variables

NASA Astrophysics Data System (ADS)

Filali Ben Sidel, Farah; Bouziane, Hassan; del Mar Trigo, Maria; El Haskouri, Fatima; Bardei, Fadoua; Redouane, Abdelbari; Kadiri, Mohamed; Riadi, Hassane; Kazzaz, Mohamed

2015-03-01

Alternaria is frequently found as airborne fungal spores and is recognized as an important cause of respiratory allergies. The aerobiological monitoring of fungal spores was performed using a Burkard volumetric spore traps. To establish predicting variables for daily and weakly spore counts, a stepwise multiple regression between spore concentrations and independent variables (meteorological parameters and lagged values from the series of spore concentrations: previous day or week concentration (Alt t - 1) and mean concentration of the same day or week in other years ( C mean)) was made with data obtained during 2009-2011. Alternaria conidia are present throughout the year in the atmosphere of Tetouan, although they show important seasonal fluctuations. The highest levels of Alternaria spores were recorded during the spring and summer or autumn. Alternaria showed maximum daily values in April, May or October depending on year. When the spore variables of Alternaria, namely C mean and Alt t - 1, and meteorological parameters were included in the equation, the resulting R 2 satisfactorily predict future concentrations for 55.5 to 81.6 % during the main spore season and the pre-peak 2. In the predictive model using weekly values, the adjusted R 2 varied from 0.655 to 0.676. The Wilcoxon test was used to compare the results from the expected values and the pre-peak spore data or weekly values for 2012, indicating that there were no significant differences between series compared. This test showed the C mean, Alt t - 1, frequency of the wind third quadrant, maximum wind speed and minimum relative humidity as the most efficient independent variables to forecast the overall trend of this spore in the air.

Weather types and the regime of wildfires in Portugal

NASA Astrophysics Data System (ADS)

Pereira, M. G.; Trigo, R. M.; Dacamara, C. C.

2009-04-01

An objective classification scheme, as developed by Trigo and DaCamara (2000), was applied to classify the daily atmospheric circulation affecting Portugal between 1980 and 2007 into a set of 10 basic weather types (WTs). The classification scheme relies on a set of atmospheric circulation indices, namely southerly flow (SF), westerly flow (WF), total flow (F), southerly shear vorticity (ZS), westerly shear vorticity (ZW) and total vorticity (Z). The weather-typing approach, together with surfacemeteorological variables (e.g. intensity and direction of geostrophic wind, maximum and minimum temperature and precipitation) were then associated to wildfire events as recorded in the official Portuguese fire database consisting of information on each fire occurred in the 18 districts of Continental Portugal within the same period (>450.000 events). The objective of this study is to explore the dependence of wildfire activity on weather and climate and then evaluate the potential of WTs to discriminate among recorded wildfires on what respects to their occurrence and development. Results show that days characterised by surface flow with an eastern component (i.e. NE, E and SE) account for a high percentage of daily burnt area, as opposed to surface westerly flow (NW, W and SW), which represents about a quarter of the total number of days but only accounts for a very low percentage of active fires and of burnt area. Meteorological variables such as minimum and maximum temperatures, that are closely associated to surface wind intensity and direction, also present a good ability to discriminate between the different types of fire events.. Trigo R.M., DaCamara C. (2000) "Circulation Weather Types and their impact on the precipitation regime in Portugal". Int J of Climatology, 20, 1559-1581.

New climate change scenarios for the Netherlands.

PubMed

van den Hurk, B; Tank, A K; Lenderink, G; Ulden, A van; Oldenborgh, G J van; Katsman, C; Brink, H van den; Keller, F; Bessembinder, J; Burgers, G; Komen, G; Hazeleger, W; Drijfhout, S

2007-01-01

A new set of climate change scenarios for 2050 for the Netherlands was produced recently. The scenarios span a wide range of possible future climate conditions, and include climate variables that are of interest to a broad user community. The scenario values are constructed by combining output from an ensemble of recent General Climate Model (GCM) simulations, Regional Climate Model (RCM) output, meteorological observations and a touch of expert judgment. For temperature, precipitation, potential evaporation and wind four scenarios are constructed, encompassing ranges of both global mean temperature rise in 2050 and the strength of the response of the dominant atmospheric circulation in the area of interest to global warming. For this particular area, wintertime precipitation is seen to increase between 3.5 and 7% per degree global warming, but mean summertime precipitation shows opposite signs depending on the assumed response of the circulation regime. Annual maximum daily mean wind speed shows small changes compared to the observed (natural) variability of this variable. Sea level rise in the North Sea in 2100 ranges between 35 and 85 cm. Preliminary assessment of the impact of the new scenarios on water management and coastal defence policies indicate that particularly dry summer scenarios and increased intensity of extreme daily precipitation deserves additional attention in the near future.

Microclimate and actual evapotranspiration in a humid coastal-plain environment

USGS Publications Warehouse

Dennehy, K.F.; McMahon, P.B.

1987-01-01

Continuous hourly measurements of twelve meteorologic variables recorded during 1983 and 1984 were used to examine the microclimate and actual evapotranspiration at a low-level radioactive-waste burial site near Barnwell, South Carolina. The study area is in the Atlantic Coastal Plain of southwestern South Carolina. Monthly, daily, and hourly trends in net radiation, incoming and reflected short-wave radiation, incoming and emitted long-wave radiation, soil-heat flux, dry- and wet-bulb temperatures, soil temperatures, wind direction and speed, and precipitation were used to characterize the microclimate. Average daily air temperatures ranged from -9 to 32?? Celsius during the period of study. Net radiation varied from about -27 to 251 watts m-2 and was dominated by incoming short-wave radiation throughout the year. The peak net radiation during a summer day generally occurred 2-3h before the peak vapor pressure deficit. In the winter, these peaks occurred at about the same time of day. Monthly precipitation varied from 15 to 241 mm. The Bowen ratio method was used to estimate hourly evapotranspiration, which was summed to also give daily and monthly evapotranspiration. Actual evapotranspiration varied from 0.0 to 0.7 mm h-1, 0.8-5 mm d-1, and 20-140 mm month-1 during 1983 and 1984. The maximum rate of evapotranspiration generally occurred at the same time of day as maximum net radiation, suggesting net radiation was the main driving force for evapotranspiration. Precipitation exceeded evapotranspiration during 14 months of the 2yr study period. Late fall, winter, and early spring contained the majority of these months. The maximum excess precipitation was 115 mm in February 1983. ?? 1987.

Seasonal forecasting of high wind speeds over Western Europe

NASA Astrophysics Data System (ADS)

Palutikof, J. P.; Holt, T.

2003-04-01

As financial losses associated with extreme weather events escalate, there is interest from end users in the forestry and insurance industries, for example, in the development of seasonal forecasting models with a long lead time. This study uses exceedences of the 90th, 95th, and 99th percentiles of daily maximum wind speed over the period 1958 to present to derive predictands of winter wind extremes. The source data is the 6-hourly NCEP Reanalysis gridded surface wind field. Predictor variables include principal components of Atlantic sea surface temperature and several indices of climate variability, including the NAO and SOI. Lead times of up to a year are considered, in monthly increments. Three regression techniques are evaluated; multiple linear regression (MLR), principal component regression (PCR), and partial least squares regression (PLS). PCR and PLS proved considerably superior to MLR with much lower standard errors. PLS was chosen to formulate the predictive model since it offers more flexibility in experimental design and gave slightly better results than PCR. The results indicate that winter windiness can be predicted with considerable skill one year ahead for much of coastal Europe, but that this deteriorates rapidly in the hinterland. The experiment succeeded in highlighting PLS as a very useful method for developing more precise forecasting models, and in identifying areas of high predictability.

Estimation of mesospheric vertical winds from a VHF meteor radar at King Sejong Station, Antarctica (62.2S, 58.8W)

NASA Astrophysics Data System (ADS)

Kim, Y.; Lee, C.; Kim, J.; Jee, G.

2013-12-01

For the first time, vertical winds near the mesopause region were estimated from radial velocities of meteor echoes detected by a VHF meteor radar at King Sejong Station (KSS) in 2011 and 2012. Since the radar usually detects more than a hundred echoes every hour in an altitude bin of 88 - 92 km, much larger than other radars, we were able to fit measured radial velocities of these echoes with a 6 component model that consists of horizontal winds, spatial gradients of horizontal winds and vertical wind. The conventional method of deriving horizontal winds from meteor echoes utilizes a 2 component model, assuming that vertical winds and spatial gradients of horizontal winds are negligible. We analyzed the radar data obtained for 8400 hours in 2012 and 8100 hours in 2011. We found that daily mean values of vertical winds are mostly within +/- 1 m/s, whereas those of zonal winds are a few tens m/s mostly eastward. The daily mean vertical winds sometimes stay positive or negative for more than 20 days, implying that the atmosphere near the mesopause experiences episodically a large scale low and high pressure environments, respectively, like the tropospheric weather system. By conducting Lomb-normalized periodogram analysis, we also found that the vertical winds have diurnal, semidiurnal and terdiurnal tidal components with about equal significance, in contrast to horizontal winds that show a dominant semidiurnal one. We will discuss about uncertainties of the estimated vertical wind and possible reasons of its tidal and daily variations.

Short-term risk of hospitalization for asthma or bronchiolitis in children living near an aluminum smelter.

PubMed

Lewin, Antoine; Buteau, Stéphane; Brand, Allan; Kosatsky, Tom; Smargiassi, Audrey

2013-01-01

Few studies have measured the effect of short-term exposure to industrial emissions on the respiratory health of children. Here we estimate the risk of hospitalization for asthma and bronchiolitis in young children associated with their recent exposure to emissions from an aluminum smelter. We used a case-crossover design to assess the risk of hospitalization, February 1999-December 2008, in relation to short-term variation in levels of exposure among children 0-4 years old living less than 7.5 km from the smelter. The percentage of hours per day that the residence of a hospitalized child was in the shadow of winds crossing the smelter was used to estimate the effect of wind-borne emissions on case and crossover days. Community-wide pollutant exposure was estimated through daily mean and daily maximum SO2 and PM2.5 concentrations measured at a fixed monitoring site near the smelter. Odds ratios (OR) were estimated using conditional logistic regressions. The risk of same-day hospitalization for asthma or bronchiolitis increased with the percentage of hours in a day that a child's residence was downwind of the smelter. For children aged 2-4 years, the OR was 1.27 (95% CI=1.03-1.56; n=103 hospitalizations), for an interquartile range (IQR) of 21% of hours being downwind. In this age group, the OR with PM2.5 daily mean levels was slightly smaller than with the hours downwind (OR: 1.22 for an IQR of 15.7 μg/m(3), 95% CI=1.03-1.44; n=94 hospitalizations). Trends were observed between hospitalizations and levels of SO2 for children 2-4 years old. Increasing short-term exposure to emissions from a Quebec aluminum smelter was associated with an increased risk of hospitalization for asthma and bronchiolitis in young children who live nearby. Estimating exposure through records of wind direction allows for the integration of exposure to all pollutants carried from the smelter stack.

Visibility characteristics and the impacts of air pollutants and meteorological conditions over Shanghai, China.

PubMed

Xue, Dan; Li, Chengfan; Liu, Qian

2015-06-01

In China, visibility condition has become an important issue that concerns both society and the scientific community. In order to study visibility characteristics and its influencing factors, visibility data, air pollutants, and meteorological data during the year 2013 were obtained over Shanghai. The temporal variation of atmospheric visibility was analyzed. The mean value of daily visibility of Shanghai was 19.1 km. Visibility exhibited an obvious seasonal cycle. The maximum and minimum visibility occurred in September and December with the values of 27.5 and 7.7 km, respectively. The relationships between the visibility and air pollutant data were calculated. The visibility had negative correlation with NO2, CO, PM2.5, PM10, and SO2 and weak positive correlation with O3. Meteorological data were clustered into four groups to reveal the joint contribution of meteorological variables to the daily average visibility. Usually, under the meteorological condition of high temperature and wind speed, the visibility of Shanghai reached about 25 km, while visibility decreased to 16 km under the weather type of low wind speed and temperature and high relative humid. Principle component analysis was also applied to identify the main cause of visibility variance. The results showed that the low visibility over Shanghai was mainly due to the high air pollution concentrations associated with low wind speed, which explained the total variance of 44.99 %. These results provide new knowledge for better understanding the variations of visibility and have direct implications to supply sound policy on visibility improvement in Shanghai.

Estimating wheat and maize daily evapotranspiration using artificial neural network

NASA Astrophysics Data System (ADS)

Abrishami, Nazanin; Sepaskhah, Ali Reza; Shahrokhnia, Mohammad Hossein

2018-02-01

In this research, artificial neural network (ANN) is used for estimating wheat and maize daily standard evapotranspiration. Ten ANN models with different structures were designed for each crop. Daily climatic data [maximum temperature (T max), minimum temperature (T min), average temperature (T ave), maximum relative humidity (RHmax), minimum relative humidity (RHmin), average relative humidity (RHave), wind speed (U 2), sunshine hours (n), net radiation (Rn)], leaf area index (LAI), and plant height (h) were used as inputs. For five structures of ten, the evapotranspiration (ETC) values calculated by ETC = ET0 × K C equation (ET0 from Penman-Monteith equation and K C from FAO-56, ANNC) were used as outputs, and for the other five structures, the ETC values measured by weighing lysimeter (ANNM) were used as outputs. In all structures, a feed forward multiple-layer network with one or two hidden layers and sigmoid transfer function and BR or LM training algorithm was used. Favorite network was selected based on various statistical criteria. The results showed the suitable capability and acceptable accuracy of ANNs, particularly those having two hidden layers in their structure in estimating the daily evapotranspiration. Best model for estimation of maize daily evapotranspiration is «M»ANN1 C (8-4-2-1), with T max, T min, RHmax, RHmin, U 2, n, LAI, and h as input data and LM training rule and its statistical parameters (NRMSE, d, and R2) are 0.178, 0.980, and 0.982, respectively. Best model for estimation of wheat daily evapotranspiration is «W»ANN5 C (5-2-3-1), with T max, T min, Rn, LAI, and h as input data and LM training rule, its statistical parameters (NRMSE, d, and R 2) are 0.108, 0.987, and 0.981 respectively. In addition, if the calculated ETC used as the output of the network for both wheat and maize, higher accurate estimation was obtained. Therefore, ANN is suitable method for estimating evapotranspiration of wheat and maize.

WIND SPEED Monitoring in Northern Eurasia

NASA Astrophysics Data System (ADS)

Bulygina, O.; Korshunova, N. N.; Razuvaev, V. N.; Groisman, P. Y.

2016-12-01

The wind regime of Russia varies a great deal due to the large size of the country's territory and variety of climate and terrain conditions. Changes in the regime of surface wind are of great practical importance. They can affect heat and water balance. Strong wind is one of the most hazardous meteorological event for various sectors of economy and for infrastructure. The main objective of this research is to monitoring wind speed change in Northern Eurasia At meteorological stations wind speed and wind direction are measured at the height of 10-12 meters over the land surface with the help of wind meters or wind wanes. Calculations were made on the basis of data for the period of 1980-2015. It allowed the massive scale disruption of homogeneity to be eliminated and sufficient period needed to obtain sustainable statistic characteristics to be retained. Data on average and maximum wind speed measured at 1457 stations of Russia were used. The analysis of changes in wind characteristics was made on the basis of point data and series of average characteristics obtained for 18 quasi-homogeneous climatic regions. Statistical characteristics (average and maximum values of wind speed, prevailing wind direction, values of the boundary of the 90%, 95% and 99%-confidence interval in the distribution of maximum wind speed) were obtained for all seasons and for the year as a whole. Values of boundaries of the 95% and 99%-confidence interval in the distribution of maximum wind speed were considered as indicators of extremeness of the wind regime. The trend of changes in average and maximum wind speed was assessed with a linear trend coefficient. A special attention was paid to wind changes in the Arctic where dramatic changes in surface air temperature and sea ice extent and density have been observed during the past decade. The analysis of the results allowed seasonal and regional features of changes in the wind regime on the territory of the northern part of Eurasia to be determined. The outcomes could help to provide specific recommendations to users of hydrometeorological information for making reasonable decisions to minimize losses caused by adverse wind-related weather conditions. The work was supported by the Ministry of Education and Science of the Russian Federation (grant 14.B25.31.0026).

Understanding the Benefits and Limitations of Increasing Maximum Rotor Tip Speed for Utility-Scale Wind Turbines

NASA Astrophysics Data System (ADS)

Ning, A.; Dykes, K.

2014-06-01

For utility-scale wind turbines, the maximum rotor rotation speed is generally constrained by noise considerations. Innovations in acoustics and/or siting in remote locations may enable future wind turbine designs to operate with higher tip speeds. Wind turbines designed to take advantage of higher tip speeds are expected to be able to capture more energy and utilize lighter drivetrains because of their decreased maximum torque loads. However, the magnitude of the potential cost savings is unclear, and the potential trade-offs with rotor and tower sizing are not well understood. A multidisciplinary, system-level framework was developed to facilitate wind turbine and wind plant analysis and optimization. The rotors, nacelles, and towers of wind turbines are optimized for minimum cost of energy subject to a large number of structural, manufacturing, and transportation constraints. These optimization studies suggest that allowing for higher maximum tip speeds could result in a decrease in the cost of energy of up to 5% for land-based sites and 2% for offshore sites when using current technology. Almost all of the cost savings are attributed to the decrease in gearbox mass as a consequence of the reduced maximum rotor torque. Although there is some increased energy capture, it is very minimal (less than 0.5%). Extreme increases in tip speed are unnecessary; benefits for maximum tip speeds greater than 100-110 m/s are small to nonexistent.

Possible signals of poleward surface ocean heat transport, of Arctic basal ice melt, and of the twentieth century solar maximum in the 1904-2012 Isle of Man daily timeseries

NASA Astrophysics Data System (ADS)

Matthews, J. B.; Matthews, J. B. R.

2014-01-01

This is the second of two papers on observational timeseries of top of ocean heat capture. The first reports hourly and daily meridional central tropical Pacific top 3 m timeseries showing high Southern Hemisphere evaporation (2.67 m yr-1) and Northern Hemisphere trapped heat (12 MJ m-2 day-1). We suggested that wind drift/geostrophic stratified gyre circulation transported warm water to the Arctic and led to three phases of Arctic basal ice melt and fluxes of brackish nutrient-rich waters to north Atlantic on centennial timescales. Here we examine daily top metre 1904-2012 timeseries at Isle of Man west coast ~54° N for evidence of tropical and polar surface waters. We compare these to Central England (CET) daily land-air temperatures and to Arctic floating ice heat content and extent. We find three phases of ocean surface heating consistent with basal icemelt buffering greenhouse gas warming until a regime shift post-1986 led to the modern surface temperature rise of ~1 °C in 20 yr. Three phases were: warming +0.018 °C yr-1 from 1904-1939, slight cooling -0.002 °C yr-11940-86 and strong warming +0.037 °C yr-1 1986-2012. For the same periods CET land-air showed: warming +0.015 °C yr-1, slight cooling -0.004 °C yr-1, about half SST warming at +0.018 °C yr-1. The mid-century cooling and a 1959/1963 hot/cold event is consistent with sunspot/solar radiation maximum 1923-2008 leading to record volumes of Arctic ice meltwater and runoff that peaked in 1962/3 British Isles extreme cold winter. The warming Arctic resulted in wind regime and surface water regime shifts post 1986. This coincides with the onset of rapid Arctic annual ice melt. Continued heat imbalance is likely to lead to tidewater glacier basal icemelt and future sealevel rise after remaining relatively stable over 4000 yr. Our work needs confirmation by further fieldwork concentrating on the dynamics and thermodynamics of ocean top 3 m that controls the 93 % anthropogenic global warming in the oceans. This may be done most cost-effectively through focussed multidisciplinary scientific research adaptively managed and funded.

Bayesian Monte Carlo and Maximum Likelihood Approach for ...

EPA Pesticide Factsheets

Model uncertainty estimation and risk assessment is essential to environmental management and informed decision making on pollution mitigation strategies. In this study, we apply a probabilistic methodology, which combines Bayesian Monte Carlo simulation and Maximum Likelihood estimation (BMCML) to calibrate a lake oxygen recovery model. We first derive an analytical solution of the differential equation governing lake-averaged oxygen dynamics as a function of time-variable wind speed. Statistical inferences on model parameters and predictive uncertainty are then drawn by Bayesian conditioning of the analytical solution on observed daily wind speed and oxygen concentration data obtained from an earlier study during two recovery periods on a eutrophic lake in upper state New York. The model is calibrated using oxygen recovery data for one year and statistical inferences were validated using recovery data for another year. Compared with essentially two-step, regression and optimization approach, the BMCML results are more comprehensive and performed relatively better in predicting the observed temporal dissolved oxygen levels (DO) in the lake. BMCML also produced comparable calibration and validation results with those obtained using popular Markov Chain Monte Carlo technique (MCMC) and is computationally simpler and easier to implement than the MCMC. Next, using the calibrated model, we derive an optimal relationship between liquid film-transfer coefficien

Sporadic increases in lunar atmospheric helium detected by LAMP

NASA Astrophysics Data System (ADS)

Cook, Jason C.; Alan Stern, S.

2014-07-01

We report on a multi-year dataset of daily averaged observations of He in the lunar atmosphere by the LAMP UV spectrograph on NASA’s Lunar Reconnaissance Orbiter (LRO). We examine data obtained from the start of the LRO orbital tour in September 2009 to March 2013. We find that the maximum He number density occurs about two hours after local midnight, which is consistent with earlier measurements by the Apollo ALSEP LACE mass spectrometer. However, our measured maximum He density is 2-3 times lower than that of LACE. We also observed several instances where the surface He number density rapidly increased to higher than normal values and then declined for several days. We term these events “He flares”. We examined several plausible causes of these events, and found two plausible mechanisms that could be responsible for generating them. One is that the He may be generated by strong, coincident bursts of α particles in the solar wind. To do so, we compare our observations with solar wind α particle observations by ARTEMIS (Acceleration, Reconnection, Turbulence and Electrodynamics of the Moon’s Interaction with the Sun). Another plausible cause we discuss is that the He in the flares may be released from the Moon itself via moonquakes. Determining which is actually the cause requires further work and new measurements.

An Evaluation of QuikSCAT data over Tropical Cyclones as Determined in an Operational Environment

NASA Astrophysics Data System (ADS)

Hawkins, J. D.; Edson, R. T.

2001-12-01

QuikSCAT data over all global tropical cyclones were examined during the past 3 1/2 years in conjunction with the development of a user¡_s guide to the forecasters at the Joint Typhoon Warning Center, Pearl Harbor, Hawaii. The active microwave scatterometer has greatly enhanced the forecaster's ability to evaluate surface winds over the data poor regions of the tropical oceans. The QuikSCAT scatterometer¡_s unique ability to provide both wind speed and direction on a nearly bi-daily basis has greatly increased the forecaster¡_s near real-time knowledge of tropical cyclone genesis, intensification potential, outer wind structure, and a ¡rminimum estimate¡_ for a tropical cyclone¡_s maximum sustained winds. Scatterometer data were compared with data available to the forecasters in a near real-time environment including ship, land and buoy reports. In addition, comparisons were also made with aircraft measurements (for Atlantic and East Pacific systems), numerical weather model wind fields, and various remote sensing techniques. Wind speeds were found to be extremely useful, especially for the radius of gale force winds. However, in rain-contaminated areas, light winds were often greatly overestimated while in heavy winds, wind speeds were often quite reasonable if not slightly underestimated. The largest issues are still focused on the correct wind direction selection. In these cases, rain-flagged wind vector cells greatly affected the results from the direction ambiguity selection procedure. The ambiguity selection algorithm often had difficulties resolving a circulation center when large areas of the tropical cyclone¡_s center were flagged. Often a block of winds would occur perpendicular to the swath irregardless of the circulation¡_s position. These winds caused considerable confusion for the operational forecasters. However, it was determined that in many cases, an accurate center position could still be obtained by using methods to incorporate the more accurate wind speeds and the outer wind field vectors that were not as seriously affected. Quantitative results and comparisons will be shown in this presentation. In addition, guides to the operational forecasters to determine system centers inspite of the ambiguity selection problems will also be discussed.

Design of Hybrid Solar and Wind Energy Harvester for Fishing Boat

NASA Astrophysics Data System (ADS)

Banjarnahor, D. A.; Hanifan, M.; Budi, E. M.

2017-07-01

In southern beach of West Java, Indonesia, there are many villagers live as fishermen. They use small boats for fishing, in one to three days. Therefore, they need a fish preservation system. Fortunately, the area has high potential of solar and wind energy. This paper presents the design of a hybrid solar and wind energy harvester to power a refrigerator in the fishing boat. The refrigerator should keep the fish in 2 - 4 °C. The energy needed is 720 Wh daily. In the area, the daily average wind velocity is 4.27 m/s and the sun irradiation is 672 W/m2. The design combined two 100W solar panels and a 300W wind turbine. The testing showed that the solar panels can harvest 815 - 817 Wh of energy, while the wind turbine can harvest 43 - 62 Wh of energy daily. Therefore, the system can fulfil the energy requirement in fishing boat, although the solar panels were more dominant. To install the wind turbine on the fishing-boat, a computational design had been conducted. The boat hydrostatic dimension was measured to determine its stability condition. To reach a stable equilibrium condition, the wind turbine should be installed no more than 1.7 m of height.

Influence of Transient Atmospheric Circulation on the Surface Heating of the Pacific Warm Pool

NASA Technical Reports Server (NTRS)

Chou, Ming-Dah; Chou, Shu-Hsien; Chan, Pui-King

2003-01-01

Analyses of data on clouds, winds, and surface heat fluxes show that the transient behavior of basin-wide large-scale circulation has a significant influence on the warm pool sea surface temperature (SST). Trade winds converge to regions of the highest SST in the equatorial western Pacific. These regions have the largest cloud cover and smallest wind speed. Both surface solar heating and evaporative cooling are weak. The reduced evaporative cooling due to weakened winds exceeds the reduced solar heating due to enhanced cloudiness. The result is a maximum surface heating in the strong convective and high SST regions. Data also show that the maximum surface heating in strong convective regions is interrupted by transient atmospheric and oceanic circulation. Due to the seasonal variation of the insolation at the top of the atmosphere, trade winds and clouds also experience seasonal variations. Regions of high SST and low-level convergence follow the Sun, where the surface heating is a maximum. As the Sun moves away from a convective region, the strong trade winds set in, and the evaporative cooling enhances, resulting in a net cooling of the surface. During an El Nino, the maximum SST and convective region shifts eastward from the maritime continent to the equatorial central Pacific. Following the eastward shift of the maximum SST, the region of maximum cloudiness and surface heating also shift eastward. As the atmospheric and oceanic circulation returns to normal situations, the trade winds increase and the surface heating decreases. We conclude that the evaporative cooling associated with the seasonal and interannual variations of trade winds is one of the major factors that modulate the SST distribution of the Pacific warm pool.

Wind-tunnel and Flight Investigations of the Use of Leading-Edge Area Suction for the Purpose of Increasing the Maximum Lift Coefficient of a 35 Degree Swept-Wing Airplane

NASA Technical Reports Server (NTRS)

Holzhauser, Curt A; Bray, Richard S

1956-01-01

An investigation was undertaken to determine the increase in maximum lift coefficient that could be obtained by applying area suction near the leading edge of a wing. This investigation was performed first with a 35 degree swept-wing model in the wind tunnel, and then with an operational 35 degree swept-wing airplane which was modified in accord with the wind-tunnel results. The wind-tunnel and flight tests indicated that the maximum lift coefficient was increased more than 50 percent by the use of area suction. Good agreement was obtained in the comparison of the wind-tunnel results with those measured in flight.

WebStart WEPS: Remote data access and model execution functionality added to WEPS

USDA-ARS?s Scientific Manuscript database

The Wind Erosion Prediction System (WEPS) is a daily time step, process based wind erosion model developed by the United States Department of Agriculture - Agricultural Research Service (USDA-ARS). WEPS simulates climate and management driven changes to the surface/vegetation/soil state on a daily b...

Multi-decadal Variability of the Wind Power Output

NASA Astrophysics Data System (ADS)

Kirchner Bossi, Nicolas; García-Herrera, Ricardo; Prieto, Luis; Trigo, Ricardo M.

2014-05-01

The knowledge of the long-term wind power variability is essential to provide a realistic outlook on the power output during the lifetime of a planned wind power project. In this work, the Power Output (Po) of a market wind turbine is simulated with a daily resolution for the period 1871-2009 at two different locations in Spain, one at the Central Iberian Plateau and another at the Gibraltar Strait Area. This is attained through a statistical downscaling of the daily wind conditions. It implements a Greedy Algorithm as classificator of a geostrophic-based wind predictor, which is derived by considering the SLP daily field from the 56 ensemble members of the longest homogeneous reanalysis available (20CR, 1871-2009). For calibration and validation purposes we use 10 years of wind observations (the predictand) at both sites. As a result, a series of 139 annual wind speed Probability Density Functions (PDF) are obtained, with a good performance in terms of wind speed uncertainty reduction (average daily wind speed MAE=1.48 m/s). The obtained centennial series allow to investigate the multi-decadal variability of wind power from different points of view. Significant periodicities around the 25-yr frequency band, as well as long-term linear trends are detected at both locations. In addition, a negative correlation is found between annual Po at both locations, evidencing the differences in the dynamical mechanisms ruling them (and possible complementary behavior). Furthermore, the impact that the three leading large-scale circulation patterns over Iberia (NAO, EA and SCAND) exert over wind power output is evaluated. Results show distinct (and non-stationary) couplings to these forcings depending on the geographical position and season or month. Moreover, significant non-stationary correlations are observed with the slow varying Atlantic Multidecadal Oscillation (AMO) index for both case studies. Finally, an empirical relationship is explored between the annual Po and the parameters of the Weibull PDF. This allowed us to derive a linear model to estimate the annual power output from those parameters, which results especially useful when no wind power data is available.

Enhanced near-surface ozone under heatwave conditions in a Mediterranean island.

PubMed

Pyrgou, Andri; Hadjinicolaou, Panos; Santamouris, Mat

2018-06-15

Near-surface ozone is enhanced under particular chemical reactions and physical processes. This study showed the seasonal variation of near-surface ozone in Nicosia, Cyprus and focused in summers when the highest ozone levels were noted using a seven year hourly dataset from 2007 to 2014. The originality of this study is that it examines how ozone levels changed under heatwave conditions (defined as 4 consecutive days with daily maximum temperature over 39 °C) with emphasis on specific air quality and meteorological parameters with respect to non-heatwave summer conditions. The influencing parameters had a medium-strong positive correlation of ozone with temperature, UVA and UVB at daytime which increased by about 35% under heatwave conditions. The analysis of the wind pattern showed a small decrease of wind speed during heatwaves leading to stagnant weather conditions, but also revealed a steady diurnal cycle of wind speed reaching a peak at noon, when the highest ozone levels were noted. The negative correlation of NOx budget with ozone was further increased under heatwave conditions leading to steeper lows of ozone in the morning. In summary, this research encourages further analysis into the persistent weather conditions prevalent during HWs stimulating ozone formation for higher temperatures.

Extreme pressure differences at 0900 NZST and winds across New Zealand

NASA Astrophysics Data System (ADS)

Salinger, M. James; Griffiths, Georgina M.; Gosai, Ashmita

2005-07-01

Trends in extremes in station daily sea-level pressure differences at 0900 NZST are examined, and extreme daily wind gusts, across New Zealand, since the 1960s. Annual time series were examined (with indices of magnitude and frequency over threshold percentiles) from the daily indices selected. These follow from earlier indices of normalized monthly mean sea-level pressure differences between station pairs, except the daily indices are not normalized. The frequency statistics quantify the number of extreme zonal (westerly and easterly), or extreme meridional (southerly or northerly), pressure gradient events. The frequency and magnitude of extreme westerly episodes has increased slightly over New Zealand, with a significant increase in the westerly extremes to the south of New Zealand. In contrast, the magnitude and frequency of easterly extremes has decreased over New Zealand, but increased to the south, with some trends weakly significant. The frequency and magnitude of daily southerly extremes has decreased significantly in the region.Extreme daily wind gust events at key climate stations in New Zealand and at Hobart, Australia, are highly likely to be associated with an extreme daily pressure difference. The converse was less likely to hold: extreme wind gusts were not always observed on days with extreme daily pressure difference, probably due to the strong influence that topography has on localized station winds. Significant correlations exist between the frequency indices and both annual-average mean sea-level pressures around the Australasian region and annual-average sea surface temperature (SST) anomalies in the Southern Hemisphere. These correlations are generally stronger for indices of extreme westerly or extreme southerly airflows. Annual-average pressures in the Tasman Sea or Southern Ocean are highly correlated to zonal indices (frequency of extreme westerlies). SST anomalies in the NINO3 region or on either side of the South Island are significantly correlated with the frequency of extreme westerly airflows.

Peak Wind Tool for General Forecasting

NASA Technical Reports Server (NTRS)

Barrett, Joe H., III; Short, David

2008-01-01

This report describes work done by the Applied Meteorology Unit (AMU) in predicting peak winds at Kennedy Space Center (KSC) and Cape Canaveral Air Force Station (CCAFS). The 45th Weather Squadron requested the AMU develop a tool to help them forecast the speed and timing of the daily peak and average wind, from the surface to 300 ft on KSC/CCAFS during the cool season. Based on observations from the KSC/CCAFS wind tower network , Shuttle Landing Facility (SLF) surface observations, and CCAFS sounding s from the cool season months of October 2002 to February 2007, the AMU created mul tiple linear regression equations to predict the timing and speed of the daily peak wind speed, as well as the background average wind speed. Several possible predictors were evaluated, including persistence , the temperature inversion depth and strength, wind speed at the top of the inversion, wind gust factor (ratio of peak wind speed to average wind speed), synoptic weather pattern, occurrence of precipitation at the SLF, and strongest wind in the lowest 3000 ft, 4000 ft, or 5000 ft.

European shags optimize their flight behavior according to wind conditions.

PubMed

Kogure, Yukihisa; Sato, Katsufumi; Watanuki, Yutaka; Wanless, Sarah; Daunt, Francis

2016-02-01

Aerodynamics results in two characteristic speeds of flying birds: the minimum power speed and the maximum range speed. The minimum power speed requires the lowest rate of energy expenditure per unit time to stay airborne and the maximum range speed maximizes air distance traveled per unit of energy consumed. Therefore, if birds aim to minimize the cost of transport under a range of wind conditions, they are predicted to fly at the maximum range speed. Furthermore, take-off is predicted to be strongly affected by wind speed and direction. To investigate the effect of wind conditions on take-off and cruising flight behavior, we equipped 14 European shags Phalacrocorax aristotelis with a back-mounted GPS logger to measure position and hence ground speed, and a neck-mounted accelerometer to record wing beat frequency and strength. Local wind conditions were recorded during the deployment period. Shags always took off into the wind regardless of their intended destination and take-off duration was correlated negatively with wind speed. We combined ground speed and direction during the cruising phase with wind speed and direction to estimate air speed and direction. Whilst ground speed was highly variable, air speed was comparatively stable, although it increased significantly during strong head winds, because of stronger wing beats. The increased air speeds in head winds suggest that birds fly at the maximum range speed, not at the minimum power speed. Our study demonstrates that European shags actively adjust their flight behavior to utilize wind power to minimize the costs of take-off and cruising flight. © 2016. Published by The Company of Biologists Ltd.

Observational study of atmospheric surface layer and coastal weather in northern Qatar

NASA Astrophysics Data System (ADS)

Samanta, Dhrubajyoti; Sadr, Reza

2016-04-01

Atmospheric surface layer is the interaction medium between atmosphere and Earth's surface. Better understanding of its turbulence nature is essential in characterizing the local weather, climate variability and modeling of turbulent exchange processes. The importance of Middle East region, with its unique geographical, economical and weather condition is well recognized. However, high quality micrometeorological observational studies are rare in this region. Here we show experimental results from micrometeorological observations from an experimental site in the coastal region of Qatar during August-December 2015. Measurements of winds are obtained from three sonic anemometers installed on a 9 m tower placed at Al Ghariyah beach in northern Qatar (26.08 °N, 51.36 °E). Different surface layer characteristics is analyzed and compared with earlier studies in equivalent weather conditions. Monthly statistics of wind speed, wind direction, temperature, humidity and heat index are made from concurrent observations from sonic anemometer and weather station to explore variations with surface layer characteristics. The results also highlights potential impact of sea breeze circulation on local weather and atmospheric turbulence. The observed daily maximum temperature and heat index during morning period may be related to sea breeze circulations. Along with the operational micrometeorological observation system, a camera system and ultrasonic wave measurement system are installed recently in the site to study coastline development and nearshore wave dynamics. Overall, the complete observational set up is going to provide new insights about nearshore wind dynamics and wind-wave interaction in Qatar.

Maximum wind energy extraction strategies using power electronic converters

NASA Astrophysics Data System (ADS)

Wang, Quincy Qing

2003-10-01

This thesis focuses on maximum wind energy extraction strategies for achieving the highest energy output of variable speed wind turbine power generation systems. Power electronic converters and controls provide the basic platform to accomplish the research of this thesis in both hardware and software aspects. In order to send wind energy to a utility grid, a variable speed wind turbine requires a power electronic converter to convert a variable voltage variable frequency source into a fixed voltage fixed frequency supply. Generic single-phase and three-phase converter topologies, converter control methods for wind power generation, as well as the developed direct drive generator, are introduced in the thesis for establishing variable-speed wind energy conversion systems. Variable speed wind power generation system modeling and simulation are essential methods both for understanding the system behavior and for developing advanced system control strategies. Wind generation system components, including wind turbine, 1-phase IGBT inverter, 3-phase IGBT inverter, synchronous generator, and rectifier, are modeled in this thesis using MATLAB/SIMULINK. The simulation results have been verified by a commercial simulation software package, PSIM, and confirmed by field test results. Since the dynamic time constants for these individual models are much different, a creative approach has also been developed in this thesis to combine these models for entire wind power generation system simulation. An advanced maximum wind energy extraction strategy relies not only on proper system hardware design, but also on sophisticated software control algorithms. Based on literature review and computer simulation on wind turbine control algorithms, an intelligent maximum wind energy extraction control algorithm is proposed in this thesis. This algorithm has a unique on-line adaptation and optimization capability, which is able to achieve maximum wind energy conversion efficiency through continuously improving the performance of wind power generation systems. This algorithm is independent of wind power generation system characteristics, and does not need wind speed and turbine speed measurements. Therefore, it can be easily implemented into various wind energy generation systems with different turbine inertia and diverse system hardware environments. In addition to the detailed description of the proposed algorithm, computer simulation results are presented in the thesis to demonstrate the advantage of this algorithm. As a final confirmation of the algorithm feasibility, the algorithm has been implemented inside a single-phase IGBT inverter, and tested with a wind simulator system in research laboratory. Test results were found consistent with the simulation results. (Abstract shortened by UMI.)

Precipitation Structure in the Sierra Nevada of California During Winter

NASA Technical Reports Server (NTRS)

Pandey, Ganesh R.; Cayan, Daniel R.; Georgakakos, Kostantine P.

1998-01-01

The influences of upper air characteristics along the coast of California upon the winter time precipitation in the Sierra Nevada region were investigated. Most precipitation episodes in the Sierra are associated with moist southwesterly winds and also tend to occur when the 700-mb temperature is close to -2 C. This favored wind direction and temperature signifies the equal importance of moisture transport and orographic lifting for maximum precipitation frequency. Making use of this observation, simple linear models were formulated to quantify the precipitation totals observed at different sites as a function of moisture transport. The skill of the model is least for daily precipitation and increases with time scale of aggregation. In terms of incremental gain, the skill of the model is optimal for an aggregation period of 5-7 days, which is also the duration of the most frequent precipitation events in the Sierra. This indicates that upper air moisture transport at can be used to make reasonable estimates of the precipitation totals for most frequent events in the Sierra region.

Physical understanding of the tropical cyclone wind-pressure relationship.

PubMed

Chavas, Daniel R; Reed, Kevin A; Knaff, John A

2017-11-08

The relationship between the two common measures of tropical cyclone intensity, the central pressure deficit and the peak near-surface wind speed, is a long-standing problem in tropical meteorology that has been approximated empirically yet lacks physical understanding. Here we provide theoretical grounding for this relationship. We first demonstrate that the central pressure deficit is highly predictable from the low-level wind field via gradient wind balance. We then show that this relationship reduces to a dependence on two velocity scales: the maximum azimuthal-mean azimuthal wind speed and half the product of the Coriolis parameter and outer storm size. This simple theory is found to hold across a hierarchy of models spanning reduced-complexity and Earth-like global simulations and observations. Thus, the central pressure deficit is an intensity measure that combines maximum wind speed, storm size, and background rotation rate. This work has significant implications for both fundamental understanding and risk analysis, including why the central pressure better explains historical economic damages than does maximum wind speed.

Wind effects on coastal zone color scanner chlorophyll patterns in the U.S. Mid-Atlantic Bight during spring 1979

NASA Technical Reports Server (NTRS)

Eslinger, David L.; Iverson, Richard L.

1986-01-01

Coastal zone color scanner (CZCS) chlorophyll concentration increases in the Mid-Atlantic Bight were associated with high wind speeds in continental shelf waters during March and May 1979. Maximum spring CZCS chlorophyll concentrations occurred during April when the water column was not thermally stratified and were spatially and temporally associated with reductions in wind speed both in onshelf and in offshelf regions. Increased chlorophyll concentrations in offshelf waters were associated with high wind speeds during May when a deep chlorophyll maximum was present. Chlorophyll patchiness was observed on length scales typical of those controlled by biological processes during the April low-wind period but not during March or May when wind speeds were greater. The spring CZCS chlorophyll maximum in the southern portion of the Mid-Atlantic Bight occurred in response to a reduction in mixed layer depth caused by decreased wind speeds and not by increased water column stratification.

Heat waves in Senegal : detection, characterization and associated processes.

NASA Astrophysics Data System (ADS)

Gnacoussa Sambou, Marie Jeanne; Janicot, Serge; Badiane, Daouda; Pohl, Benjamin; Dieng, Abdou L.; Gaye, Amadou T.

2017-04-01

Atmospheric configuration and synoptic evolution of patterns associated with Senegalese heat wave (HW) are examined on the period 1979-2014 using the Global Surface Summary of the Day (GSOD) observational database and ERA-Interim reanalysis. Since there is no objective and uniform definition of HW events, threshold methods based on atmospheric variables as daily maximum (Tmax) / minimum (Tmin) temperatures and daily mean apparent temperature (AT) are used to define HW threshold detection. Each criterion is related to a specific category of HW events: Tmax (warm day events), Tmin (warm night events) and AT (combining temperature and moisture). These definitions are used in order to characterize as well as possible the warm events over the Senegalese regions (oceanic versus continental region). Statistics on time evolution and spatial distribution of warm events are carried out over the 2 seasons of maximum temperature (March-May and October-November). For each season, a composite of HW events, as well as the most extended event over Senegal (as a case study) are analyzed using usual atmospheric fields (sea level pressure, geopotential height, total column water content, wind components, 2m temperature). This study is part of the project ACASIS (https://acasis.locean-ipsl.upmc.fr/doku.php) on heat waves occurrences over the Sahel and their impact on health. Keywords: heat wave, Senegal, ACASIS.

A globally calibrated scheme for generating daily meteorology from monthly statistics: Global-WGEN (GWGEN) v1.0

NASA Astrophysics Data System (ADS)

Sommer, Philipp S.; Kaplan, Jed O.

2017-10-01

While a wide range of Earth system processes occur at daily and even subdaily timescales, many global vegetation and other terrestrial dynamics models historically used monthly meteorological forcing both to reduce computational demand and because global datasets were lacking. Recently, dynamic land surface modeling has moved towards resolving daily and subdaily processes, and global datasets containing daily and subdaily meteorology have become available. These meteorological datasets, however, cover only the instrumental era of the last approximately 120 years at best, are subject to considerable uncertainty, and represent extremely large data files with associated computational costs of data input/output and file transfer. For periods before the recent past or in the future, global meteorological forcing can be provided by climate model output, but the quality of these data at high temporal resolution is low, particularly for daily precipitation frequency and amount. Here, we present GWGEN, a globally applicable statistical weather generator for the temporal downscaling of monthly climatology to daily meteorology. Our weather generator is parameterized using a global meteorological database and simulates daily values of five common variables: minimum and maximum temperature, precipitation, cloud cover, and wind speed. GWGEN is lightweight, modular, and requires a minimal set of monthly mean variables as input. The weather generator may be used in a range of applications, for example, in global vegetation, crop, soil erosion, or hydrological models. While GWGEN does not currently perform spatially autocorrelated multi-point downscaling of daily weather, this additional functionality could be implemented in future versions.

Variation of the low level winds during the passage of a thunderstorm gust front

NASA Technical Reports Server (NTRS)

Sinclair, R. W.; Anthes, R. A.; Panofsky, H. A.

1973-01-01

Three time histories of wind profiles in thunderstorm gust fronts at Cape Kennedy and three at Oklahoma City are analyzed. Wind profiles at maximum wind strength below 100 m follow logarithmic laws, so that winds above the surface layer can be estimated from surface winds once the roughness length is known. A statistical analysis of 81 cases of surface winds during thunderstorms at Tampa revealed no predictor with skill to predict the time of maximum gust. Some 34% of the variance of the strength of the gust is accounted for by a stability index and surface wind prior to the gust; the regression equations for these variables are given. The coherence between microscale wind speed variations at the different levels has the same proportions as in non-thunderstorm cases.

Wind energy potential assessment of Cameroon's coastal regions for the installation of an onshore wind farm.

PubMed

Arreyndip, Nkongho Ayuketang; Joseph, Ebobenow; David, Afungchui

2016-11-01

For the future installation of a wind farm in Cameroon, the wind energy potentials of three of Cameroon's coastal cities (Kribi, Douala and Limbe) are assessed using NASA average monthly wind data for 31 years (1983-2013) and compared through Weibull statistics. The Weibull parameters are estimated by the method of maximum likelihood, the mean power densities, the maximum energy carrying wind speeds and the most probable wind speeds are also calculated and compared over these three cities. Finally, the cumulative wind speed distributions over the wet and dry seasons are also analyzed. The results show that the shape and scale parameters for Kribi, Douala and Limbe are 2.9 and 2.8, 3.9 and 1.8 and 3.08 and 2.58, respectively. The mean power densities through Weibull analysis for Kribi, Douala and Limbe are 33.7 W/m2, 8.0 W/m2 and 25.42 W/m2, respectively. Kribi's most probable wind speed and maximum energy carrying wind speed was found to be 2.42 m/s and 3.35 m/s, 2.27 m/s and 3.03 m/s for Limbe and 1.67 m/s and 2.0 m/s for Douala, respectively. Analysis of the wind speed and hence power distribution over the wet and dry seasons shows that in the wet season, August is the windiest month for Douala and Limbe while September is the windiest month for Kribi while in the dry season, March is the windiest month for Douala and Limbe while February is the windiest month for Kribi. In terms of mean power density, most probable wind speed and wind speed carrying maximum energy, Kribi shows to be the best site for the installation of a wind farm. Generally, the wind speeds at all three locations seem quite low, average wind speeds of all the three studied locations fall below 4.0m/s which is far below the cut-in wind speed of many modern wind turbines. However we recommend the use of low cut-in speed wind turbines like the Savonius for stand alone low energy needs.

Multifractal analysis of the time series of daily means of wind speed in complex regions

NASA Astrophysics Data System (ADS)

Laib, Mohamed; Golay, Jean; Telesca, Luciano; Kanevski, Mikhail

2018-04-01

In this paper, we applied the multifractal detrended fluctuation analysis to the daily means of wind speed measured by 119 weather stations distributed over the territory of Switzerland. The analysis was focused on the inner time fluctuations of wind speed, which could be more linked with the local conditions of the highly varying topography of Switzerland. Our findings point out to a persistent behaviour of all the measured wind speed series (indicated by a Hurst exponent significantly larger than 0.5), and to a high multifractality degree indicating a relative dominance of the large fluctuations in the dynamics of wind speed, especially in the Swiss plateau, which is comprised between the Jura and Alp mountain ranges. The study represents a contribution to the understanding of the dynamical mechanisms of wind speed variability in mountainous regions.

Regional downscaling of temporal resolution in near-surface wind from statistically downscaled Global Climate Models (GCMs) for use in San Francisco Bay coastal flood modeling

NASA Astrophysics Data System (ADS)

O'Neill, A.; Erikson, L. H.; Barnard, P.

2013-12-01

While Global Climate Models (GCMs) provide useful projections of near-surface wind vectors into the 21st century, resolution is not sufficient enough for use in regional wave modeling. Statistically downscaled GCM projections from Multivariate Adaptive Constructed Analogues (MACA) provide daily near-surface winds at an appropriate spatial resolution for wave modeling within San Francisco Bay. Using 30 years (1975-2004) of climatological data from four representative stations around San Francisco Bay, a library of example daily wind conditions for four corresponding over-water sub-regions is constructed. Empirical cumulative distribution functions (ECDFs) of station conditions are compared to MACA GFDL hindcasts to create correction factors, which are then applied to 21st century MACA wind projections. For each projection day, a best match example is identified via least squares error among all stations from the library. The best match's daily variation in velocity components (u/v) is used as an analogue of representative wind variation and is applied at 3-hour increments about the corresponding sub-region's projected u/v values. High temporal resolution reconstructions using this methodology on hindcast MACA fields from 1975-2004 accurately recreate extreme wind values within the San Francisco Bay, and because these extremes in wind forcing are of key importance in wave and subsequent coastal flood modeling, this represents a valuable method of generating near-surface wind vectors for use in coastal flood modeling.

Analysis of wind-resistant and stability for cable tower in cable-stayed bridge with four towers

NASA Astrophysics Data System (ADS)

Meng, Yangjun; Li, Can

2017-06-01

Wind speed time history simulation methods have been introduced first, especially the harmonic synthesis method introduced in detail. Second, taking Chishi bridge for example, choosing the particular sections, and combined with the design wind speed, three-component coefficient simulate analysis between -4°and 4°has been carry out with the Fluent software. The results show that drag coefficient reaches maximum when the attack Angle is 1°. According to measured wind speed samples,time history curves of wind speed at bridge deck and tower roof have been obtained,and wind-resistant time history analysis for No.5 tower has been carry out. Their results show that the dynamic coefficients are different with different calculation standard, especially transverse bending moment, pulsating crosswind load does not show a dynamic amplification effect.Under pulsating wind loads at bridge deck or tower roof, the maximum displacement at the top of the tower and the maximum stress at the bottom of the tower are within the allowable range. The transverse stiffness of tower is greater than that of the longitudinal stiffness, therefore wind-resistant analysis should give priority to the longitudinal direction. Dynamic coefficients are different with different standard, the maximum dynamic coefficient should be used for the pseudo-static analysis.Finally, the static stability of tower is analyzed with different load combinations, and the galloping stabilities of cable tower is proved.

Hourly, daily, and seasonal variability in the absorption spectra of chromophoric dissolved organic matter in a eutrophic, humic lake

NASA Astrophysics Data System (ADS)

Müller, R. A.; Kothawala, D. N.; Podgrajsek, E.; Sahlée, E.; Koehler, B.; Tranvik, L. J.; Weyhenmeyer, G. A.

2014-10-01

The short-term (hourly and daily) variation in chromophoric dissolved organic matter (CDOM) in lakes is largely unknown. We assessed the spectral characteristics of light absorption by CDOM in a eutrophic, humic shallow mixed lake of temperate Sweden at a high-frequency (30 min) interval and during a full growing season (May to October). Physical time series, such as solar radiation, temperature, wind, and partial pressures of carbon dioxide in water and air, were measured synchronously. We identified a strong radiation-induced summer CDOM loss (25 to 50%) that developed over 4 months, which was accompanied by strong changes in CDOM absorption spectral shape. The magnitude of the CDOM loss exceeded subhourly to daily variability by an order of magnitude. Applying Fourier analysis, we demonstrate that variation in CDOM remained largely unaffected by rapid shifts in weather, and no apparent response to in-lake dissolved organic carbon production was found. In autumn, CDOM occasionally showed variation at hourly to daily time scales, reaching a maximum daily coefficient of variation of 15%. We suggest that lake-internal effects on CDOM are quenched in humic lake waters by dominating effects associated with imported CDOM and solar exposure. Since humic lake waters belong to one of the most abundant lake types on Earth, our results have important implications for the understanding of global CDOM cycling.

Tool for Forecasting Cool-Season Peak Winds Across Kennedy Space Center and Cape Canaveral Air Force Station (CCAFS)

NASA Technical Reports Server (NTRS)

Barrett, Joe H., III; Roeder, William P.

2010-01-01

Peak wind speed is important element in 24-Hour and Weekly Planning Forecasts issued by 45th Weather Squadron (45 WS). Forecasts issued for planning operations at KSC/CCAFS. 45 WS wind advisories issued for wind gusts greater than or equal to 25 kt. 35 kt and 50 kt from surface to 300 ft. AMU developed cool-season (Oct - Apr) tool to help 45 WS forecast: daily peak wind speed, 5-minute average speed at time of peak wind, and probability peak speed greater than or equal to 25 kt, 35 kt, 50 kt. AMU tool also forecasts daily average wind speed from 30 ft to 60 ft. Phase I and II tools delivered as a Microsoft Excel graphical user interface (GUI). Phase II tool also delivered as Meteorological Interactive Data Display System (MIDDS) GUI. Phase I and II forecast methods were compared to climatology, 45 WS wind advisories and North American Mesoscale model (MesoNAM) forecasts in a verification data set.

The influence of meteorology on the spread of influenza: survival analysis of an equine influenza (A/H3N8) outbreak.

PubMed

Firestone, Simon M; Cogger, Naomi; Ward, Michael P; Toribio, Jenny-Ann L M L; Moloney, Barbara J; Dhand, Navneet K

2012-01-01

The influences of relative humidity and ambient temperature on the transmission of influenza A viruses have recently been established under controlled laboratory conditions. The interplay of meteorological factors during an actual influenza epidemic is less clear, and research into the contribution of wind to epidemic spread is scarce. By applying geostatistics and survival analysis to data from a large outbreak of equine influenza (A/H3N8), we quantified the association between hazard of infection and air temperature, relative humidity, rainfall, and wind velocity, whilst controlling for premises-level covariates. The pattern of disease spread in space and time was described using extraction mapping and instantaneous hazard curves. Meteorological conditions at each premises location were estimated by kriging daily meteorological data and analysed as time-lagged time-varying predictors using generalised Cox regression. Meteorological covariates time-lagged by three days were strongly associated with hazard of influenza infection, corresponding closely with the incubation period of equine influenza. Hazard of equine influenza infection was higher when relative humidity was <60% and lowest on days when daily maximum air temperature was 20-25°C. Wind speeds >30 km hour(-1) from the direction of nearby infected premises were associated with increased hazard of infection. Through combining detailed influenza outbreak and meteorological data, we provide empirical evidence for the underlying environmental mechanisms that influenced the local spread of an outbreak of influenza A. Our analysis supports, and extends, the findings of studies into influenza A transmission conducted under laboratory conditions. The relationships described are of direct importance for managing disease risk during influenza outbreaks in horses, and more generally, advance our understanding of the transmission of influenza A viruses under field conditions.

Daily reference crop evapotranspiration with reduced data sets in the humid environments of Azores islands using estimates of actual vapor pressure, solar radiation, and wind speed

NASA Astrophysics Data System (ADS)

Paredes, P.; Fontes, J. C.; Azevedo, E. B.; Pereira, L. S.

2017-11-01

Reference crop evapotranspiration (ETo) estimations using the FAO Penman-Monteith equation (PM-ETo) require a set of weather data including maximum and minimum air temperatures (T max, T min), actual vapor pressure (e a), solar radiation (R s), and wind speed (u 2). However, those data are often not available, or data sets are incomplete due to missing values. A set of procedures were proposed in FAO56 (Allen et al. 1998) to overcome these limitations, and which accuracy for estimating daily ETo in the humid climate of Azores islands is assessed in this study. Results show that after locally and seasonally calibrating the temperature adjustment factor a d used for dew point temperature (T dew) computation from mean temperature, ETo estimations shown small bias and small RMSE ranging from 0.15 to 0.53 mm day-1. When R s data are missing, their estimation from the temperature difference (T max-T min), using a locally and seasonal calibrated radiation adjustment coefficient (k Rs), yielded highly accurate ETo estimates, with RMSE averaging 0.41 mm day-1 and ranging from 0.33 to 0.58 mm day-1. If wind speed observations are missing, the use of the default u 2 = 2 m s-1, or 3 m s-1 in case of weather measurements over clipped grass in airports, revealed appropriated even for the windy locations (u 2 > 4 m s-1), with RMSE < 0.36 mm day-1. The appropriateness of procedure to estimating the missing values of e a, R s, and u 2 was confirmed.

The Influence of Meteorology on the Spread of Influenza: Survival Analysis of an Equine Influenza (A/H3N8) Outbreak

PubMed Central

Firestone, Simon M.; Cogger, Naomi; Ward, Michael P.; Toribio, Jenny-Ann L. M. L.; Moloney, Barbara J.; Dhand, Navneet K.

2012-01-01

The influences of relative humidity and ambient temperature on the transmission of influenza A viruses have recently been established under controlled laboratory conditions. The interplay of meteorological factors during an actual influenza epidemic is less clear, and research into the contribution of wind to epidemic spread is scarce. By applying geostatistics and survival analysis to data from a large outbreak of equine influenza (A/H3N8), we quantified the association between hazard of infection and air temperature, relative humidity, rainfall, and wind velocity, whilst controlling for premises-level covariates. The pattern of disease spread in space and time was described using extraction mapping and instantaneous hazard curves. Meteorological conditions at each premises location were estimated by kriging daily meteorological data and analysed as time-lagged time-varying predictors using generalised Cox regression. Meteorological covariates time-lagged by three days were strongly associated with hazard of influenza infection, corresponding closely with the incubation period of equine influenza. Hazard of equine influenza infection was higher when relative humidity was <60% and lowest on days when daily maximum air temperature was 20–25°C. Wind speeds >30 km hour−1 from the direction of nearby infected premises were associated with increased hazard of infection. Through combining detailed influenza outbreak and meteorological data, we provide empirical evidence for the underlying environmental mechanisms that influenced the local spread of an outbreak of influenza A. Our analysis supports, and extends, the findings of studies into influenza A transmission conducted under laboratory conditions. The relationships described are of direct importance for managing disease risk during influenza outbreaks in horses, and more generally, advance our understanding of the transmission of influenza A viruses under field conditions. PMID:22536366

Good Days, Bad Days: Wind as a Driver of Foraging Success in a Flightless Seabird, the Southern Rockhopper Penguin

PubMed Central

Dehnhard, Nina; Ludynia, Katrin; Poisbleau, Maud; Demongin, Laurent; Quillfeldt, Petra

2013-01-01

Due to their restricted foraging range, flightless seabirds are ideal models to study the short-term variability in foraging success in response to environmentally driven food availability. Wind can be a driver of upwelling and food abundance in marine ecosystems such as the Southern Ocean, where wind regime changes due to global warming may have important ecological consequences. Southern rockhopper penguins (Eudyptes chrysocome) have undergone a dramatic population decline in the past decades, potentially due to changing environmental conditions. We used a weighbridge system to record daily foraging mass gain (the difference in mean mass of adults leaving the colony in the morning and returning to the colony in the evening) of adult penguins during the chick rearing in two breeding seasons. We related the day-to-day variability in foraging mass gain to ocean wind conditions (wind direction and wind speed) and tested for a relationship between wind speed and sea surface temperature anomaly (SSTA). Foraging mass gain was highly variable among days, but did not differ between breeding seasons, chick rearing stages (guard and crèche) and sexes. It was strongly correlated between males and females, indicating synchronous changes among days. There was a significant interaction of wind direction and wind speed on daily foraging mass gain. Foraging mass gain was highest under moderate to strong winds from westerly directions and under weak winds from easterly directions, while decreasing under stronger easterly winds and storm conditions. Ocean wind speed showed a negative correlation with daily SSTA, suggesting that winds particularly from westerly directions might enhance upwelling and consequently the prey availability in the penguins' foraging areas. Our data emphasize the importance of small-scale, wind-induced patterns in prey availability on foraging success, a widely neglected aspect in seabird foraging studies, which might become more important with increasing changes in climatic variability. PMID:24236139

On the impacts of computing daily temperatures as the average of the daily minimum and maximum temperatures

NASA Astrophysics Data System (ADS)

Villarini, Gabriele; Khouakhi, Abdou; Cunningham, Evan

2017-12-01

Daily temperature values are generally computed as the average of the daily minimum and maximum observations, which can lead to biases in the estimation of daily averaged values. This study examines the impacts of these biases on the calculation of climatology and trends in temperature extremes at 409 sites in North America with at least 25 years of complete hourly records. Our results show that the calculation of daily temperature based on the average of minimum and maximum daily readings leads to an overestimation of the daily values of 10+ % when focusing on extremes and values above (below) high (low) thresholds. Moreover, the effects of the data processing method on trend estimation are generally small, even though the use of the daily minimum and maximum readings reduces the power of trend detection ( 5-10% fewer trends detected in comparison with the reference data).

Estimating missing daily temperature extremes in Jaffna, Sri Lanka

NASA Astrophysics Data System (ADS)

Thevakaran, A.; Sonnadara, D. U. J.

2018-04-01

The accuracy of reconstructing missing daily temperature extremes in the Jaffna climatological station, situated in the northern part of the dry zone of Sri Lanka, is presented. The adopted method utilizes standard departures of daily maximum and minimum temperature values at four neighbouring stations, Mannar, Anuradhapura, Puttalam and Trincomalee to estimate the standard departures of daily maximum and minimum temperatures at the target station, Jaffna. The daily maximum and minimum temperatures from 1966 to 1980 (15 years) were used to test the validity of the method. The accuracy of the estimation is higher for daily maximum temperature compared to daily minimum temperature. About 95% of the estimated daily maximum temperatures are within ±1.5 °C of the observed values. For daily minimum temperature, the percentage is about 92. By calculating the standard deviation of the difference in estimated and observed values, we have shown that the error in estimating the daily maximum and minimum temperatures is ±0.7 and ±0.9 °C, respectively. To obtain the best accuracy when estimating the missing daily temperature extremes, it is important to include Mannar which is the nearest station to the target station, Jaffna. We conclude from the analysis that the method can be applied successfully to reconstruct the missing daily temperature extremes in Jaffna where no data is available due to frequent disruptions caused by civil unrests and hostilities in the region during the period, 1984 to 2000.

Forecasting Cool Season Daily Peak Winds at Kennedy Space Center and Cape Canaveral Air Force Station

NASA Technical Reports Server (NTRS)

Barrett, Joe, III; Short, David; Roeder, William

2008-01-01

The expected peak wind speed for the day is an important element in the daily 24-Hour and Weekly Planning Forecasts issued by the 45th Weather Squadron (45 WS) for planning operations at Kennedy Space Center (KSC) and Cape Canaveral Air Force Station (CCAFS). The morning outlook for peak speeds also begins the warning decision process for gusts ^ 35 kt, ^ 50 kt, and ^ 60 kt from the surface to 300 ft. The 45 WS forecasters have indicated that peak wind speeds are a challenging parameter to forecast during the cool season (October-April). The 45 WS requested that the Applied Meteorology Unit (AMU) develop a tool to help them forecast the speed and timing of the daily peak and average wind, from the surface to 300 ft on KSC/CCAFS during the cool season. The tool must only use data available by 1200 UTC to support the issue time of the Planning Forecasts. Based on observations from the KSC/CCAFS wind tower network, surface observations from the Shuttle Landing Facility (SLF), and CCAFS upper-air soundings from the cool season months of October 2002 to February 2007, the AMU created multiple linear regression equations to predict the timing and speed of the daily peak wind speed, as well as the background average wind speed. Several possible predictors were evaluated, including persistence, the temperature inversion depth, strength, and wind speed at the top of the inversion, wind gust factor (ratio of peak wind speed to average wind speed), synoptic weather pattern, occurrence of precipitation at the SLF, and strongest wind in the lowest 3000 ft, 4000 ft, or 5000 ft. Six synoptic patterns were identified: 1) surface high near or over FL, 2) surface high north or east of FL, 3) surface high south or west of FL, 4) surface front approaching FL, 5) surface front across central FL, and 6) surface front across south FL. The following six predictors were selected: 1) inversion depth, 2) inversion strength, 3) wind gust factor, 4) synoptic weather pattern, 5) occurrence of precipitation at the SLF, and 6) strongest wind in the lowest 3000 ft. The forecast tool was developed as a graphical user interface with Microsoft Excel to help the forecaster enter the variables, and run the appropriate regression equations. Based on the forecaster's input and regression equations, a forecast of the day's peak and average wind is generated and displayed. The application also outputs the probability that the peak wind speed will be ^ 35 kt, 50 kt, and 60 kt.

Simulation and experiment of a fuzzy logic based MPPT controller for a small wind turbine system

NASA Astrophysics Data System (ADS)

Petrila, Diana; Muntean, Nicolae

2012-09-01

This paper describes the development of a fuzzy logic based maximum power point tracking (MPPT) strategy for a variable speed wind turbine system (VSWT). For this scope, a fuzzy logic controller (FLC) was described, simulated and tested on a real time "hardware in the loop" wind turbine emulator. Simulation and experimental results show that the controller is able to track the maximum power point for various wind conditions and validate the proposed control strategy.

Analytical expressions for maximum wind turbine average power in a Rayleigh wind regime

DOE Office of Scientific and Technical Information (OSTI.GOV)

Carlin, P.W.

Average or expectation values for annual power of a wind turbine in a Rayleigh wind regime are calculated and plotted as a function of cut-out wind speed. This wind speed is expressed in multiples of the annual average wind speed at the turbine installation site. To provide a common basis for comparison of all real and imagined turbines, the Rayleigh-Betz wind machine is postulated. This machine is an ideal wind machine operating with the ideal Betz power coefficient of 0.593 in a Rayleigh probability wind regime. All other average annual powers are expressed in fractions of that power. Cases consideredmore » include: (1) an ideal machine with finite power and finite cutout speed, (2) real machines operating in variable speed mode at their maximum power coefficient, and (3) real machines operating at constant speed.« less

Correlations between solar wind parameters and auroral kilometric radiation intensity

NASA Technical Reports Server (NTRS)

Gallagher, D. L.; Dangelo, N.

1981-01-01

The relationship between solar wind properties and the influx of energy into the nightside auroral region as indicated by the intensity of auroral kilometric radiation is investigated. Smoothed Hawkeye satellite observations of auroral radiation at 178, 100 and 56.2 kHz for days 160 through 365 of 1974 are compared with solar wind data from the composite Solar Wind Plasma Data Set, most of which was supplied by the IMP-8 spacecraft. Correlations are made between smoothed daily averages of solar wind ion density, bulk flow speed, total IMF strength, electric field, solar wind speed in the southward direction, solar wind speed multiplied by total IMF strength, the substorm parameter epsilon and the Kp index. The greatest correlation is found between solar wind bulk flow speed and auroral radiation intensity, with a linear correlation coefficient of 0.78 for the 203 daily averages examined. A possible mechanism for the relationship may be related to the propagation into the nightside magnetosphere of low-frequency long-wavelength electrostatic waves produced in the magnetosheath by the solar wind.

Resilience of a High Latitude Red Sea Frining Corals Exposed to Extreme Temperatures

NASA Astrophysics Data System (ADS)

Moustafa, M.; Moustafa, M. S.; Moustafa, S.; Moustafa, Z. D.

2013-05-01

Since 2004, multi-year study set out to establish linkages between fringing coral reefs in the northern Gulf of Suez, Red Sea, and local weather. Insight into local meteorological processes may provide a better understanding of the direct influence weather has on a fringing coral reef. To establish trends, seawater temperature and meteorological record were collected at a small fringing coral reef (Zaki's Reef), located near Ein Sokhna, Egypt (29.5oN & 32.4oE). Monitoring air and water temperature provides evidence of seasonality and interannual variability and may reveal correlations between reef health and climate conditions in this region. Prior to this study, there were no known long-term studies investigating coral reefs in this region. Approximately 35 coral taxa are known to survive the extreme temperature and salinity regime found here, yet only six corals compose 94% of coral cover on Zaki's Reef. Dominant corals include: Acropora humilis, A. microclados, A. hemprichii, Litophyton arboretum, Stylophora pistillata, Porites columna, and P. plantulata. Seawater temperatures were collected at 30 minutes intervals at 5 locations. Seawater temperature data indicate that corals experience 4-6.5oC daily temperature variations and seasonal variations that exceed 29oC. Air temperatures were collected just landward of the reef were compared to Hurghada and Ismailia 400 and 200 km south and north of the study site, respectively. Time series analysis results indicate that air temperature dominant frequencies are half-daily, daily, and yearly cycles, while water temperatures show yearly cycles. A comparison of air temperature with neighboring locations indicates that air temperatures at Ein Sokhna ranged between near 0o C to an excess of 55o C, yet, daily means for Ein Sokhna and Hurghada were very similar (24.2o C and. 25.2o C, respectively). Maximum daily air temperatures at the study site exceeded maximum air temperature at Hurghada (400 km south) by almost 7o C, while minimum daily means at Ein Sokhna were almost equal to those at Ismailia (200 km north). These trends were opposite to what was expected considering each stations geographical locations. The unexpected temperature trends, the daily/half daily dominant frequencies, and the short distance between the mountain range and Zaki's Reef vs. Hurghada (0.5 vs. 35 km), prompted us to hypothesize that a Foehn wind may be responsible for the high air temperatures observed at Ein Sokhna. We applied NOAA's HYSPLIT model to explore local circulation patterns, which suggest that the high mountain range blocks the year-round trade wind and forces it to climb up the western slope, where it loses moisture and reduces its temperature. As this cool, denser air reaches the mountain top, the air parcel starts rolling down the eastern slopes, which causes air temperature to rise and result in an increase in local air temperatures. These warmer than normal air temperatures measured here may aid in securing these northernmost reefs survival. Further scrutiny of the mechanisms by which area reefs are able to thrive extreme environmental conditions continues to be investigated.

40 CFR 420.134 - New source performance standards (NSPS).

Code of Federal Regulations, 2010 CFR

2010-07-01

... Source Performance Standards (NSPS) Pollutant Maximum daily 1 Maximum monthly avg. 1 TSS 0.00998 0.00465... operations. Subpart M—New Source Performance Standards (NSPS) Pollutant Maximum daily 1 Maximum monthly avg...

40 CFR 420.134 - New source performance standards (NSPS).

Code of Federal Regulations, 2011 CFR

2011-07-01

... Source Performance Standards (NSPS) Pollutant Maximum daily 1 Maximum monthly avg. 1 TSS 0.00998 0.00465... operations. Subpart M—New Source Performance Standards (NSPS) Pollutant Maximum daily 1 Maximum monthly avg...

Water quality in Rhode River at Smithsonian Institution Pier near Annapolis, Maryland, January 1976 through December 1978

USGS Publications Warehouse

Cory, Robert L.; Dresler, P.V.

1980-01-01

Water temperature, salinity, turbidity, dissolved oxygen, pH, and water level data were continuously monitored and recorded from the Smithsonian Institution pier near Annapolis, Md., from January 1976 through December 1978. Daily maximum and minimum values are tabulated and summarized, and monthly averages and extremes are presented. Water temperature ranged from 0.0 to 33.9 Celsius. Both high and low extreme values exceeded those recorded during the previous 6 years. Salinity patterns showed normal seasonal variations and were related to the Susquehanna River inflow, which controls the upper bay salinity. Salinity between 13 and 15 parts per thousand in November and December 1978 were the highest recorded over a 9-year period. Turbidity varied seasonally, with lowest values in winter and highest in spring. Dissolved oxygen ranged from 2.0 to 18.7 milligrams per liter. Large variations between summertime daily minima and maxima indicated the high state of eutrophication of the water being monitored. Hydrogen-ion activity (pH) ranged from 7.0 to 10.2 over the 3-year period. The pH changes reflect daily variation in partial pressure of carbon dioxide, which varies inversely with the dissolved oxygen. Water level variation at the monitoring site for the 3-year period was 1.89 meters, with highest water 0.59 meter above mean high water and lowest 0.83 meter below mean low water. An apparent decline of 0.07 meter below previously recorded mean high and mean low water was associated with stronger winds and a prevalance of westerly winds in February during the winter of 1976-1977. (USGS)

Tropical cyclone induced asymmetry of sea level surge and fall and its presentation in a storm surge model with parametric wind fields

NASA Astrophysics Data System (ADS)

Peng, Machuan; Xie, Lian; Pietrafesa, Leonard J.

The asymmetry of tropical cyclone induced maximum coastal sea level rise (positive surge) and fall (negative surge) is studied using a three-dimensional storm surge model. It is found that the negative surge induced by offshore winds is more sensitive to wind speed and direction changes than the positive surge by onshore winds. As a result, negative surge is inherently more difficult to forecast than positive surge since there is uncertainty in tropical storm wind forecasts. The asymmetry of negative and positive surge under parametric wind forcing is more apparent in shallow water regions. For tropical cyclones with fixed central pressure, the surge asymmetry increases with decreasing storm translation speed. For those with the same translation speed, a weaker tropical cyclone is expected to gain a higher AI (asymmetry index) value though its induced maximum surge and fall are smaller. With fixed RMW (radius of maximum wind), the relationship between central pressure and AI is heterogeneous and depends on the value of RMW. Tropical cyclone's wind inflow angle can also affect surge asymmetry. A set of idealized cases as well as two historic tropical cyclones are used to illustrate the surge asymmetry.

Solar wind structure suggested by bimodal correlations of solar wind speed and density between the spacecraft SOHO and Wind

NASA Astrophysics Data System (ADS)

Ogilvie, K. W.; Coplan, M. A.; Roberts, D. A.; Ipavich, F.

2007-08-01

We calculate the cross-spacecraft maximum lagged-cross-correlation coefficients for 2-hour intervals of solar wind speed and density measurements made by the plasma instruments on the Solar and Heliospheric Observatory (SOHO) and Wind spacecraft over the period from 1996, the minimum of solar cycle 23, through the end of 2005. During this period, SOHO was located at L1, about 200 R E upstream from the Earth, while Wind spent most of the time in the interplanetary medium at distances of more than 100 R E from the Earth. Yearly histograms of the maximum, time-lagged correlation coefficients for both the speed and density are bimodal in shape, suggesting the existence of two distinct solar wind regimes. The larger correlation coefficients we suggest are due to structured solar wind, including discontinuities and shocks, while the smaller are likely due to Alfvénic turbulence. While further work will be required to firmly establish the physical nature of the two populations, the results of the analysis are consistent with a solar wind that consists of turbulence from quiet regions of the Sun interspersed with highly filamentary structures largely convected from regions in the inner solar corona. The bimodal appearance of the distributions is less evident in the solar wind speed than in the density correlations, consistent with the observation that the filamentary structures are convected with nearly constant speed by the time they reach 1 AU. We also find that at solar minimum the fits for the density correlations have smaller high-correlation components than at solar maximum. We interpret this as due to the presence of more relatively uniform Alfvénic regions at solar minimum than at solar maximum.

Organization of vertical shear of wind and daily variability of monsoon rainfall

NASA Astrophysics Data System (ADS)

Gouda, K. C.; Goswami, P.

2016-10-01

Very little is known about the mechanisms that govern the day to day variability of the Indian summer monsoon (ISM) rainfall; in the current dominant view, the daily rainfall is essentially a result of chaotic dynamics. Most studies in the past have thus considered monsoon in terms of its seasonal (June-September) or monthly rainfall. We show here that the daily rainfall in June is associated with vertical shear of horizontal winds at specific scales. While vertical shear had been used in the past to investigate interannual variability of seasonal rainfall, rarely any effort has been made to examine daily rainfall. Our work shows that, at least during June, the daily rainfall variability of ISM rainfall is associated with a large scale dynamical coherence in the sense that the vertical shear averaged over large spatial extents are significantly correlated with area-averaged daily rainfall. An important finding from our work is the existence of a clearly delineated monsoon shear domain (MSD) with strong coherence between area-averaged shear and area-averaged daily rainfall in June; this association of daily rainfall is not significant with shear over only MSD. Another important feature is that the association between daily rainfall and vertical shear is present only during the month of June. Thus while ISM (June-September) is a single seasonal system, it is important to consider the dynamics and variation of June independently of the seasonal ISM rainfall. The association between large-scale organization of circulation and daily rainfall is suggested as a basis for attempting prediction of daily rainfall by ensuring accurate simulation of wind shear.

The potential of different artificial neural network (ANN) techniques in daily global solar radiation modeling based on meteorological data

DOE Office of Scientific and Technical Information (OSTI.GOV)

Behrang, M.A.; Assareh, E.; Ghanbarzadeh, A.

2010-08-15

The main objective of present study is to predict daily global solar radiation (GSR) on a horizontal surface, based on meteorological variables, using different artificial neural network (ANN) techniques. Daily mean air temperature, relative humidity, sunshine hours, evaporation, and wind speed values between 2002 and 2006 for Dezful city in Iran (32 16'N, 48 25'E), are used in this study. In order to consider the effect of each meteorological variable on daily GSR prediction, six following combinations of input variables are considered: (I)Day of the year, daily mean air temperature and relative humidity as inputs and daily GSR as output.more » (II)Day of the year, daily mean air temperature and sunshine hours as inputs and daily GSR as output. (III)Day of the year, daily mean air temperature, relative humidity and sunshine hours as inputs and daily GSR as output. (IV)Day of the year, daily mean air temperature, relative humidity, sunshine hours and evaporation as inputs and daily GSR as output. (V)Day of the year, daily mean air temperature, relative humidity, sunshine hours and wind speed as inputs and daily GSR as output. (VI)Day of the year, daily mean air temperature, relative humidity, sunshine hours, evaporation and wind speed as inputs and daily GSR as output. Multi-layer perceptron (MLP) and radial basis function (RBF) neural networks are applied for daily GSR modeling based on six proposed combinations. The measured data between 2002 and 2005 are used to train the neural networks while the data for 214 days from 2006 are used as testing data. The comparison of obtained results from ANNs and different conventional GSR prediction (CGSRP) models shows very good improvements (i.e. the predicted values of best ANN model (MLP-V) has a mean absolute percentage error (MAPE) about 5.21% versus 10.02% for best CGSRP model (CGSRP 5)). (author)« less

Vector control of wind turbine on the basis of the fuzzy selective neural net*

NASA Astrophysics Data System (ADS)

Engel, E. A.; Kovalev, I. V.; Engel, N. E.

2016-04-01

An article describes vector control of wind turbine based on fuzzy selective neural net. Based on the wind turbine system’s state, the fuzzy selective neural net tracks an maximum power point under random perturbations. Numerical simulations are accomplished to clarify the applicability and advantages of the proposed vector wind turbine’s control on the basis of the fuzzy selective neuronet. The simulation results show that the proposed intelligent control of wind turbine achieves real-time control speed and competitive performance, as compared to a classical control model with PID controllers based on traditional maximum torque control strategy.

Impacts of day versus night warming on soil microclimate: results from a semiarid temperate steppe.

PubMed

Xia, Jianyang; Chen, Shiping; Wan, Shiqiang

2010-06-15

One feature of climate warming is that increases in daily minimum temperature are greater than those in daily maximum temperature. Changes in soil microclimate in response to the asymmetrically diurnal warming scenarios can help to explain responses of ecosystem processes. In the present study, we examined the impacts of day, night, and continuous warming on soil microclimate in a temperate steppe in northern China. Our results showed that day, night, and continuous warming (approximately 13Wm(-2) with constant power mode) significantly increased daily mean soil temperature at 10cm depth by 0.71, 0.78, and 1.71 degrees C, respectively. Night warming caused greater increases in nighttime mean and daily minimum soil temperatures (0.74 and 0.99 degrees C) than day warming did (0.60 and 0.66 degrees C). However, there were no differences in the increases in daytime mean and daily maximum soil temperature between day (0.81 and 1.13 degrees C) and night (0.81 and 1.10 degrees C) warming. The differential effects of day and night warming on soil temperature varied with environmental factors, including photosynthetic active radiation, vapor-pressure deficit, and wind speed. When compared with the effect of continuous warming on soil temperature, the summed effects of day and night warming were lower during daytime, but greater at night, thus leading to equality at daily scale. Mean volumetric soil moisture at the depth of 0-40cm significantly decreased under continuous warming in both 2006 (1.44 V/V%) and 2007 (0.76 V/V%). Day warming significantly reduced volumetric soil moisture only in 2006, whereas night warming had no effect on volumetric soil moisture in both 2006 and 2007. Given the different diurnal warming patterns and variability of environmental factors among ecosystems, these results highlight the importance of incorporating the differential impacts of day and night warming on soil microclimate into the predictions of terrestrial ecosystem responses to climate warming. Copyright 2010 Elsevier B.V. All rights reserved.

Remote sensing of mesospheric winds with the High-Resolution Doppler Imager

NASA Technical Reports Server (NTRS)

Hays, Paul B.; Abreu, V. J.; Burrage, M. D.; Gell, D. A.; Grassi, H. J.; Marshall, A. R.; Morton, Y. T.; Ortland, D. A.; Skinner, W. R.; Wu, D. L.

1992-01-01

Observations of the winds in the upper atmosphere obtained with the High-Resolution Doppler Imager (HRDI) on the Upper Atmosphere Research Satellite (UARS) are discussed. This instrument is a very stable high-resolution triple-etalon Fabry-Perot interferometer, which is used to observe the slight Doppler shifts of absorption and emission lines in the O2 Atmospheric bands induced by atmospheric motions. Preliminary observations indicate that the winds in the mesosphere and lower thermosphere are a mixture of migrating and non-migrating tides, and planetary-scale waves. The mean meridional winds are dominated by the 1,1 diurnal tide which is easily extracted from the daily zonal means of the satellite observations. The daily mean zonal winds are a mixture of the diurnal tide and a zonal flow which is consistent with theoretical expectations.

Energy from the Wind

ERIC Educational Resources Information Center

Pelka, David G.; And Others

1978-01-01

The large-scale generation of electrical power by wind turbine fields is discussed. It is shown that the maximum power that can be extracted by a wind turbine is 16/27 of the power available in the wind. (BB)

Variations of Scale Height at F-Region Peak Based on Ionosonde Measurements during Solar Maximum over the Crest of Equatorial Ionization Anomaly Region

PubMed Central

Chuo, Yu-Jung

2014-01-01

Scale height is an important parameter in characterizing the shape of the ionosphere and its physical processes. In this study, we attempt to examine and discuss the variation of scale height, H m, around the F-layer peak height during high solar activity at the northern crest of the equatorial ionization anomaly (EIA) region. H m exhibits day-to-day variation and seasonal variation, with a greater average daily variation during daytime in summer. Furthermore, the diurnal variation of H m exhibits an abnormal peak at presunrise during all the seasons, particularly in winter. This increase is also observed in the F2-layer peak height for the same duration with an upward movement associated with thermospheric wind toward the equator; this upward movement increases the N2/O ratio and H m, but it causes a decrease in the F2-layer maximum critical frequency during the presunrise period. PMID:25162048

Short-term risk of hospitalization for asthma or bronchiolitis in children living near an aluminum smelter

PubMed Central

Lewin, Antoine; Buteau, Stéphane; Brand, Allan; Kosatsky, Tom; Smargiassi, Audrey

2013-01-01

Few studies have measured the effect of short-term exposure to industrial emissions on the respiratory health of children. Here we estimate the risk of hospitalization for asthma and bronchiolitis in young children associated with their recent exposure to emissions from an aluminum smelter. We used a case–crossover design to assess the risk of hospitalization, February 1999–December 2008, in relation to short-term variation in levels of exposure among children 0–4 years old living less than 7.5 km from the smelter. The percentage of hours per day that the residence of a hospitalized child was in the shadow of winds crossing the smelter was used to estimate the effect of wind-borne emissions on case and crossover days. Community-wide pollutant exposure was estimated through daily mean and daily maximum SO2 and PM2.5 concentrations measured at a fixed monitoring site near the smelter. Odds ratios (OR) were estimated using conditional logistic regressions. The risk of same-day hospitalization for asthma or bronchiolitis increased with the percentage of hours in a day that a child's residence was downwind of the smelter. For children aged 2–4 years, the OR was 1.27 (95% CI=1.03–1.56; n=103 hospitalizations), for an interquartile range (IQR) of 21% of hours being downwind. In this age group, the OR with PM2.5 daily mean levels was slightly smaller than with the hours downwind (OR: 1.22 for an IQR of 15.7 μg/m3, 95% CI=1.03–1.44; n=94 hospitalizations). Trends were observed between hospitalizations and levels of SO2 for children 2–4 years old. Increasing short-term exposure to emissions from a Quebec aluminum smelter was associated with an increased risk of hospitalization for asthma and bronchiolitis in young children who live nearby. Estimating exposure through records of wind direction allows for the integration of exposure to all pollutants carried from the smelter stack. PMID:23695491

Impact of downward-mixing ozone on surface ozone accumulation in southern Taiwan.

PubMed

Lin, Ching-Ho

2008-04-01

The ozone that initially presents in the previous day's afternoon mixing layer can remain in the nighttime atmosphere and then be carried over to the next morning. Finally, this ozone can be brought to the ground by downward mixing as mixing depth increases during the daytime, thereby increasing surface ozone concentrations. Variation of ozone concentration during each of these periods is investigated in this work. First, ozone concentrations existing in the daily early morning atmosphere at the altitude range of the daily maximum mixing depth (residual ozone concentrations) were measured using tethered ozonesondes on 52 experimental days during 2004-2005 in southern Taiwan. Daily downward-mixing ozone concentrations were calculated by a box model coupling the measured daily residual ozone concentrations and daily mixing depth variations. The ozone concentrations upwind in the previous day's afternoon mixing layer were estimated by the combination of back air trajectory analysis and known previous day's surface ozone distributions. Additionally, the relationship between daily downward-mixing ozone concentration and daily photochemically produced ozone concentration was examined. The latter was calculated by removing the former from daily surface maximum ozone concentration. The measured daily residual ozone concentrations distributed at 12-74 parts per billion (ppb) with an average of 42 +/- 17 ppb are well correlated with the previous upwind ozone concentration (R2 = 0.54-0.65). Approximately 60% of the previous upwind ozone was estimated to be carried over to the next morning and became the observed residual ozone. The daily downward-mixing ozone contributes 48 +/- 18% of the daily surface maximum ozone concentration, indicating that the downward-mixing ozone is as important as daily photochemically produced ozone to daily surface maximum ozone accumulation. The daily downward-mixing ozone is poorly correlated with the daily photochemically produced ozone and contributes significantly to the daily variation of surface maximum ozone concentrations (R2 = 0.19). However, the contribution of downward-mixing ozone to daily ozone variation is not included in most existing statistical models developed for predicting daily ozone variation. Finally, daily surface maximum ozone concentration is positively correlated with daily afternoon mixing depth, attributable to the downward-mixing ozone.

Combined effects of total grain-size distribution and crosswind on the rise of eruptive volcanic columns

NASA Astrophysics Data System (ADS)

Girault, F.; Carazzo, G.; Tait, S.; Kaminski, E.

2016-10-01

The maximum height of an explosive volcanic column, H, depends on the 1/4th power of the eruptive mass flux, Q, and on the 3/4th power of the stratification of the atmosphere, N. Expressed as scaling laws, this relationship has made H a widely used proxy to estimate Q. Two additional effects are usually included to produce more accurate and robust estimates of Q based on H: particle sedimentation from the volcanic column, which depends on the total grain-size distribution (TGSD) and the atmospheric crosswind. Both coarse TGSD and strong crosswind have been shown to decrease strongly the maximum column height, and TGSD, which also controls the effective gas content in the column, influences the stability of the column. However, the impact of TGSD and of crosswind on the dynamics of the volcanic column are commonly considered independently. We propose here a steady-state 1D model of an explosive volcanic column rising in a windy atmosphere that explicitly accounts for particle sedimentation and wind together. We consider three typical wind profiles: uniform, linear, and complex, with the same maximum wind velocity of 15 m s- 1. Subject to a uniform wind profile, the calculations show that the maximum height of the plume strongly decreases for any TGSD. The effect of TGSD on maximum height is smaller for uniform and complex wind profiles than for a linear profile or without wind. The largest differences of maximum heights arising from different wind profiles are observed for the largest source mass fluxes (> 107 kg s- 1) for a given TGSD. Compared to no wind conditions, the field of column collapse is reduced for any wind profile and TGSD at the vent, an effect that is the strongest for small mass fluxes and coarse TGSD. Provided that the maximum plume height and the wind profile are known from real-time observations, the model predicts the mass discharge rate feeding the eruption for a given TGSD. We apply our model to a set of eight historical volcanic eruptions for which all the required information is known. Taking into account the measured wind profile and the actual TGSD at the vent substantially improves (by ≈ 30%) the agreement between the mass discharge rate calculated from the model based on plume height and the field observation of deposit mass divided by eruption duration, relative to a model taking into account TGSD only. This study contributes to the improvement of the characterization of volcanic source term required as input to larger scale models of ash and aerosol dispersion.

Ground-based measurements of the vertical E-field in mountainous regions and the "Austausch" effect

NASA Astrophysics Data System (ADS)

Yaniv, Roy; Yair, Yoav; Price, Colin; Mkrtchyan, Hripsime; Lynn, Barry; Reymers, Artur

2017-06-01

Past measurements of the atmospheric vertical electric field (Ez or potential gradient) at numerous land stations showed a strong response of the daily electric field to a morning local effect known as ;Austausch; - the transport of electrical charges due to increased turbulence. In mountainous regions, nocturnal charge accumulation, followed by an attachment process to aerosols near the surface in valleys, known as the electrode effect, is lifted as a charged aerosol layer by anabatic (upslope) winds during the morning hours due to solar heating. Ground-based measurements during fair weather days were conducted at three mountain stations in Israel and Armenia. We present results of the mean diurnal variation of Ez and make comparisons with the well-known Carnegie curve and with past measurements of Ez on mountains. We report a good agreement between the mean diurnal curves of Ez at various mountain stations and the time of local sunrise when the Ez is found to increase. We attribute this morning maximum to the Austausch (or exchange) layer effect. We support our findings with conduction and turbulent current measurements showing high values of ions and charged aerosols being transported by winds from morning to noon local time, and by model simulations showing the convergence of winds in the early morning hours toward the mountain peak.

Changes in European wind energy generation potential within a 1.5 °C warmer world

NASA Astrophysics Data System (ADS)

Hosking, J. Scott; MacLeod, D.; Phillips, T.; Holmes, C. R.; Watson, P.; Shuckburgh, E. F.; Mitchell, D.

2018-05-01

Global climate model simulations from the ‘Half a degree Additional warming, Prognosis and Projected Impacts’ (HAPPI) project were used to assess how wind power generation over Europe would change in a future world where global temperatures reach 1.5 °C above pre-industrial levels. Comparing recent historical (2006–2015) and future 1.5 °C forcing experiments highlights that the climate models demonstrate a northward shift in the Atlantic jet, leading to a significant (p < 0.01) increase in surface winds over the UK and Northern Europe and a significant (p < 0.05) reduction over Southern Europe. We use a wind turbine power model to transform daily near-surface (10 m) wind speeds into daily wind power output, accounting for sub-daily variability, the height of the turbine, and power losses due to transmission and distribution of electricity. To reduce regional model biases we use bias-corrected 10 m wind speeds. We see an increase in power generation potential over much of Europe, with the greatest increase in load factor over the UK of around four percentage points. Increases in variability are seen over much of central and northern Europe with the largest seasonal change in summer. Focusing on the UK, we find that wind energy production during spring and autumn under 1.5 °C forcing would become as productive as it is currently during the peak winter season. Similarly, summer winds would increase driving up wind generation to resemble levels currently seen in spring and autumn. We conclude that the potential for wind energy in Northern Europe may be greater than has been previously assumed, with likely increases even in a 1.5 °C warmer world. While there is the potential for Southern Europe to see a reduction in their wind resource, these decreases are likely to be negligible.

Comparative Measurements of Condensation and Evaporation In The Alpine Regions of Thegiant Mountains, Poland and The Dischma, E. Switzerland

NASA Astrophysics Data System (ADS)

de Jong, C.; Mundelius, M.; Migala, K.

During the summers of 1998, 1999 and 2001, two basins were instrumented for detailed comparative measurements of evaporation, transpiration and condensation. The catchments of the Reifträger, situated in the Giant Mountains of Poland and the Dischma, situated in the Kanton Graubünden in Eastern Switzerland range in altitude between 850 - 1410 m and 1600 - 3100 m respectively. All hydrological and meteorological measurements were carried out above the treeline. Both regions consist mainly of dwarf shrubs with dwarf pines, ferns, and moors dominating in the Reifträger and alpine pasture and dwarf shrubs in the Dischma. Automatic we ighing lysimeters and evaporation pans recorded evaporation, transpiration, condensation and rainfall data at 10 minute intervals over different slope profiles. On the Reifträger, condensation occurs between 05:00-07:00 and is followed by the onset of evaporation. Evaporation stagnates nearly entirely between 11:00-12:00 but it is subsequently reinitiated due to rapidly increasing wind speeds, reaching a maximum at 14:00. Evaporation continues until 18:00, followed by some nighttime evaporation in the early morning hours. Unlike the Reifträger, the Dischma has two daily maxima for evaporation and transpiration, again preceded in the morning hours by intensive condensation. In the Dischma, evaporation and transpiration is variable according to valley side but the first maximum usually occurs at 15:00 followed by a second maximum between 18:00-19:00 after sunset. The differences in the timing and pattern of evaporation and transpiration of the two catchments can be explained by influence of fog on the Reifträger compared to the regular exchange of moist and dry air from the glacier in the Dischma. In both cases, evaporation is delayed relative to radiation so that there is an evaporation lag of approximately 30 - 50 minutes on the Reifträger and up to 2 hours in the Dischma. Evaporation should therefore be modelled through a function of the temperature profile and wind distribution i.e. with a well-developed advection term. In both cases, transpiration exceeds evaporation, with about 70% for the Reifträger and 30% for the Dischma. The Reifträger has a dynamic local wind system that, together with temperature, has a significant influence on evaporation and transpiration. As the name suggests, the Reifträger experiences up to 124 days per year with 24 hours of fog. Although barely any evaporation or radiation is recorded on such days, the highest transpiration rates are observed due to windy conditions with relatively high temperatures. In the Dischma the strong influence of winds is also very significant for evaporation and transpiration, with some daily maxima occurring after sunset under the influence of warm, dry katabatic winds descending from the high altitudes. As such, condensation is a limiting factor for evaporation on clear days, but there may be an intensive interrelationship between condensation and evaporation on cloudy, humid days. Condensation during the night time replaces about 15% of the water evaporated during the daytime for the Polish example and 25 % for the Swiss example. This is strongly dependant on the capacity of the vegetation layer to absorb moisture. If the water balance is to be modelled accurately, it is advisable to measure evaporation, transpiration as well as discharge precisely to obtain a good estimate of both condensation and precipitation.

A Lyapunov based approach to energy maximization in renewable energy technologies

NASA Astrophysics Data System (ADS)

Iyasere, Erhun

This dissertation describes the design and implementation of Lyapunov-based control strategies for the maximization of the power captured by renewable energy harnessing technologies such as (i) a variable speed, variable pitch wind turbine, (ii) a variable speed wind turbine coupled to a doubly fed induction generator, and (iii) a solar power generating system charging a constant voltage battery. First, a torque control strategy is presented to maximize wind energy captured in variable speed, variable pitch wind turbines at low to medium wind speeds. The proposed strategy applies control torque to the wind turbine pitch and rotor subsystems to simultaneously control the blade pitch and tip speed ratio, via the rotor angular speed, to an optimum point at which the capture efficiency is maximum. The control method allows for aerodynamic rotor power maximization without exact knowledge of the wind turbine model. A series of numerical results show that the wind turbine can be controlled to achieve maximum energy capture. Next, a control strategy is proposed to maximize the wind energy captured in a variable speed wind turbine, with an internal induction generator, at low to medium wind speeds. The proposed strategy controls the tip speed ratio, via the rotor angular speed, to an optimum point at which the efficiency constant (or power coefficient) is maximal for a particular blade pitch angle and wind speed by using the generator rotor voltage as a control input. This control method allows for aerodynamic rotor power maximization without exact wind turbine model knowledge. Representative numerical results demonstrate that the wind turbine can be controlled to achieve near maximum energy capture. Finally, a power system consisting of a photovoltaic (PV) array panel, dc-to-dc switching converter, charging a battery is considered wherein the environmental conditions are time-varying. A backstepping PWM controller is developed to maximize the power of the solar generating system. The controller tracks a desired array voltage, designed online using an incremental conductance extremum-seeking algorithm, by varying the duty cycle of the switching converter. The stability of the control algorithm is demonstrated by means of Lyapunov analysis. Representative numerical results demonstrate that the grid power system can be controlled to track the maximum power point of the photovoltaic array panel in varying atmospheric conditions. Additionally, the performance of the proposed strategy is compared to the typical maximum power point tracking (MPPT) method of perturb and observe (P&O), where the converter dynamics are ignored, and is shown to yield better results.

An Observational and Analytical Study of Marginal Ice Zone Atmospheric Jets

DTIC Science & Technology

2016-12-01

layer or in the capping temperature inversion just above. The three strongest jets had maximum wind speeds at elevations near 350 m to 400 m...geostrophic wind due to horizontal temperature changes in the atmospheric boundary layer and capping inversion . The jets were detected using...temperature inversion just above. The three strongest jets had maximum wind speeds at elevations near 350 m to 400 m elevation; one of these jets had a

Baseline predictability of daily east Asian summer monsoon circulation indices

NASA Astrophysics Data System (ADS)

Ai, Shucong; Chen, Quanliang; Li, Jianping; Ding, Ruiqiang; Zhong, Quanjia

2017-05-01

The nonlinear local Lyapunov exponent (NLLE) method is adopted to quantitatively determine the predictability limit of East Asian summer monsoon (EASM) intensity indices on a synoptic timescale. The predictability limit of EASM indices varies widely according to the definitions of indices. EASM indices defined by zonal shear have a limit of around 7 days, which is higher than the predictability limit of EASM indices defined by sea level pressure (SLP) difference and meridional wind shear (about 5 days). The initial error of EASM indices defined by SLP difference and meridional wind shear shows a faster growth than indices defined by zonal wind shear. Furthermore, the indices defined by zonal wind shear appear to fluctuate at lower frequencies, whereas the indices defined by SLP difference and meridional wind shear generally fluctuate at higher frequencies. This result may explain why the daily variability of the EASM indices defined by zonal wind shear tends be more predictable than those defined by SLP difference and meridional wind shear. Analysis of the temporal correlation coefficient (TCC) skill for EASM indices obtained from observations and from NCEP's Global Ensemble Forecasting System (GEFS) historical weather forecast dataset shows that GEFS has a higher forecast skill for the EASM indices defined by zonal wind shear than for indices defined by SLP difference and meridional wind shear. The predictability limit estimated by the NLLE method is shorter than that in GEFS. In addition, the June-September average TCC skill for different daily EASM indices shows significant interannual variations from 1985 to 2015 in GEFS. However, the TCC for different types of EASM indices does not show coherent interannual fluctuations.

The turbulence structure of katabatic flows below and above wind-speed maximum

NASA Astrophysics Data System (ADS)

Grachev, Andrey; Leo, Laura; Di Sabatino, Silvana; Fernando, Harindra; Pardyjak, Eric; Fairall, Christopher

2015-04-01

Measurements of atmospheric small-scale turbulence made over the complex-terrain at the US Army Dugway Proving Grounds in Utah during the Mountain Terrain Atmospheric Modeling and Observations (MATERHORN) Program are used to describe the turbulence structure of katabatic flows. Turbulent and mean meteorological data were continuously measured at multiple levels (up to seven) on four towers deployed along East lower slope (2-4 degrees) of Granite Mountain. The multi-level, multi-tower observations obtained during a 30-day long MATERHORN-Fall field campaign in September-October 2102 allow studying temporal and spatial structure of nocturnal slope flows in detail. In this study, we focus on the various statistics (fluxes, variances, spectra, cospectra, etc.) of the small-scale turbulence of katabatic winds. Observed vertical profiles of velocity, turbulent fluxes, and other quantities show steep gradients near the surface but in the layer above the slope jet these variables vary with height more slowly than near the surface. It is found that vertical momentum flux and horizontal heat (buoyancy) flux in a slope-following coordinate system change their sign below and above the wind maximum of a katabatic flow. The vertical momentum flux is directed downward (upward) whereas the horizontal heat flux is downslope (upslope) below (above) the wind maximum. Our study, therefore, suggests that a position of the jet speed maximum can be derived from linear interpolation between positive and negative values of the momentum flux (or the horizontal heat flux) and determination of a height where a flux becomes zero. It is shown that the standard deviations of all wind speed components (and therefore the turbulent kinetic energy) and the dissipation rate of turbulent kinetic energy have a local minimum, whereas the standard deviation of air temperature has an absolute maximum at the height of wind speed maximum. We report several cases when the destructive effect of vertical heat (buoyancy) flux is completely cancelled by the generation of turbulence due to the horizontal heat (buoyancy) flux. Turbulence in the layer above the wind-speed maximum is decoupled from the surface and it is consistent with the classical local z-less predictions for stably stratified boundary layer.

Relationship between boundary layer heights and growth rates with ground-level ozone in Houston, Texas

NASA Astrophysics Data System (ADS)

Haman, C. L.; Couzo, E.; Flynn, J. H.; Vizuete, W.; Heffron, B.; Lefer, B. L.

2014-05-01

Measurements and predictions of ambient ozone (O3), planetary boundary layer (PBL) height, the surface energy budget, wind speed, and other meteorological parameters were made near downtown Houston, Texas, and were used to investigate meteorological controls on elevated levels of ground-level O3. Days during the study period (1 April 2009 to 31 December 2010 for measurements and 15 April 2009 to 17 October 2009 for modeled) were classified into low (LO3) and high ozone (HO3) days. The majority of observed high HO3 days occurred in a postfrontal environment. Observations showed there is not a significant difference in daily maximum PBL heights on HO3 and LO3 days. Modeling results showed large differences between maximum PBL heights on HO3 and LO3 days. Nighttime and early morning observed and modeled PBL heights are consistently lower on HO3 days than on LO3 days. The observed spring LO3 days had the most rapid early morning PBL growth (~350 m h-1) while the fall HO3 group had the slowest (~200 m h-1). The predicted maximum average hourly morning PBL growth rates were greater on HO3 (624 m h-1) days than LO3 days (361 m h-1). Observed turbulent mixing parameters were up to 2-3 times weaker on HO3 days, which indicate large-scale subsidence associated with high-pressure systems (leading to clear skies and weak winds) substantially suppresses mixing. Lower surface layer ventilation coefficients were present in the morning on HO3 days in the spring and fall, which promotes the accumulation of O3 precursors near the surface.

A new approach used to explore associations of current Ambrosia pollen levels with current and past meteorological elements

NASA Astrophysics Data System (ADS)

Matyasovszky, István; Makra, László; Csépe, Zoltán; Deák, Áron József; Pál-Molnár, Elemér; Fülöp, Andrea; Tusnády, Gábor

2015-09-01

The paper examines the sensitivity of daily airborne Ambrosia (ragweed) pollen levels of a current pollen season not only on daily values of meteorological variables during this season but also on the past meteorological conditions. The results obtained from a 19-year data set including daily ragweed pollen counts and ten daily meteorological variables are evaluated with special focus on the interactions between the phyto-physiological processes and the meteorological elements. Instead of a Pearson correlation measuring the strength of the linear relationship between two random variables, a generalised correlation that measures every kind of relationship between random vectors was used. These latter correlations between arrays of daily values of the ten meteorological elements and the array of daily ragweed pollen concentrations during the current pollen season were calculated. For the current pollen season, the six most important variables are two temperature variables (mean and minimum temperatures), two humidity variables (dew point depression and rainfall) and two variables characterising the mixing of the air (wind speed and the height of the planetary boundary layer). The six most important meteorological variables before the current pollen season contain four temperature variables (mean, maximum, minimum temperatures and soil temperature) and two variables that characterise large-scale weather patterns (sea level pressure and the height of the planetary boundary layer). Key periods of the past meteorological variables before the current pollen season have been identified. The importance of this kind of analysis is that a knowledge of the past meteorological conditions may contribute to a better prediction of the upcoming pollen season.

A new approach used to explore associations of current Ambrosia pollen levels with current and past meteorological elements.

PubMed

Matyasovszky, István; Makra, László; Csépe, Zoltán; Deák, Áron József; Pál-Molnár, Elemér; Fülöp, Andrea; Tusnády, Gábor

2015-09-01

The paper examines the sensitivity of daily airborne Ambrosia (ragweed) pollen levels of a current pollen season not only on daily values of meteorological variables during this season but also on the past meteorological conditions. The results obtained from a 19-year data set including daily ragweed pollen counts and ten daily meteorological variables are evaluated with special focus on the interactions between the phyto-physiological processes and the meteorological elements. Instead of a Pearson correlation measuring the strength of the linear relationship between two random variables, a generalised correlation that measures every kind of relationship between random vectors was used. These latter correlations between arrays of daily values of the ten meteorological elements and the array of daily ragweed pollen concentrations during the current pollen season were calculated. For the current pollen season, the six most important variables are two temperature variables (mean and minimum temperatures), two humidity variables (dew point depression and rainfall) and two variables characterising the mixing of the air (wind speed and the height of the planetary boundary layer). The six most important meteorological variables before the current pollen season contain four temperature variables (mean, maximum, minimum temperatures and soil temperature) and two variables that characterise large-scale weather patterns (sea level pressure and the height of the planetary boundary layer). Key periods of the past meteorological variables before the current pollen season have been identified. The importance of this kind of analysis is that a knowledge of the past meteorological conditions may contribute to a better prediction of the upcoming pollen season.

Two methods for estimating limits to large-scale wind power generation

PubMed Central

Miller, Lee M.; Brunsell, Nathaniel A.; Mechem, David B.; Gans, Fabian; Monaghan, Andrew J.; Vautard, Robert; Keith, David W.; Kleidon, Axel

2015-01-01

Wind turbines remove kinetic energy from the atmospheric flow, which reduces wind speeds and limits generation rates of large wind farms. These interactions can be approximated using a vertical kinetic energy (VKE) flux method, which predicts that the maximum power generation potential is 26% of the instantaneous downward transport of kinetic energy using the preturbine climatology. We compare the energy flux method to the Weather Research and Forecasting (WRF) regional atmospheric model equipped with a wind turbine parameterization over a 105 km2 region in the central United States. The WRF simulations yield a maximum generation of 1.1 We⋅m−2, whereas the VKE method predicts the time series while underestimating the maximum generation rate by about 50%. Because VKE derives the generation limit from the preturbine climatology, potential changes in the vertical kinetic energy flux from the free atmosphere are not considered. Such changes are important at night when WRF estimates are about twice the VKE value because wind turbines interact with the decoupled nocturnal low-level jet in this region. Daytime estimates agree better to 20% because the wind turbines induce comparatively small changes to the downward kinetic energy flux. This combination of downward transport limits and wind speed reductions explains why large-scale wind power generation in windy regions is limited to about 1 We⋅m−2, with VKE capturing this combination in a comparatively simple way. PMID:26305925

The management submodel of the Wind Erosion Prediction System

USDA-ARS?s Scientific Manuscript database

The Wind Erosion Prediction System (WEPS) is a process-based, daily time-step, computer model that predicts soil erosion via simulation of the physical processes controlling wind erosion. WEPS is comprised of several individual modules (submodels) that reflect different sets of physical processes, ...

Climate related trends and meteorological conditions in European Arctic region - Porsanger fjord, Norway

NASA Astrophysics Data System (ADS)

Cieszyńska, Agata; Stramska, Małgorzata

2017-04-01

Climate change has significant effect on the Arctic environment, where global trends are amplified. In this study, we have focused on the Porsanger fjord, located in European Arctic in the coastal region of the Barents Sea. We have analyzed climate related trends and meteorological condititions in the area of interest. Meteorological data included wind speed and direction, air temperature (AT) and precipitation from Era-Interim reanalysis (1986-2015) and local observations (1996-2015) from Lakselv (L, fjord's head area) and Honningsvaag (H - fjord's exit area). Our results confirm that this region is undergoing climate change related warming, which is indicated by rising air temperatures. Based on long-term reanalysis data, estimated trends for air temperature (AT) in Porsanger fjord are: 0.0536 °C year-1 at fjord's exit and 0.0428 °C year-1 at fjord's head. The results show that climate change does not seem to have a significant effect on long-term changes of wind speed and precipitation in the Porsanger fjord. Statistical analysis underlined significant spatial variability of meteorological conditions inside the fjord. For example, there are large differences in the annual cycle of AT with monthly mean January and July values of -8.4 and 12.6 °C in L and -2.5 and 10.1 °C in H. Dominant wind directions in Lakselv are S and SSE, while in Honningsvaag S and SSW directions prevail. Strong wind events (above 12 m s-1) are more frequent in H than in L. Annual cycle is characterized by stronger winds in winter and seasonality of wind direction. Precipitation for a given location can change by about 50% between years and varies spatially. Synoptic scale and within day variability are extremely intense in the area of interest. Air temperature and wind speed and direction can change dramatically in hours. In addition, regular patterns of the daily cycle of AT have different intensity in L and H. It is interesting to note that in spring/summer season, the daily cycle of air temperature difference between L and H is also strong and has an influence on winds. Estimates of land-originated water discharge (derived from the E-Hype model) show seasonal cycle with the maximum runoff in late spring/early summer. The main features of climate related trends and the effects of oceanic/continental interactions, presented in this study, shape the environment of the fjord and are possible to be analogous in other Norwegian fjords with comparable geographical location. This work was funded by the Norway Grants (NCBR contract No. 201985, project NORDFLUX). Partial support for MS comes from the Institute of Oceanology (IO PAN).

Recovery, statistical validation and analysis of a historical meteorological dataset collected at the Hanbury Botanical Gardens (Liguria, northwestern Italy) from 1900 to 1940

NASA Astrophysics Data System (ADS)

Vagge, Greta; Cutroneo, Laura; Gandolfi, Daniela; Ferretti, Gabriele; Scafidi, Davide; Capello, Marco

2018-05-01

A historical set of daily meteorological data collected at the Hanbury Botanical Gardens (Liguria, northwestern Italy) from 1900 to 1940 was recovered from five manually entered registers. They were digitised and statistically analysed to check their reliability and study their trends and variations. In particular, air temperature, precipitation and their extreme values were considered, together with wind direction, sea state, sky conditions and relative humidity. The results show a decreasing trend in mean annual temperature of approximately 0.2 °C/decade due to a decrease in maximum air temperature. Annual cumulative precipitation increased by 65.2 mm/decade over the study period. The data analysis showed a summer temperature decrease in 1912 and a severe drought in 1921. Moreover, the years with most days with extreme temperatures were associated to the negative phases of the North Atlantic oscillation (NAO). During the study period, SW winds were prevailing. Sky conditions followed seasonal trends, while slight sea was the most frequent sea state.

Loss of efficiency in a coaxial arrangement of a pair of wind rotors

NASA Astrophysics Data System (ADS)

Okulov, V. L.; Naumov, I. V.; Tsoy, M. A.; Mikkelsen, R. F.

2017-07-01

The efficiency of a pair of wind turbines is experimentally investigated for the case when the model of the second rotor is coaxially located in the wake of the first one. This configuration implies the maximum level of losses in wind farms, as in the rotor wakes, the deceleration of the freestream is maximum. As a result of strain gauge measurements, the dependences of dimensionless power characteristics of both rotors on the distances between them were determined for different modes at different tip speed ratios. The obtained results are of interest for further development of aerodynamics of wind turbines, for optimizing the work of existing wind farms and reducing their power losses due to interactions with wakes of other wind turbines during design and calculation.

Maximum capacity model of grid-connected multi-wind farms considering static security constraints in electrical grids

NASA Astrophysics Data System (ADS)

Zhou, W.; Qiu, G. Y.; Oodo, S. O.; He, H.

2013-03-01

An increasing interest in wind energy and the advance of related technologies have increased the connection of wind power generation into electrical grids. This paper proposes an optimization model for determining the maximum capacity of wind farms in a power system. In this model, generator power output limits, voltage limits and thermal limits of branches in the grid system were considered in order to limit the steady-state security influence of wind generators on the power system. The optimization model was solved by a nonlinear primal-dual interior-point method. An IEEE-30 bus system with two wind farms was tested through simulation studies, plus an analysis conducted to verify the effectiveness of the proposed model. The results indicated that the model is efficient and reasonable.

SeaWinds - Greenland

NASA Image and Video Library

2000-05-08

The frequent coverage provided by NASA SeaWinds instrument on the QuikScat satellite in 1999 provided unprecedented capability to monitor daily and seasonal changes in the key melt zones of Greenland.

The Relationships between Weather-Related Factors and Daily Outdoor Physical Activity Counts on an Urban Greenway

PubMed Central

Wolff, Dana; Fitzhugh, Eugene C.

2011-01-01

The purpose of this study was to examine relationships between weather and outdoor physical activity (PA). An online weather source was used to obtain daily max temperature [DMT], precipitation, and wind speed. An infra-red trail counter provided data on daily trail use along a greenway, over a 2-year period. Multiple regression analysis was used to examine associations between PA and weather, while controlling for day of the week and month of the year. The overall regression model explained 77.0% of the variance in daily PA (p < 0.001). DMT (b = 10.5), max temp-squared (b = −4.0), precipitation (b = −70.0), and max wind speed (b = 1.9) contributed significantly. Conclusion: Aggregated daily data can detect relationships between weather and outdoor PA. PMID:21556205

Diurnal warming in shallow coastal seas: Observations from the Caribbean and Great Barrier Reef regions

NASA Astrophysics Data System (ADS)

Zhu, X.; Minnett, P. J.; Berkelmans, R.; Hendee, J.; Manfrino, C.

2014-07-01

A good understanding of diurnal warming in the upper ocean is important for the validation of satellite-derived sea surface temperature (SST) against in-situ buoy data and for merging satellite SSTs taken at different times of the same day. For shallow coastal regions, better understanding of diurnal heating could also help improve monitoring and prediction of ecosystem health, such as coral reef bleaching. Compared to its open ocean counterpart which has been studied extensively and modeled with good success, coastal diurnal warming has complicating localized characteristics, including coastline geometry, bathymetry, water types, tidal and wave mixing. Our goal is to characterize coastal diurnal warming using two extensive in-situ temperature and weather datasets from the Caribbean and Great Barrier Reef (GBR), Australia. Results showed clear daily warming patterns in most stations from both datasets. For the three Caribbean stations where solar radiation is the main cause of daily warming, the mean diurnal warming amplitudes were about 0.4 K at depths of 4-7 m and 0.6-0.7 K at shallower depths of 1-2 m; the largest warming value was 2.1 K. For coral top temperatures of the GBR, 20% of days had warming amplitudes >1 K, with the largest >4 K. The bottom warming at shallower sites has higher daily maximum temperatures and lower daily minimum temperatures than deeper sites nearby. The averaged daily warming amplitudes were shown to be closely related to daily average wind speed and maximum insolation, as found in the open ocean. Diurnal heating also depends on local features including water depth, location on different sections of the reef (reef flat vs. reef slope), the relative distance from the barrier reef chain (coast vs. lagoon stations vs. inner barrier reef sites vs. outer rim sites); and the proximity to the tidal inlets. In addition, the influence of tides on daily temperature changes and its relative importance compared to solar radiation was quantified by calculating the ratio of power spectrum densities at the principal lunar semidiurnal M2 tide versus 24-hour cycle frequency representing mainly solar radiation forcing, i.e., (PSDM2/PSD24). Despite the fact that GBR stations are generally located at regions with large tidal changes, the tidal effects were modest: 80% of stations showed value of (PSDM2/PSD24) of less than 10%.

On estimating total daily evapotranspiration from remote surface temperature measurements

NASA Technical Reports Server (NTRS)

Carlson, Toby N.; Buffum, Martha J.

1989-01-01

A method for calculating daily evapotranspiration from the daily surface energy budget using remotely sensed surface temperature and several meteorological variables is presented. Vaules of the coefficients are determined from simulations with a one-dimensional boundary layer model with vegetation cover. Model constants are obtained for vegetation and bare soil at two air temperature and wind speed levels over a range of surface roughness and wind speeds. A different means of estimating the daily evapotranspiration based on the time rate of increase of surface temperature during the morning is also considered. Both the equations using our model-derived constants and field measurements are evaluated, and a discussion of sources of error in the use of the formulation is given.

Deconflicting Wind-Optimal Aircraft Trajectories in North Atlantic Oceanic Airspace

NASA Technical Reports Server (NTRS)

Rodionova, Olga; Delahaye, Daniel; Sridhar, Banavar; Ng, Hok K.

2016-01-01

North Atlantic oceanic airspace accommodates more than 1000 flights daily, and is subjected to very strong winds. Flying wind-optimal trajectories yields time and fuel savings for each individual flight. However, when taken together, these trajectories induce a large amount of potential en-route conflicts. This paper analyses the detected conflicts, figuring out conflict distribution in time and space. It further describes an optimization algorithm aimed at reducing the number of conflicts for a daily set of flights on strategic level. Several trajectory modification strategies are discussed, followed with simulation results. Finally, an algorithm improvement is presented aiming at better preserving the trajectory optimality.

Long-range fluctuations and multifractality in connectivity density time series of a wind speed monitoring network

NASA Astrophysics Data System (ADS)

Laib, Mohamed; Telesca, Luciano; Kanevski, Mikhail

2018-03-01

This paper studies the daily connectivity time series of a wind speed-monitoring network using multifractal detrended fluctuation analysis. It investigates the long-range fluctuation and multifractality in the residuals of the connectivity time series. Our findings reveal that the daily connectivity of the correlation-based network is persistent for any correlation threshold. Further, the multifractality degree is higher for larger absolute values of the correlation threshold.

14 CFR 151.79 - Runway paving: Second runway; wind conditions.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 14 Aeronautics and Space 3 2014-01-01 2014-01-01 false Runway paving: Second runway; wind...: Second runway; wind conditions. (a) All airports. Paving a second runway on the basis of wind conditions... second runway is oriented with the existing paved runway to achieve the maximum wind coverage, with due...

14 CFR 151.79 - Runway paving: Second runway; wind conditions.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 14 Aeronautics and Space 3 2013-01-01 2013-01-01 false Runway paving: Second runway; wind...: Second runway; wind conditions. (a) All airports. Paving a second runway on the basis of wind conditions... second runway is oriented with the existing paved runway to achieve the maximum wind coverage, with due...

14 CFR 151.79 - Runway paving: Second runway; wind conditions.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 14 Aeronautics and Space 3 2012-01-01 2012-01-01 false Runway paving: Second runway; wind...: Second runway; wind conditions. (a) All airports. Paving a second runway on the basis of wind conditions... second runway is oriented with the existing paved runway to achieve the maximum wind coverage, with due...

14 CFR 151.79 - Runway paving: Second runway; wind conditions.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 14 Aeronautics and Space 3 2011-01-01 2011-01-01 false Runway paving: Second runway; wind...: Second runway; wind conditions. (a) All airports. Paving a second runway on the basis of wind conditions... second runway is oriented with the existing paved runway to achieve the maximum wind coverage, with due...

Analysis of vector wind change with respect to time for Vandenberg Air Force Base, California

NASA Technical Reports Server (NTRS)

Adelfang, S. I.

1978-01-01

A statistical analysis of the temporal variability of wind vectors at 1 km altitude intervals from 0 to 27 km altitude taken from a 10-year data sample of twice-daily rawinsode wind measurements over Vandenberg Air Force Base, California is presented.

78 FR 76643 - Atlantic Wind Lease Sale 3 (ATLW3) Commercial Leasing for Wind Power on the Outer Continental...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-12-18

...: Nameplate capacity is the maximum rated electric output, expressed in MW, which the turbines of the wind facility under commercial operations can produce at their rated wind speed as designated by the turbine's...; MMAA104000] Atlantic Wind Lease Sale 3 (ATLW3) Commercial Leasing for Wind Power on the Outer Continental...

Climate and its change over the Tibetan Plateau and its Surroundings in 1963-2015

NASA Astrophysics Data System (ADS)

Ding, J.; Cuo, L.

2017-12-01

Tibetan Plateau and its surroundings (TPS, 23°-43°N, 73°-106°E) lies in the southwest of China and includes Tibet Autonomous Region, Qinghai Province, southern Xinjiang Uygur Autonomous Region, part of Gansu Province, western Sichuan Province, and northern Yunnan Province. The region is of strategic importance in water resources because it is the headwater of ten large rivers that support more than 16 billion population. In this study, we use daily temperature maximum and minimum, precipitation and wind speed in 1963-2015 obtained from Climate Data Center of China Meteorological Administration and Qinghai Meteorological Bureau to investigate extreme climate conditions and their changes over the TPS. The extreme events are selected based on annual extreme values and percentiles. Annual extreme value approach produces one value each year for all variables, which enables us to examine the magnitude of extreme events; whereas percentile approach selects extreme values by setting 95th percentile as thresholds for maximum temperature, precipitation and wind speed, and 5th percentile for minimum temperature. Percentile approach not only enables us to investigate the magnitude but also frequency of the extreme events. Also, Mann-Kendall trend and mutation analysis were applied to analyze the changes in mean and extreme conditions. The results will help us understand more about the extreme events during the past five decades on the TPS and will provide valuable information for the upcoming IPCC reports on climate change.

Coupled effects of wind-storms and drought on tree mortality across 115 forest stands from the Western Alps and the Jura mountains.

PubMed

Csilléry, Katalin; Kunstler, Georges; Courbaud, Benoît; Allard, Denis; Lassègues, Pierre; Haslinger, Klaus; Gardiner, Barry

2017-12-01

Damage due to wind-storms and droughts is increasing in many temperate forests, yet little is known about the long-term roles of these key climatic factors in forest dynamics and in the carbon budget. The objective of this study was to estimate individual and coupled effects of droughts and wind-storms on adult tree mortality across a 31-year period in 115 managed, mixed coniferous forest stands from the Western Alps and the Jura mountains. For each stand, yearly mortality was inferred from management records, yearly drought from interpolated fields of monthly temperature, precipitation and soil water holding capacity, and wind-storms from interpolated fields of daily maximum wind speed. We performed a thorough model selection based on a leave-one-out cross-validation of the time series. We compared different critical wind speeds (CWSs) for damage, wind-storm, and stand variables and statistical models. We found that a model including stand characteristics, drought, and storm strength using a CWS of 25 ms -1 performed the best across most stands. Using this best model, we found that drought increased damage risk only in the most southerly forests, and its effect is generally maintained for up to 2 years. Storm strength increased damage risk in all forests in a relatively uniform way. In some stands, we found positive interaction between drought and storm strength most likely because drought weakens trees, and they became more prone to stem breakage under wind-loading. In other stands, we found negative interaction between drought and storm strength, where excessive rain likely leads to soil water saturation making trees more susceptible to overturning in a wind-storm. Our results stress that temporal data are essential to make valid inferences about ecological impacts of disturbance events, and that making inferences about disturbance agents separately can be of limited validity. Under projected future climatic conditions, the direction and strength of these ecological interactions could also change. © 2017 John Wiley & Sons Ltd.

The shape of the Eiffel Tower

NASA Astrophysics Data System (ADS)

Gallant, Joseph

2002-02-01

The distinctive shape of the Eiffel Tower is based on simple physics and is designed so that the maximum torque created by the wind is balanced by the torque due to the Tower's weight. We use this idea to generate an equation for the shape of the Tower. The solution depends only on the width of the base and the maximum wind pressure. We parametrize the wind pressure and reproduce the shape of the Tower. We also discuss some of the Tower's interesting history and characteristics.

The de-correlation of westerly winds and westerly-wind stress over the Southern Ocean during the Last Glacial Maximum

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Wei; Lu, Jian; Leung, Lai-Yung R.

2015-02-22

This paper investigates the changes of the Southern Westerly Winds (SWW) and Southern Ocean (SO) upwelling between the Last Glacial Maximum (LGM) and preindustrial (PI) in the PMIP3/CMIP5 simulations, highlighting the role of the Antarctic sea ice in modulating the wind stress effect on the ocean. Particularly, a discrepancy may occur between the changes in SWW and westerly wind stress, caused primarily by an equatorward expansion of winter Antarctic sea ice that undermines the wind stress in driving the liquid ocean. Such discrepancy may reflect the LGM condition in reality, in view of that the model simulates this condition hasmore » most credible simulation of modern SWW and Antarctic sea ice. The effect of wind stress on the SO upwelling is further explored via the wind-induced Ekman pumping, which is reduced under the LGM condition in all models, in part by the sea-ice “capping” effect present in the models.« less

A model study of the response of hypoxia to upwelling-favorable wind on the northern Gulf of Mexico shelf

NASA Astrophysics Data System (ADS)

Feng, Yang; Fennel, Katja; Jackson, George A.; DiMarco, Steven F.; Hetland, Robert D.

2014-03-01

The hypoxic region in the northern Gulf of Mexico, one of the largest man-made hypoxic zones in the world, has received extensive scientific study and management interest. A previous statistical study has concluded that in addition to anthropogenic nitrogen loading, the observed hypoxic extent is correlated to the duration of upwelling favorable (westerly) wind without elucidating the underlying mechanism. In this study, we use a three-dimensional, coupled hydrological-biogeochemical model to mechanistically examine how variations of the hypoxic area are related to the duration of upwelling-favorable wind. We performed scenario experiments with different durations of upwelling-favorable wind using realistic winds from summer 2002 (when upwelling-favorable winds were present only for about 1 month) and summer 2009 (when upwelling-favorable conditions started early and persisted for about 2 months). While the maximum simulated hypoxic area is approximately 15,000 km2 in both cases, the evolutions of the hypoxic area and the dates when its maximum extent are reached are different. With an early start of persistently upwelling-favorable wind in 2009, the hypoxic area reached its maximum in early summer and decreased afterwards. By contrast, the hypoxic area was small in early summer of 2002 and peaked during the short period of upwelling-favorable wind in late summer. The model revealed that the wind influences the evolution of the hypoxic area by changing the vertical and horizontal distributions of the low salinity, high chlorophyll water on the shelf.

Current-wave spectra coupling project. Volume I. Hurricane fields and cross sections, surface winds and currents, significant waves and wave spectra for potential OTEC sites: (A) Keahole Point, Hawaii, 100 year hurricane; (B) Punta Tuna, Puerto Rico, 100 year hurricane; (C) New Orleans, Louisiana, 100 year hurricane; (D) West Coast of Florida, 100 year hurricane; and for (E) Hurricane Camille (1969) off Louisiana Coast

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bretschneider, C.L.

1980-06-01

This volume is an extension of and consists of several modifications to the earlier report by Bretschneider (April 1979) on the subject of hurricane design wind, wave and current criteria for the four potential OTEC sites. The 100-year hurricane criteria for the design of OTEC plants is included. The criteria, in addition to the maximum conditions of winds, waves and surface current, include: hurricane fields for wind speed U/sub s/ and significant wave height H/sub s/; hurricane fields for modal wave period f/sub 0//sup -1/ and maximum energy density S/sub max/ of the wave spectrum; the corresponding Ekman wind-driven surfacemore » current V/sub s/; tabulated cross-sections for U/sub s/, H/sub s/, f/sub 0//sup -1/ and S/sub max/ through max U/sub s/ and through max H/sub s/ along traverses at right angles to and along traverses parallel to the forward movement of the hurricane; most probable maximum wave height and the expected corresponding wave period, based on statistical analysis of maximum wave heights from five hurricanes; design wave spectra for maximum U/sub s/ and also maximum H/sub s/, since maximum U/sub s/ and maximum H/sub s/ do not occur simultaneously; the envelope of wave spectra through maximum U/sub s/ and through maximum H/sub s/ along traverses parallel to the forward movement of the hurricane; the above same determinations for Hurricane Camille (1969) as for the four OTEC locations; and alternative methods (suggested) for obtaining design wave spectra from the joint probability distribution functions for wave height and period given by Longuet-Higgins (1975) and C.N.E.X.O. after Arhan, et al (1976).« less

Diurnal, seasonal, and annual trends in tropospheric CO in Southwest London during 2000-2015: Wind sector analysis and comparisons with urban and remote sites

NASA Astrophysics Data System (ADS)

Hernández-Paniagua, Iván Y.; Lowry, David; Clemitshaw, Kevin C.; Palmer, Paul I.; Fisher, Rebecca E.; France, James L.; Mendoza, Alberto; O'Doherty, Simon; Forster, Grant; Lanoisellé, M.; Nisbet, Euan G.

2018-03-01

Ambient carbon monoxide (CO) and meteorological parameters measured at the Egham (EGH) semi-rural site in SW London during 2000-2015 have permitted wind sector analysis of diurnal and seasonal cycles, and interpretation of long-term trends. CO daily amplitudes are used as a proxy for anthropogenic emissions. At EGH, morning and evening peaks in CO arise from the dominant contribution of road transport sources. Smaller amplitudes are observed during weekends than weekdays due to lower combustion emissions, and for mornings compared to evenings due to the timing of the development and break-up of the nocturnal inversion layer or planetary boundary layer (PBL). A wavelet transform revealed that the dominant mode of CO variability is the annual cycle, with apparent winter maxima likely due to increased CO emissions from domestic heating with summer minima ascribed to enhanced dispersion and dilution during the annual maximum of PBL mixing heights. Over the last two decades, both mitigation measures to reduce CO emissions and also a major switch to diesel cars, have accompanied a change at EGH from the dominance of local diurnal sources to a site measuring close to Atlantic background levels in summer months. CO observed in the S and SW wind sectors has declined by 4.7 and 5.9 ppb yr-1 respectively. The EGH CO record shows the highest levels in the early 2000s, with levels in E and calm winds comparable to those recorded at background stations in Greater London. However, since 2012, levels in S-SW sector have become more comparable with Mace Head background except during rush-hour periods. Marked declines in CO are observed during 2000-2008 for the NE, E, SE (London) and calm wind sectors, with the smallest declines observed for the S, SW and W (background) sectors. For the majority of wind sectors, the decline in CO is less noticeable since 2008, with an apparent stabilisation for NE, E and SE after 2009. The EGH CO data record exhibits a similar but slower exponential decay, but from a much lower starting concentration, than do CO data recorded at selected monitoring sites in urban areas in SE England. CO/CO2 residuals determined using hourly averaged datain the diurnal cycle demonstrate a clear decline in CO from 2000 to 2015 during daily periods of increased vehicle traffic, which is consistent with a sustained reduction in CO emissions from the road transport sector.

Secure Automated Microgrid Energy System (SAMES)

DTIC Science & Technology

2016-12-01

with embedded algorithm to share power between each other; • Wind Turbine (WT) Simulator, max 80 kW (4×20 kW), 480 V, Running Wind Generation...Temp, Rain, Wind ........................ 39 Figure 22. Point Loma, Box and Whisker Plot, Hourly Sum of Consumption ............................ 40...Figure 27. Coronado, Consumption vs Average Daily SD Temp, Rainfall, Wind ....................... 44 Figure 28. Naval Base Point Loma, One Line, Solar

Wind Observations of Anomalous Cosmic Rays from Solar Minimum to Maximum

NASA Technical Reports Server (NTRS)

Reames, D. V.; McDonald, F. B.

2003-01-01

We report the first observation near Earth of the time behavior of anomalous cosmic-ray N, O, and Ne ions through the period surrounding the maximum of the solar cycle. These observations were made by the Wind spacecraft during the 1995-2002 period spanning times from solar minimum through solar maximum. Comparison of anomalous and galactic cosmic rays provides a powerful tool for the study of the physics of solar modulation throughout the solar cycle.

Actual daily evapotranspiration estimated from MERIS and AATSR data over the Chinese Loess Plateau

NASA Astrophysics Data System (ADS)

Liu, R.; Wen, J.; Wang, X.; Wang, L.; Tian, H.; Zhang, T. T.; Shi, X. K.; Zhang, J. H.; Lu, Sh. N.

2009-02-01

The Loess Plateau is located in north of China and has a significant impact on the climate and ecosystem evolvement over the East Asian continent. Based on the land surface energy balance theory, the potential of using Medium Resolution Imaging Spectrometer (onboard sensor of the Environmental Satellite) remote sensing data on 7, 11 and 27 June 2005 is explored. The "split-window" algorithm is used to retrieve surface temperature from the Advanced the Along-Track Scanning Radiometer, another onboard senor of the Environmental Satellite. Then the near surface net radiation, sensible heat flux and soil heat flux are estimated by using the developed algorithm. We introduce a simple algorithm to predict the heat flux partitioning between the soil and vegetation. Combining the sunshine hours, air temperature, sunshine duration and wind speed measured by weather stations, a model for estimating daily ET is proposed. The instantaneous ET is also converted to daily value. Comparison of latent heats flux retrieved by remote sensing data with ground observation from eddy covariance flux system during Loess Plateau land surface process field Experiment, the maximum and minimum error of this approach are 10.96% and 4.80% respectively, the cause of the bias is also explored and discussed.

Downscaling of RCM outputs for representative catchments in the Mediterranean region, for the 1951-2100 time-frame

NASA Astrophysics Data System (ADS)

Deidda, Roberto; Marrocu, Marino; Pusceddu, Gabriella; Langousis, Andreas; Mascaro, Giuseppe; Caroletti, Giulio

2013-04-01

Within the activities of the EU FP7 CLIMB project (www.climb-fp7.eu), we developed downscaling procedures to reliably assess climate forcing at hydrologically relevant scales, and applied them to six representative hydrological basins located in the Mediterranean region: Riu Mannu and Noce in Italy, Chiba in Tunisia, Kocaeli in Turkey, Thau in France, and Gaza in Palestine. As a first step towards this aim, we used daily precipitation and temperature data from the gridded E-OBS project (www.ecad.eu/dailydata), as reference fields, to rank 14 Regional Climate Model (RCM) outputs from the ENSEMBLES project (http://ensembles-eu.metoffice.com). The four best performing model outputs were selected, with the additional constraint of maintaining 2 outputs obtained from running different RCMs driven by the same GCM, and 2 runs from the same RCM driven by different GCMs. For these four RCM-GCM model combinations, a set of downscaling techniques were developed and applied, for the period 1951-2100, to variables used in hydrological modeling (i.e. precipitation; mean, maximum and minimum daily temperatures; direct solar radiation, relative humidity, magnitude and direction of surface winds). The quality of the final products is discussed, together with the results obtained after applying a bias reduction procedure to daily temperature and precipitation fields.

Wind-influenced projectile motion

NASA Astrophysics Data System (ADS)

Bernardo, Reginald Christian; Perico Esguerra, Jose; Day Vallejos, Jazmine; Jerard Canda, Jeff

2015-03-01

We solved the wind-influenced projectile motion problem with the same initial and final heights and obtained exact analytical expressions for the shape of the trajectory, range, maximum height, time of flight, time of ascent, and time of descent with the help of the Lambert W function. It turns out that the range and maximum horizontal displacement are not always equal. When launched at a critical angle, the projectile will return to its starting position. It turns out that a launch angle of 90° maximizes the time of flight, time of ascent, time of descent, and maximum height and that the launch angle corresponding to maximum range can be obtained by solving a transcendental equation. Finally, we expressed in a parametric equation the locus of points corresponding to maximum heights for projectiles launched from the ground with the same initial speed in all directions. We used the results to estimate how much a moderate wind can modify a golf ball’s range and suggested other possible applications.

40 CFR 432.15 - New source performance standards (NSPS).

Code of Federal Regulations, 2013 CFR

2013-07-01

... § 432.12(a)(1); and standards for ammonia (as N) are as follows: Performance Standards [NSPS] Regulatedparameter Maximum daily 1 Maximum monthly avg. 1 Ammonia (as N) 0.34 0.17 1 Pounds per 1000 lbs (or g/kg... ammonia (as N) apply: Performance Standards [NSPS] Regulatedparameter Maximum daily 1 Maximum monthly avg...

Intermediate photovoltaic system application experiment operational performance report: Volume 5, for Beverly High School, Beverly, Mass.

NASA Astrophysics Data System (ADS)

1982-02-01

Performance data for the month of January, 1982 for a grid connected photovoltaic power supply in Massachusetts are presented. Data include: monthly and daily electrical energy produced; monthly and daily solar energy incident on the array; monthly and daily array efficiency; plots of energy produced as a function of power level, voltage, cell temperature and time of day; power conditioner input, output and efficiency for each of two individual units and for the total power conditioning system; photovoltaic system efficiency; capacity factor; PV system to load and grid to load energies and corresponding dollar values; daily energy supplies to the load by the PV system; daily PV system availability; monthly and hourly insolation; monthly and hourly temperature average; monthly and hourly wind speed; wind direction distribution; average heating and cooling degree days; number of freeze/thaw cycles; and the data acquisition mode and recording interval plot.

Estimating Tropical Cyclone Surface Wind Field Parameters with the CYGNSS Constellation

NASA Astrophysics Data System (ADS)

Morris, M.; Ruf, C. S.

2016-12-01

A variety of parameters can be used to describe the wind field of a tropical cyclone (TC). Of particular interest to the TC forecasting and research community are the maximum sustained wind speed (VMAX), radius of maximum wind (RMW), 34-, 50-, and 64-kt wind radii, and integrated kinetic energy (IKE). The RMW is the distance separating the storm center and the VMAX position. IKE integrates the square of surface wind speed over the entire storm. These wind field parameters can be estimated from observations made by the Cyclone Global Navigation Satellite System (CYGNSS) constellation. The CYGNSS constellation consists of eight small satellites in a 35-degree inclination circular orbit. These satellites will be operating in standard science mode by the 2017 Atlantic TC season. CYGNSS will provide estimates of ocean surface wind speed under all precipitating conditions with high temporal and spatial sampling in the tropics. TC wind field data products can be derived from the level-2 CYGNSS wind speed product. CYGNSS-based TC wind field science data products are developed and tested in this paper. Performance of these products is validated using a mission simulator prelaunch.

Abundance of adult saugers across the Wind River watershed, Wyoming

USGS Publications Warehouse

Amadio, C.J.; Hubert, W.A.; Johnson, K.; Oberlie, D.; Dufek, D.

2006-01-01

The abundance of adult saugers Sander canadensis was estimated over 179 km of continuous lotic habitat across a watershed on the western periphery of their natural distribution in Wyoming. Three-pass depletions with raft-mounted electrofishing gear were conducted in 283 pools and runs among 19 representative reaches totaling 51 km during the late summer and fall of 2002. From 2 to 239 saugers were estimated to occur among the 19 reaches of 1.6-3.8 km in length. The estimates were extrapolated to a total population estimate (mean ?? 95% confidence interval) of 4,115 ?? 308 adult saugers over 179 km of lotie habitat. Substantial variation in mean density (range = 1.0-32.5 fish/ha) and mean biomass (range = 0.5-16.8 kg/ha) of adult saugers in pools and runs was observed among the study reaches. Mean density and biomass were highest in river reaches with pools and runs that had maximum depths of more than 1 m, mean daily summer water temperatures exceeding 20??C, and alkalinity exceeding 130 mg/L. No saugers were captured in the 39 pools or runs with maximum water depths of 0.6 m or less. Multiple-regression analysis and the information-theoretic approach were used to identify watershed-scale and instream habitat features accounting for the variation in biomass among the 244 pools and runs across the watershed with maximum depths greater than 0.6 m. Sauger biomass was greater in pools than in runs and increased as mean daily summer water temperature, maximum depth, and mean summer alkalinity increased and as dominant substrate size decreased. This study provides an estimate of adult sauger abundance and identifies habitat features associated with variation in their density and biomass across a watershed, factors important to the management of both populations and habitat. ?? Copyright by the American Fisheries Society 2006.

NCEP Model Verification

Science.gov Websites

daily and monthly statistics. The daily and monthly verification processing is broken down into three geopotential height and wind using daily statistics from the gdas1 prepbufr files at 00Z; 06Z; 12Z; and, 18Z Hemisphere; the Southern Hemisphere; and the Tropics. Daily S1 scores from the GFS and NAM models are

Intensity of Cold Water and its effects on marine culturing farms along the southeast coast of Korea

NASA Astrophysics Data System (ADS)

Lee, Yong-Hwa; Shim, JeongHee; Choi, Yang-Ho; Kim, Sang-Woo; Shim, Jeong-Min

2017-04-01

To understand the characteristics and strength of the cold water that has caused damage to marine-culturing farms around Guryongpo, in the southeast coast of Korea, surface and water column temperatures were collected from temperature loggers deployed at a sea squirt farm during August-November 2007 and from a Real-time Information System for aquaculture environments operated by NIFS during July-August 2015 and 2016. During the study period, surface temperature at Guryongpo decreased sharply when south/southwestern winds prevailed (the 18-26th of August and 20-22nd of September 2007 and the 13-15th of July 2015) as a result of upwelling. However, the deep-water (20-30m) temperature increased during periods of strong north/northeasterly winds (the 5-7th and 16-18th of September 2007) as a result of downwelling. Among the cold water events that occurred at Guryongpo, the mass death of cultured fish followed strong cold water events (surface temperatures below 10℃) that were caused by more than two days of successive south/southeastern winds with maximum speeds higher than 5 m/s. A Cold Water Index (CWI) was defined and calculated using maximum wind speed and direction as measured daily at Pohang Meteorological Observatory. When the average CWI over two days (CWI2d) was higher than 100, mass fish mortality occurred. The four-day average CWI (CWI4d) showed a high negative correlation with surface temperature from July-August in the Guryongpo area (R2 = 0.5), suggesting that CWI is a good index for predicting strong cold water events and massive mortality. In October 2007, the sea temperature at a depth of 30 m showed a high fluctuation that ranged from 7-23℃, with frequency and spectrum coinciding with tidal levels at Ulsan, affected by the North Korean Cold Current. If temperature variations at the depth of fish cages also regularly fluctuate within this range, damage may be caused to the fish industry along the southeast coast of Korea.

Evidence of gravity wave-tidal interaction observed near the summer mesopause at Poker Flat, Alaska

NASA Technical Reports Server (NTRS)

Wang, Ding-Yi; Fritts, David C.

1991-01-01

An analysis of gravity wave-tidal interaction observed near the mesopause by the MST radar at Poker Flat in July of 1986 is presented. The observations revealed daily mean wind maxima of about 60 m/sec westward and 20 m/sec southward with daily mean momentum fluxes, contributed by gravity waves with periods less than 1 hour of 4-5 sq m/sec sq eastward and 1-2 sq m/sec sq northward. Considerable hourly height variability was found to exist for both winds and momentum fluxes. A significant modulation of the fluxes by tidal winds was observed, characterized by out-of-phase correlations over a number of heights.

Continuous atmospheric CO2 and its δ13C measurements (2012-2014) at Environment Research Station Schneefernerhaus, Germany

NASA Astrophysics Data System (ADS)

Ghasemifard, Homa; Yuan, Ye; Luepke, Marvin; Chen, Jia; Ries, Ludwig; Menzel, Annette

2017-04-01

This study presents continuous measurement of atmospheric CO2 and δ13C by PICARRO Wavelength-Scanned Cavity Ring Down Spectrometer (WS-CRDS, G1101- i) for a period of two and a half years at the remote Global Atmosphere Watch (GAW) site Environment Research Station Schneefernerhaus (UFS, Germany, 2650 m a.s.l). Both water vapor and methane concentration show spectroscopic interferences with CO2 and δ13C in this measuring device. Without analyzer upgrade to account automatically for these effects, we present approaches for corrections for δ13C and CO2 mixing ratio as well as test the precision and stability of the device. The mean annual cycle from May 2012 to November 2014 exhibited peak-to-peak amplitudes of 13.34 ppm for CO2 and 1.82 ‰ for δ13C. Regarding CO2 mean diurnal cycle, daily maxima occurred around noon and daily minima in the afternoon. However, clear seasonal differences can be observed. For δ13C, the minimum of diurnal cycle occurred in the morning and the maximum in the afternoon with peak-to peak amplitude of around 0.4 ‰ in summer, 0.2 ‰ both in spring and autumn and no diurnal cycle in winter. HYSPLIT (Hybrid Single Particle Lagrangian Integrated Trajectory Model) was used to calculate 96 hours backward trajectories reaching at UFS with an altitude of 1500 m a.g.l to characterize the origin of air masses transported to the site. Trajectories clustering resulted in five major directions, which were from west (41.2 %), southwest (14.8 %), northwest (19.7 %), southeast (12.5 %) and northeast (11.8 %). Wind speed and wind direction showed clear influences on CO2 mixing ratio. Higher levels of CO2 mixing ratio were measured at wind speeds higher than 6 m s-1 from the northwest, northeast and southwest. The research is financed by the Bavarian State Ministry of the Environment and Consumer Protection.

Relevance analysis and short-term prediction of PM2.5 concentrations in Beijing based on multi-source data

NASA Astrophysics Data System (ADS)

Ni, X. Y.; Huang, H.; Du, W. P.

2017-02-01

The PM2.5 problem is proving to be a major public crisis and is of great public-concern requiring an urgent response. Information about, and prediction of PM2.5 from the perspective of atmospheric dynamic theory is still limited due to the complexity of the formation and development of PM2.5. In this paper, we attempted to realize the relevance analysis and short-term prediction of PM2.5 concentrations in Beijing, China, using multi-source data mining. A correlation analysis model of PM2.5 to physical data (meteorological data, including regional average rainfall, daily mean temperature, average relative humidity, average wind speed, maximum wind speed, and other pollutant concentration data, including CO, NO2, SO2, PM10) and social media data (microblog data) was proposed, based on the Multivariate Statistical Analysis method. The study found that during these factors, the value of average wind speed, the concentrations of CO, NO2, PM10, and the daily number of microblog entries with key words 'Beijing; Air pollution' show high mathematical correlation with PM2.5 concentrations. The correlation analysis was further studied based on a big data's machine learning model- Back Propagation Neural Network (hereinafter referred to as BPNN) model. It was found that the BPNN method performs better in correlation mining. Finally, an Autoregressive Integrated Moving Average (hereinafter referred to as ARIMA) Time Series model was applied in this paper to explore the prediction of PM2.5 in the short-term time series. The predicted results were in good agreement with the observed data. This study is useful for helping realize real-time monitoring, analysis and pre-warning of PM2.5 and it also helps to broaden the application of big data and the multi-source data mining methods.

A study of the correlation between dengue and weather in Kandy City, Sri Lanka (2003 -2012) and lessons learned.

PubMed

Ehelepola, N D B; Ariyaratne, Kusalika; Buddhadasa, W M N P; Ratnayake, Sunil; Wickramasinghe, Malani

2015-09-24

Weather variables affect dengue transmission. This study aimed to identify a dengue weather correlation pattern in Kandy, Sri Lanka, compare the results with results of similar studies, and establish ways for better control and prevention of dengue. We collected data on reported dengue cases in Kandy and mid-year population data from 2003 to 2012, and calculated weekly incidences. We obtained daily weather data from two weather stations and converted it into weekly data. We studied correlation patterns between dengue incidence and weather variables using the wavelet time series analysis, and then calculated cross-correlation coefficients to find magnitudes of correlations. We found a positive correlation between dengue incidence and rainfall in millimeters, the number of rainy and wet days, the minimum temperature, and the night and daytime, as well as average, humidity, mostly with a five- to seven-week lag. Additionally, we found correlations between dengue incidence and maximum and average temperatures, hours of sunshine, and wind, with longer lag periods. Dengue incidences showed a negative correlation with wind run. Our results showed that rainfall, temperature, humidity, hours of sunshine, and wind are correlated with local dengue incidence. We have suggested ways to improve dengue management routines and to control it in these times of global warming. We also noticed that the results of dengue weather correlation studies can vary depending on the data analysis.

Barriers to movement: Modelling energetic costs of avoiding marine wind farms amongst breeding seabirds.

PubMed

Masden, Elizabeth A; Haydon, Daniel T; Fox, Anthony D; Furness, Robert W

2010-07-01

Proposals for wind farms in areas of known importance for breeding seabirds highlight the need to understand the impacts of these structures. Using an energetic modelling approach, we examine the effects of wind farms as barriers to movement on seabirds of differing morphology. Additional costs, expressed in relation to typical daily energetic expenditures, were highest per unit flight for seabirds with high wing loadings, such as cormorants. Taking species-specific differences into account, costs were relatively higher in terns, due to the high daily frequency of foraging flights. For all species, costs of extra flight to avoid a wind farm appear much less than those imposed by low food abundance or adverse weather, although such costs will be additive to these. We conclude that adopting a species-specific approach is essential when assessing the impacts of wind farms on breeding seabird populations, to fully anticipate the effects of avoidance flights. Copyright 2010 Elsevier Ltd. All rights reserved.

Calculation of wind speeds required to damage or destroy buildings

NASA Astrophysics Data System (ADS)

Liu, Henry

Determination of wind speeds required to damage or destroy a building is important not only for the improvement of building design and construction but also for the estimation of wind speeds in tornadoes and other damaging storms. For instance, since 1973 the U.S. National Weather Service has been using the well-known Fujita scale (F scale) to estimate the maximum wind speeds of tornadoes [Fujita, 1981]. The F scale classifies tornadoes into 13 numbers, F-0 through F-12. The wind speed (maximum gust speed) associated with each F number is given in Table 1. Note that F-6 through F-12 are for wind speeds between 319 mi/hr (mph) and the sonic velocity (approximately 760 mph; 1 mph = 1.6 km/kr). However, since no tornadoes have been classified to exceed F-5, the F-6 through F-12 categories have no practical meaning [Fujita, 1981].

Power Maximization Control of Variable Speed Wind Generation System Using Permanent Magnet Synchronous Generator

NASA Astrophysics Data System (ADS)

Morimoto, Shigeo; Nakamura, Tomohiko; Takeda, Yoji

This paper proposes the sensorless output power maximization control of the wind generation system. A permanent magnet synchronous generator (PMSG) is used as a variable speed generator in the proposed system. The generator torque is suitably controlled according to the generator speed and thus the power from a wind turbine settles down on the maximum power point by the proposed MPPT control method, where the information of wind velocity is not required. Moreover, the maximum available generated power is obtained by the optimum current vector control. The current vector of PMSG is optimally controlled according to the generator speed and the required torque in order to minimize the losses of PMSG considering the voltage and current constraints. The proposed wind power generation system can be achieved without mechanical sensors such as a wind velocity detector and a position sensor. Several experimental results show the effectiveness of the proposed control method.

Curios relationship revealed by looking at long term data sets-The geometry and allometric scaling of diel xylem sap flux in tropical trees.

PubMed

Kunert, Norbert

2016-10-20

Daily xylem sap flux values (daily J s ) and maximum xylem sap flux values (max J s ) from 125 tropical trees from different study sites in the Neotropics were compared. A cross species and study site relationship was found between daily and maximum values. The relationship can be expressed as daily J s =6.5x max J s . The geometrical relationship between the maximum xylem sap flux of a given day is thus defining the daily xylem sap flux rates. Assuming a bell-shaped diurnal sap flux course and a relatively constant day length the maximum xylem sap flux is the only possible changing variable to define daily fluxes. Further, this relationship is showing the inertia of the xylem sap flux as a physical object and highlights the delayed response to environmental changes and its subsequent inevitable susceptibility under environmental stress to hydraulic failure. Copyright © 2016 Elsevier GmbH. All rights reserved.

Influence of Different Solar Drivers on the Winds in the Middle Atmosphere and on Geomagnetic Disturbances

DTIC Science & Technology

2007-05-18

number and intensity are highest in sunspot maximum. CME’s are considered the sources of the most intense geomagnetic storms (Gonzalez et al., 2002... storm . High speed solar wind The geomagnetic activity during the declining phase of the solar cycle can be even higher that at sunspot maximum. In...characteristic “calm before the storm ” – the decrease a couple of days before the maximum disturbance – in the case of high speed streams (Borovsky and

Benchmark Data Set for Wheat Growth Models: Field Experiments and AgMIP Multi-Model Simulations.

NASA Technical Reports Server (NTRS)

Asseng, S.; Ewert, F.; Martre, P.; Rosenzweig, C.; Jones, J. W.; Hatfield, J. L.; Ruane, A. C.; Boote, K. J.; Thorburn, P.J.; Rotter, R. P.

2015-01-01

The data set includes a current representative management treatment from detailed, quality-tested sentinel field experiments with wheat from four contrasting environments including Australia, The Netherlands, India and Argentina. Measurements include local daily climate data (solar radiation, maximum and minimum temperature, precipitation, surface wind, dew point temperature, relative humidity, and vapor pressure), soil characteristics, frequent growth, nitrogen in crop and soil, crop and soil water and yield components. Simulations include results from 27 wheat models and a sensitivity analysis with 26 models and 30 years (1981-2010) for each location, for elevated atmospheric CO2 and temperature changes, a heat stress sensitivity analysis at anthesis, and a sensitivity analysis with soil and crop management variations and a Global Climate Model end-century scenario.

Canadian crop calendars in support of the early warning project

NASA Technical Reports Server (NTRS)

Trenchard, M. H.; Hodges, T. (Principal Investigator)

1980-01-01

The Canadian crop calendars for LACIE are presented. Long term monthly averages of daily maximum and daily minimum temperatures for subregions of provinces were used to simulate normal daily maximum and minimum temperatures. The Robertson (1968) spring wheat and Williams (1974) spring barley phenology models were run using the simulated daily temperatures and daylengths for appropriate latitudes. Simulated daily temperatures and phenology model outputs for spring wheat and spring barley are given.

Wind extremes in the North Sea basin under climate change: an ensemble study of 12 CMIP5 GCMs

NASA Astrophysics Data System (ADS)

de Winter, R.; Ruessink, G.; Sterl, A.

2012-12-01

Coastal safety may be influenced by climate change, as changes in extreme surge levels and wave extremes may increase the vulnerability of dunes and other coastal defenses. In the North Sea, an area already prone to severe flooding, these high surge levels and waves are generated by severe wind speeds during storm events. As a result of the geometry of the North Sea, not only the maximum wind speed is relevant, but also wind direction. Analyzing changes in a changing climate implies that several uncertainties need to be taken into account. First, there is the uncertainty in climate experiments, which represents the possible development of the emission of greenhouse gases. Second, there is uncertainty between the climate models that are used to analyze the effect of different climate experiments. The third uncertainty is the natural variability of the climate. When this system variability is large, small trends will be difficult to detect. The natural variability results in statistical uncertainty, especially for events with high return values. We addressed the first two types of uncertainties for extreme wind conditions in the North Sea using 12 CMIP5 GCMs. To evaluate the differences between the climate experiments, two climate experiments (rcp4.5 and rcp8.5) from 2050-2100 are compared with historical runs, running from 1950-2000. Rcp4.5 is considered to be a middle climate experiment and rcp8.5 represents high-end climate scenarios. The projections of the 12 GCMs for a given scenario illustrate model uncertainty. We focus on the North Sea basin, because changes in wind conditions could have a large impact on safety of the densely populated North Sea coast, an area that has already a high exposure to flooding. Our results show that, consistent with ERA-Interim results, the annual maximum wind speed in the historical run demonstrates large interannual variability. For the North Sea, the annual maximum wind speed is not projected to change in either rcp4.5 or rcp8.5. In fact, the differences in the 12 GCMs are larger than the difference between the three experiments. Furthermore, our results show that, the variation in direction of annual maximum wind speed is large and this precludes a firm statement on climate-change induced changes in these directions. Nonetheless, most models indicate a decrease in annual maximum wind speed from south-eastern directions and an increase from south-western and western directions. This might be caused by a poleward shift of the storm track. The amount of wind from north-west and north-north-west, wind directions that are responsible for the development of extreme storm surges in the southern part of the North Sea, are not projected to change. However, North Sea coasts that have the longest fetch for western direction, e.g. the German Bight, may encounter more often high storm surge levels and extreme waves when the annual maximum wind will indeed be more often from western direction.

Wind Power Generation Design Considerations.

DTIC Science & Technology

1984-12-01

DISTRIBUTION 4 I o ....................................... . . . e . * * TABLES Number Page I Wind Turbine Characteristics II 0- 2 Maximum Economic Life II 3...Ratio of Blade Tip Speed to Wind Speed 10 4 Interference with Microwave and TV Reception by Wind Turbines 13 5 Typical Flow Patterns Over Two...18 * 12 Annual Mean Wind Power Density 21 5 FIGURES (Cont’d) Number Page 13 Wind - Turbine /Generator Types Currently Being Tested on Utility Sites 22 14

78 FR 44150 - Atlantic Wind Lease Sale 1 (ATLW1) Commercial Leasing for Wind Power on the Outer Continental...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-07-23

... for the siting of two 6-megawatt (MW) wind turbines for demonstration and research purposes. The... the maximum rated electric output, expressed in MW, which the turbines of the wind farm facility under commercial operations can produce at their rated wind speed as designated by the turbine's manufacturer. The...

Associations between weather conditions during the first 45 days after feedlot arrival and daily respiratory disease risks in autumn-placed feeder cattle in the United States.

PubMed

Cernicchiaro, N; Renter, D G; White, B J; Babcock, A H; Fox, J T

2012-04-01

Data on associations between weather conditions and bovine respiratory disease (BRD) morbidity in autumn-placed feedlot cattle are sparse. The goal of our study was to quantify how different weather variables during corresponding lag periods (considering up to 7 d before the day of disease measure) were associated with daily BRD incidence during the first 45 d of the feeding period based on a post hoc analysis of existing feedlot operational data. Our study population included 1,904 cohorts of feeder cattle (representing 288,388 total cattle) that arrived to 9 US commercial feedlots during September to November in 2005 to 2007. There were 24,947 total cases of initial respiratory disease (animals diagnosed by the feedlots with BRD and subsequently treated with an antimicrobial). The mean number of BRD cases during the study period (the first 45 d after arrival) was 0.3 cases per day per cohort (range = 0 to 53.0), and cumulative BRD incidence risks ranged from 0 to 36% within cattle cohorts. Data were analyzed with a multivariable mixed-effects binomial regression model. Results indicate that several weather factors (maximum wind speed, mean wind chill temperature, and temperature change in different lag periods) were significantly (P < 0.05) associated with increased daily BRD incidence, but their effects depended on several cattle demographic factors (month of arrival, BRD risk code, BW class, and cohort size). In addition, month and year of arrival, sex of the cohort, days on feed, mean BW of the cohort at entry, predicted BRD risk designation of the cohort (high or low risk), cohort size, and the interaction between BRD risk code and arrival year were significantly (P < 0.05) associated with daily BRD incidence. Our results demonstrate that weather conditions are significantly associated with BRD risk in populations of feedlot cattle. Defining these conditions for specific cattle populations may enable cattle health managers to predict and potentially manage these effects more effectively; further, estimates of effects may contribute to the development of quantitative predictive models for this important disease syndrome.

Demagnetization using a determined estimated magnetic state

DOEpatents

Denis, Ronald J; Makowski, Nathanael J

2015-01-13

A method for demagnetizing comprising positioning a core within the electromagnetic field generated by a first winding until the generated first electrical current is not substantially increasing, thereby determining a saturation current. A second voltage, having the opposite polarity, is then applied across the first winding until the generated second electrical current is approximately equal to the magnitude of the determined saturation current. The maximum magnetic flux within the core is then determined using the voltage across said first winding and the second current. A third voltage, having the opposite polarity, is then applied across the first winding until the core has a magnetic flux equal to approximately half of the determined maximum magnetic flux within the core.

Transient response to three-phase faults on a wind turbine generator. Ph.D. Thesis - Toledo Univ.

NASA Technical Reports Server (NTRS)

Gilbert, L. J.

1978-01-01

In order to obtain a measure of its responses to short circuits a large horizontal axis wind turbine generator was modeled and its performance was simulated on a digital computer. Simulation of short circuit faults on the synchronous alternator of a wind turbine generator, without resort to the classical assumptions generally made for that analysis, indicates that maximum clearing times for the system tied to an infinite bus are longer than the typical clearing times for equivalent capacity conventional machines. Also, maximum clearing times are independent of tower shadow and wind shear. Variation of circuit conditions produce the modifications in the transient response predicted by analysis.

Distribution Strategies for Solar and Wind Renewables in NW Europe

NASA Astrophysics Data System (ADS)

Smedley, Andrew; Webb, Ann

2017-04-01

Whilst the UNFCCC Paris Agreement Climate change was ratified in November, 2016 saw the highest global temperature anomaly on record at 1.2°C above pre-industrial levels. As such there is urgent need to reduce CO2 emissions by a move away from fossil fuels and towards renewable electricity energy technologies. As the principal renewable technologies of solar PV and wind turbines contribute an increasing fraction to the electricity grid, questions of cumulative intermittency and the large-scale geographic distribution of each technology need to be addressed. In this study our initial emphasis is on a calculation of a relatively high spatial resolution (0.1° × 0.1°) daily gridded dataset of solar irradiance data, over a 10 year period (2006-2015). This is achieved by coupling established sources of satellite data (MODIS SSF level2 instantaneous footprint data) to a well-validated radiative transfer model, here LibRadTran. We utilise both a morning and afternoon field for two cloud layers (optical depth and cloud fraction) interpolated to hourly grids, together with aerosol optical depth, topographic height and solar zenith angle. These input parameters are passed to a 5-D LUT of LibRadTran results to construct hourly estimates of the solar irradiance field, which is then integrated to a daily total. For the daily wind resource we rely on the 6 hourly height-adjusted ECMWF ERA-Interim reanalysis wind fields, but separated into onshore, offshore and deep water components. From these datasets of the solar and wind resources we construct 22 different distribution strategies for solar PV and wind turbines based on the long-term availability of each resource. Combining these distributions with the original daily gridded datasets enables each distribution strategy to be then assessed in terms of the day-to-day variability, the installed capacity required to maintain a baseline supply, and the relative proportions of each technology. Notably for the NW European area considered we find that distribution strategies that only deploy renewables in regions with the highest annual mean irradiance or wind resource, also minimise the total required installed capacity and typically exhibit the smallest output range. Further in the majority of strategies we find that the onshore and offshore wind resource fractions fall to zero with the wind contribution being fully composed of deep water installations. Only as the strategy is to increasingly concentrate each technology in areas with the highest annual mean resource do firstly offshore, and then onshore wind, contribute.

Sources of Geomagnetic Activity during Nearly Three Solar Cycles (1972-2000)

NASA Technical Reports Server (NTRS)

Richardson, I. G.; Cane, H. V.; Cliver, E. W.; White, Nicholas E. (Technical Monitor)

2002-01-01

We examine the contributions of the principal solar wind components (corotating highspeed streams, slow solar wind, and transient structures, i.e., interplanetary coronal mass ejections (CMEs), shocks, and postshock flows) to averages of the aa geomagnetic index and the interplanetary magnetic field (IMF) strength in 1972-2000 during nearly three solar cycles. A prime motivation is to understand the influence of solar cycle variations in solar wind structure on long-term (e.g., approximately annual) averages of these parameters. We show that high-speed streams account for approximately two-thirds of long-term aa averages at solar minimum, while at solar maximum, structures associated with transients make the largest contribution (approx. 50%), though contributions from streams and slow solar wind continue to be present. Similarly, high-speed streams are the principal contributor (approx. 55%) to solar minimum averages of the IMF, while transient-related structures are the leading contributor (approx. 40%) at solar maximum. These differences between solar maximum and minimum reflect the changing structure of the near-ecliptic solar wind during the solar cycle. For minimum periods, the Earth is embedded in high-speed streams approx. 55% of the time versus approx. 35% for slow solar wind and approx. 10% for CME-associated structures, while at solar maximum, typical percentages are as follows: high-speed streams approx. 35%, slow solar wind approx. 30%, and CME-associated approx. 35%. These compositions show little cycle-to-cycle variation, at least for the interval considered in this paper. Despite the change in the occurrences of different types of solar wind over the solar cycle (and less significant changes from cycle to cycle), overall, variations in the averages of the aa index and IMF closely follow those in corotating streams. Considering solar cycle averages, we show that high-speed streams account for approx. 44%, approx. 48%, and approx. 40% of the solar wind composition, aa, and the IMF strength, respectively, with corresponding figures of approx. 22%, approx. 32%, and approx. 25% for CME-related structures, and approx. 33%, approx. 19%, and approx. 33% for slow solar wind.

Vandenberg Air Force Base Upper Level Wind Launch Weather Constraints

NASA Technical Reports Server (NTRS)

Shafer, Jaclyn A.; Wheeler, Mark M.

2012-01-01

The 30th Operational Support Squadron Weather Flight (30 OSSWF) provides comprehensive weather services to the space program at Vandenberg Air Force Base (VAFB) in California. One of their responsibilities is to monitor upper-level winds to ensure safe launch operations of the Minuteman III ballistic missile. The 30 OSSWF tasked the Applied Meteorology Unit (AMU) to analyze VAFB sounding data with the goal of determining the probability of violating (PoV) their upper-level thresholds for wind speed and shear constraints specific to this launch vehicle, and to develop a tool that will calculate the PoV of each constraint on the day of launch. In order to calculate the probability of exceeding each constraint, the AMU collected and analyzed historical data from VAFB. The historical sounding data were retrieved from the National Oceanic and Atmospheric Administration Earth System Research Laboratory archive for the years 1994-2011 and then stratified into four sub-seasons: January-March, April-June, July-September, and October-December. The maximum wind speed and 1000-ft shear values for each sounding in each subseason were determined. To accurately calculate the PoV, the AMU determined the theoretical distributions that best fit the maximum wind speed and maximum shear datasets. Ultimately it was discovered that the maximum wind speeds follow a Gaussian distribution while the maximum shear values follow a lognormal distribution. These results were applied when calculating the averages and standard deviations needed for the historical and real-time PoV calculations. In addition to the requirements outlined in the original task plan, the AMU also included forecast sounding data from the Rapid Refresh model. This information provides further insight for the launch weather officers (LWOs) when determining if a wind constraint violation will occur over the next few hours on day of launch. The interactive graphical user interface (GUI) for this project was developed in Microsoft Excel using Visual Basic for Applications. The GUI displays the critical sounding data easily and quickly for the LWOs on day of launch. This tool will replace the existing one used by the 30 OSSWF, assist the LWOs in determining the probability of exceeding specific wind threshold values, and help to improve the overall upper winds forecast for the launch customer.

The Sinuosity of Atmospheric Circulation over North America and its Relationship to Arctic Climate Change and Extreme Events

NASA Astrophysics Data System (ADS)

Vavrus, S. J.; Wang, F.; Martin, J. E.; Francis, J. A.

2015-12-01

Recent research has suggested a relationship between mid-latitude weather and Arctic amplification (AA) of global climate change via a slower and wavier extratropical circulation inducing more extreme events. To test this hypothesis and to quantify the waviness of the extratropical flow, we apply a novel application of the geomorphological concept of sinuosity (SIN) over greater North America. SIN is defined as the ratio of the curvilinear length of a geopotential height contour to the perimeter of its equivalent latitude, where the contour and the equivalent latitude enclose the same area. We use 500 hPa daily heights from reanalysis and model simulations to calculate past and future SIN. The circulation exhibits a distinct annual cycle of maximum SIN (waviness) in summer and a minimum in winter, inversely related to the annual cycle of zonal wind speed. Positive trends in SIN have emerged in recent decades during winter and summer at several latitude bands, generally collocated with negative trends in zonal wind speeds. High values of SIN coincide with many prominent extreme-weather events, including Superstorm Sandy. RCP8.5 simulations (2006-2100) project a dipole pattern of zonal wind changes that varies seasonally. In winter, AA causes inflated heights over the Arctic relative to mid-latitudes and an associated weakening (strengthening) of the westerlies north (south) of 40N. The AA signal in summer is strongest over upper-latitude land, promoting localized atmospheric ridging aloft with lighter westerlies to the south and stronger zonal winds to the north. The changes in wind speeds in both seasons are inversely correlated with SIN, indicating a wavier circulation where the flow weakens. In summer the lighter winds over much of the U. S. resemble circulation anomalies observed during extreme summer heat and drought. Such changes may be linked to enhanced heating of upper-latitude land surfaces caused by earlier snow melt during spring-summer.

Analysis of Change in the Wind Speed Ratio according to Apartment Layout and Solutions

PubMed Central

Hyung, Won-gil; Kim, Young-Moon; You, Ki-Pyo

2014-01-01

Apartment complexes in various forms are built in downtown areas. The arrangement of an apartment complex has great influence on the wind flow inside it. There are issues of residents' walking due to gust occurrence within apartment complexes, problems with pollutant emission due to airflow congestion, and heat island and cool island phenomena in apartment complexes. Currently, the forms of internal arrangements of apartment complexes are divided into the flat type and the tower type. In the present study, a wind tunnel experiment and computational fluid dynamics (CFD) simulation were performed with respect to internal wind flows in different apartment arrangement forms. Findings of the wind tunnel experiment showed that the internal form and arrangement of an apartment complex had significant influence on its internal airflow. The wind velocity of the buildings increased by 80% at maximum due to the proximity effects between the buildings. The CFD simulation for relaxing such wind flows indicated that the wind velocity reduced by 40% or more at maximum when the paths between the lateral sides of the buildings were extended. PMID:24688430

Analysis of change in the wind speed ratio according to apartment layout and solutions.

PubMed

Hyung, Won-gil; Kim, Young-Moon; You, Ki-Pyo

2014-01-01

Apartment complexes in various forms are built in downtown areas. The arrangement of an apartment complex has great influence on the wind flow inside it. There are issues of residents' walking due to gust occurrence within apartment complexes, problems with pollutant emission due to airflow congestion, and heat island and cool island phenomena in apartment complexes. Currently, the forms of internal arrangements of apartment complexes are divided into the flat type and the tower type. In the present study, a wind tunnel experiment and computational fluid dynamics (CFD) simulation were performed with respect to internal wind flows in different apartment arrangement forms. Findings of the wind tunnel experiment showed that the internal form and arrangement of an apartment complex had significant influence on its internal airflow. The wind velocity of the buildings increased by 80% at maximum due to the proximity effects between the buildings. The CFD simulation for relaxing such wind flows indicated that the wind velocity reduced by 40% or more at maximum when the paths between the lateral sides of the buildings were extended.

[Effects of synoptic type on surface ozone pollution in Beijing].

PubMed

Tang, Gui-qian; Li, Xin; Wang, Xiao-ke; Xin, Jin-yuan; Hu, Bo; Wang, Li-li; Ren, Yu-fen; Wang, Yue-Si

2010-03-01

Ozone (O), influenced by meteorological factors, is a primary gaseous photochemical pollutant during summer to fall in Beijing' s urban ambient. Continuous monitoring during July to September in 2008 was carried out at four sites in Beijing. Analyzed with synoptic type, the results show that the ratios of pre-low cylonic (mainly Mongolia cyclone) and pre-high anticylonic to total weather conditions are about 42% and 20%, illustrating the high-and low-ozone episodes, respectively. At the pre-low cylonic conditions, high temperature, low humidity, mountain and valley winds caused by local circulation induce average hourly maximum ozone concentration (volume fraction) up to 102.2 x 10(-9), negative correlated with atmospheric pressure with a slope of -3.4 x 10(-9) Pa(-1). The time of mountain wind changed to valley wind dominates the diurnal time of maximum ozone, generally around 14:00. At the pre-high anticylonic conditions, low temperature, high humidity and systematic north wind induce average hourly maximum ozone concentration (volume fraction) only 49.3 x 10(-9), the diurnal time of maximum ozone is deferred by continuous north wind till about 16:00. The consistency of photochemical pollution in Beijing region shows that good correlation exists between synoptic type and ozone concentration. Therefore, getting an eye on the structure and evolution of synoptic type is of great significances for forecasting the photochemical pollution.

Monte Carlo studies of ocean wind vector measurements by SCATT: Objective criteria and maximum likelihood estimates for removal of aliases, and effects of cell size on accuracy of vector winds

NASA Technical Reports Server (NTRS)

Pierson, W. J.

1982-01-01

The scatterometer on the National Oceanic Satellite System (NOSS) is studied by means of Monte Carlo techniques so as to determine the effect of two additional antennas for alias (or ambiguity) removal by means of an objective criteria technique and a normalized maximum likelihood estimator. Cells nominally 10 km by 10 km, 10 km by 50 km, and 50 km by 50 km are simulated for winds of 4, 8, 12 and 24 m/s and incidence angles of 29, 39, 47, and 53.5 deg for 15 deg changes in direction. The normalized maximum likelihood estimate (MLE) is correct a large part of the time, but the objective criterion technique is recommended as a reserve, and more quickly computed, procedure. Both methods for alias removal depend on the differences in the present model function at upwind and downwind. For 10 km by 10 km cells, it is found that the MLE method introduces a correlation between wind speed errors and aspect angle (wind direction) errors that can be as high as 0.8 or 0.9 and that the wind direction errors are unacceptably large, compared to those obtained for the SASS for similar assumptions.

Using sinuosity to measure the waviness of the extratropical circulation under climate change

NASA Astrophysics Data System (ADS)

Wang, F.; Vavrus, S. J.; Martin, J. E.; Francis, J. A.

2014-12-01

Extreme weather events, such as heat and cold waves, droughts, and floods, have substantial social and economic impacts. Whether these extreme events are related to one of the prominent components of climate change --- Arctic Amplification (AA)--- is controversial. The hypothesis proposed by Francis and Vavrus (2012) is that a reduced meridional temperature gradient owing to AA will cause a weaker and wavier extratropical circulation, which will result in slower progression of weather systems and more atmospheric blocking events. To test this hypothesis we borrow the concept of "sinuosity" from geomorphology to measure the waviness of the boreal extratropical circulation. As applied here, sinuosity is defined as the ratio of the curvilinear length of a circumhemispheric geopotential height contour to the perimeter of its equivalent latitude, where the contour and the equivalent latitude enclose the same area. We use 500hPa daily geopotential heights from NCEP/NCAR Reanalysis and from the CESM climate model's historical and RCP8.5 greenhouse simulations to calculate sinuosity. Observations and simulations exhibit similar annual cycles of sinuosity, with the maximum sinuosity occurring in summer and minimum sinuosity during winter. Although no long-term trend (1948-2013) in sinuosity is observed in winter (DJF) or summer (JJA), a positive linear trend has occurred since the 1980s and accelerated after 1995 at middle latitudes (winter) and high latitudes (summer). The 500hPa zonal wind is found to weaken at latitudes where sinuosity increases. The change of sinuosity and corresponding zonal wind in RCP8.5 simulations is also explored. Our study finds a strong negative correlation between observed daily sinuosity and the daily Arctic Oscillation (AO) index in all seasons. This negative correlation and the tendency of CMIP5 models to simulate a negative AO-like pattern aloft during winter in a warmer climate suggest a trend toward a wavier extratropical atmospheric circulation in the future.

Extreme daily precipitation: the case of Serbia in 2014

NASA Astrophysics Data System (ADS)

Tošić, Ivana; Unkašević, Miroslava; Putniković, Suzana

2017-05-01

The extreme daily precipitation in Serbia was examined at 16 stations during the period 1961-2014. Two synoptic situations in May and September of 2014 were analysed, when extreme precipitation was recorded in western and eastern Serbia, respectively. The synoptic situation from 14 to 16 May 2014 remained nearly stationary over the western and central Serbia for the entire period. On 15 May 2014, the daily rainfall broke previous historical records in Belgrade (109.8 mm), Valjevo (108.2 mm) and Loznica (110 mm). Precipitation exceeded 200 mm in 72 h, producing the most catastrophic floods in the recent history of Serbia. In Negotin (eastern Serbia), daily precipitation of 161.3 mm was registered on 16 September 2014, which was the maximum value recorded during the period 1961-2014. The daily maximum in 2014 was registered at 6 out of 16 stations. The total annual precipitation for 2014 was the highest for the period 1961-2014 at almost all stations in Serbia. A non-significant positive trend was found for all precipitation indices: annual daily maximum precipitation, the total precipitation in consecutive 3 and 5 days, the total annual precipitation, and number of days with at least 10 and 20 mm of precipitation. The generalised extreme value distribution was fitted to the annual daily maximum precipitation. The estimated 100-year return levels were 123.4 and 147.4 mm for the annual daily maximum precipitation in Belgrade and Negotin, respectively.

On the Seasonality of Sudden Stratospheric Warmings

NASA Astrophysics Data System (ADS)

Reichler, T.; Horan, M.

2017-12-01

The downward influence of sudden stratospheric warmings (SSWs) creates significant tropospheric circulation anomalies that last for weeks. It is therefore of theoretical and practical interest to understand the time when SSWs are most likely to occur and the controlling factors for the temporal distribution of SSWs. Conceivably, the distribution between mid-winter and late-winter is controlled by the interplay between decreasing eddy convergence in the region of the polar vortex and the weakening strength of the polar vortex. General circulation models (GCMs) tend to produce SSW maxima later in winter than observations, which has been considered as a model deficiency. However, the observed record is short, suggesting that under-sampling of SSWs may contribute to this discrepancy. Here, we study the climatological frequency distribution of SSWs and related events in a long control simulation with a stratosphere resolving GCM. We also create a simple statistical model to determine the primary factors controlling the SSW distribution. The statistical model is based on the daily climatological mean, standard deviation, and autocorrelation of stratospheric winds, and assumes that the winds follow a normal distribution. We find that the null hypothesis, that model and observations stem from the same distribution, cannot be rejected, suggesting that the mid-winter SSW maximum seen in the observations is due to sampling uncertainty. We also find that the statistical model faithfully reproduces the seasonal distribution of SSWs, and that the decreasing climatological strength of the polar vortex is the primary factor for it. We conclude that the late-winter SSW maximum seen in most models is realistic and that late events will be more prominent in future observations. We further conclude that SSWs simply form the tail of normally distributed stratospheric winds, suggesting that there is a continuum of weak polar vortex states and that statistically there is nothing special about the zero-threshold used to define SSWs.

Relationship between Acute Phase of Chronic Periodontitis and Meteorological Factors in the Maintenance Phase of Periodontal Treatment: A Pilot Study.

PubMed

Takeuchi, Noriko; Ekuni, Daisuke; Tomofuji, Takaaki; Morita, Manabu

2015-08-05

The acute phase of chronic periodontitis may occur even in patients during supportive periodontal therapy. However, the details are not fully understood. Since the natural environment, including meteorology affects human health, we hypothesized that weather conditions may affect occurrence of acute phase of chronic periodontitis. The aim of this study was to investigate the relationship between weather conditions and acute phase of chronic periodontitis in patients under supportive periodontal therapy. Patients who were diagnosed with acute phase of chronic periodontitis under supportive periodontal therapy during 2011-2013 were selected for this study. We performed oral examinations and collected questionnaires and meteorological data. Of 369 patients who experienced acute phase of chronic periodontitis, 153 had acute phase of chronic periodontitis without direct-triggered episodes. When using the autoregressive integrated moving average model of time-series analysis, the independent covariant of maximum hourly range of barometric pressure, maximum hourly range of temperature, and maximum daily wind speed were significantly associated with occurrence of acute phase of chronic periodontitis (p < 0.05), and 3.1% of the variations in these occurrence over the study period were explained by these factors. Meteorological variables may predict occurrence of acute phase of chronic periodontitis.

Airflow energy harvesting with high wind velocities for industrial applications

NASA Astrophysics Data System (ADS)

Chew, Z. J.; Tuddenham, S. B.; Zhu, M.

2016-11-01

An airflow energy harvester capable of harvesting energy from vortices at high speed is presented in this paper. The airflow energy harvester is implemented using a modified helical Savonius turbine and an electromagnetic generator. A power management module with maximum power point finding capability is used to manage the harvested energy and convert the low voltage magnitude from the generator to a usable level for wireless sensors. The airflow energy harvester is characterized using vortex generated by air hitting a plate in a wind tunnel. By using an aircraft environment with wind speed of 17 m/s as case study, the output power of the airflow energy harvester is measured to be 126 mW. The overall efficiency of the power management module is 45.76 to 61.2%, with maximum power point tracking efficiency of 94.21 to 99.72% for wind speed of 10 to 18 m/s, and has a quiescent current of 790 nA for the maximum power point tracking circuit.

Near-surface coherent structures explored by large eddy simulation of entire tropical cyclones.

PubMed

Ito, Junshi; Oizumi, Tsutao; Niino, Hiroshi

2017-06-19

Taking advantage of the huge computational power of a massive parallel supercomputer (K-supercomputer), this study conducts large eddy simulations of entire tropical cyclones by employing a numerical weather prediction model, and explores near-surface coherent structures. The maximum of the near-surface wind changes little from that simulated based on coarse-resolution runs. Three kinds of coherent structures appeared inside the boundary layer. The first is a Type-A roll, which is caused by an inflection-point instability of the radial flow and prevails outside the radius of maximum wind. The second is a Type-B roll that also appears to be caused by an inflection-point instability but of both radial and tangential winds. Its roll axis is almost orthogonal to the Type-A roll. The third is a Type-C roll, which occurs inside the radius of maximum wind and only near the surface. It transports horizontal momentum in an up-gradient sense and causes the largest gusts.

Radar Cross Section (RCS) Simulation for Wind Turbines

DTIC Science & Technology

2013-06-01

SECTION (RCS) SIMULATION FOR WIND TURBINES by Cuong Ton June 2013 Thesis Advisor: David C. Jenn Second Reader: Ric Romero THIS PAGE...TITLE AND SUBTITLE RADAR CROSS SECTION (RCS) SIMULATION FOR WIND TURBINES 5. FUNDING NUMBERS 6. AUTHOR(S) Cuong Ton 7. PERFORMING ORGANIZATION...ABSTRACT (maximum 200 words) Wind - turbine power provides energy-independence and greenhouse-gas reduction benefits, but if wind turbines are built

Identification of wind fields for wave modeling near Qatar

NASA Astrophysics Data System (ADS)

Nayak, Sashikant; Balan Sobhana, Sandeepan; Panchang, Vijay

2016-04-01

Due to the development of coastal and offshore infrastructure in and around the Arabian Gulf, a large semi-enclosed sea, knowledge of met-ocean factors like prevailing wind systems, wind generated waves, and currents etc. are of great importance. Primarily it is important to identify the wind fields that are used as forcing functions for wave and circulation models for hindcasting and forecasting purposes. The present study investigates the effects of using two sources of wind-fields on the modeling of wind-waves in the Arabian Gulf, in particular near the coastal regions of Qatar. Two wind sources are considered here, those obtained from ECMWF and those generated by us using the WRF model. The wave model SWAN was first forced with the 6 hourly ERA Interim daily winds (from ECMWF) having spatial resolution of 0.125°. For the second option, wind fields were generated by us using the mesoscale wind model (WRF) with a high spatial resolution (0.1°) at every 30 minute intervals. The simulations were carried out for a period of two months (7th October-7th December, 2015) during which measurements were available from two moored buoys (deployed and operated by the Qatar Meteorological Department), one in the north of Qatar ("Qatar North", in water depth of 58.7 m) and other in the south ("Shiraouh Island", in water depth of 16.64 m). This period included a high-sea event on 11-12th of October, recorded by the two buoys where the significant wave heights (Hs) reached as high as 2.9 m (i.e. max wave height H ~ 5.22 m) and 1.9 (max wave height H ~ 3.4 m) respectively. Model results were compared with the data for this period. The scatter index (SI) of the Hs simulated using the WRF wind fields and the observed Hs was found to be about 30% and 32% for the two buoys (total period). The observed Hs were generally reproduced but there was consistent underestimation. (Maximum 27% for the high-sea event). For the Hs obtained with ERA interim wind fields, the underestimation was of the order of 50% (on average) for the entire duration. The study therefore suggests the use of a mesoscale weather forecasting model such as WRF, for deriving the wind fields for a large but marginal semi-enclosed sea where small scale phenomena dominate, and when used as forcing in the wave model, it provides wave-climate predictions with less error.

Comparative Flight and Full-Scale Wind-Tunnel Measurements of the Maximum Lift of an Airplane

NASA Technical Reports Server (NTRS)

Silverstein, Abe; Katzoff, S; Hootman, James A

1938-01-01

Determinations of the power-off maximum lift of a Fairchild 22 airplane were made in the NACA full-scale wind tunnel and in flight. The results from the two types of test were in satisfactory agreement. It was found that, when the airplane was rotated positively in pitch through the angle of stall at rates of the order of 0.1 degree per second, the maximum lift coefficient was considerably higher than that obtained in the standard tests, in which the forces are measured with the angles of attack fixed. Scale effect on the maximum lift coefficient was also investigated.

Survey of the spectral properties of turbulence in the solar wind, the magnetospheres of Venus and Earth, at solar minimum and maximum

NASA Astrophysics Data System (ADS)

Echim, Marius M.

2014-05-01

In the framework of the European FP7 project STORM ("Solar system plasma Turbulence: Observations, inteRmittency and Multifractals") we analyze the properties of turbulence in various regions of the solar system, for the minimum and respectively maximum of the solar activity. The main scientific objective of STORM is to advance the understanding of the turbulent energy transfer, intermittency and multifractals in space plasmas. Specific analysis methods are applied on magnetic field and plasma data provided by Ulysses, Venus Express and Cluster, as well as other solar system missions (e.g. Giotto, Cassini). In this paper we provide an overview of the spectral properties of turbulence derived from Power Spectral Densities (PSD) computed in the solar wind (from Ulysses, Cluster, Venus Express) and at the interface of planetary magnetospheres with the solar wind (from Venus Express, Cluster). Ulysses provides data in the solar wind between 1992 and 2008, out of the ecliptic, at radial distances ranging between 1.3 and 5.4 AU. We selected only those Ulysses data that satisfy a consolidated set of selection criteria able to identify "pure" fast and slow wind. We analyzed Venus Express data close to the orbital apogee, in the solar wind, at 0.72 AU, and in the Venus magnetosheath. We investigated Cluster data in the solar wind (for time intervals not affected by planetary ions effects), the magnetosheath and few crossings of other key magnetospheric regions (cusp, plasma sheet). We organize our PSD results in three solar wind data bases (one for the solar maximum, 1999-2001, two for the solar minimum, 1997-1998 and respectively, 2007-2008), and two planetary databases (one for the solar maximum, 2000-2001, that includes PSD obtained in the terrestrial magnetosphere, and one for the solar minimum, 2007-2008, that includes PSD obtained in the terrestrial and Venus magnetospheres and magnetosheaths). In addition to investigating the properties of turbulence for the minimum and maximum of the solar cycle we also analyze the spectral similarities and differences between fast and slow wind turbulence. We emphasize the importance of our data survey and analysis in the context of understanding the solar wind turbulence, the exploitation of data bases and as a first step towards developing a (virtual) laboratory for studying solar system plasma turbulence. Research supported by the European Community's Seventh Framework Programme (FP7/2007-2013) under grant agreement no 313038/STORM, and a grant of the Romanian Ministry of National Education, CNCS - UEFISCDI, project number PN-II-ID-PCE-2012-4-0418.

Influence of time scale wind speed data on sustainability analysis for irrigating greenhouse crops

NASA Astrophysics Data System (ADS)

Díaz Méndez, Rodrigo; García Llaneza, Joaquín; Peillón, Manuel; Perdigones, Alicia; Sanchez, Raul; Tarquis, Ana M.; Garcia, Jose Luis

2014-05-01

Appropriate water supply at crop/farm level, with suitable costs, is becoming more and more important. Energy management is closely related to water supply in this context, being wind energy one of the options to be considered, using wind pumps for irrigation water supply. Therefore, it is important to characterize the wind speed frequency distribution to study the technical feasibility to use its energy for irrigation management purpose. The general objective of this present research is to analyze the impact of time scale recorded wind speed data in the sustainability for tomato (Solanum lycopersicum L.) grown under greenhouse at Cuban conditions using drip irrigation system. For this porpoise, a daily estimation balance between water needs and water availability was used to evaluate the feasibility of the most economic windmill irrigation system. Several factors were included: wind velocity (W, m/s) in function of the time scale averaged, flow supplied by the wind pump as a function of the elevation height (H, m) and daily greenhouse evapotranspiration. Monthly volumes of water required for irrigation (Dr, m3/ha) and in the water tank (Vd, m3), as well as the monthly irrigable area (Ar, ha), were estimated by cumulative deficit water budgeting taking in account these factors. Three-hourly wind velocity (W3h, m/s) data from 1992 till 2008 was available for this study. The original data was grouped in six and twelve hourly data (W6h and W12h respectively) as well as daily data (W24h). For each time scale the daily estimation balance was applied. A comparison of the results points out a need for at least three-hourly data to be used mainly in the months in which mean wind speed are close or below the pumps threshold speed to start-up functioning. References Manuel Esteban Peillon Mesa, Ana Maria Tarquis Alfonso, José Luis García Fernández, and Raúl Sánchez Calvo. The use of wind pumps for irrigating greenhouse tomato crops: a case study in Cuba. Geophysical Research Abstracts, 13, EGU2011-64-1, 2011. EGU General Assembly 2011 M. Peillón, R. Sánchez, A.M. Tarquis and J.L. García. Wind pumps for irrigating greenhouse crops. Geophysical Research Abstracts, 14, EGU2012-14155, 2012. EGU General Assembly 2012. Manuel Peillón, Raúl Sánchez, Ana M. Tarquis, José L. García-Fernández. The use of wind pumps for greenhouse microirrigation: A case study for tomato in Cuba. Agricultural Water Management, 120, 107-114, 2013. R. Díaz, A. Rasheed, M. Peillón, A. Perdigones, R. Sánchez, A.M. Tarquis, and J.L. García. Wind pumps for irrigating greenhouse crops: a comparison in different socio-economical frameworks. Submitted to Biosystems, 2014.

Analysis of Correlation Tendency between Wind and Solar from Various Spatio-temporal Perspectives

NASA Astrophysics Data System (ADS)

Wang, X.; Weihua, X.; Mei, Y.

2017-12-01

Analysis of correlation between wind resources and solar resources could explore their complementary features, enhance the utilization efficiency of renewable energy and further alleviate the carbon emission issues caused by the fossil energy. In this paper, we discuss the correlation between wind and solar from various spatio-temporal perspectives (from east to west, in terms of plain, plateau, hill, and mountain, from hourly to daily, ten days and monthly) with observed data and modeled data from NOAA (National Oceanic and Atmospheric Administration) and NERL (National Renewable Energy Laboratory). With investigation of wind speed time series and solar radiation time series (period: 10 years, resolution: 1h) of 72 stations located in various landform and distributed dispersedly in USA, the results show that the correlation coefficient, Kendall's rank correlation coefficient, changes negative to positive value from east coast to west coast of USA, and this phenomena become more obvious when the time scale of resolution increases from daily to ten days and monthly. Furthermore, considering the differences of landforms which influence the local meteorology the Kendall coefficients of diverse topographies are compared and it is found that the coefficients descend from mountain to hill, plateau and plain. However, no such evident tendencies could be found in daily scale. According to this research, it is proposed that the complementary feature of wind resources and solar resources in the east or in the mountain area of USA is conspicuous. Subsequent study would try to further verify this analysis by investigating the operation status of wind power station and solar power station.

Unsteady Flow in Different Atmospheric Boundary Layer Regimes and Its Impact on Wind-Turbine Performance

NASA Astrophysics Data System (ADS)

Gohari, Iman; Korobenko, Artem; Yan, Jinhui; Bazilevs, Yuri; Sarkar, Sutanu

2016-11-01

Wind is a renewable energy resource that offers several advantages including low pollutant emission and inexpensive construction. Wind turbines operate in conditions dictated by the Atmospheric Boundary Layer (ABL) and that motivates the study of coupling ABL simulations with wind turbine dynamics. The ABL simulations can be used for realistic modeling of the environment which, with the use of fluid-structure interaction, can give realistic predictions of extracted power, rotor loading, and blade structural response. The ABL simulations provide inflow boundary conditions to the wind-turbine simulator which uses arbitrary Lagrangian-Eulerian variational multiscale formulation. In the present work, ABL simulations are performed to examine two different scenarios: (i) A neutral ABL with zero heat-flux and inversion layer at 350m, in which the wind turbine experiences maximum mean shear; (2) A shallow ABL with the surface cooling-rate of -1 K/hr, in which the wind turbine experiences maximum mean velocity at the low-level-jet nose height. We will discuss differences in the unsteady flow between the two different ABL conditions and their impact on the performance of the wind turbine cluster in the coupled ABL-wind turbine simulations.

Objective estimation of tropical cyclone innercore surface wind structure using infrared satellite images

NASA Astrophysics Data System (ADS)

Zhang, Changjiang; Dai, Lijie; Ma, Leiming; Qian, Jinfang; Yang, Bo

2017-10-01

An objective technique is presented for estimating tropical cyclone (TC) innercore two-dimensional (2-D) surface wind field structure using infrared satellite imagery and machine learning. For a TC with eye, the eye contour is first segmented by a geodesic active contour model, based on which the eye circumference is obtained as the TC eye size. A mathematical model is then established between the eye size and the radius of maximum wind obtained from the past official TC report to derive the 2-D surface wind field within the TC eye. Meanwhile, the composite information about the latitude of TC center, surface maximum wind speed, TC age, and critical wind radii of 34- and 50-kt winds can be combined to build another mathematical model for deriving the innercore wind structure. After that, least squares support vector machine (LSSVM), radial basis function neural network (RBFNN), and linear regression are introduced, respectively, in the two mathematical models, which are then tested with sensitivity experiments on real TC cases. Verification shows that the innercore 2-D surface wind field structure estimated by LSSVM is better than that of RBFNN and linear regression.

On the predictability of high water level along the US East Coast: can the Florida Current measurement be an indicator for flooding caused by remote forcing?

NASA Astrophysics Data System (ADS)

Ezer, Tal; Atkinson, Larry P.

2017-06-01

Recent studies show that in addition to wind and air pressure effects, a significant portion of the variability of coastal sea level (CSL) along the US East Coast can be attributed to non-local factors such as variations in the Gulf Stream and the North Atlantic circulation; these variations can cause unpredictable coastal flooding. The Florida Current transport (FCT) measurement across the Florida Straits monitors those variations, and thus, the study evaluated the potential of using the FCT as an indicator for anomalously high water level along the coast. Hourly water level data from 12 tide gauge stations over 12 years are used to construct records of maximum daily water levels (MDWL) that are compared with the daily FCT data. An empirical mode decomposition (EMD) approach is used to divide the data into high-frequency modes (periods T < ˜30 days), middle-frequency modes (˜30 days < T < ˜90 days), and low-frequency modes (˜90 days < T < ˜1 year). Two predictive measures are tested: FCT and FCT change (FCC). FCT is anti-correlated with MDWL in high-frequency modes but positively correlated with MDWL in low-frequency modes. FCC on the other hand is always anti-correlated with MDWL for all frequency bands, and the high water signal lags behind FCC for almost all stations, thus providing a potential predictive skill (i.e., whenever a weakening trend is detected in the FCT, anomalously high water is expected along the coast over the next few days). The MDWL-FCT correlation in the high-frequency modes is maximum in the lower Mid-Atlantic Bight, suggesting influence from the meandering Gulf Stream after it separates from the coast. However, the correlation in low-frequency modes is maximum in the South Atlantic Bight, suggesting impact from variations in the wind pattern over subtropical regions. The middle-frequency and low-frequency modes of the FCT seem to provide the best predictor for medium to large flooding events; it is estimated that ˜10-25% of the sea level variability in those modes can be attributed to variations in the FCT. An example from Hurricane Joaquin (September-October, 2015) demonstrates how an offshore storm that never made landfall can cause a weakening of the FCT and unexpected high water level and flooding along the US East Coast. A regression-prediction model based on the MDWL-FCT correlation shows some skill in estimating high water levels during past storms; the water level prediction is more accurate for slow-moving and offshore storms than it is for fast-moving storms. The study can help to improve water level prediction since current storm surge models rely on local wind but may ignore remote forcing.

Daily mean temperature estimate at the US SUFRAD stations as an average of the maximum and minimum temperatures

DOE PAGES

Chylek, Petr; Augustine, John A.; Klett, James D.; ...

2017-09-30

At thousands of stations worldwide, the mean daily surface air temperature is estimated as a mean of the daily maximum (T max) and minimum (T min) temperatures. In this paper, we use the NOAA Surface Radiation Budget Network (SURFRAD) of seven US stations with surface air temperature recorded each minute to assess the accuracy of the mean daily temperature estimate as an average of the daily maximum and minimum temperatures and to investigate how the accuracy of the estimate increases with an increasing number of daily temperature observations. We find the average difference between the estimate based on an averagemore » of the maximum and minimum temperatures and the average of 1440 1-min daily observations to be - 0.05 ± 1.56 °C, based on analyses of a sample of 238 days of temperature observations. Considering determination of the daily mean temperature based on 3, 4, 6, 12, or 24 daily temperature observations, we find that 2, 4, or 6 daily observations do not reduce significantly the uncertainty of the daily mean temperature. The bias reduction in a statistically significant manner (95% confidence level) occurs only with 12 or 24 daily observations. The daily mean temperature determination based on 24 hourly observations reduces the sample daily temperature uncertainty to - 0.01 ± 0.20 °C. Finally, estimating the parameters of population of all SURFRAD observations, the 95% confidence intervals based on 24 hourly measurements is from - 0.025 to 0.004 °C, compared to a confidence interval from - 0.15 to 0.05 °C based on the mean of T max and T min.« less

Daily mean temperature estimate at the US SUFRAD stations as an average of the maximum and minimum temperatures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chylek, Petr; Augustine, John A.; Klett, James D.

At thousands of stations worldwide, the mean daily surface air temperature is estimated as a mean of the daily maximum (T max) and minimum (T min) temperatures. In this paper, we use the NOAA Surface Radiation Budget Network (SURFRAD) of seven US stations with surface air temperature recorded each minute to assess the accuracy of the mean daily temperature estimate as an average of the daily maximum and minimum temperatures and to investigate how the accuracy of the estimate increases with an increasing number of daily temperature observations. We find the average difference between the estimate based on an averagemore » of the maximum and minimum temperatures and the average of 1440 1-min daily observations to be - 0.05 ± 1.56 °C, based on analyses of a sample of 238 days of temperature observations. Considering determination of the daily mean temperature based on 3, 4, 6, 12, or 24 daily temperature observations, we find that 2, 4, or 6 daily observations do not reduce significantly the uncertainty of the daily mean temperature. The bias reduction in a statistically significant manner (95% confidence level) occurs only with 12 or 24 daily observations. The daily mean temperature determination based on 24 hourly observations reduces the sample daily temperature uncertainty to - 0.01 ± 0.20 °C. Finally, estimating the parameters of population of all SURFRAD observations, the 95% confidence intervals based on 24 hourly measurements is from - 0.025 to 0.004 °C, compared to a confidence interval from - 0.15 to 0.05 °C based on the mean of T max and T min.« less

Accuracy assessment of NOAA gridded daily reference evapotranspiration for the Texas High Plains

USGS Publications Warehouse

Moorhead, Jerry; Gowda, Prasanna H.; Hobbins, Michael; Senay, Gabriel; Paul, George; Marek, Thomas; Porter, Dana

2015-01-01

The National Oceanic and Atmospheric Administration (NOAA) provides daily reference evapotranspiration (ETref) maps for the contiguous United States using climatic data from North American Land Data Assimilation System (NLDAS). This data provides large-scale spatial representation of ETref, which is essential for regional scale water resources management. Data used in the development of NOAA daily ETref maps are derived from observations over surfaces that are different from short (grass — ETos) or tall (alfalfa — ETrs) reference crops, often in nonagricultural settings, which carries an unknown discrepancy between assumed and actual conditions. In this study, NOAA daily ETos and ETrs maps were evaluated for accuracy, using observed data from the Texas High Plains Evapotranspiration (TXHPET) network. Daily ETos, ETrs and the climatic data (air temperature, wind speed, and solar radiation) used for calculating ETref were extracted from the NOAA maps for TXHPET locations and compared against ground measurements on reference grass surfaces. NOAA ETrefmaps generally overestimated the TXHPET observations (1.4 and 2.2 mm/day ETos and ETrs, respectively), which may be attributed to errors in the NLDAS modeled air temperature and wind speed, to which reference ETref is most sensitive. Therefore, a bias correction to NLDAS modeled air temperature and wind speed data, or adjustment to the resulting NOAA ETref, may be needed to improve the accuracy of NOAA ETref maps.

An algorithm to estimate PBL heights from wind profiler data

NASA Astrophysics Data System (ADS)

Molod, A.; Salmun, H.

2016-12-01

An algorithm was developed to estimate planetary boundary layer (PBL) heights from hourlyarchived wind profiler data from the NOAA Profiler Network (NPN) sites located throughoutthe central United States from the period 1992-2012. The long period of record allows ananalysis of climatological mean PBL heights as well as some estimates of year to yearvariability. Under clear conditions, summertime averaged hourly time series of PBL heightscompare well with Richardson-number based estimates at the few NPN stations with hourlytemperature measurements. Comparisons with clear sky MERRA estimates show that the windprofiler (WP) and the Richardson number based PBL heights are lower by approximately 250-500 m.The geographical distribution of daily maximum WP PBL heights corresponds well with theexpected distribution based on patterns of surface temperature and soil moisture. Windprofiler PBL heights were also estimated under mostly cloudy conditions, but the WP estimatesshow a smaller clear-cloudy condition difference than either of the other two PBL height estimates.The algorithm presented here is shown to provide a reliable summer, fall and springclimatology of daytime hourly PBL heights throughout the central United States. The reliabilityof the algorithm has prompted its use to obtain hourly PBL heights from other archived windprofiler data located throughout the world.

A conceptual weather-type classification procedure for the Philadelphia, Pennsylvania, area

USGS Publications Warehouse

McCabe, Gregory J.

1990-01-01

A simple method of weather-type classification, based on a conceptual model of pressure systems that pass through the Philadelphia, Pennsylvania, area, has been developed. The only inputs required for the procedure are daily mean wind direction and cloud cover, which are used to index the relative position of pressure systems and fronts to Philadelphia.Daily mean wind-direction and cloud-cover data recorded at Philadelphia, Pennsylvania, from January 1954 through August 1988 were used to categorize daily weather conditions. The conceptual weather types reflect changes in daily air and dew-point temperatures, and changes in monthly mean temperature and monthly and annual precipitation. The weather-type classification produced by using the conceptual model was similar to a classification produced by using a multivariate statistical classification procedure. Even though the conceptual weather types are derived from a small amount of data, they appear to account for the variability of daily weather patterns sufficiently to describe distinct weather conditions for use in environmental analyses of weather-sensitive processes.

Who Moved Those Rain Clouds to Town? Making Windbirds to Learn about the Power of Wind

ERIC Educational Resources Information Center

Samarakoon, Deepanee; Smith, Latisha L.

2016-01-01

In this practical article, a kindergarten teacher shares a lesson designed to teach students about the power of wind. To address the Next Generation Science Standards engineering standards, students discussed the negative and positive aspects of wind and made daily weather observations (K-ESS2-1). Students constructed bird-shaped windsocks, called…

Frequency of urban building fires as related to daily weather conditions

Treesearch

Arthur R. Pirsko; Wallace L. Fons

1956-01-01

Daily weather elements of precipitation, wind, mean temperature, relative humidity, and dew-point temperature for selected urban areas (approximately 850,000 population) in the United States are statistically analyzed to determine their correlation with daily number of building fires. The frequency of urban building fires is found to be significantly correlated with...

Wind Energy Facilities

DOE Office of Scientific and Technical Information (OSTI.GOV)

Laurie, Carol

2017-02-01

This book takes readers inside the places where daily discoveries shape the next generation of wind power systems. Energy Department laboratory facilities span the United States and offer wind research capabilities to meet industry needs. The facilities described in this book make it possible for industry players to increase reliability, improve efficiency, and reduce the cost of wind energy -- one discovery at a time. Whether you require blade testing or resource characterization, grid integration or high-performance computing, Department of Energy laboratory facilities offer a variety of capabilities to meet your wind research needs.

Wind Energy Facilities

DOE Office of Scientific and Technical Information (OSTI.GOV)

Office of Energy Efficiency and Renewable Energy

This book takes readers inside the places where daily discoveries shape the next generation of wind power systems. Energy Department laboratory facilities span the United States and offer wind research capabilities to meet industry needs. The facilities described in this book make it possible for industry players to increase reliability, improve efficiency, and reduce the cost of wind energy -- one discovery at a time. Whether you require blade testing or resource characterization, grid integration or high-performance computing, Department of Energy laboratory facilities offer a variety of capabilities to meet your wind research needs.

Interpretation of 3He variations in the solar wind

NASA Technical Reports Server (NTRS)

Coplan, M. A.; Ogilvie, K. W.; Geiss, J.; Bochsler, P.

1983-01-01

The ion composition instrument (ICI) on ISEE-3 observed the isotopes of helium of mass 3 and 4 in the solar wind almost continuously between August 1978 and July 1982. This period included the increase towards the maximum of solar activity cycle 21, the maximum period, and the beginning of the descent towards solar minimum. Observations were made when the solar wind speed was between 300 and 620 km/s. For part of the period evidence for regular interplanetary magnetic sector structure was clear and a number of 3He flares occurred during this time.

Interpretation of He-3 abundance variations in the solar wind

NASA Technical Reports Server (NTRS)

Coplan, M. A.; Ogilvie, K. W.; Bochsler, P.; Geiss, J.

1984-01-01

The ion composition instrument (ICI) on ISEE-3 observed the isotopes of helium of mass 3 and 4 in the solar wind almost continuously between August 1978 and July 1982. This period included the increase towards the maximum of solar activity cycle 21, the maximum period, and the beginning of the descent towards solar minimum. Observations were made when the solar wind speed was between 300 and 620 km/s. For part of the period evidence for regular interplanetary magnetic sector structure was clear and a number of He-3 flares occurred during this time.

The sun and heliosphere at solar maximum

NASA Technical Reports Server (NTRS)

Smith, E. J.; Marsden, R. G.; Balogh, A.; Gloeckler, G.; Geiss, J.; McComas, D. J.; McKibben, R. B.; MacDowall, R. J.; Lanzerotti, L. J.; Krupp, N.;

MO and DA on the SWIE Instrument on the Wind Spacecraft

NASA Technical Reports Server (NTRS)

Lazarus, Alan J.

2002-01-01

The construction of the Faraday Cup portion of the SWIE instrument on the Wind spacecraft, participation in Mission Operations, and Data Analysis (MO and DA) of observations of the solar wind has been supported by a sequence of grants. This 'final' Report represents work done on Mission Operations and Data Analysis for the Faraday Cup portion of the SWE. The work reported here was supported under NASA Grant NAG5-7359 (OSP 6701100) from June 1998 to October 2001. It should be noted that this work is continuing under NASA Grant NAG-10915, and therefore this report is 'final' only in the sense that the Grant has changed its number; a future report will cover the entire period of work. We have two types of obligations under these contracts: (1) To provide and assure the validity of "Key Parameters" which describe the basic properties of the solar wind on a daily basis. We have provided our 92 second observations daily via plots and parameters available from our Web site: http://web.mit.edu/space/www/wind/wind.html (2). To carry out scientific studies based on our observations. To document the extent of our research, we are including below a list of publications and presentations related to this project. The observations from Wind have made a major contribution to the study of the solar wind, and have every indication of continuing to do so.

Efficacy of spatial averaging of infrasonic pressure in varying wind speeds.

PubMed

DeWolf, Scott; Walker, Kristoffer T; Zumberge, Mark A; Denis, Stephane

2013-06-01

Wind noise reduction (WNR) is important in the measurement of infrasound. Spatial averaging theory led to the development of rosette pipe arrays. The efficacy of rosettes decreases with increasing wind speed and only provides a maximum of ~20 dB WNR due to a maximum size limitation. An Optical Fiber Infrasound Sensor (OFIS) reduces wind noise by instantaneously averaging infrasound along the sensor's length. In this study two experiments quantify the WNR achieved by rosettes and OFISs of various sizes and configurations. Specifically, it is shown that the WNR for a circular OFIS 18 m in diameter is the same as a collocated 32-inlet pipe array of the same diameter. However, linear OFISs ranging in length from 30 to 270 m provide a WNR of up to ~30 dB in winds up to 5 m/s. The measured WNR is a logarithmic function of the OFIS length and depends on the orientation of the OFIS with respect to wind direction. OFISs oriented parallel to the wind direction achieve ~4 dB greater WNR than those oriented perpendicular to the wind. Analytical models for the rosette and OFIS are developed that predict the general observed relationships between wind noise reduction, frequency, and wind speed.

Wind tunnel test of a tailless aircraft with a belly-flap control surface used in combination with wing flaps

NASA Astrophysics Data System (ADS)

Dougherty, Daniel A.

A wind tunnel tat of a tailless aircraft configuration that has been quipped with a belly-flap control surface, was conducted with the goal of improving the trimmed maximum-lift coefficient. Tailless aircraft have aerodynamic and structural efficiencies that are superior to those of a traditionally configured wing/body/tail aircraft. However, tailless aircraft have a low maximum-lift coefficient such that; when sized for equivalent takeoff performance, the tailless aircraft suffers a large reduction in aerodynamic and structural efficiencies. A Belly-Flap control surface used in combination with wing trailing edge flaps was tested in a wind tunnel with the goal of achieving a longitudinally trimmed solution at a higher maximum lift coefficient. It was determined that, though the Belly-Flap increases the trimmed lift of the tailless configuration at low angles of attack, the maximum lift coefficient is slightly reduced in relation to the controls neutral configuration.

Energy optimization for a wind DFIG with flywheel energy storage

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hamzaoui, Ihssen, E-mail: hamzaoui-ihssen2000@yahoo.fr; Laboratory of Instrumentation, Faculty of Electronics and Computer, University of Khemis Miliana, Ain Defla; Bouchafaa, Farid, E-mail: fbouchafa@gmail.com

2016-07-25

The type of distributed generation unit that is the subject of this paper relates to renewable energy sources, especially wind power. The wind generator used is based on a double fed induction Generator (DFIG). The stator of the DFIG is connected directly to the network and the rotor is connected to the network through the power converter with three levels. The objective of this work is to study the association a Flywheel Energy Storage System (FESS) in wind generator. This system is used to improve the quality of electricity provided by wind generator. It is composed of a flywheel; anmore » induction machine (IM) and a power electronic converter. A maximum power tracking technique « Maximum Power Point Tracking » (MPPT) and a strategy for controlling the pitch angle is presented. The model of the complete system is developed in Matlab/Simulink environment / to analyze the results from simulation the integration of wind chain to networks.« less

Performance analysis of air-water quantum key distribution with an irregular sea surface

NASA Astrophysics Data System (ADS)

Xu, Hua-bin; Zhou, Yuan-yuan; Zhou, Xue-jun; Wang, Lian

2018-05-01

In the air-water quantum key distribution (QKD), the irregular sea surface has some influence on the photon polarization state. The wind is considered as the main factor causing the irregularity, so the model of irregular sea surface based on the wind speed is adopted. The relationships of the quantum bit error rate with the wind speed and the initial incident angle are simulated. Therefore, the maximum secure transmission depth of QKD is confirmed, and the limitation of the wind speed and the initial incident angle is determined. The simulation results show that when the wind speed and the initial incident angle increase, the performance of QKD will fall down. Under the intercept-resend attack condition, the maximum safe transmission depth of QKD is up to 105 m. To realize safe communications in the safe diving depth of submarines (100 m), the initial incident angle is requested to be not exceeding 26°, and with the initial incident angle increased, the limitation of wind speed is decreased.

Low-latitude thermospheric neutral winds determined from AE-E measurements of the 6300-A nightglow at solar maximum

NASA Technical Reports Server (NTRS)

Burrage, M. D.; Abreu, V. J.; Fesen, C. G.

1990-01-01

Atmosphere Explorer E (AE-E) measurements of the O(1D) 6300-A emission in the nighttime equatorial thermosphere are used to infer the height of the F2 layer peak as a function of latitude and local time. The investigation is conducted both for northern hemisphere winter solstice and for spring equinox, under solar maximum conditions. The layer heights are used to derive magnetic meridional components of the transequatorial neutral wind, in conjunction with the MSIS-86 model and previous Jicamarca incoherent scatter measurements of the zonal electric field. The AE-E wind estimates indicate a predominant summer to winter flow for the winter solstice case. Comparisons are made with the empirical horizontal wind model HWM87 and with winds generated by the thermospheric general circulation model. The model predictions and experimental results are generally in good agreement, confirming the applicability of visible airglow data to studies of the global neutral wind pattern.

Reply to comment by Ma and Zhang on "Rescaling the complementary relationship for land surface evaporation"

NASA Astrophysics Data System (ADS)

Crago, Richard; Qualls, Russell; Szilagyi, Jozsef; Huntington, Justin

2017-07-01

Ma and Zhang (2017) note a concern they have with our rescaled Complementary Relationship (CR) for land surface evaporation when daily average wind speeds are very low (perhaps less than 1 m/s). We discuss conditions and specific formulations that lead to this concern, but ultimately argue that under these conditions, a key assumption behind the CR itself may not be satisfied at the daily time scale. Thus, careful consideration of the reliability of the CR is needed when wind speeds are very low.

Statistical Compression of Wind Speed Data

NASA Astrophysics Data System (ADS)

Tagle, F.; Castruccio, S.; Crippa, P.; Genton, M.

2017-12-01

In this work we introduce a lossy compression approach that utilizes a stochastic wind generator based on a non-Gaussian distribution to reproduce the internal climate variability of daily wind speed as represented by the CESM Large Ensemble over Saudi Arabia. Stochastic wind generators, and stochastic weather generators more generally, are statistical models that aim to match certain statistical properties of the data on which they are trained. They have been used extensively in applications ranging from agricultural models to climate impact studies. In this novel context, the parameters of the fitted model can be interpreted as encoding the information contained in the original uncompressed data. The statistical model is fit to only 3 of the 30 ensemble members and it adequately captures the variability of the ensemble in terms of seasonal internannual variability of daily wind speed. To deal with such a large spatial domain, it is partitioned into 9 region, and the model is fit independently to each of these. We further discuss a recent refinement of the model, which relaxes this assumption of regional independence, by introducing a large-scale component that interacts with the fine-scale regional effects.

Natural variability of the Keetch-Byram Drought Index in the Hawaiian Islands

Treesearch

Klaus Dolling; Pao-Shin Chu; Francis Fujioka

2009-01-01

The Hawaiian Islands experience damaging wildfires on a yearly basis. Soil moisture or lack thereof influences the amount and flammability of vegetation. Incorporating daily maximum temperatures and daily rainfall amounts, the Keetch–Byram Drought Index (KBDI) estimates the amount of soil moisture by tracking daily maximum temperatures and rainfall. A previous study...

Simulated wind-generated inertial oscillations compared to current measurements in the northern North Sea

NASA Astrophysics Data System (ADS)

Bruserud, Kjersti; Haver, Sverre; Myrhaug, Dag

2018-06-01

Measured current speed data show that episodes of wind-generated inertial oscillations dominate the current conditions in parts of the northern North Sea. In order to acquire current data of sufficient duration for robust estimation of joint metocean design conditions, such as wind, waves, and currents, a simple model for episodes of wind-generated inertial oscillations is adapted for the northern North Sea. The model is validated with and compared against measured current data at one location in the northern North Sea and found to reproduce the measured maximum current speed in each episode with considerable accuracy. The comparison is further improved when a small general background current is added to the simulated maximum current speeds. Extreme values of measured and simulated current speed are estimated and found to compare well. To assess the robustness of the model and the sensitivity of current conditions from location to location, the validated model is applied at three other locations in the northern North Sea. In general, the simulated maximum current speeds are smaller than the measured, suggesting that wind-generated inertial oscillations are not as prominent at these locations and that other current conditions may be governing. Further analysis of the simulated current speed and joint distribution of wind, waves, and currents for design of offshore structures will be presented in a separate paper.

Simulated wind-generated inertial oscillations compared to current measurements in the northern North Sea

NASA Astrophysics Data System (ADS)

Bruserud, Kjersti; Haver, Sverre; Myrhaug, Dag

2018-04-01

Measured current speed data show that episodes of wind-generated inertial oscillations dominate the current conditions in parts of the northern North Sea. In order to acquire current data of sufficient duration for robust estimation of joint metocean design conditions, such as wind, waves, and currents, a simple model for episodes of wind-generated inertial oscillations is adapted for the northern North Sea. The model is validated with and compared against measured current data at one location in the northern North Sea and found to reproduce the measured maximum current speed in each episode with considerable accuracy. The comparison is further improved when a small general background current is added to the simulated maximum current speeds. Extreme values of measured and simulated current speed are estimated and found to compare well. To assess the robustness of the model and the sensitivity of current conditions from location to location, the validated model is applied at three other locations in the northern North Sea. In general, the simulated maximum current speeds are smaller than the measured, suggesting that wind-generated inertial oscillations are not as prominent at these locations and that other current conditions may be governing. Further analysis of the simulated current speed and joint distribution of wind, waves, and currents for design of offshore structures will be presented in a separate paper.

Global Network of Slow Solar Wind

NASA Technical Reports Server (NTRS)

Crooker, N. U.; Antiochos, S. K.; Zhao, X.; Neugebauer, M.

2012-01-01

The streamer belt region surrounding the heliospheric current sheet (HCS) is generally treated as the primary or sole source of the slow solar wind. Synoptic maps of solar wind speed predicted by the Wang-Sheeley-Arge model during selected periods of solar cycle 23, however, show many areas of slow wind displaced from the streamer belt. These areas commonly have the form of an arc that is connected to the streamer belt at both ends. The arcs mark the boundaries between fields emanating from different coronal holes of the same polarity and thus trace the paths of belts of pseudostreamers, i.e., unipolar streamers that form over double arcades and lack current sheets. The arc pattern is consistent with the predicted topological mapping of the narrow open corridor or singular separator line that must connect the holes and, thus, consistent with the separatrix-web model of the slow solar wind. Near solar maximum, pseudostreamer belts stray far from the HCS-associated streamer belt and, together with it, form a global-wide web of slow wind. Recognition of pseudostreamer belts as prominent sources of slow wind provides a new template for understanding solar wind stream structure, especially near solar maximum.

The Electromagnetic Impact of Wind Turbines

DTIC Science & Technology

2015-07-06

Applied Project 4. TITLE AND SUBTITLE THE ELECTROMAGNETIC IMPACT OF WIND TURBINES 5. FUNDING NUMBERS 6. AUTHOR(S) Gregory Sasarita and Charles R...DISTRIBUTION CODE A 13. ABSTRACT (maximum 200 words) The objective of this project was to investigate the impact that a wind turbine can have on

Spatial structure of directional wave spectra in hurricanes

NASA Astrophysics Data System (ADS)

Esquivel-Trava, Bernardo; Ocampo-Torres, Francisco J.; Osuna, Pedro

2015-01-01

The spatial structure of the wave field during hurricane conditions is studied using the National Data Buoy Center directional wave buoy data set from the Caribbean Sea and the Gulf of Mexico. The buoy information, comprising the directional wave spectra during the passage of several hurricanes, was referenced to the center of the hurricane using the path of the hurricane, the propagation velocity, and the radius of the maximum winds. The directional wave spectra were partitioned into their main components to quantify the energy corresponding to the observed wave systems and to distinguish between wind-sea and swell. The findings are consistent with those found using remote sensing data (e.g., Scanning Radar Altimeter data). Based on the previous work, the highest waves are found in the right forward quadrant of the hurricane, where the spectral shape tends to become uni-modal, in the vicinity of the region of maximum winds. More complex spectral shapes are observed in distant regions at the front of and in the rear quadrants of the hurricane, where there is a tendency of the spectra to become bi- and tri-modal. The dominant waves generally propagate at significant angles to the wind direction, except in the regions next to the maximum winds of the right quadrants. Evidence of waves generated by concentric eyewalls associated with secondary maximum winds was also found. The frequency spectra display some of the characteristics of the JONSWAP spectrum adjusted by Young (J Geophys Res 111:8020, 2006); however, at the spectral peak, the similarity with the Pierson-Moskowitz spectrum is clear. These results establish the basis for the use in assessing the ability of numerical models to simulate the wave field in hurricanes.

Ozone trends and their relationship to characteristic weather patterns.

PubMed

Austin, Elena; Zanobetti, Antonella; Coull, Brent; Schwartz, Joel; Gold, Diane R; Koutrakis, Petros

2015-01-01

Local trends in ozone concentration may differ by meteorological conditions. Furthermore, the trends occurring at the extremes of the Ozone distribution are often not reported even though these may be very different than the trend observed at the mean or median and they may be more relevant to health outcomes. Classify days of observation over a 16-year period into broad categories that capture salient daily local weather characteristics. Determine the rate of change in mean and median O3 concentrations within these different categories to assess how concentration trends are impacted by daily weather. Further examine if trends vary for observations in the extremes of the O3 distribution. We used k-means clustering to categorize days of observation based on the maximum daily temperature, standard deviation of daily temperature, mean daily ground level wind speed, mean daily water vapor pressure and mean daily sea-level barometric pressure. The five cluster solution was determined to be the appropriate one based on cluster diagnostics and cluster interpretability. Trends in cluster frequency and pollution trends within clusters were modeled using Poisson regression with penalized splines as well as quantile regression. There were five characteristic groupings identified. The frequency of days with large standard deviations in hourly temperature decreased over the observation period, whereas the frequency of warmer days with smaller deviations in temperature increased. O3 trends were significantly different within the different weather groupings. Furthermore, the rate of O3 change for the 95th percentile and 5th percentile was significantly different than the rate of change of the median for several of the weather categories.We found that O3 trends vary between different characteristic local weather patterns. O3 trends were significantly different between the different weather groupings suggesting an important interaction between changes in prevailing weather conditions and O3 concentration.

Evapotranspiration Measurement and Crop Coefficient Estimation over a Spring Wheat Farmland Ecosystem in the Loess Plateau

PubMed Central

Yang, Fulin; Zhang, Qiang; Wang, Runyuan; Zhou, Jing

2014-01-01

Evapotranspiration (ET) is an important component of the surface energy balance and hydrological cycle. In this study, the eddy covariance technique was used to measure ET of the semi-arid farmland ecosystem in the Loess Plateau during 2010 growing season (April to September). The characteristics and environmental regulations of ET and crop coefficient (Kc) were investigated. The results showed that the diurnal variation of latent heat flux (LE) was similar to single-peak shape for each month, with the largest peak value of LE occurring in August (151.4 W m−2). The daily ET rate of the semi-arid farmland in the Loess Plateau also showed clear seasonal variation, with the maximum daily ET rate of 4.69 mm day−1. Cumulative ET during 2010 growing season was 252.4 mm, and lower than precipitation. Radiation was the main driver of farmland ET in the Loess Plateau, which explained 88% of the variances in daily ET (p<0.001). The farmland Kc values showed the obvious seasonal fluctuation, with the average of 0.46. The correlation analysis between daily Kc and its major environmental factors indicated that wind speed (Ws), relative humidity (RH), soil water content (SWC), and atmospheric vapor pressure deficit (VPD) were the major environmental regulations of daily Kc. The regression analysis results showed that Kc exponentially decreased with Ws increase, an exponentially increased with RH, SWC increase, and a linearly decreased with VPD increase. An experiential Kc model for the semi-arid farmland in the Loess Plateau, driven by Ws, RH, SWC and VPD, was developed, showing a good consistency between the simulated and the measured Kc values. PMID:24941017

Evapotranspiration measurement and crop coefficient estimation over a spring wheat Farmland ecosystem in the Loess Plateau.

PubMed

Yang, Fulin; Zhang, Qiang; Wang, Runyuan; Zhou, Jing

2014-01-01

Evapotranspiration (ET) is an important component of the surface energy balance and hydrological cycle. In this study, the eddy covariance technique was used to measure ET of the semi-arid farmland ecosystem in the Loess Plateau during 2010 growing season (April to September). The characteristics and environmental regulations of ET and crop coefficient (Kc) were investigated. The results showed that the diurnal variation of latent heat flux (LE) was similar to single-peak shape for each month, with the largest peak value of LE occurring in August (151.4 W m(-2)). The daily ET rate of the semi-arid farmland in the Loess Plateau also showed clear seasonal variation, with the maximum daily ET rate of 4.69 mm day(-1). Cumulative ET during 2010 growing season was 252.4 mm, and lower than precipitation. Radiation was the main driver of farmland ET in the Loess Plateau, which explained 88% of the variances in daily ET (p<0.001). The farmland Kc values showed the obvious seasonal fluctuation, with the average of 0.46. The correlation analysis between daily Kc and its major environmental factors indicated that wind speed (Ws), relative humidity (RH), soil water content (SWC), and atmospheric vapor pressure deficit (VPD) were the major environmental regulations of daily Kc. The regression analysis results showed that Kc exponentially decreased with Ws increase, an exponentially increased with RH, SWC increase, and a linearly decreased with VPD increase. An experiential Kc model for the semi-arid farmland in the Loess Plateau, driven by Ws, RH, SWC and VPD, was developed, showing a good consistency between the simulated and the measured Kc values.

New results on equatorial thermospheric winds and temperatures from Ethiopia, Africa

NASA Astrophysics Data System (ADS)

Tesema, Fasil; Mesquita, Rafael; Meriwether, John; Damtie, Baylie; Nigussie, Melessew; Makela, Jonathan; Fisher, Daniel; Harding, Brian; Yizengaw, Endawoke; Sanders, Samuel

2017-03-01

Measurements of equatorial thermospheric winds, temperatures, and 630 nm relative intensities were obtained using an imaging Fabry-Perot interferometer (FPI), which was recently deployed at Bahir Dar University in Ethiopia (11.6° N, 37.4° E, 3.7° N magnetic). The results obtained in this study cover 6 months (53 nights of useable data) between November 2015 and April 2016. The monthly-averaged values, which include local winter and equinox seasons, show the magnitude of the maximum monthly-averaged zonal wind is typically within the range of 70 to 90 ms-1 and is eastward between 19:00 and 21:00 LT. Compared to prior studies of the equatorial thermospheric wind for this local time period, the magnitude is considerably weaker as compared to the maximum zonal wind speed observed in the Peruvian sector but comparable to Brazilian FPI results. During the early evening, the meridional wind speeds are 30 to 50 ms-1 poleward during the winter months and 10 to 25 ms-1 equatorward in the equinox months. The direction of the poleward wind during the winter months is believed to be mainly caused by the existence of the interhemispheric wind flow from the summer to winter hemispheres. An equatorial wind surge is observed later in the evening and is shifted to later local times during the winter months and to earlier local times during the equinox months. Significant night-to-night variations are also observed in the maximum speed of both zonal and meridional winds. The temperature observations show the midnight temperature maximum (MTM) to be generally present between 00:30 and 02:00 LT. The amplitude of the MTM was ˜ 110 K in January 2016 with values smaller than this in the other months. The local time difference between the appearance of the MTM and a pre-midnight equatorial wind was generally 60 to 180 min. A meridional wind reversal was also observed after the appearance of the MTM (after 02:00 LT). Climatological models, HWM14 and MSIS-00, were compared to the observations and the HWM14 model generally predicted the zonal wind observations well with the exception of higher model values by 25 ms-1 in the winter months. The HWM14 model meridional wind showed generally good agreement with the observations. Finally, the MSIS-00 model overestimated the temperature by 50 to 75 K during the early evening hours of local winter months. Otherwise, the agreement was generally good, although, in line with prior studies, the model failed to reproduce the MTM peak for any of the 6 months compared with the FPI data.

Energetics characteristics accounting for the explosive development of a twin extratropical cyclone over the Northwest Pacific Ocean

NASA Astrophysics Data System (ADS)

Fu, Shenming

2017-04-01

A twin extratropical cyclone that appeared over the Northwest Pacific Ocean during the winter of 2011 is reproduced reasonably well by the fifth-generation PSU-NCAR Mesoscale Model (MM5). One cyclone in this event has developed into an extreme explosive extratropical cyclone (EEC), with a maximum deepening rate up to 2.7 Bergeron, a minimum SLP of 933 hPa, and a maximum surface wind of 33 m s-1, which means its intensity is comparable with the intensity of a typhoon. The rotational and divergent wind kinetic energy (KE) budget equations are applied to this twin cyclone event so as to understand the rapid enhancement of the wind speed in this case. Preliminary results indicate that, overall, the rotational wind KE is much larger than the divergent wind KE, however, the latter can be of comparable intensity with the rotational wind KE around the regions where the wind speed strengthened most rapidly. Different quadrants of the twin cyclone show significant unevenness, overall, the southeastern quadrant of the EEC features the rapidest enhancement of wind speed, whereas the northwestern quadrant shows the slowest wind-speed acceleration. The vertical stretching of the EEC show consistent variation features with the rotational wind KE. The transport of KE by rotational wind, the conversion from divergent wind KE to rotational wind KE, and the work done by pressure gradient force all contributed to the enhancement of rotational wind KE. In contrast, the divergent wind KE is mainly produced by the baroclinic energy conversion.

The structure and dynamics of barrier jets along the southeast Alaskan coast

NASA Astrophysics Data System (ADS)

Olson, Joseph Benjamin

Coastal barrier jets along the complex orography of southeastern Alaska were investigated using high resolution observations and model simulations. Barrier jet events were sampled with the Wyoming King-Air research aircraft during the Southeastern Alaskan Regional Jet (SARJET) field experiment in 2004. These observations, combined with simulations of select cases by the Penn State-NCAR Mesoscale Model (MM5), were used to better understand barrier jet structure and dynamics. A suite of idealized simulations were used to put the case studies in perspective with a larger set of atmospheric conditions, while also evaluating previous theoretical and observational results. Two SARJET case studies were investigated along the tall and steep Fairweather Mountains near Juneau, Alaska. The first case (24 September 2004) was a classical barrier jet forced primarily by onshore flow and upslope adiabatic cooling, with maximum winds >30 m s-1 at the coast between 600-800 m ASL and an offshore extent of ˜60 km. In contrast, the hybrid jet (12 October 2004) was influenced by an offshore-directed gap flow at the coast, which produced a warm anomaly over the coast associated with downslope flow and a wind maximum (˜30 m s-1) that was displaced 30-40 km offshore at 500 m ASL. A sensitivity experiment in which the coastal mountain gap was filled led to a ˜40% reduction in the jet width, and the position of the jet maximum shifted ˜40 km to the coast, but the overall jet intensity remained approximately the same. The generality of these SARJET results was tested by generating a set of three-dimensional idealized MM5 simulations by varying wind speeds, wind directions, and static stabilities for the classical jet simulations, while incrementing the magnitude of the inland cold pool (instead of static stability) for hybrid jet simulations. The broad inland terrain was shown to impact the upstream winds by rotating them cyclonically to become more terrain-parallel within 500-1000 km of the coast. This reduced cross-barrier component acted to reduce the local Froude number of the impinging flow, thus enhancing the potential for flow blocking. Thus, the enhancement of the large-scale mountain anticyclone by the inland terrain acts to "precondition" the impinging flow for barrier jet development. The largest simulated wind speed enhancements (˜1.9-2.0) for the classic and hybrid jets occurred for low Froude numbers ( Fr), with a maximum at Fr ˜0.3-0.4. Low ambient wind speeds (10--15 m s-1) and southerly (170-180°) wind directions (˜30-45° from coast-parallel) were also ingredients for the largest wind speed enhancements. The widest barrier jets were found in simulations with ambient winds oriented nearly terrain-parallel (˜160°) with strong static stability (N > 0.01 s-1). Hybrid barrier jets were slightly wider than the classical, with the gap outflows acting to shift the position of the jet maximum further away from the coast. During periods of maximal gap outflow (hrs 6-18), the height of the jet maximums were typically lower than the classical simulations, since the hybrid jet maximum was located at the top of the shallow gap outflow. The jet height was most correlated with total wind speed, Utotal, and negatively correlated with static stability, N, suggesting that the height of the jet maximum approximately scales as U total/N, which is proportional to the vertical wavelength of a mountain wave. Finally, a detailed assessment of the usefulness of the previous linear theory and scale analysis on barrier jets was performed. The high Fr relationship (L = Nhm/ f) performed better than the low Fr relationship (L = Un/f) in determining the offshore extent of the barrier jet. The implementation of the dividing streamline concept of Sheppard's model for determining the proper blocking height (hd) resulted in a modified form (L = Nhd/ f), which improved the predictive skill. For the determination of maximum wind speeds, the high Fr relationship (DeltaV = Nhm) was found to be better correlated with the measured values than the low Fr relationship ( DeltaV = Un) throughout the full range of Fr. Two-dimensional linear theory performed poorly for Fr < 0.5. Modifications were made to these previous relationships to better account for the three dimensional winds, which helped to improve the estimated wind speed enhancements.

Association between dengue fever incidence and meteorological factors in Guangzhou, China, 2005-2014.

PubMed

Xiang, Jianjun; Hansen, Alana; Liu, Qiyong; Liu, Xiaobo; Tong, Michael Xiaoliang; Sun, Yehuan; Cameron, Scott; Hanson-Easey, Scott; Han, Gil-Soo; Williams, Craig; Weinstein, Philip; Bi, Peng

2017-02-01

This study aims to (1) investigate the associations between climatic factors and dengue; and (2) identify the susceptible subgroups. De-identified daily dengue cases in Guangzhou for 2005-2014 were obtained from the Chinese Center for Disease Control and Prevention. Weather data were downloaded from the China Meteorological Data Sharing Service System. Distributed lag non-linear models (DLNM) were used to graphically demonstrate the three-dimensional temperature-dengue association. Generalised estimating equation models (GEE) with piecewise linear spline functions were used to quantify the temperature-dengue associations. Threshold values were estimated using a broken-stick model. Middle-aged and older people, people undertaking household duties, retirees, and those unemployed were at high risk of dengue. Reversed U-shaped non-linear associations were found between ambient temperature, relative humidity, extreme wind velocity, and dengue. The optimal maximum temperature (T max ) range for dengue transmission in Guangzhou was 21.6-32.9°C, and 11.2-23.7°C for minimum temperature (T min ). A 1°C increase of T max and T min within these ranges was associated with 11.9% and 9.9% increase in dengue at lag0, respectively. Although lag effects of temperature were observed for up to 141 days for T max and 150 days for T min , the maximum lag effects were observed at 32 days and 39 days respectively. Average relative humidity was negatively associated with dengue when it exceeded 78.9%. Maximum wind velocity (>10.7m/s) inhibited dengue transmission. Climatic factors had significant impacts on dengue in Guangzhou. Lag effects of temperature on dengue lasted the local whole epidemic season. To reduce the likely increasing dengue burden, more efforts are needed to strengthen the capacity building of public health systems. Copyright © 2016 Elsevier Inc. All rights reserved.

Change in diurnal variations of meteorological variables induced by anthropogenic aerosols over the North China Plain in summer 2008

NASA Astrophysics Data System (ADS)

Gao, Yi; Zhang, Meigen; Liu, Xiaohong; Wang, Lili

2016-04-01

This study investigates the impacts of all anthropogenic aerosols and anthropogenic black carbon (BC) on the diurnal variations of meteorological variables in the atmospheric boundary layer over the North China Plain (NCP) during June to August 2008, using a coupled meteorology and chemistry model (WRF-Chem). The results of the ensemble numerical experiments show that surface air temperature decreases by about 0.6 to 1.2 K with the maximum decrease over the Beijing urban area and the southern part of Hebei province, and the surface relative humidity (RH) increases by 2-4 % owing to all anthropogenic aerosols. On the contrary, anthropogenic BC induces a small change of temperature and RH at surface. Averaged for Beijing, Tianjin, and Hebei province (BTH region) and High Particle Concentration (HPC) periods when PM2.5 surface concentration is more than 60 μg m-3 and daily AOD is more than 0.9, all anthropogenic aerosols decrease air temperature under 850 hPa and increase it between 500 and 850 hPa, while anthropogenic BC increases it for whole atmosphere. The maximum changes occur at 08:00-20:00 (local time). Aerosol-induced surface energy and diabatic heating change leads to a cooling at the surface and in the lower atmosphere and a warming in the middle troposphere at 08:00-17:00, with reversed effects at 20:00-05:00. BC cools the atmosphere at the surface and warms the atmosphere above for the whole day. As a result, the equivalent potential temperature profile change shows that the lower atmosphere is more stable at 08:00 and 14:00. All anthropogenic aerosols decrease the surface wind speed by 20-60 %, while anthropogenic BC decreases the wind speed by 10-40 % over the NCP with the maximum decrease at 08:00. The aerosol-induced stabilization of the lower atmosphere favors the accumulation of air pollutants and thus contributes to deterioration of visibility and fog-haze events.

Characterization of the lower boundary layer based on Sodar observations (2010-2013) in Bauru, São Paulo, Brazil

NASA Astrophysics Data System (ADS)

Held, Gerhard; Cruz, Felipe

2014-05-01

Continuous Sodar observations from Bauru, located in the central State of São Paulo, are presented in this paper for a 4-year period (January 2010 - December 2013). The data were collected at the Meteorological Research Institute (IPMet) of the Universidade Estadual Paulista "Júlio de Mesquita Filho" (UNESP), Campus Bauru, which is situated at the southeastern outskirts of the town, in a pristine environment with mostly indigenous vegetation. The medium-sized Sodar was programmed to record 60-minute averages of the vertical wind profiles (u, v, w) between 30 and 800 m above ground level (AGL, station height 624 m above mean sea level) at 30-minute intervals with a vertical resolution of 10 m. The data recovery was almost 100% in the first 160 m, subsequently diminishing gradually to 50% at 370 m, 20% at 500 m and then tailing off to only 1% at 800 m AGL. Since the Sodar is an acoustic sensor, the reception of the backscattered signals is strongly dependent on meteorological conditions. The maximum height of 800 m was maintained, despite the low recovery rate, because it is important for individual case studies. However, mean wind roses will only be presented up to 500 m AGL, to avoid a possible bias in sampling wind directions. In this paper wind roses at selected heights are presented to document the variation of the wind direction and speed with height, as well as their seasonal variation. Besides the standard primary data of the 3 wind components, the scalar hourly mean wind speed and the mean vector direction, the Sodar also generates their standard deviations. Furthermore, a variety of derived parameters, such as shear, shear direction, sigma speed, sigma Phi, sigma Theta, turbulence intensity, Pasquill-Gifford (PG) stability class, turbulent kinetic energy and eddy dissipation rate are generated as hourly means at each height level and recorded as sliding means every 30 min. The Software also offers the facility to generate a separate daily file with so called Non-Profile Variables, providing a single value for every vertical profile of the following variables: PG stability, surface heat flux, Monin Obukov Length and friction velocity. These are important input data for dispersion modeling, but only being calculated under convective conditions (mostly mid-day & early afternoon). Furthermore, the maximum range of the backscatter signal, as well as estimates of the lowest inversion height and the mixing height, if detected, are also being recorded for every profile. However, the last two variables mentioned are only estimated from the backscatter profile and thus not very reliable. Nevertheless, since there is no RASS attached to this Sodar, the statistics of all these parameters do provide a good record of the diurnal variation of the nocturnal stable Planetary Boundary Layer and daytime instability. Finally, the seasonal variation and characteristics of the nocturnal Low-Level-Jets (LLJs), developing on top of the surface radiation inversion, will be presented. These LLJs generally form during late evening at altitudes ranging from 200-500 m AGL, with maximum speeds of 12-25 m/s from east-south-east. They usually last until 08:00-09:00 LT (Local Time), when the inversion has been eroded by the solar radiation. LLJs could be identified on about 30-70 % of the days per month throughout the year. The practical importance of the LLJ lies in the rapid transport of moisture and pollutants in a narrow vertical band above the radiation inversion.

40 CFR 420.132 - Effluent limitations attainable by the application of the best practicable control technology...

Code of Federal Regulations, 2010 CFR

2010-07-01

... daily 1 Maximum monthly avg. 1 TSS 0.00998 0.00465 pH (2) (2) 1 Pounds per thousand pound of product. 2... Maximum daily 1 Maximum monthly avg. 1 O&G (as HEM) 0.00746 0.00446 TSS 0.0123 0.00508 pH (2) (2) 1 Pounds...

40 CFR 420.132 - Effluent limitations attainable by the application of the best practicable control technology...

Code of Federal Regulations, 2011 CFR

2011-07-01

... daily 1 Maximum monthly avg. 1 TSS 0.00998 0.00465 pH (2) (2) 1 Pounds per thousand pound of product. 2... Maximum daily 1 Maximum monthly avg. 1 O&G (as HEM) 0.00746 0.00446 TSS 0.0123 0.00508 pH (2) (2) 1 Pounds...

Shock heating of the solar wind plasma

NASA Technical Reports Server (NTRS)

Whang, Y. C.; Liu, Shaoliang; Burlaga, L. F.

1990-01-01

The role played by shocks in heating solar-wind plasma is investigated using data on 413 shocks which were identified from the plasma and magnetic-field data collected between 1973 and 1982 by Pioneer and Voyager spacecraft. It is found that the average shock strength increased with the heliocentric distance outside 1 AU, reaching a maximum near 5 AU, after which the shock strength decreased with the distance; the entropy of the solar wind protons also reached a maximum at 5 AU. An MHD simulation model in which shock heating is the only heating mechanism available was used to calculate the entropy changes for the November 1977 event. The calculated entropy agreed well with the value calculated from observational data, suggesting that shocks are chiefly responsible for heating solar wind plasma between 1 and 15 AU.

High Winds and the Vertical Structure of Chl-a in the Southern Ocean: Insights from Remote Sensing and Novel in situ Sensors

NASA Astrophysics Data System (ADS)

Carranza, M. M.; Gille, S. T.; Franks, P. J. S.; Johnson, K. S.; Girton, J. B.

2016-02-01

The Southern Ocean is under the influence of strong atmospheric synoptic activity and contains some of the oceans deepest mixed layers. Deep mixed layers can transport phytoplankton below the euphotic zone, and phytoplankton growth is hypothesized to be co-limited by iron and light. Atmospheric forcing drives changes in the mixed-layer depth (MLD) that influence light levels and nutrient input to the euphotic zone. In summer, when the MLD is shallow and close to the euphotic depth, high satellite Chl-a correlate with high winds, consistent with wind-driven entrainment that can potentially increase nutrient concentrations in the euphotic zone. However, correlations between Chl-a and diurnal winds are largest at zero time lag. High winds can inject nutrients on short timescales (< 1 day), but in situ incubation experiments after iron addition indicate phytoplankton growth on slightly longer timescales (> 3-4 days), suggesting that the correlations are not a result of growth. High winds can also entrain Chl-a from a subsurface Chl-a maximum. Novel bio-optical sensors mounted on elephant seals and autonomous floats allow us to examine the vertical structure of Chl-a in the Southern Ocean. In this study, we investigate the occurrence of subsurface Chl-a maxima. We find that surface Chl-a is a relatively good proxy for depth-integrated Chl-a within the euphotic zone but gives an inadequate representation of biomass within the mixed layer, particularly in the summer. Subsurface Chl-a maxima are not uncommon and may occur in all seasons. Chl-a maxima that correlate with particle backscattering in summer and fall are found near the base of the mixed layer, closer to the nutrient maximum than the light maximum, suggesting that nutrient limitation (i.e., essentially iron) can play a greater role than light limitation in governing productivity, and that high winds potentially entrain a subsurface Chl-a maximum into the summer mixed layer.

Upwelling characteristics in the Gulf of Finland (Baltic Sea) as revealed by Ferrybox measurements in 2007-2013

NASA Astrophysics Data System (ADS)

Kikas, Villu; Lips, Urmas

2016-07-01

Ferrybox measurements have been carried out between Tallinn and Helsinki in the Gulf of Finland (Baltic Sea) on a regular basis since 1997. The system measures autonomously water temperature, salinity, chlorophyll a fluorescence and turbidity and takes water samples for further analyses at a predefined time interval. We aimed to show how the Ferrybox technology could be used to study the coastal upwelling events in the Gulf of Finland. Based on the introduced upwelling index and related criteria, 33 coastal upwelling events were identified in May-September 2007-2013. The number of events, as well as the frequency of their occurrence and intensity expressed as a sum of daily average temperature deviations in the 20 km wide coastal area, were almost equal near the northern and southern coasts. Nevertheless, the wind impulse, which was needed to generate upwelling events of similar intensity, differed between the northern and southern coastal areas. It is suggested that the general thermohaline structure adapted to the prevailing forcing and the estuarine character of the basin weaken the upwelling created by the westerly to southwesterly (up-estuary) winds and strengthen the upwelling created by the easterly to northeasterly (down-estuary) winds. Two types of upwelling events were identified - one characterized by a strong temperature front and the other revealing gradual decrease in temperature from the open sea to the coastal area, with maximum temperature deviation close to the shore.

Extreme Windstorms and Related Impacts on Iberia

NASA Astrophysics Data System (ADS)

Liberato, Margarida L. R.; Ordóñez, Paulina; Pinto, Joaquim G.; Ramos, Alexandre M.; Karremann, Melanie K.; Trigo, Isabel F.

2014-05-01

Extreme windstorms are one of the major natural catastrophes in the mid latitudes, one of the most costly natural hazards in Europe and are responsible for substantial economic damages and even fatalities. During the recent winters, the Iberian Peninsula was hit by severe (wind) storms such as Klaus (January 2009), Xynthia (February 2010) and Gong (January 2013) which exhibited uncommon characteristics. They were all explosive extratropical cyclones formed over the mid-Atlantic, travelling then eastwards at lower latitudes than usual along the edge of the dominant North Atlantic storm track. In this work we present a windstorm catalogue for the Iberian Peninsula, where the characteristics of the potentially more destructive windstorms for the 1979-2012 period are identified. For this purpose, the potential impact of high winds over the Iberian Peninsula is assessed by using a daily damage index based on maximum wind speeds that exceeds the local 98th percentile threshold. Then, the characteristics of extratropical cyclones associated with these events are analyzed. Results indicate that these are fast moving, intense cyclones, typically located near the northwestern tip of the Iberian Peninsula. This work was partially supported by FEDER (Fundo Europeu de Desenvolvimento Regional) funds through the COMPETE (Programa Operacional Factores de Competitividade) and by national funds through FCT (Fundação para a Ciência e a Tecnologia, Portugal) under project STORMEx FCOMP-01-0124-FEDER- 019524 (PTDC/AAC-CLI/121339/2010). A. M. Ramos was also supported by a FCT postdoctoral Grant (FCT/DFRH/SFRH/BPD/84328/2012).

Distinctive Features of Surface Winds over Indian Ocean Between Strong and Weak Indian Summer Monsoons: Implications With Respect To Regional Rainfall Change in India

NASA Astrophysics Data System (ADS)

Zheng, Y.; Bourassa, M. A.; Ali, M. M.

2017-12-01

This observational study focuses on characterizing the surface winds in the Arabian Sea (AS), the Bay of Bengal (BoB), and the southern Indian Ocean (SIO) with special reference to the strong and weak Indian summer monsoon rainfall (ISMR) using the latest daily gridded rainfall dataset provided by the Indian Meteorological Department (IMD) and the Cross-Calibrated Multi-Platform (CCMP) gridded wind product version 2.0 produced by Remote Sensing System (RSS) over the overlapped period 1991-2014. The potential links between surface winds and Indian regional rainfall are also examined. Results indicate that the surface wind speeds in AS and BoB during June-August are almost similar during strong ISMRs and weak ISMRs, whereas significant discrepancies are observed during September. By contrast, the surface wind speeds in SIO during June-August are found to be significantly different between strong and weak ISMRs, where they are similar during September. The significant differences in monthly mean surface wind convergence between strong and weak ISMRs are not coherent in space in the three regions. However, the probability density function (PDF) distributions of daily mean area-averaged values are distinctive between strong and weak ISMRs in the three regions. The correlation analysis indicates the area-averaged surface wind speeds in AS and the area-averaged wind convergence in BoB are highly correlated with regional rainfall for both strong and weak ISMRs. The wind convergence in BoB during strong ISMRs is relatively better correlated with regional rainfall than during weak ISMRs. The surface winds in SIO do not greatly affect Indian rainfall in short timescales, however, they will ultimately affect the strength of monsoon circulation by modulating Indian Ocean Dipole (IOD) mode via atmosphere-ocean interactions.

Estimating vertical velocity and radial flow from Doppler radar observations of tropical cyclones

NASA Astrophysics Data System (ADS)

Lee, J. L.; Lee, W. C.; MacDonald, A. E.

2006-01-01

The mesoscale vorticity method (MVM) is used in conjunction with the ground-based velocity track display (GBVTD) to derive the inner-core vertical velocity from Doppler radar observations of tropical cyclone (TC) Danny (1997). MVM derives the vertical velocity from vorticity variations in space and in time based on the mesoscale vorticity equation. The use of MVM and GBVTD allows us to derive good correlations among the eye-wall maximum wind, bow-shaped updraught and echo east of the eye-wall in Danny. Furthermore, we demonstrate the dynamically consistent radial flow can be derived from the vertical velocity obtained from MVM using the wind decomposition technique that solves the Poisson equations over a limited-area domain. With the wind decomposition, we combine the rotational wind which is obtained from Doppler radar wind observations and the divergent wind which is inferred dynamically from the rotational wind to form the balanced horizontal wind in TC inner cores, where rotational wind dominates the divergent wind. In this study, we show a realistic horizontal and vertical structure of the vertical velocity and the induced radial flow in Danny's inner core. In the horizontal, the main eye-wall updraught draws in significant surrounding air, converging at the strongest echo where the maximum updraught is located. In the vertical, the main updraught tilts vertically outwards, corresponding very well with the outward-tilting eye-wall. The maximum updraught is located at the inner edge of the eye-wall clouds, while downward motions are found at the outer edge. This study demonstrates that the mesoscale vorticity method can use high-temporal-resolution data observed by Doppler radars to derive realistic vertical velocity and the radial flow of TCs. The vorticity temporal variations crucial to the accuracy of the vorticity method have to be derived from a high-temporal-frequency observing system such as state-of-the-art Doppler radars.

Selected micrometeorological and soil-moisture data at Amargosa Desert Research Site, an arid site near Beatty, Nye County, Nevada, 1998-2000

USGS Publications Warehouse

Johnson, Michael J.; Mayers, Charles J.; Andraski, Brian J.

2002-01-01

Selected micrometeorological and soil-moisture data were collected at the Amargosa Desert Research Site adjacent to a low-level radioactive waste and hazardous chemical waste facility near Beatty, Nev., 1998-2000. Data were collected in support of ongoing research studies to improve the understanding of hydrologic and contaminant-transport processes in arid environments. Micrometeorological data include precipitation, air temperature, solar radiation, net radiation, relative humidity, ambient vapor pressure, wind speed and direction, barometric pressure, soil temperature, and soil-heat flux. All micrometeorological data were collected using a 10-second sampling interval by data loggers that output daily mean, maximum, and minimum values, and hourly mean values. For precipitation, data output consisted of daily, hourly, and 5-minute totals. Soil-moisture data included periodic measurements of soil-water content at nine neutron-probe access tubes with measurable depths ranging from 5.25 to 29.75 meters. The computer data files included in this report contain the complete micrometeorological and soil-moisture data sets. The computer data consists of seven files with about 14 megabytes of information. The seven files are in tabular format: (1) one file lists daily mean, maximum, and minimum micrometeorological data and daily total precipitation; (2) three files list hourly mean micrometeorological data and hourly precipitation for each year (1998-2000); (3) one file lists 5-minute precipitation data; (4) one file lists mean soil-water content by date and depth at four experimental sites; and (5) one file lists soil-water content by date and depth for each neutron-probe access tube. This report highlights selected data contained in the computer data files using figures, tables, and brief discussions. Instrumentation used for data collection also is described. Water-content profiles are shown to demonstrate variability of water content with depth. Time-series data are plotted to illustrate temporal variations in micrometeorological and soil-water content data. Substantial precipitation at the end of an El Ni?o cycle in early 1998 resulted in measurable water penetration to a depth of 1.25 meters at one of the four experimental soil-monitoring sites.

From Dust Devil to Sustainable Swirling Wind Energy

NASA Astrophysics Data System (ADS)

Zhang, Mingxu; Luo, Xilian; Li, Tianyu; Zhang, Liyuan; Meng, Xiangzhao; Kase, Kiwamu; Wada, Satoshi; Yu, Chuck Wah; Gu, Zhaolin

2015-02-01

Dust devils are common but meteorologically unique phenomena on Earth and on Mars. The phenomenon produces a vertical vortex motion in the atmosphere boundary layer and often occurs in hot desert regions, especially in the afternoons from late spring to early summer. Dust devils usually contain abundant wind energy, for example, a maximum swirling wind velocity of up to 25 m/s, with a 15 m/s maximum vertical velocity and 5 m/s maximum near-surface horizontal velocity can be formed. The occurrences of dust devils cannot be used for energy generation because these are generally random and short-lived. Here, a concept of sustained dust-devil-like whirlwind is proposed for the energy generation. A prototype of a circular shed with pre-rotation vanes has been devised to generate the whirlwind flow by heating the air inflow into the circular shed. The pre-rotation vanes can provide the air inflow with angular momentum. The results of numerical simulations and experiment illustrate a promising potential of the circular shed for generating swirling wind energy via the collection of low-temperature solar energy.

Impact of Monsoon to Aquatic Productivity and Fish Landing at Pesawaran Regency Waters

NASA Astrophysics Data System (ADS)

Kunarso; Zainuri, Muhammad; Ario, Raden; Munandar, Bayu; Prayogi, Harmon

2018-02-01

Monsoon variability influences the productivity processes in the ocean and has different responses in each waters. Furthermore, variability of marine productivity affects to the fisheries resources fluctuation. This research has conducted using descriptive method to investigate the consequences of monsoon variability to aquatic productivity, sea surface temperature (SST), fish catches, and fish season periods at Pesawaran Regency waters, Lampung. Variability of aquatic productivity was determined based on chlorophyll-a indicator from MODIS satellite images. Monsoon variability was governed based on wind parameters and fish catches from fish landing data of Pesawaran fish market. The result showed that monsoon variability had affected to aquatic productivity, SST, and fish catches at Pesawaran Regency waters. Maximum wind speed and lowest SST occurred twice in a year, December to March and August to October, which the peaks were on January (2.55 m/s of wind speed and 29.66°C of SST) and September (2.44 m/s of wind speed and 29.06°C of SST). Also, Maximum aquatic productivity happened on January to March and July to September, which it was arisen simultaneously with maximum wind speed and the peaks was 0.74 mg/m3 and 0.78 mg/m3, on February and August respectively. The data showed that fish catches decreased along with strong wind speed and low SST. However, when weak wind speed and high SST occurred, fish catches increased. The correlation between Catch per Unit Effort (CPUE) with SST, wind speed, and chlorophyll-a was at value 0.76, -0.67, and -0.70, respectively. The high rate fish catches in Pesawaran emerged on March-May and September-December.

Maximum power point tracking techniques for wind energy systems using three levels boost converter

NASA Astrophysics Data System (ADS)

Tran, Cuong Hung; Nollet, Frédéric; Essounbouli, Najib; Hamzaoui, Abdelaziz

2018-05-01

This paper presents modeling and simulation of three level Boost DC-DC converter in Wind Energy Conversion System (WECS). Three-level Boost converter has significant advantage compared to conventional Boost. A maximum power point tracking (MPPT) method for a variable speed wind turbine using permanent magnet synchronous generator (PMSG) is also presented. Simulation of three-level Boost converter topology with Perturb and Observe algorithm and Fuzzy Logic Control is implemented in MATLAB/SIMULINK. Results of this simulation show that the system with MPPT using fuzzy logic controller has better performance to the Perturb and Observe algorithm: fast response under changing conditions and small oscillation.

Sensitivity of the reference evapotranspiration to key climatic variables during the growing season in the Ejina oasis northwest China.

PubMed

Hou, Lan-Gong; Zou, Song-Bing; Xiao, Hong-Lang; Yang, Yong-Gang

2013-01-01

The standardized FAO56 Penman-Monteith model, which has been the most reasonable method in both humid and arid climatic conditions, provides reference evapotranspiration (ETo) estimates for planning and efficient use of agricultural water resources. And sensitivity analysis is important in understanding the relative importance of climatic variables to the variation of reference evapotranspiration. In this study, a non-dimensional relative sensitivity coefficient was employed to predict responses of ETo to perturbations of four climatic variables in the Ejina oasis northwest China. A 20-year historical dataset of daily air temperature, wind speed, relative humidity and daily sunshine duration in the Ejina oasis was used in the analysis. Results have shown that daily sensitivity coefficients exhibited large fluctuations during the growing season, and shortwave radiation was the most sensitive variable in general for the Ejina oasis, followed by air temperature, wind speed and relative humidity. According to this study, the response of ETo can be preferably predicted under perturbation of air temperature, wind speed, relative humidity and shortwave radiation by their sensitivity coefficients.

Elemental and charge state composition of the fast solar wind observed with SMS instruments on WIND

NASA Technical Reports Server (NTRS)

Gloeckler, G.; Galvin, A. B.; Ipavich, F. M.; Hamilton, D. C.; Bochsler, P.; Geiss, J.; Fisk, L. A.; Wilken, B.

1995-01-01

The elemental composition and charge state distributions of heavy ions of the solar wind provide essential information about: (1) atom-ion separation processes in the solar atmosphere leading to the 'FIP effect' (the overabundance of low First Ionization potential (FIP) elements in the solar wind compared to the photosphere); and (2) coronal temperature profiles, as well as mechanisms which heat the corona and accelerate the solar wind. This information is required for solar wind acceleration models. The SWICS instrument on Ulysses measures for all solar wind flow conditions the relative abundance of about 8 elements and 20 charge states of the solar wind. Furthermore, the Ulysses high-latitude orbit provides an unprecedented look at the solar wind from the polar coronal holes near solar minimum conditions. The MASS instrument on the WIND spacecraft is a high-mass resolution solar wind ion mass spectrometer that will provide routinely not only the abundances and charge state of all elements easily measured with SWICS, but also of N, Mg, S. The MASS sensor was fully operational at the end of 1994 and has sampled the in-ecliptic solar wind composition in both the slow and the corotating fast streams. This unique combination of SWICS on Ulysses and MASS on WIND allows us to view for the first time the solar wind from two regions of the large coronal hole. Observations with SWICS in the coronal hole wind: (1) indicate that the FIP effect is small; and (2) allow us determine the altitude of the maximum in the electron temperature profile, and indicate a maximum temperature of approximately 1.5 MK. New results from the SMS instruments on Wind will be compared with results from SWICS on Ulysses.

Sensitivity of southern hemisphere westerly wind to boundary conditions for the last glacial maximum

NASA Astrophysics Data System (ADS)

Jun, S. Y.; Kim, S. J.; Kim, B. M.

2017-12-01

To examine the change in SH westerly wind in the LGM, we performed LGM simulation with sensitivity experiments by specifying the LGM sea ice in the Southern Ocean (SO), ice sheet over Antarctica, and tropical pacific sea surface temperature to CAM5 atmosphere general circulation model (GCM). The SH westerly response to LGM boundary conditions in the CAM5 was compared with those from CMIP5 LGM simulations. In the CAM5 LGM simulation, the SH westerly wind substantially increases between 40°S and 65°S, while the zonal-mean zonal wind decreases at latitudes higher than 65°S. The position of the SH maximum westerly wind moves poleward by about 8° in the LGM simulation. Sensitivity experiments suggest that the increase in SH westerly winds is mainly due to the increase in sea ice in the SO that accounts for 60% of total wind change. In the CMIP5-PMIP3 LGM experiments, most of the models show the slight increase and poleward shift of the SH westerly wind as in the CAM5 experiment. The increased and poleward shifted westerly wind in the LGM obtained in the current model result is consistent with previous model results and some lines of proxy evidence, though opposite model responses and proxy evidence exist for the SH westerly wind change.

Regional and local background ozone in Houston during Texas Air Quality Study 2006

NASA Astrophysics Data System (ADS)

Langford, A. O.; Senff, C. J.; Banta, R. M.; Hardesty, R. M.; Alvarez, R. J.; Sandberg, Scott P.; Darby, Lisa S.

2009-04-01

Principal Component Analysis (PCA) is used to isolate the common modes of behavior in the daily maximum 8-h average ozone mixing ratios measured at 30 Continuous Ambient Monitoring Stations in the Houston-Galveston-Brazoria area during the Second Texas Air Quality Study field intensive (1 August to 15 October 2006). Three principal components suffice to explain 93% of the total variance. Nearly 84% is explained by the first component, which is attributed to changes in the "regional background" determined primarily by the large-scale winds. The second component (6%) is attributed to changes in the "local background," that is, ozone photochemically produced in the Houston area and spatially and temporally averaged by local circulations. Finally, the third component (3.5%) is attributed to short-lived plumes containing high ozone originating from industrial areas along Galveston Bay and the Houston Ship Channel. Regional background ozone concentrations derived using the first component compare well with mean ozone concentrations measured above the Gulf of Mexico by the tunable profiler for aerosols and ozone lidar aboard the NOAA Twin Otter. The PCA regional background values also agree well with background values derived using the lowest daily 8-h maximum method of Nielsen-Gammon et al. (2005), provided the Galveston Airport data (C34) are omitted from that analysis. The differences found when Galveston is included are caused by the sea breeze, which depresses ozone at Galveston relative to sites further inland. PCA removes the effects of this and other local circulations to obtain a regional background value representative of the greater Houston area.

Integrated approach using multi-platform sensors for enhanced high-resolution daily ice cover product

NASA Astrophysics Data System (ADS)

Bonev, George; Gladkova, Irina; Grossberg, Michael; Romanov, Peter; Helfrich, Sean

2016-09-01

The ultimate objective of this work is to improve characterization of the ice cover distribution in the polar areas, to improve sea ice mapping and to develop a new automated real-time high spatial resolution multi-sensor ice extent and ice edge product for use in operational applications. Despite a large number of currently available automated satellite-based sea ice extent datasets, analysts at the National Ice Center tend to rely on original satellite imagery (provided by satellite optical, passive microwave and active microwave sensors) mainly because the automated products derived from satellite optical data have gaps in the area coverage due to clouds and darkness, passive microwave products have poor spatial resolution, automated ice identifications based on radar data are not quite reliable due to a considerable difficulty in discriminating between the ice cover and rough ice-free ocean surface due to winds. We have developed a multisensor algorithm that first extracts maximum information on the sea ice cover from imaging instruments VIIRS and MODIS, including regions covered by thin, semitransparent clouds, then supplements the output by the microwave measurements and finally aggregates the results into a cloud gap free daily product. This ability to identify ice cover underneath thin clouds, which is usually masked out by traditional cloud detection algorithms, allows for expansion of the effective coverage of the sea ice maps and thus more accurate and detailed delineation of the ice edge. We have also developed a web-based monitoring system that allows comparison of our daily ice extent product with the several other independent operational daily products.

Seasonal and daily snowmelt runoff estimates utilizing satellite data. [Wind River Mountains, Wyoming

NASA Technical Reports Server (NTRS)

1980-01-01

Methods using snowcovered area to update seasonal forecasts as snowmelt progresses are also being used in quasi-operational situations. The input of snowcovered area to snowmelt models for short term perdictions was attempted in two ways; namely, the modification of existing hydrologic models and/or the use of models that were specifically designed to use snowcovered area. A daily snowmelt runoff model was used with LANDSAT data to simulate discharge on remote basins in the Wind River Mountains of Wyoming. Daily predicted and actual flows compare closely, and, summarized over the entire snowmelt season (April 1 - September 30), the average difference is only three percent. The model and snowcovered area data are currently being tested on additional watersheds to determine the method's transferability.

Influence of trap modifications and environmental predictors on capture success of southern flying squirrels

USGS Publications Warehouse

Jacques, Christopher N.; Zweep, James S.; Scheihing, Mary E.; Rechkemmer, Will T.; Jenkins, Sean E.; Klaver, Robert W.; Dubay, Shelli A.

2017-01-01

Sherman traps are the most commonly used live traps in studies of small mammals and have been successfully used in the capture of arboreal species such as the southern flying squirrel (Glaucomys volans). However, southern flying squirrels spend proportionately less time foraging on the ground, which necessitates above-ground trapping methods and modifications of capture protocols. Further, quantitative estimates of the factors affecting capture success of flying squirrel populations have focused solely on effects of trapping methodologies. We developed and evaluated the efficacy of a portable Sherman trap design for capturing southern flying squirrels during 2015–2016 at the Alice L. Kibbe Field Station, Illinois, USA. Additionally, we used logistic regression to quantify potential effects of time-dependent (e.g., weather) and time-independent (e.g., habitat, extrinsic) factors on capture success of southern flying squirrels. We recorded 165 capture events (119 F, 44 M, 2 unknown) using our modified Sherman trap design. Probability of capture success decreased 0.10/1° C increase in daily maximum temperature and by 0.09/unit increase (km/hr) in wind speed. Conversely, probability of capture success increased by 1.2/1° C increase in daily minimum temperature. The probability of capturing flying squirrels was negatively associated with trap orientation. When tree-mounted traps are required, our modified trap design is a safe, efficient, and cost-effective method of capturing animals when moderate weather (temp and wind speed) conditions prevail. Further, we believe that strategic placement of traps (e.g., northeast side of tree) and quantitative information on site-specific (e.g., trap location) characteristics (e.g., topographical features, slope, aspect, climatologic factors) could increase southern flying squirrel capture success. © 2017 The Wildlife Society.

Report: Total Maximum Daily Load Program Needs Better Data and Measures to Demonstrate Environmental Results

EPA Pesticide Factsheets

Report #2007-P-00036, September 19, 2007. EPA does not have comprehensive information on the outcomes of the Total Maximum Daily Load (TMDL) program nationwide, nor national data on TMDL implementation activities.

Empirical models of wind conditions on Upper Klamath Lake, Oregon

USGS Publications Warehouse

Buccola, Norman L.; Wood, Tamara M.

2010-01-01

Upper Klamath Lake is a large (230 square kilometers), shallow (mean depth 2.8 meters at full pool) lake in southern Oregon. Lake circulation patterns are driven largely by wind, and the resulting currents affect the water quality and ecology of the lake. To support hydrodynamic modeling of the lake and statistical investigations of the relation between wind and lake water-quality measurements, the U.S. Geological Survey has monitored wind conditions along the lakeshore and at floating raft sites in the middle of the lake since 2005. In order to make the existing wind archive more useful, this report summarizes the development of empirical wind models that serve two purposes: (1) to fill short (on the order of hours or days) wind data gaps at raft sites in the middle of the lake, and (2) to reconstruct, on a daily basis, over periods of months to years, historical wind conditions at U.S. Geological Survey sites prior to 2005. Empirical wind models based on Artificial Neural Network (ANN) and Multivariate-Adaptive Regressive Splines (MARS) algorithms were compared. ANNs were better suited to simulating the 10-minute wind data that are the dependent variables of the gap-filling models, but the simpler MARS algorithm may be adequate to accurately simulate the daily wind data that are the dependent variables of the historical wind models. To further test the accuracy of the gap-filling models, the resulting simulated winds were used to force the hydrodynamic model of the lake, and the resulting simulated currents were compared to measurements from an acoustic Doppler current profiler. The error statistics indicated that the simulation of currents was degraded as compared to when the model was forced with observed winds, but probably is adequate for short gaps in the data of a few days or less. Transport seems to be less affected by the use of the simulated winds in place of observed winds. The simulated tracer concentration was similar between model results when simulated winds were used to force the model, and when observed winds were used to force the model, and differences between the two results did not accumulate over time.

Diel variation of ichthyoplankton recruitment in a wind-dominated temperate coastal lagoon (Argentina)

NASA Astrophysics Data System (ADS)

Bruno, Daniel O.; Delpiani, Sergio M.; Acha, Eduardo M.

2018-05-01

This study aimed to assess the diel changes of ichthyoplankton occurrence, during a known recruitment period, to a wind-dominated coastal lagoon (Argentina). We collected plankton samples at three sites of the lagoon's inlet area every 3 h during four 24 h cycles in mid austral summer. For each early-life history stage (eggs, yolk sac, preflexion larvae, postflexion larvae and early juveniles), the relationship between the abundance and possible combinations of the time of sampling, the wind effect, the wave period and the tidal state was evaluated by fitting generalized linear mix-effects models (GLMM). The wind effects depending on the time of sampling mainly affected fish abundance in all developmental stages. Overall, the highest abundances were collected at nocturnal hours when low-speed offshore winds blew. In addition, higher abundances of eggs, yolk sac and preflexion larvae were related to the incoming flood tide; whereas higher abundances of postflexion larvae and early juveniles were related to longer wave periods. We argued that the daily variation in the abundance of early-life history stages of fishes is related to the sea-land breeze cycle. Therefore, a conceptual framework of the recruitment process of eggs, larvae and early juveniles of fishes into this estuarine system considering the daily effect of winds is proposed.

Destroyer Engineered Operating Cycle (DDEOC) System Maintenance Analysis DDG-37 Class Firemain and Auxiliary Machinery Cooling Water Systems SMA 37-201- 521. Review of Experience

DTIC Science & Technology

1978-02-01

establish a PMS requirement to operate firepumps 1 and 6 daily to warm up and dry out the electric motor windings. Equaliza- tion of the use of the...daily to warm up and dry out the electric motor windings and the recommendations of Section 3.2.2.1 to establish a uniform firepump operating policy...bolted up . This problem, as discussed in Section 3.3.1.3, should be reduced by the promulgation and use of the comprehensive centrifugal pump overhaul

Daily weather variables and affective disorder admissions to psychiatric hospitals

NASA Astrophysics Data System (ADS)

McWilliams, Stephen; Kinsella, Anthony; O'Callaghan, Eadbhard

2014-12-01

Numerous studies have reported that admission rates in patients with affective disorders are subject to seasonal variation. Notwithstanding, there has been limited evaluation of the degree to which changeable daily meteorological patterns influence affective disorder admission rates. A handful of small studies have alluded to a potential link between psychiatric admission rates and meteorological variables such as environmental temperature (heat waves in particular), wind direction and sunshine. We used the Kruskal-Wallis test, ARIMA and time-series regression analyses to examine whether daily meteorological variables—namely wind speed and direction, barometric pressure, rainfall, hours of sunshine, sunlight radiation and temperature—influence admission rates for mania and depression across 12 regions in Ireland over a 31-year period. Although we found some very weak but interesting trends for barometric pressure in relation to mania admissions, daily meteorological patterns did not appear to affect hospital admissions overall for mania or depression. Our results do not support the small number of papers to date that suggest a link between daily meteorological variables and affective disorder admissions. Further study is needed.

CLIGEN: Addressing deficiencies in the generator and its databases

USDA-ARS?s Scientific Manuscript database

CLIGEN is a stochastic generator that estimates daily temperatures, precipitation and other weather related phenomena. It is an intermediate model used by the Water Erosion Prediction Program (WEPP), the Wind Erosion Prediction System (WEPS), and other models that require daily weather observations....

Quiet-Time Suprathermal ( 0.1-1.5 keV) Electrons in the Solar Wind

NASA Astrophysics Data System (ADS)

Wang, L.; Tao, J.; Zong, Q.; Li, G.; Salem, C. S.; Wimmer-Schweingruber, R. F.; He, J.; Tu, C.; Bale, S. D.

2016-12-01

We present a statistical survey of the energy spectrum of solar wind suprathermal (˜0.1-1.5 keV) electrons measured by the WIND/3DP instrument at 1 AU during quiet times at the minimum and maximum of solar cycles 23 and 24. After separating (beaming) strahl electrons from (isotropic) halo electrons according to their different behaviors in the angular distribution, we fit the observed energy spectrum of both strahl and halo electrons at ˜0.1-1.5 keV to a Kappa distribution function with an index κ and effective temperature Teff. We also calculate the number density n and average energy Eavg of strahl and halo electrons by integrating the electron measurements between ˜0.1 and 1.5 keV. We find a strong positive correlation between κ and Teff for both strahl and halo electrons, and a strong positive correlation between the strahl n and halo n, likely reflecting the nature of the generation of these suprathermal electrons. In both solar cycles, κ is larger at solar minimum than at solar maximum for both strahl and halo electrons. The halo κ is generally smaller than the strahl κ (except during the solar minimum of cycle 23). The strahl n is larger at solar maximum, but the halo n shows no difference between solar minimum and maximum. Both the strahl n and halo n have no clear association with the solar wind core population, but the density ratio between the strahl and halo roughly anti-correlates (correlates) with the solar wind density (velocity).

Quiet-time Suprathermal (~0.1-1.5 keV) Electrons in the Solar Wind

NASA Astrophysics Data System (ADS)

Tao, Jiawei; Wang, Linghua; Zong, Qiugang; Li, Gang; Salem, Chadi S.; Wimmer-Schweingruber, Robert F.; He, Jiansen; Tu, Chuanyi; Bale, Stuart D.

2016-03-01

We present a statistical survey of the energy spectrum of solar wind suprathermal (˜0.1-1.5 keV) electrons measured by the WIND 3DP instrument at 1 AU during quiet times at the minimum and maximum of solar cycles 23 and 24. After separating (beaming) strahl electrons from (isotropic) halo electrons according to their different behaviors in the angular distribution, we fit the observed energy spectrum of both strahl and halo electrons at ˜0.1-1.5 keV to a Kappa distribution function with an index κ and effective temperature Teff. We also calculate the number density n and average energy Eavg of strahl and halo electrons by integrating the electron measurements between ˜0.1 and 1.5 keV. We find a strong positive correlation between κ and Teff for both strahl and halo electrons, and a strong positive correlation between the strahl n and halo n, likely reflecting the nature of the generation of these suprathermal electrons. In both solar cycles, κ is larger at solar minimum than at solar maximum for both strahl and halo electrons. The halo κ is generally smaller than the strahl κ (except during the solar minimum of cycle 23). The strahl n is larger at solar maximum, but the halo n shows no difference between solar minimum and maximum. Both the strahl n and halo n have no clear association with the solar wind core population, but the density ratio between the strahl and halo roughly anti-correlates (correlates) with the solar wind density (velocity).

Gauging the Nearness and Size of Cycle Maximum

NASA Technical Reports Server (NTRS)

Wilson, Robert M.; Hathaway, David H.

2003-01-01

A simple method for monitoring the nearness and size of conventional cycle maximum for an ongoing sunspot cycle is examined. The method uses the observed maximum daily value and the maximum monthly mean value of international sunspot number and the maximum value of the 2-mo moving average of monthly mean sunspot number to effect the estimation. For cycle 23, a maximum daily value of 246, a maximum monthly mean of 170.1, and a maximum 2-mo moving average of 148.9 were each observed in July 2000. Taken together, these values strongly suggest that conventional maximum amplitude for cycle 23 would be approx. 124.5, occurring near July 2002 +/-5 mo, very close to the now well-established conventional maximum amplitude and occurrence date for cycle 23-120.8 in April 2000.

77 FR 26572 - Notice of Availability of the Draft Environmental Impact Statement for the Proposed Mohave County...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-05-04

... be supplemented with internal access/service roads to each wind turbine. Proposed ancillary... action alternatives, project features within the wind-farm site would include turbines aligned within... maximum of 283 turbines. The Alternative B wind-farm site would encompass approximately 30,872 acres of...

Assessing the Impact of Different Measurement Time Intervals on Observed Long-Term Wind Speed Trends

NASA Astrophysics Data System (ADS)

Azorin-Molina, C.; Vicente-Serrano, S. M.; McVicar, T.; Jerez, S.; Revuelto, J.; López Moreno, J. I.

2014-12-01

During the last two decades climate studies have reported a tendency toward a decline in measured near-surface wind speed in some regions of Europe, North America, Asia and Australia. This weakening in observed wind speed has been recently termed "global stilling", showing a worldwide average trend of -0.140 m s-1 dec-1 during last 50-years. The precise cause of the "global stilling" remains largely uncertain and has been hypothetically attributed to several factors, mainly related to: (i) an increasing surface roughness (i.e. forest growth, land use changes, and urbanization); (ii) a slowdown in large-scale atmospheric circulation; (iii) instrumental drifts and technological improvements, maintenance, and shifts in measurements sites and calibration issues; (iv) sunlight dimming due to air pollution; and (v) astronomical changes. This study proposed a novel investigation aimed at analyzing how different measurement time intervals used to calculate a wind speed series can affect the sign and magnitude of long-term wind speed trends. For instance, National Weather Services across the globe estimate daily average wind speed using different time intervals and formulae that may affect the trend results. Firstly, we carried out a comprehensive review of wind studies reporting the sign and magnitude of wind speed trend and the sampling intervals used. Secondly, we analyzed near-surface wind speed trends recorded at 59 land-based stations across Spain comparing monthly mean wind speed series obtained from: (a) daily mean wind speed data averaged from standard 10-min mean observations at 0000, 0700, 1300 and 1800 UTC; and (b) average wind speed of 24 hourly measurements (i.e., wind run measurements) from 0000 to 2400 UTC. Thirdly and finally, we quantified the impact of anemometer drift (i.e. bearing malfunction) by presenting preliminary results (1-year of paired measurements) from a comparison of one new anemometer sensor against one malfunctioned anenometer sensor due to old bearings.

78 FR 23335 - Energy Conservation Program: Energy Conservation Standards for Distribution Transformers

Federal Register 2010, 2011, 2012, 2013, 2014

2013-04-18

... Basic Impulse Level 4. Dual/Multiple-Voltage Primary Windings 5. Dual/Multiple-Voltage Secondary Windings 6. Loading B. Technological Feasibility 1. General 2. Maximum Technologically Feasible Levels C...

Determination of the effects of wind-induced vibration on cylindrical beams

NASA Technical Reports Server (NTRS)

Artusa, E. A.

1991-01-01

The objective of the analysis was to determine the critical length to diameter ratio (L/Do) of a hollow, cylindrical beam subjected to wind-induced vibration. The sizes of beams ranged from 4 to 24 inches and were composed of ASTM grade A and grade B and American Petroleum Institute grade X42 steels. Calculations used maximum steady-state wind speeds of 130 mph associated with hurricane conditions possible at the Kennedy Space Center. The study examined the effect that different end support and load conditions have on the natural frequencies of the beams. Finally, methods of changing the frequency of the wind-induced vibration were examined. The conclusions drawn were that the greatest possible L/Do is achieved using welded supports and limiting the maximum applied axial and bending loads to less than 50 percent.

Remote Sensing of Three-dimensional Winds with Elastic Lidar: Explanation of Maximum Cross-correlation Method

NASA Astrophysics Data System (ADS)

Buttler, William T.; Soriano, Cecilia; Baldasano, Jose M.; Nickel, George H.

Maximum cross-correlation provides a method toremotely de-ter-mine high-lyre-solved three-dimensional fields of horizontalwinds with e-las-tic li-darthrough-out large volumes of the planetaryboundary layer (PBL). This paperdetails the technique and shows comparisonsbetween elastic lidar winds, remotelysensed laser Doppler velocimeter (LDV) windprofiles, and radiosonde winds.Radiosonde wind data were acquired at Barcelona,Spain, during the BarcelonaAir-Quality Initiative (1992), and the LDVwind data were acquired at SunlandPark, New Mexico during the 1994 Border AreaAir-Quality Study. Comparisonsshow good agreement between the differentinstruments, and demonstrate the methoduseful for air pollution management at thelocal/regional scale. Elastic lidar windscould thus offer insight into aerosol andpollution transport within the PBL. Lidarwind fields might also be used to nudge orimprove initialization and evaluation ofatmospheric meteorological models.

Added value of non-calibrated and BMA calibrated AEMET-SREPS probabilistic forecasts: the 24 January 2009 extreme wind event over Catalonia

NASA Astrophysics Data System (ADS)

Escriba, P. A.; Callado, A.; Santos, D.; Santos, C.; Simarro, J.; García-Moya, J. A.

2009-09-01

At 00 UTC 24 January 2009 an explosive ciclogenesis originated over the Atlantic Ocean reached its maximum intensity with observed surface pressures lower than 970 hPa on its center and placed at Gulf of Vizcaya. During its path through southern France this low caused strong westerly and north-westerly winds over the Iberian Peninsula higher than 150 km/h at some places. These extreme winds leaved 10 casualties in Spain, 8 of them in Catalonia. The aim of this work is to show whether exists an added value in the short range prediction of the 24 January 2009 strong winds when using the Short Range Ensemble Prediction System (SREPS) of the Spanish Meteorological Agency (AEMET), with respect to the operational forecasting tools. This study emphasizes two aspects of probabilistic forecasting: the ability of a 3-day forecast of warn an extreme windy event and the ability of quantifying the predictability of the event so that giving value to deterministic forecast. Two type of probabilistic forecasts of wind are carried out, a non-calibrated and a calibrated one using Bayesian Model Averaging (BMA). AEMET runs daily experimentally SREPS twice a day (00 and 12 UTC). This system consists of 20 members that are constructed by integrating 5 local area models, COSMO (COSMO), HIRLAM (HIRLAM Consortium), HRM (DWD), MM5 (NOAA) and UM (UKMO), at 25 km of horizontal resolution. Each model uses 4 different initial and boundary conditions, the global models GFS (NCEP), GME (DWD), IFS (ECMWF) and UM. By this way it is obtained a probabilistic forecast that takes into account the initial, the contour and the model errors. BMA is a statistical tool for combining predictive probability functions from different sources. The BMA predictive probability density function (PDF) is a weighted average of PDFs centered on the individual bias-corrected forecasts. The weights are equal to posterior probabilities of the models generating the forecasts and reflect the skill of the ensemble members. Here BMA is applied to provide probabilistic forecasts of wind speed. In this work several forecasts for different time ranges (H+72, H+48 and H+24) of 10 meters wind speed over Catalonia are verified subjectively at one of the instants of maximum intensity, 12 UTC 24 January 2009. On one hand, three probabilistic forecasts are compared, ECMWF EPS, non-calibrated SREPS and calibrated SREPS. On the other hand, the relationship between predictability and skill of deterministic forecast is studied by looking at HIRLAM 0.16 deterministic forecasts of the event. Verification is focused on location and intensity of 10 meters wind speed and 10-minutal measures from AEMET automatic ground stations are used as observations. The results indicate that SREPS is able to forecast three days ahead mean winds higher than 36 km/h and that correctly localizes them with a significant probability of ocurrence in the affected area. The probability is higher after BMA calibration of the ensemble. The fact that probability of strong winds is high allows us to state that the predictability of the event is also high and, as a consequence, deterministic forecasts are more reliable. This is confirmed when verifying HIRLAM deterministic forecasts against observed values.

Application of a combined measurement and modeling method to quantify windblown dust emissions from the exposed playa at Mono Lake, California.

PubMed

Ono, Duane; Kiddoo, Phill; Howard, Christopher; Davis, Guy; Richmond, Kenneth

2011-10-01

Particulate matter < or =10 microm (PM10) emissions due to wind erosion can vary dramatically with changing surface conditions. Crust formation, mechanical disturbance, soil texture, moisture, and chemical content of the soil can affect the amount of dust emitted during a wind event. A refined method of quantifying windblown dust emissions was applied at Mono Lake, CA, to account for changing surface conditions. This method used a combination of real-time sand flux monitoring, ambient PM10 monitoring, and dispersion modeling to estimate dust emissions and their downwind impact. The method identified periods with high emissions and periods when the surface was stable (no sand flux), even though winds may have been high. A network of 25 Cox sand catchers (CSCs) was used to measure the mass of saltating particles to estimate sand flux rates across a 2-km2 area. Two electronic sensors (Sensits) were used to time-resolve the CSC sand mass to estimate hourly sand flux rates, and a perimeter tapered element oscillating microbalance (TEOM) monitor measured hourly PM10 concentrations. Hourly sand flux rates were related by dispersion modeling to hourly PM10 concentrations to back-calculate the ratio of vertical PM10 flux to horizontal sand flux (K-factors). Geometric mean K-factor values (K(f)) were found to change seasonally, ranging from 1.3 x 10(-5) to 5.1 x 10(-5) for sand flux measured at 15 cm above the surface (q15). Hourly PM10 emissions, F, were calculated by applying seasonal K-factors to sand flux measurements (F = K(f) x q15). The maximum hourly PM10 emission rate from the study area was 76 g/m2 x hr (10-m wind speed = 23.5 m/sec). Maximum daily PM10 emissions were estimated at 450 g/m2 x day, and annual emissions at 1095 g/m2 x yr. Hourly PM10 emissions were used by the U.S. Environmental Protection Agency (EPA) guideline AERMOD dispersion model to estimate downwind ambient impacts. Model predictions compared well with monitor concentrations, with hourly PM10 ranging from 16 to over 60,000 microg/m3 (slope = 0.89, R2 = 0.77).

Diurnal variation of wind-chill at Thessaloniki, Greece

NASA Astrophysics Data System (ADS)

Balafoutis, Ch. J.

1989-12-01

The diurnal variations of wind-chill at Thessaloniki, Greece, are considered using hourly data from January 1960 to December 1977. This is the first attempt in Greece to describe bioclimatic conditions using wind-chill data. The hourly values of wind-chill were calculated by Siple-Passel's formula which still appears to be most widely used. The values of wind-chill are discussed in terms of Terjung's scale. Thessaloniki does not experience “frost-bite” conditions during the coldest months but does experience “warm” conditions during the summer period. A comparison of hourly and daily mean values show that the means do not indicate the real range of wind-chill during the day.

Coronal holes as sources of solar wind

NASA Technical Reports Server (NTRS)

Nolte, J. T.; Krieger, A. S.; Timothy, A. F.; Gold, R. E.; Roelof, E. C.; Vaiana, G.; Lazarus, A. J.; Sullivan, J. D.; Mcintosh, P. S.

1976-01-01

We investigate the association of high-speed solar wind with coronal holes during the Skylab mission by: (1) direct comparison of solar wind and coronal X-ray data; (2) comparison of near-equatorial coronal hole area with maximum solar wind velocity in the associated streams; and (3) examination of the correlation between solar and interplanetary magnetic polarities. We find that all large near-equatorial coronal holes seen during the Skylab period were associated with high-velocity solar wind streams observed at 1 AU.

Impact of wind on ambient noise recorded by the "13 BB star" seismic array in northern Poland

NASA Astrophysics Data System (ADS)

Lepore, Simone; Markowicz, Krzysztof; Grad, Marek

2016-04-01

Seismic interferometry and beam forming techniques were applied to ambient noise recorded during January 2014 at the "13 BB star" array, composed of thirteen seismic stations located in northern Poland, with the aim of evaluating the azimuth of noise sources and the velocities of surface waves. After normalizing the raw recordings in time and frequency domain, the spectral characteristics of the ambient noise were studied to choose a frequency band suitable for the waves' retrieval. To get the velocity of surface waves by seismic interferometry, the crosscorrelation between all station pairs was analysed for the vertical and horizontal components in the 0.05-0.1 Hz, 0.1-1 Hz and 1 10 Hz frequency bands. For each pair, the crosscorrelation was applied to one hour recordings extracted from the ambient noise. The obtained traces were calculated for a complete day, and then summed together: the daily results were stacked for the whole January 2014. In the lowest frequency range, most of the energy is located around the 3.0 km/s line, meaning that the surface waves coming from the uppermost mantle will be retrieved. The intermediate frequency range shows most of the energy between the 2.0 km/s and 1.5 km/s lines: consequently, surface waves originating from the crust will be retrieved. In the highest frequency range, the surface waves are barely visible on the crosscorrelation traces, implying that the associated energy is strongly attenuated. The azimuth variation associated to the noise field was evaluated by means of the beam forming method, using the data from the whole array for all the three components. To that, the beam power was estimated in a small range of frequencies every day for the whole month. For each day, one hour long results of beam forming applications were stacked together. To avoid aliasing and near field effects, the minimum frequency was set at 0.05 Hz and the maximum to 0.1 Hz. In this frequency band, the amplitude maximum was sought corresponding to the best fit between phase slowness and back azimuth. The azimuth was mainly associated to the angle of the highest peak on the vertical component; however, if the related energy was not large enough, the angle of the main noise source on the horizontal component was employed. In some cases, the azimuth of the secondary peak was taken into account, if its energy was strong enough. The results were related to the daily mean wind speed around Europe recorded during the same month. A significant correlation between the daily average level of ambient noise and the mean wind speed was found. The main source of the ambient noise was located in the Atlantic Ocean and in the North Sea: some weaker sources, however, were identified as the Barents, Baltic, Mediterranean, and Black Seas. National Science Centre Poland provided financial support for this work by NCN grant DEC 2011/02/A/ST10/00284.

Large Scale Winter Time Disturbances in Meteor Winds over Central and Eastern Europe

NASA Technical Reports Server (NTRS)

Greisiger, K. M.; Portnyagin, Y. I.; Lysenko, I. A.

1984-01-01

Daily zonal wind data of the four pre-MAP-winters 1978/79 to 1981/82 obtained over Central Europe and Eastern Europe by the radar meteor method were studied. Available temperature and satellite radiance data of the middle and upper stratosphere were used for comparison, as well as wind data from Canada. The existence or nonexistence of coupling between the observed large scale zonal wind disturbances in the upper mesopause region (90 to 100 km) and corresponding events in the stratosphere are discussed.

75 FR 75961 - Notice of Implementation of the Wind Erosion Prediction System for Soil Erodibility System...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-12-07

... Wind Erosion Prediction System for Soil Erodibility System Calculations for the Natural Resources... Erosion Prediction System (WEPS) for soil erodibility system calculations scheduled for implementation for... computer model is a process-based, daily time-step computer model that predicts soil erosion via simulation...

CMEs, the Tail of the Solar Wind Magnetic Field Distribution, and 11-yr Cosmic Ray Modulation at 1 AU. Revised

NASA Technical Reports Server (NTRS)

Cliver, E. W.; Ling, A. G.; Richardson, I. G.

2003-01-01

Using a recent classification of the solar wind at 1 AU into its principal components (slow solar wind, high-speed streams, and coronal mass ejections (CMEs) for 1972-2000, we show that the monthly-averaged galactic cosmic ray intensity is anti-correlated with the percentage of time that the Earth is imbedded in CME flows. We suggest that this correlation results primarily from a CME related change in the tail of the distribution function of hourly-averaged values of the solar wind magnetic field (B) between solar minimum and solar maximum. The number of high-B (square proper subset 10 nT) values increases by a factor of approx. 3 from minimum to maximum (from 5% of all hours to 17%), with about two-thirds of this increase due to CMEs. On an hour-to-hour basis, average changes of cosmic ray intensity at Earth become negative for solar wind magnetic field values square proper subset 10 nT.

Voltage oriented control of self-excited induction generator for wind energy system with MPPT

NASA Astrophysics Data System (ADS)

Amieur, Toufik; Taibi, Djamel; Amieur, Oualid

2018-05-01

This paper presents the study and simulation of the self-excited induction generator in the wind power production in isolated sites. With this intention, a model of the wind turbine was established. Extremum-seeking control algorithm method by using Maximum Power Point Tracking (MPPT) is proposed control solution aims at driving the average position of the operating point near to optimality. The reference of turbine rotor speed is adjusted such that the turbine operates around maximum power for the current wind speed value. After a brief review of the concepts of converting wind energy into electrical energy. The proposed modeling tools were developed to study the performance of standalone induction generators connected to capacitor bank. The purpose of this technique is to maintain a constant voltage at the output of the rectifier whatever the loads and speeds. The system studied in this work is developed and tested in MATLAB/Simulink environment. Simulation results validate the performance and effectiveness of the proposed control methods.

Influence of atmospheric states in semi-arid areas on hospital admission in cardio-surgical department

NASA Astrophysics Data System (ADS)

Yackerson, Naomy S.; Zilberman, Arkadi; Aizenberg, Alexander

2017-04-01

The influence of the changes in atmospheric state, typical for areas close to big deserts, on acute myocardial infarction (AMI) was analyzed. Under test was the group of 3256 patients (77 % males, 23 % females), hospitalized in the Cardio-Surgical Department of Soroka Medical Center at Ben-Gurion University (BGU, Israel) during 2000-2008. To explore the relationship between atmospheric parameters and AMI, multivariate regression analysis has been performed. AMI was most frequent in winter to spring and least in summer. The highest number of cases was recorded in December and the lowest in September. Hospital admissions showed a higher prevalence in men than in women; the ratio is 3.3/1.0. About 60 % of males were aged between 45 and 65 years old with maximum ˜55 (21 %), whereas 60 % of women hospital admissions were aged between 65 and 80 years old with maximum ˜72 (24 %). The result suggested that the monthly mean relative humidity at daytime and its overall daily differences, wind speed, and respirable fraction of particulate concentration are associated with the admission for AMI. The results of the study confirm the importance of atmospheric state variability for cardiovascular diseases.

The effects of meteorological factors on the occurrence of Ganoderma sp. spores in the air

NASA Astrophysics Data System (ADS)

Grinn-Gofroń, Agnieszka; Strzelczak, Agnieszka

2011-03-01

Ganoderma sp. is an airborne fungal spore type known to trigger respiratory allergy symptoms in sensitive patients. Aiming to reduce the risk for allergic individuals, we analysed fungal spore circulation in Szczecin, Poland, and its dependence on meteorological conditions. Statistical models for the airborne spore concentrations of Ganoderma sp.—one of the most abundant fungal taxa in the area—were developed. Aerobiological sampling was conducted over 2004-2008 using a volumetric Lanzoni trap. Simultaneously, the following meteorological parameters were recorded: daily level of precipitation, maximum and average wind speed, relative humidity and maximum, minimum, average and dew point temperatures. These data were used as the explaining variables. Due to the non-linearity and non-normality of the data set, the applied modelling techniques were artificial neural networks (ANN) and mutlivariate regression trees (MRT). The obtained classification and MRT models predicted threshold conditions above which Ganoderma sp. appeared in the air. It turned out that dew point temperature was the main factor influencing the presence or absence of Ganoderma sp. spores. Further analysis of spore seasons revealed that the airborne fungal spore concentration depended only slightly on meteorological factors.

Evaluating wind extremes in CMIP5 climate models

NASA Astrophysics Data System (ADS)

Kumar, Devashish; Mishra, Vimal; Ganguly, Auroop R.

2015-07-01

Wind extremes have consequences for renewable energy sectors, critical infrastructures, coastal ecosystems, and insurance industry. Considerable debates remain regarding the impacts of climate change on wind extremes. While climate models have occasionally shown increases in regional wind extremes, a decline in the magnitude of mean and extreme near-surface wind speeds has been recently reported over most regions of the Northern Hemisphere using observed data. Previous studies of wind extremes under climate change have focused on selected regions and employed outputs from the regional climate models (RCMs). However, RCMs ultimately rely on the outputs of global circulation models (GCMs), and the value-addition from the former over the latter has been questioned. Regional model runs rarely employ the full suite of GCM ensembles, and hence may not be able to encapsulate the most likely projections or their variability. Here we evaluate the performance of the latest generation of GCMs, the Coupled Model Intercomparison Project phase 5 (CMIP5), in simulating extreme winds. We find that the multimodel ensemble (MME) mean captures the spatial variability of annual maximum wind speeds over most regions except over the mountainous terrains. However, the historical temporal trends in annual maximum wind speeds for the reanalysis data, ERA-Interim, are not well represented in the GCMs. The historical trends in extreme winds from GCMs are statistically not significant over most regions. The MME model simulates the spatial patterns of extreme winds for 25-100 year return periods. The projected extreme winds from GCMs exhibit statistically less significant trends compared to the historical reference period.

Analysis of trends in selected streamflow statistics for the Concho River Basin, Texas, 1916-2009

USGS Publications Warehouse

Barbie, Dana L.; Wehmeyer, Loren L.; May, Jayne E.

2012-01-01

Six U.S. Geological Survey streamflow-gaging stations were selected for analysis. Streamflow-gaging station 08128000 South Concho River at Christoval has downward trends for annual maximum daily discharge and annual instantaneous peak discharge for the combined period 1931-95, 2002-9. Streamflow-gaging station 08128400 Middle Concho River above Tankersley has downward trends for annual maximum daily discharge and annual instantaneous peak discharge for the combined period 1962-95, 2002-9. Streamflow-gaging station 08128500 Middle Concho River near Tankersley has no significant trends in the streamflow statistics considered for the period 1931-60. Streamflow-gaging station 08134000 North Concho River near Carlsbad has downward trends for annual mean daily discharge, annual 7-day minimum daily discharge, annual maximum daily discharge, and annual instantaneous peak discharge for the period 1925-2009. Streamflow-gaging stations 08136000 Concho River at San Angelo and 08136500 Concho River at Paint Rock have downward trends for 1916-2009 for all streamflow statistics calculated, but streamflow-gaging station 08136000 Concho River at San Angelo has an upward trend for annual maximum daily discharge during 1964-2009. The downward trends detected during 1916-2009 for the Concho River at San Angelo are not unexpected because of three reservoirs impounding and profoundly regulating streamflow.

Which metric of ambient ozone to predict daily mortality?

NASA Astrophysics Data System (ADS)

Moshammer, Hanns; Hutter, Hans-Peter; Kundi, Michael

2013-02-01

It is well known that ozone concentration is associated with daily cause specific mortality. But which ozone metric is the best predictor of the daily variability in mortality? We performed a time series analysis on daily deaths (all causes, respiratory and cardiovascular causes as well as death in elderly 65+) in Vienna for the years 1991-2009. We controlled for seasonal and long term trend, day of the week, temperature and humidity using the same basic model for all pollutant metrics. We found model fit was best for same day variability of ozone concentration (calculated as the difference between daily hourly maximum and minimum) and hourly maximum. Of these the variability displayed a more linear dose-response function. Maximum 8 h moving average and daily mean value performed not so well. Nitrogen dioxide (daily mean) in comparison performed better when previous day values were assessed. Same day ozone and previous day nitrogen dioxide effect estimates did not confound each other. Variability in daily ozone levels or peak ozone levels seem to be a better proxy of a complex reactive secondary pollutant mixture than daily average ozone levels in the Middle European setting. If this finding is confirmed this would have implications for the setting of legally binding limit values.

Evaluation of different methods to estimate daily reference evapotranspiration in ungauged basins in Southern Brazil

NASA Astrophysics Data System (ADS)

Ribeiro Fontoura, Jessica; Allasia, Daniel; Herbstrith Froemming, Gabriel; Freitas Ferreira, Pedro; Tassi, Rutineia

2016-04-01

Evapotranspiration is a key process of hydrological cycle and a sole term that links land surface water balance and land surface energy balance. Due to the higher information requirements of the Penman-Monteith method and the existing data uncertainty, simplified empirical methods for calculating potential and actual evapotranspiration are widely used in hydrological models. This is especially important in Brazil, where the monitoring of meteorological data is precarious. In this study were compared different methods for estimating evapotranspiration for Rio Grande do Sul, the Southernmost State of Brazil, aiming to suggest alternatives to the recommended method (Penman-Monteith-FAO 56) for estimate daily reference evapotranspiration (ETo) when meteorological data is missing or not available. The input dataset included daily and hourly-observed data from conventional and automatic weather stations respectively maintained by the National Weather Institute of Brazil (INMET) from the period of 1 January 2007 to 31 January 2010. Dataset included maximum temperature (Tmax, °C), minimum temperature (Tmin, °C), mean relative humidity (%), wind speed at 2 m height (u2, m s-1), daily solar radiation (Rs, MJ m- 2) and atmospheric pressure (kPa) that were grouped at daily time-step. Was tested the Food and Agriculture Organization of the United Nations (FAO) Penman-Monteith method (PM) at its full form, against PM assuming missing several variables not normally available in Brazil in order to calculate daily reference ETo. Missing variables were estimated as suggested in FAO56 publication or from climatological means. Furthermore, PM was also compared against the following simplified empirical methods: Hargreaves-Samani, Priestley-Taylor, Mccloud, McGuiness-Bordne, Romanenko, Radiation-Temperature, Tanner-Pelton. The statistical analysis indicates that even if just Tmin and Tmax are available, it is better to use PM estimating missing variables from syntetic data than simplified empirical methods evaluated except for Tanner-Pelton and Priestley-Taylor.

One- to two-month oscillations in SSMI surface wind speed in western tropical Pacific Ocean

NASA Technical Reports Server (NTRS)

Collins, Michael L.; Stanford, John L.; Halpern, David

1994-01-01

The 10-m wind speed over the ocean can be estimated from microwave brightness temperature measurements recorded by the Special Sensor Microwave Imager (SSMI) instrument mounted on a polar-orbiting spacecraft. Four-year (1988-1991) time series of average daily 1 deg x 1 deg SSMI wind speeds were analyzed at selected sites in the western tropical Pacific Ocean. One- to two-month period wind speed oscillations with amplitudes statistically significant at the 95% confidence level were observed near Kanton, Eniwetok, Guam, and Truk. This is the first report of such an oscillation in SSMI wind speeds.

Establishing Total Maximum Daily Load (TMDL) Wasteload Allocations (WLAs) for Storm Water Sources and NPDES Permit Requirements Based on Those WLAs

EPA Pesticide Factsheets

The memoranda clarify existing EPA regulatory requirements for, and provide guidance on, establishing wasteload allocations (WLAs) for storm water discharges in total maximum daily loads (TMDLs) approved or established by EPA.

SELECTION OF CANDIDATE EUTROPHICATION MODELS FOR TOTAL MAXIMUM DAILY LOADS ANALYSES

EPA Science Inventory

A tiered approach was developed to evaluate candidate eutrophication models to select a common suite of models that could be used for Total Maximum Daily Loads (TMDL) analyses in estuaries, rivers, and lakes/reservoirs. Consideration for linkage to watershed models and ecologica...

Texas | Solar Research | NREL

Science.gov Websites

per non-residential customer (equivalent to a 25-kW system) Maximum $81,450 per service provider or megawatts in 2015, to 10,000 megawatts in 2030. Carve-out: Goal of voluntary 500 MW of non-wind generation target was already achieved by 2009, mostly through wind energy. The voluntary carve-out for non-wind

78 FR 20690 - Draft Environmental Impact Statement, Draft Habitat Conservation Plan, Draft Programmatic...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-04-05

.... Background The Fowler Ridge application is unusual in that 355 wind turbines are already in place and have... turbines under Phase IV and operate a maximum of 449 wind turbines and associated facilities (described below) for a period of 22 years in Benton County, Indiana. The project will consist of wind turbines...

77 FR 38819 - Availability of a Draft Environmental Impact Statement and Habitat Conservation Plan; Receipt of...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-06-29

... to construct and operate a maximum of 100 wind turbines and associated facilities (described below) for a period of 30 years in eastern Champaign County, Ohio. The project will consist of wind turbines... connection of the wind turbines to the local transmission system, four permanent meteorological towers, and...

Environmental Influences on Daily Emergency Admissions in Sickle-Cell Disease Patients

PubMed Central

Mekontso Dessap, Armand; Contou, Damien; Dandine-Roulland, Claire; Hemery, François; Habibi, Anoosha; Charles-Nelson, Anaïs; Galacteros, Frederic; Brun-Buisson, Christian; Maitre, Bernard; Katsahian, Sandrine

2014-01-01

Abstract Previous reports have suggested a role for weather conditions and air pollution on the variability of sickle cell disease (SCD) severity, but large-scale comprehensive epidemiological studies are lacking. In order to evaluate the influence of air pollution and climatic factors on emergency hospital admissions (EHA) in SCD patients, we conducted an 8-year observational retrospective study in 22 French university hospitals in Paris conurbation, using distributed lag non-linear models, a methodology able to flexibly describe simultaneously non-linear and delayed associations, with a multivariable approach. During the 2922 days of the study, there were 17,710 EHA, with a mean daily number of 6.1 ± 2.8. Most environmental factors were significantly correlated to each other. The risk of EHA was significantly associated with higher values of nitrogen dioxide, atmospheric particulate matters, and daily mean wind speed; and with lower values of carbon monoxide, ozone, sulfur dioxide, daily temperature (minimal, maximal, mean, and range), day-to-day mean temperature change, daily bright sunshine, and occurrence of storm. There was a lag effect for 12 of 15 environmental factors influencing hospitalization rate. Multivariate analysis identified carbon monoxide, day-to-day temperature change, and mean wind speed, along with calendar factors (weekend, summer season, and year) as independent factors associated with EHA. In conclusion, most weather conditions and air pollutants assessed were correlated to each other and influenced the rate of EHA in SCD patients. In multivariate analysis, lower carbon monoxide concentrations, day-to-day mean temperature drop and higher wind speed were associated with increased risk of EHA. PMID:25546672

Environmental influences on daily emergency admissions in sickle-cell disease patients.

PubMed

Mekontso Dessap, Armand; Contou, Damien; Dandine-Roulland, Claire; Hemery, François; Habibi, Anoosha; Charles-Nelson, Anaïs; Galacteros, Frederic; Brun-Buisson, Christian; Maitre, Bernard; Katsahian, Sandrine

2014-12-01

Previous reports have suggested a role for weather conditions and air pollution on the variability of sickle cell disease (SCD) severity, but large-scale comprehensive epidemiological studies are lacking. In order to evaluate the influence of air pollution and climatic factors on emergency hospital admissions (EHA) in SCD patients, we conducted an 8-year observational retrospective study in 22 French university hospitals in Paris conurbation, using distributed lag non-linear models, a methodology able to flexibly describe simultaneously non-linear and delayed associations, with a multivariable approach. During the 2922 days of the study, there were 17,710 EHA, with a mean daily number of 6.1 ± 2.8. Most environmental factors were significantly correlated to each other. The risk of EHA was significantly associated with higher values of nitrogen dioxide, atmospheric particulate matters, and daily mean wind speed; and with lower values of carbon monoxide, ozone, sulfur dioxide, daily temperature (minimal, maximal, mean, and range), day-to-day mean temperature change, daily bright sunshine, and occurrence of storm. There was a lag effect for 12 of 15 environmental factors influencing hospitalization rate. Multivariate analysis identified carbon monoxide, day-to-day temperature change, and mean wind speed, along with calendar factors (weekend, summer season, and year) as independent factors associated with EHA. In conclusion, most weather conditions and air pollutants assessed were correlated to each other and influenced the rate of EHA in SCD patients. In multivariate analysis, lower carbon monoxide concentrations, day-to-day mean temperature drop and higher wind speed were associated with increased risk of EHA.

Wind Characterization for the Assessment of Collision Risk During Flight Level Changes

NASA Technical Reports Server (NTRS)

Carreno, Victor; Chartrand, Ryan

2009-01-01

A model of vertical wind gradient is presented based on National Oceanic and Atmospheric Administration (NOAA) wind data. The objective is to have an accurate representation of wind to be used in Collision Risk Models (CRM) of aircraft procedures. Depending on how an aircraft procedure is defined, wind and the different characteristics of the wind will have a more severe or less severe impact on distances between aircraft. For the In-Trail Procedure, the non-linearity of the vertical wind gradient has the greatest impact on longitudinal distance. The analysis in this paper extracts standard deviation, mean, maximum, and linearity characteristics from the NOAA data.

Effects of Meteorological Data Quality on Snowpack Modeling

NASA Astrophysics Data System (ADS)

Havens, S.; Marks, D. G.; Robertson, M.; Hedrick, A. R.; Johnson, M.

2017-12-01

Detailed quality control of meteorological inputs is the most time-intensive component of running the distributed, physically-based iSnobal snow model, and the effect of data quality of the inputs on the model is unknown. The iSnobal model has been run operationally since WY2013, and is currently run in several basins in Idaho and California. The largest amount of user input during modeling is for the quality control of precipitation, temperature, relative humidity, solar radiation, wind speed and wind direction inputs. Precipitation inputs require detailed user input and are crucial to correctly model the snowpack mass. This research applies a range of quality control methods to meteorological input, from raw input with minimal cleaning, to complete user-applied quality control. The meteorological input cleaning generally falls into two categories. The first is global minimum/maximum and missing value correction that could be corrected and/or interpolated with automated processing. The second category is quality control for inputs that are not globally erroneous, yet are still unreasonable and generally indicate malfunctioning measurement equipment, such as temperature or relative humidity that remains constant, or does not correlate with daily trends observed at nearby stations. This research will determine how sensitive model outputs are to different levels of quality control and guide future operational applications.

A NEW MODEL TO ESTIMATE DAILY ENERGY EXPENDITURE FOR WINTERING WATERFOWL

EPA Science Inventory

Activity budgets of wintering waterfowl have been widely used to assess habitat quality. However, when factors such as prey abundance or protection from exposure to cold or wind determine quality, measures of daily energy expenditure (DEE) may be more appropriate for this purpos...

Observed Trend in Surface Wind Speed Over the Conterminous USA and CMIP5 Simulations

NASA Technical Reports Server (NTRS)

Hashimoto, Hirofumi; Nemani, Ramakrishna R.

2016-01-01

There has been no spatial surface wind map even over the conterminous USA due to the difficulty of spatial interpolation of wind field. As a result, the reanalysis data were often used to analyze the statistics of spatial pattern in surface wind speed. Unfortunately, no consistent trend in wind field was found among the available reanalysis data, and that obstructed the further analysis or projection of spatial pattern of wind speed. In this study, we developed the methodology to interpolate the observed wind speed data at weather stations using random forest algorithm. We produced the 1-km daily climate variables over the conterminous USA from 1979 to 2015. The validation using Ameriflux daily data showed that R2 is 0.59. Existing studies have found the negative trend over the Eastern US, and our study also showed same results. However, our new datasets also revealed the significant increasing trend over the southwest US especially from April to June. The trend in the southwestern US represented change or seasonal shift in North American Monsoon. Global analysis of CMIP5 data projected the decrease trend in mid-latitude, while increase trend in tropical region over the land. Most likely because of the low resolution in GCM, CMIP5 data failed to simulate the increase trend in the southwest US, even though it was qualitatively predicted that pole ward shift of anticyclone help the North American Monsoon.

Spatial distribution of threshold wind speeds for dust outbreaks in northeast Asia

NASA Astrophysics Data System (ADS)

Kimura, Reiji; Shinoda, Masato

2010-01-01

Asian windblown dust events cause human and animal health effects and agricultural damage in dust source areas such as China and Mongolia and cause "yellow sand" events in Japan and Korea. It is desirable to develop an early warning system to help prevent such damage. We used our observations at a Mongolian station together with data from previous studies to model the spatial distribution of threshold wind speeds for dust events in northeast Asia (35°-45°N and 100°-115°E). Using a map of Normalized Difference Vegetation Index (NDVI), we estimated spatial distributions of vegetation cover, roughness length, threshold friction velocity, and threshold wind speed. We also recognized a relationship between NDVI in the dust season and maximum NDVI in the previous year. Thus, it may be possible to predict the threshold wind speed in the next dust season using the maximum NDVI in the previous year.

Dynamics of Monsoon-Induced Biennial Variability in ENSO

NASA Technical Reports Server (NTRS)

Kim, Kyu-Myong; Lau, K.-M.; Einaudi, Franco (Technical Monitor)

2000-01-01

The mechanism of the quasi-biennial tendency in El Nino Southern Oscillation (ENSO)-monsoon coupled system is investigated using an intermediate coupled model. The monsoon wind forcing is prescribed as a function of Sea Surface Temperature (SST) anomalies based on the relationship between zonal wind anomalies over the western Pacific to sea level change in the equatorial eastern Pacific. The key mechanism of quasi-biennial tendency in El Nino evolution is found to be in the strong coupling of ENSO to monsoon wind forcing over the western Pacific. Strong boreal summer monsoon wind forcing, which lags the maximum SST anomaly in the equatorial eastern Pacific approximately 6 months, tends to generate Kelvin waves of the opposite sign to anomalies in the eastern Pacific and initiates the turnabout in the eastern Pacific. Boreal winter monsoon forcing, which has zero lag with maximum SST in the equatorial eastern Pacific, tends to damp the ENSO oscillations.

Analysis of WindSat Data over Arctic Sea Ice

USDA-ARS?s Scientific Manuscript database

The radiation of the 3rd and 4th Stokes components emitted by Arctic sea ice and observed by the spaceborne fully polarimetric radiometer WindSat is investigated. Two types of analysis are carried out, spatial (maps of different quadrants of azimuth look angles) and temporal (time series of daily av...

Wind power forecasting for a real onshore wind farm on complex terrain using WRF high resolution simulations.

NASA Astrophysics Data System (ADS)

Ángel Prósper Fernández, Miguel; Casal, Carlos Otero; Canoura Fernández, Felipe; Miguez-Macho, Gonzalo

2017-04-01

Regional meteorological models are becoming a generalized tool for forecasting wind resource, due to their capacity to simulate local flow dynamics impacting wind farm production. This study focuses on the production forecast and validation of a real onshore wind farm using high horizontal and vertical resolution WRF (Weather Research and Forecasting) model simulations. The wind farm is located in Galicia, in the northwest of Spain, in a complex terrain region with high wind resource. Utilizing the Fitch scheme, specific for wind farms, a period of one year is simulated with a daily operational forecasting set-up. Power and wind predictions are obtained and compared with real data provided by the management company. Results show that WRF is able to yield good wind power operational predictions for this kind of wind farms, due to a good representation of the planetary boundary layer behaviour of the region and the good performance of the Fitch scheme under these conditions.

Fabrication and assembly of the ERDA/NASA 100 kilowatt experimental wind turbine

NASA Technical Reports Server (NTRS)

Puthoff, R. L.

1976-01-01

As part of the Energy Research and Development Administration (ERDA) wind-energy program, NASA Lewis Research Center has designed and built an experimental 100-kW wind turbine. The two-bladed turbines drives a synchronous alternator that generates its maximum output of 100 kW of electrical power in a 29-km/hr (18-mph) wind. The design and assembly of the wind turbine were performed at Lewis from components that were procured from industry. The machine was installed atop the tower on September 3, 1975.

Uncertainty and feasibility of dynamical downscaling for modeling tropical cyclones for storm surge simulation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Zhaoqing; Taraphdar, Sourav; Wang, Taiping

This paper presents a modeling study conducted to evaluate the uncertainty of a regional model in simulating hurricane wind and pressure fields, and the feasibility of driving coastal storm surge simulation using an ensemble of region model outputs produced by 18 combinations of three convection schemes and six microphysics parameterizations, using Hurricane Katrina as a test case. Simulated wind and pressure fields were compared to observed H*Wind data for Hurricane Katrina and simulated storm surge was compared to observed high-water marks on the northern coast of the Gulf of Mexico. The ensemble modeling analysis demonstrated that the regional model wasmore » able to reproduce the characteristics of Hurricane Katrina with reasonable accuracy and can be used to drive the coastal ocean model for simulating coastal storm surge. Results indicated that the regional model is sensitive to both convection and microphysics parameterizations that simulate moist processes closely linked to the tropical cyclone dynamics that influence hurricane development and intensification. The Zhang and McFarlane (ZM) convection scheme and the Lim and Hong (WDM6) microphysics parameterization are the most skillful in simulating Hurricane Katrina maximum wind speed and central pressure, among the three convection and the six microphysics parameterizations. Error statistics of simulated maximum water levels were calculated for a baseline simulation with H*Wind forcing and the 18 ensemble simulations driven by the regional model outputs. The storm surge model produced the overall best results in simulating the maximum water levels using wind and pressure fields generated with the ZM convection scheme and the WDM6 microphysics parameterization.« less

Multifractal two-scale Cantor set model for slow solar wind turbulence in the outer heliosphere during solar maximum

NASA Astrophysics Data System (ADS)

Macek, W. M.; Wawrzaszek, A.

2011-05-01

To quantify solar wind turbulence, we consider a generalized two-scale weighted Cantor set with two different scales describing nonuniform distribution of the kinetic energy flux between cascading eddies of various sizes. We examine generalized dimensions and the corresponding multifractal singularity spectrum depending on one probability measure parameter and two rescaling parameters. In particular, we analyse time series of velocities of the slow speed streams of the solar wind measured in situ by Voyager 2 spacecraft in the outer heliosphere during solar maximum at various distances from the Sun: 10, 30, and 65 AU. This allows us to look at the evolution of multifractal intermittent scaling of the solar wind in the distant heliosphere. Namely, it appears that while the degree of multifractality for the solar wind during solar maximum is only weakly correlated with the heliospheric distance, but the multifractal spectrum could substantially be asymmetric in a very distant heliosphere beyond the planetary orbits. Therefore, one could expect that this scaling near the frontiers of the heliosphere should rather be asymmetric. It is worth noting that for the model with two different scaling parameters a better agreement with the solar wind data is obtained, especially for the negative index of the generalized dimensions. Therefore we argue that there is a need to use a two-scale cascade model. Hence we propose this model as a useful tool for analysis of intermittent turbulence in various environments and we hope that our general asymmetric multifractal model could shed more light on the nature of turbulence.

Pollutant Concentrations in Street Canyons of Different Aspect Ratio with Avenues of Trees for Various Wind Directions

NASA Astrophysics Data System (ADS)

Gromke, Christof; Ruck, Bodo

2012-07-01

This study summarizes the effects of avenues of trees in urban street canyons on traffic pollutant dispersion. We describe various wind-tunnel experiments with different tree-avenue models in combination with variations in street-canyon aspect ratio W/ H (with W the street-canyon width and H the building height) and approaching wind direction. Compared to tree-free street canyons, in general, higher pollutant concentrations are found. Avenues of trees do not suppress canyon vortices, although the air ventilation in canyons is hindered significantly. For a perpendicular wind direction, increases in wall-average and wall-maximum concentrations at the leeward canyon wall and decreases in wall-average concentrations at the windward wall are found. For oblique and perpendicular wind directions, increases at both canyon walls are obtained. The strongest effects of avenues of trees on traffic pollutant dispersion are observed for oblique wind directions for which also the largest concentrations at the canyon walls are found. Thus, the prevailing assumption that attributes the most harmful dispersion conditions to a perpendicular wind direction does not hold for street canyons with avenues of trees. Furthermore, following dimensional analysis, an estimate of the normalized wall-maximum traffic pollutant concentration in street canyons with avenues of trees is derived.

21 CFR 331.11 - Listing of specific active ingredients.

Code of Federal Regulations, 2013 CFR

2013-04-01

... contributing at least 25 percent of the total acid neutralizing capacity; maximum daily dosage limit is 8 grams...., 8 grams calcium carbonate). (e) Citrate-containing active ingredients: Citrate ion, as citric acid or salt; maximum daily dosage limit 8 grams. (f) Glycine (aminoacetic acid). (g) Magnesium-containing...

40 CFR 57.203 - Contents of the application.

Code of Federal Regulations, 2010 CFR

2010-07-01

... emission of sulfur dioxide; the characteristics of all gas streams emitted from the smelter's process...'s maximum daily production capacity (as defined in § 57.103(r)), the operational rate (in pounds of... smelter is operating at that capacity; and the smelter's average and maximum daily production rate for...

Maximum power extraction under different vector-control schemes and grid-synchronization strategy of a wind-driven Brushless Doubly-Fed Reluctance Generator.

PubMed

Mousa, Mohamed G; Allam, S M; Rashad, Essam M

2018-01-01

This paper proposes an advanced strategy to synchronize the wind-driven Brushless Doubly-Fed Reluctance Generator (BDFRG) to the grid-side terminals. The proposed strategy depends mainly upon determining the electrical angle of the grid voltage, θ v and using the same transformation matrix of both the power winding and grid sides to ensure that the generated power-winding voltage has the same phase-sequence of the grid-side voltage. On the other hand, the paper proposes a vector-control (power-winding flux orientation) technique for maximum wind-power extraction under two schemes summarized as; unity power-factor operation and minimum converter-current. Moreover, a soft-starting method is suggested to avoid the employed converter over-current. The first control scheme is achieved by adjusting the command power-winding reactive power at zero for a unity power-factor operation. However, the second scheme depends on setting the command d-axis control-winding current at zero to maximize the ratio of the generator electromagnetic-torque per the converter current. This enables the system to get a certain command torque under minimum converter current. A sample of the obtained simulation and experimental results is presented to check the effectiveness of the proposed control strategies. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.

33 CFR 156.320 - Maximum operating conditions.

Code of Federal Regulations, 2010 CFR

2010-07-01

... of the following conditions exist: (1) The wind velocity is 56 km/hr (30 knots) or more; or (2) The... shall be drained when— (1) The wind velocity exceeds 82 km/hr (44 knots); or (2) Wave heights exceed 5...

33 CFR 156.320 - Maximum operating conditions.

Code of Federal Regulations, 2011 CFR

2011-07-01

... of the following conditions exist: (1) The wind velocity is 56 km/hr (30 knots) or more; or (2) The... shall be drained when— (1) The wind velocity exceeds 82 km/hr (44 knots); or (2) Wave heights exceed 5...

On the Sizes of the North Atlantic Basin Tropical Cyclones Based on 34- and 64-kt Wind Radii Data, 2004-2013

NASA Technical Reports Server (NTRS)

Wilson, Robert M.

2014-01-01

At end of the 2012 hurricane season the National Hurricane Center retired the original HURDAT dataset and replaced it with the newer version HURDAT2, which reformatted the original data and included additional information, in particular, estimates of the 34-, 50, and 64-kt wind radii for the interval 2004-2013. During the brief 10-year interval, some 164 tropical cyclones are noted to have formed in the North Atlantic basin, with 77 becoming hurricanes. Hurricane Sandy (2012) stands out as being the largest individual storm that occurred in the North Atlantic basin during the 2004 -2013 timeframe, both in terms of its 34- and 64-kt wind radii and wind areas, having maximum 34- and 64-kt wind radii, maximum wind areas, and average wind areas each more than 2 standard deviations larger than the corresponding means. In terms of the largest yearly total 34-kt wind area (i.e., the sum of all individual storm 34-kt wind areas during the year), the year 2010 stands out as being the largest (about 423 × 10(exp 6) nmi(exp 2)), compared to the mean of about 174 × 10(exp 6) nmi(exp 2)), surpassing the year 2005 (353 x 10(exp 6) nmi(exp 2)) that had the largest number of individual storms (28). However, in terms of the largest yearly total 64-kt wind area, the year 2005 was the largest (about 9 × 10(exp 6) nmi(exp 2)), compared to the mean of about 3 × 106 nmi(exp 2)). Interesting is that the ratio of total 64-kt wind area to total 34-kt wind area has decreased over time, from 0.034 in 2004 to 0.008 in 2013.

Grid-connected wind and photovoltaic system

NASA Astrophysics Data System (ADS)

Devabakthuni, Sindhuja

The objective of this thesis is to design a grid connected wind and photovoltaic system. A new model of converter control was designed which maintains the voltage of the bus to grid as constant when combined system of solar and wind is connected to AC bus. The model is designed to track maximum power at each point irrespective of changes in irradiance, temperature and wind speed which affects the power supplied to grid. Solar power from the sun is not constant as it is affected by changes in irradiances and temperature. Even the wind power is affected by wind speed. A MPPT controller was designed for both systems. A boost converter is designed which uses the pulses from MPPT controller to boost the output. Wind system consists of wind turbine block from the MATLAB with a pitch angle controller to maintain optimum pitch angle. The output from wind turbine is connected to a permanent magnet synchronous generator. The unregulated DC output from the photovoltaic system is directly given to boost converter. The AC output from the wind system is given to an uncontrolled rectifier to get a unregulated DC output. The unregulated DC output goes to the boost converter. A voltage source inverter was designed which converts the rectified DC output from the boost converter to AC power. The inverter is designed to maintain constant AC bus voltage irrespective of the disturbances in the power supply. Photovoltaic and wind systems are individually designed for 5KW each in MATLAB-Simulink environment. In this thesis, the models were subjected to changes in irradiance, temperature and wind speed and the results were interpreted. The model was successful in tracking maximum at every instant and the AC bus voltage was maintained constant throughout the simulation.

The effect of subauroral polarization streams on the mid-latitude thermospheric disturbance neutral winds: a universal time effect

NASA Astrophysics Data System (ADS)

Wang, Hui; Zhang, Kedeng; Zheng, Zhichao; Ridley, Aaron James

2018-03-01

The temporal and spatial variations in thermospheric neutral winds at an altitude of 400 km in response to subauroral polarization streams (SAPS) are investigated using global ionosphere and thermosphere model simulations under the southward interplanetary magnetic field (IMF) condition. During SAPS periods the westward neutral winds in the subauroral latitudes are greatly strengthened at dusk. This is due to the ion drag effect, through which SAPS can accelerate neutral winds in the westward direction. The new findings are that for SAPS commencing at different universal times, the strongest westward neutral winds exhibit large variations in amplitudes. The ion drag and Joule heating effects are dependent on the solar illumination, which exhibit UT variations due to the displacement of the geomagnetic and geographic poles. With more sunlight, stronger westward neutral winds can be generated, and the center of these neutral winds shifts to a later magnetic local time than neutral winds with less solar illumination. In the Northern Hemisphere and Southern Hemisphere, the disturbance neutral wind reaches a maximum at 18:00 and 04:00 UT, and a minimum at 04:00 and 16:00 UT, respectively. There is a good correlation between the neutral wind velocity and cos0.5(SZA) (solar zenith angle). The reduction in the electron density and enhancement in the air mass density at an altitude of 400 km are strongest when the maximum solar illumination collocates with the SAPS. The correlation between the neutral wind velocity and cos0.5(SZA) is also good during the northward IMF period. The effect of a sine-wave oscillation of SAPS on the neutral wind also exhibits UT variations in association with the solar illumination.

Design guidelines for wind-resistant structures

DOE Office of Scientific and Technical Information (OSTI.GOV)

McDonald, J.R.; Mehta, K.C.; Minor, J.E.

1975-06-01

The purpose of this document is to prescribe criteria and to provide guidance for professional personnel who are involved in the design and evaluation of buildings and structures to resist tornadoes and extreme winds at the Oak Ridge, Tennessee, Portsmouth, Ohio, and Paducah, Kentucky, Plant Sites. The scope of the document covers loads due to extreme winds and tornadoes. Other loading conditions such as dead, live, or earthquake loads shall be considered as prescribed by the Union Carbide Corporation. In Section II the method for determining the maximum design windspeed for any specified level of risk is described. The straightmore » wind and tornado parameters are then deduced from the value of maximum design windspeed. The three types of tornado and extreme wind loads (aerodynamic, atmospheric pressure change and missiles) are treated in Sections III, IV, and V, respectively. Appropriate load combinations are defined in Section VI. The final section contains several examples showing how the design guidelines are used to determine appropriate design wind pressures. A description of the computer program used to predict missile accelerations, velocities and trajectories is contained in Appendix A. Additional design examples are provided in Appendix B.« less

Verification and Calibration of a Reduced Order Wind Farm Model by Wind Tunnel Experiments

NASA Astrophysics Data System (ADS)

Schreiber, J.; Nanos, E. M.; Campagnolo, F.; Bottasso, C. L.

2017-05-01

In this paper an adaptation of the FLORIS approach is considered that models the wind flow and power production within a wind farm. In preparation to the use of this model for wind farm control, this paper considers the problem of its calibration and validation with the use of experimental observations. The model parameters are first identified based on measurements performed on an isolated scaled wind turbine operated in a boundary layer wind tunnel in various wind-misalignment conditions. Next, the wind farm model is verified with results of experimental tests conducted on three interacting scaled wind turbines. Although some differences in the estimated absolute power are observed, the model appears to be capable of identifying with good accuracy the wind turbine misalignment angles that, by deflecting the wake, lead to maximum power for the investigated layouts.

Applications of the PUFF model to forecasts of volcanic clouds dispersal from Etna and Vesuvio

NASA Astrophysics Data System (ADS)

Daniele, P.; Lirer, L.; Petrosino, P.; Spinelli, N.; Peterson, R.

2009-05-01

PUFF is a numerical volcanic ash tracking model developed to simulate the behaviour of ash clouds in the atmosphere. The model uses wind field data provided by meteorological models and adds dispersion and sedimentation physics to predict the evolution of the cloud once it reaches thermodynamic equilibrium with the atmosphere. The software is intended for use in emergency response situations during an eruption to quickly forecast the position and trajectory of the ash cloud in the near (˜1-72 h) future. In this paper, we describe the first application of the PUFF model in forecasting volcanic ash dispersion from the Etna and Vesuvio volcanoes. We simulated the daily occurrence of an eruptive event of Etna utilizing ash cloud parameters describing the paroxysm of 22nd July 1998 and wind field data for the 1st September 2005-31st December 2005 time span from the Global Forecast System (GFS) model at the approximate location of the Etna volcano (38N 15E). The results show that volcanic ash particles are dispersed in a range of directions in response to changing wind field at various altitudes and that the ash clouds are mainly dispersed toward the east and southeast, although the exact trajectory is highly variable, and can change within a few hours. We tested the sensitivity of the model to the mean particle grain size and found that an increased concentration of ash particles in the atmosphere results when the mean grain size is decreased. Similarly, a dramatic variation in dispersion results when the logarithmic standard deviation of the particle-size distribution is changed. Additionally, we simulated the occurrence of an eruptive event at both Etna and Vesuvio, using the same parameters describing the initial volcanic plume, and wind field data recorded for 1st September 2005, at approximately 38N 15E for Etna and 41N 14E for Vesuvio. The comparison of the two simulations indicates that identical eruptions occurring at the same time at the two volcanic centres display significantly different dispersal axes as a consequence of the different local wind field acting at the respective eruptive vents. At the Vesuvio the volcano, a plinian eruptive event with the dynamical parameters of the 79 A.D. eruption was simulated daily for one year, from 1st July 2005 to 30th June 2006. The statistical processing of results points out that, although in most cases the ash cloud dispersal encompasses many different areas, generally the easterly southeasterly direction is preferred. Our results highlight the significant role of wind field trends in influencing the distribution of ash particles from eruptive columns and prove that the dynamical parameters that most influence the variability of plume dispersal are the duration of the eruption and the maximum column height. Finally, the possible use of cloud simulations for refining hazard maps of areas exposed to volcanic ash dispersal is proposed.

Evaluation of different recall periods for the US National Cancer Institute's PRO-CTCAE.

PubMed

Mendoza, Tito R; Dueck, Amylou C; Bennett, Antonia V; Mitchell, Sandra A; Reeve, Bryce B; Atkinson, Thomas M; Li, Yuelin; Castro, Kathleen M; Denicoff, Andrea; Rogak, Lauren J; Piekarz, Richard L; Cleeland, Charles S; Sloan, Jeff A; Schrag, Deborah; Basch, Ethan

2017-06-01

The US National Cancer Institute recently developed the PRO-CTCAE (Patient-Reported Outcomes version of the Common Terminology Criteria for Adverse Events). PRO-CTCAE is a library of questions for clinical trial participants to self-report symptomatic adverse events (e.g. nausea). The objective of this study is to inform evidence-based selection of a recall period when PRO-CTCAE is included in a trial. We evaluated differences between 1-, 2-, 3-, and 4-week recall periods, using daily reporting as the reference. English-speaking patients with cancer receiving chemotherapy and/or radiotherapy were enrolled at four US cancer centers and affiliated community clinics. Participants completed 27 PRO-CTCAE items electronically daily for 28 days, and then weekly over 4 weeks, using 1-, 2-, 3-, and 4-week recall periods. For each recall period, mean differences, effect sizes, and intraclass correlation coefficients were calculated to evaluate agreement between the maximum of daily ratings and the corresponding ratings obtained using longer recall periods (e.g. maximum of daily scores over 7 days vs 1-week recall). Analyses were repeated using the average of daily scores within each recall period rather than the maximum of daily scores. A total of 127 subjects completed questionnaires (57% male; median age: 57). The median of the 27 mean differences in scores on the PRO-CTCAE 5-point response scale comparing the maximum daily versus the longer recall period (and corresponding effect size) was -0.20 (-0.20) for 1-week recall, -0.36 (-0.31) for 2-week recall, -0.45 (-0.39) for 3-week recall, and -0.47 (-0.40) for 4-week recall. The median intraclass correlation across 27 items between the maximum of daily ratings and the corresponding longer recall ratings for 1-week recall was 0.70 (range: 0.54-0.82), for 2-week recall was 0.74 (range: 0.58-0.83), for 3-week recall was 0.72 (range: 0.61-0.84), and for 4-week recall was 0.72 (range: 0.64-0.86). Similar results were observed for all analyses using the average of daily scores rather than the maximum of daily scores. A 1-week recall corresponds best to daily reporting. Although intraclass correlations remain stable over time, there are small but progressively larger differences between daily and longer recall periods at 2, 3, and 4 weeks, respectively. The preferred recall period for the PRO-CTCAE is the past 7 days, although investigators may opt for recall periods of 2, 3, or 4 weeks with an understanding that there may be some information loss.

Trends in Middle East climate extreme indices from 1950 to 2003

NASA Astrophysics Data System (ADS)

Zhang, Xuebin; Aguilar, Enric; Sensoy, Serhat; Melkonyan, Hamlet; Tagiyeva, Umayra; Ahmed, Nader; Kutaladze, Nato; Rahimzadeh, Fatemeh; Taghipour, Afsaneh; Hantosh, T. H.; Albert, Pinhas; Semawi, Mohammed; Karam Ali, Mohammad; Said Al-Shabibi, Mansoor Halal; Al-Oulan, Zaid; Zatari, Taha; Al Dean Khelet, Imad; Hamoud, Saleh; Sagir, Ramazan; Demircan, Mesut; Eken, Mehmet; Adiguzel, Mustafa; Alexander, Lisa; Peterson, Thomas C.; Wallis, Trevor

2005-11-01

A climate change workshop for the Middle East brought together scientists and data for the region to produce the first area-wide analysis of climate extremes for the region. This paper reports trends in extreme precipitation and temperature indices that were computed during the workshop and additional indices data that became available after the workshop. Trends in these indices were examined for 1950-2003 at 52 stations covering 15 countries, including Armenia, Azerbaijan, Bahrain, Cyprus, Georgia, Iran, Iraq, Israel, Jordan, Kuwait, Oman, Qatar, Saudi Arabia, Syria, and Turkey. Results indicate that there have been statistically significant, spatially coherent trends in temperature indices that are related to temperature increases in the region. Significant, increasing trends have been found in the annual maximum of daily maximum and minimum temperature, the annual minimum of daily maximum and minimum temperature, the number of summer nights, and the number of days where daily temperature has exceeded its 90th percentile. Significant negative trends have been found in the number of days when daily temperature is below its 10th percentile and daily temperature range. Trends in precipitation indices, including the number of days with precipitation, the average precipitation intensity, and maximum daily precipitation events, are weak in general and do not show spatial coherence. The workshop attendees have generously made the indices data available for the international research community.

A study of the relationship between micropulsations and solar wind properties

NASA Technical Reports Server (NTRS)

Yedidia, B. A.; Lazarus, A. J.; Vellante, M.; Villante, U.

1991-01-01

A year-long comparison between daily averages of solar wind parameters obtained from the MIT experiment on IMP-8 and micropulsation measurements made by the Universita dell'Aquila has shown a correlation between solar wind speed and micropulsation power with peaks of the correlation coefficient greater than 0.8 in the period range from 20 to 40 s. Different behavior observed for different period bands suggests that the shorter period activity tends to precede the highest values of the solar wind speed while the longer period activity tends to persist for longer intervals within high velocity solar wind streams. A comparison with simultaneous interplanetary magnetic field measurements supports the upstream origin of the observed ground pulsations.

Estimation of the high-spatial-resolution variability in extreme wind speeds for forestry applications

NASA Astrophysics Data System (ADS)

Venäläinen, Ari; Laapas, Mikko; Pirinen, Pentti; Horttanainen, Matti; Hyvönen, Reijo; Lehtonen, Ilari; Junila, Päivi; Hou, Meiting; Peltola, Heli M.

2017-07-01

The bioeconomy has an increasing role to play in climate change mitigation and the sustainable development of national economies. In Finland, a forested country, over 50 % of the current bioeconomy relies on the sustainable management and utilization of forest resources. Wind storms are a major risk that forests are exposed to and high-spatial-resolution analysis of the most vulnerable locations can produce risk assessment of forest management planning. In this paper, we examine the feasibility of the wind multiplier approach for downscaling of maximum wind speed, using 20 m spatial resolution CORINE land-use dataset and high-resolution digital elevation data. A coarse spatial resolution estimate of the 10-year return level of maximum wind speed was obtained from the ERA-Interim reanalyzed data. Using a geospatial re-mapping technique the data were downscaled to 26 meteorological station locations to represent very diverse environments. Applying a comparison, we find that the downscaled 10-year return levels represent 66 % of the observed variation among the stations examined. In addition, the spatial variation in wind-multiplier-downscaled 10-year return level wind was compared with the WAsP model-simulated wind. The heterogeneous test area was situated in northern Finland, and it was found that the major features of the spatial variation were similar, but in some locations, there were relatively large differences. The results indicate that the wind multiplier method offers a pragmatic and computationally feasible tool for identifying at a high spatial resolution those locations with the highest forest wind damage risks. It can also be used to provide the necessary wind climate information for wind damage risk model calculations, thus making it possible to estimate the probability of predicted threshold wind speeds for wind damage and consequently the probability (and amount) of wind damage for certain forest stand configurations.

Introduction to Voigt's wind power plant. [energy conversion efficiency

NASA Technical Reports Server (NTRS)

Tompkin, J.

1973-01-01

The design and operation of a 100 kilowatt wind driven generator are reported. Its high speed three-bladed turbine operates at a height of 50 meters. Blades are rigidly connected to the hub and turbine revolutions change linearly with wind velocity, maintaining a constant speed ratio of blade tip velocity to wind velocity over the full predetermined wind range. Three generators installed in the gondola generate either dc or ac current. Based on local wind conditions, the device has a maximum output of 720 kilowatts at a wind velocity of 16 meters per second. Total electrical capacity is 750 kilowatts, and power output per year is 2,135,000 kilowatt/hours.

Geophysical Potential for Wind Energy over the Open Oceans

NASA Astrophysics Data System (ADS)

Possner, A.; Caldeira, K.

2017-12-01

Wind turbines continuously remove kinetic energy from the lower troposphere thereby reducing the wind speed near hub height. The rate of electricity generation in large wind farms containing multiple wind arrays is therefore constrained by the rate of kinetic energy replenishment from the atmosphere above. In particular, this study focuses on the maximum sustained transport of kinetic energy through the troposphere to the lowest hundreds of meters above the surface. In recent years, a growing body of research argues that the rate of generated power is limited to around 1.5 Wm-2 within large wind farms. However, in this study we demonstrate that considerably higher power generation rates may be sustainable over some open ocean areas in giant wind farms. We find that in the North Atlantic maximum extraction rates of up to 6.7 Wm-2 may be sustained by the atmosphere in the annual mean over giant wind farm areas approaching the size of Greenland. In contrast, only a third of this rate is sustained on land for areas of equivalent size. Our simulations indicate a fundamental difference in response of the troposphere and its vertical kinetic energy flux to giant near-surface wind farms. We find that the surface heat flux from the oceans to the atmosphere may play an important role in creating regions where large sustained rates of downward transport of kinetic energy and thus rates of kinetic energy extraction may be geophysically possible. While no commercial-scale deep-water wind turbines yet exist, our results suggest that such technologies, if they became technically and economically feasible, could potentially provide civilization-scale power.

Analysis of vector wind change with respect to time for Cape Kennedy, Florida: Wind aloft profile change vs. time, phase 1

NASA Technical Reports Server (NTRS)

Adelfang, S. I.

1977-01-01

Wind vector change with respect to time at Cape Kennedy, Florida, is examined according to the theory of multivariate normality. The joint distribution of the four variables represented by the components of the wind vector at an initial time and after a specified elapsed time is hypothesized to be quadravariate normal; the fourteen statistics of this distribution, calculated from fifteen years of twice daily Rawinsonde data are presented by monthly reference periods for each month from 0 to 27 km. The hypotheses that the wind component changes with respect to time is univariate normal, the joint distribution of wind component changes is bivariate normal, and the modulus of vector wind change is Rayleigh, has been tested by comparison with observed distributions. Statistics of the conditional bivariate normal distributions of vector wind at a future time given the vector wind at an initial time are derived. Wind changes over time periods from one to five hours, calculated from Jimsphere data, are presented.

The air quality analysis of Dalian based on the data of AQI

NASA Astrophysics Data System (ADS)

Gu, Ji-lin; Liu, Miao

2018-02-01

The data of AQI from 10 countries accused of automatic air quality monitoring station of Dalian from June 2015 to December 2016 were analyzed to investigate the daily mean change of air quality index, the change of the hour and the correlation analysis between AQI and PM2.5, PM10, SO2, NO2, CO, O3 six parameters. The 856,800 index samples showed that the air quality index of autumn and winter was obviously higher than that of summer. The maximum AQI value in autumn and winter reached 389, with an average of 82. The maximum value of AQI in summer was 130, and the average was 50. From 2015 to 2016, the excellent air quality in the summer in Dalian was 60.3%; the standard rate was 98.4%. The autumn and winter air quality accounted for 39.1% and the compliance rate was 68.5%. The mean of the AQI average daily was a wavy trend, and the changes of summer and autumn and winter were roughly the same. The regularity of AQI 24-hour showed multi-peak changes, bimodal changes and single peak changes. The air quality in Dalian is affected by the weather conditions such as wind direction, rainfall and fog, the air quality in surrounding cities, urban pollution, vehicle exhaust and excessive consumption of coal energy. Through correlation calculation, AQI, PM2.5, and PM10 were significantly correlated irrespective of season. AQI and O3 were positively correlated in summer, but negatively correlated in autumn and winter, which is the basis for the treatment of air pollution in Dalian.

75 FR 23798 - Environmental Assessment Prepared for Proposed Cape Wind Energy Project in Nantucket Sound...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-05-04

... calls for 130, 3.6 megawatt (MW) wind turbine generators, each with a maximum blade height of 440 feet... transmission cables, which would run through Massachusetts' territory to shore. For reference, the northernmost...

75 FR 10500 - Environmental Assessment Prepared for Proposed Cape Wind Energy Project in Nantucket Sound, MA

Federal Register 2010, 2011, 2012, 2013, 2014

2010-03-08

... calls for 130, 3.6 megawatt (MW) wind turbine generators, each with a maximum blade height of 440 feet... in Federal waters, aside from transmission cables running through Massachusetts waters ashore. For...

Crop production and economic loss due to wind erosion in hot arid ecosystem of India

NASA Astrophysics Data System (ADS)

Santra, Priyabrata; Moharana, P. C.; Kumar, Mahesh; Soni, M. L.; Pandey, C. B.; Chaudhari, S. K.; Sikka, A. K.

2017-10-01

Wind erosion is a severe land degradation process in hot arid western India and affects the agricultural production system. It affects crop yield directly by damaging the crops through abrasion, burial, dust deposition etc. and indirectly by reducing soil fertility. In this study, an attempt was made to quantify the indirect impact of wind erosion process on crop production loss and associated economic loss in hot arid ecosystem of India. It has been observed that soil loss due to wind erosion varies from minimum 1.3 t ha-1 to maximum 83.3 t ha-1 as per the severity. Yield loss due to wind erosion was found maximum for groundnut (Arachis hypogea) (5-331 kg ha-1 yr-1), whereas minimum for moth bean (Vigna aconitifolia) (1-93 kg ha-1 yr-1). For pearl millet (Pennisetum glaucum), which covers a major portion of arable lands in western Rajasthan, the yield loss was found 3-195 kg ha-1 yr-1. Economic loss was found higher for groundnut and clusterbean (Cyamopsis tetragonoloba) than rest crops, which are about

A Broad Continuum of Aeolian Impact Ripple Sizes on Mars is Allowed by Low Dynamic Wind Pressures

NASA Astrophysics Data System (ADS)

Sullivan, R. J., Jr.; Kok, J. F.; Yizhaq, H.

2017-12-01

Aeolian impact ripples are generated by impacts of wind-blown sand grains, and are common in environments with loose sand on Earth and Mars. Previous work has shown that, within a fully developed saltation cloud, impact ripple height grows upward into the boundary layer until limited by the effects of increasing wind dynamic pressure at the crest (e.g., lengthening of splash trajectories, or direct entrainment of grains by the wind). On Earth, this process limits ripples of well-sorted 250 µm dune sands to heights of millimeters, and strong winds can impose sufficient lateral dynamic pressure to flatten and erase these ripples. Rover observations show much larger ripple-like bedforms on Mars, raising questions about their formative mechanism. Here, we hypothesize that two factors allow impact ripples to grow much higher on Mars than on Earth: (1) previous work predicts a much larger difference between impact threshold and fluid threshold wind speeds on Mars than on Earth; and (2) recent analysis has revealed how low saltation flux can be initiated and sustained well below fluid threshold on Mars, allowing impact ripples to migrate entirely under prevailing conditions of relatively low wind speeds in the thin martian atmosphere. Under these circumstances, martian ripples would need to grow much larger than on Earth before reaching their maximum height limited by wind dynamic pressure effects. Because the initial size of impact ripples is similar on Mars and Earth, this should generate a much broader continuum of impact ripple sizes on Mars. Compared with Earth, far more time should be needed on Mars for impact ripples to achieve their maximum possible size. Consequently, in cases where wind azimuths are mixed but one azimuth is more dominant than others, martian impact ripples of all sizes can exist together in the same setting, with the largest examples reflecting the most common/formative wind azimuths. In cases where wind azimuth is not dominated by a single azimuth over others, ripple height should vary with orientation and the maximum possible height might never have the chance to be achieved. Our hypothesis could explain the wide range of observed ripple sizes on Mars having wavelengths from cm to several m, and suggests that the largest martian ripples are in fact large impact ripples.

Climate refugia: The physical, hydrologic and disturbance basis

NASA Astrophysics Data System (ADS)

Holden, Z. A.; Maneta, M. P.; Forthofer, J.

2015-12-01

Projected changes in global climate and associated shifts in vegetation have increased interest in understanding species persistence at local scales. We examine the climatic and physical factors that could mediate changes in the distribution of vegetation in regions of complex topography. Using massive networks of low-cost temperature and humidity sensors, we developed topographically-resolved daily historical gridded temperature data for the US Northern Rockies. We used the WindNinja model to create daily historical wind speed maps across the same domain. Using a spatially distributed ecohydrology model (ECH2O) we examine separately the sensitivity of modeled evapotranspiration and soil moisture to wind, radiation, soil properties, minimum temperature and humidity. A suite of physical factors including lower wind speeds, cold air drainage, solar shading and increased soil depth reduce evapotranspiration and increase late season moisture availability in valley bottoms. Evapotranspiration shows strong sensitivity to spatial variability in surface wind speed, suggesting that sheltering effects from winds may be an important factor contributing to mountain refugia. Fundamental to our understanding of patterns of vegetation change is the role of stand-replacing wildfires, which modify the physical environment and subsequent patterns of species persistence and recruitment. Using satellite-derived maps of burn severity for recent fires in the US Northern Rockies we examined relationships between wind speed, cold air drainage potential and soil depth and the occurrence of unburned and low severity fire. Severe fire is less likely to occur in areas with high cold air drainage potential and low wind speeds, suggesting that sheltered valley bottoms have mediated the severity of recent wildfires. Our finding highlight the complex physical mechanisms by which mountain weather and climate mediate fire-induced vegetation changes in the US Northern Rocky Mountains.

Intraocular Pressure Fluctuations and 24-Hour Continuous Monitoring for Glaucoma Risk in Wind Instrument Players.

PubMed

de Crom, Ronald M P C; Webers, Carroll A B; van Kooten-Noordzij, Marina A W; Michiels, Agnes C; Schouten, Jan S A G; Berendschot, Tos T J M; Beckers, Henny J M

2017-10-01

The purpose of this study is to investigate the influence of playing a wind instrument on intraocular pressure (IOP) and to monitor 24-hour (IOP) fluctuations in wind musicians of symphony and wind orchestras to compare IOP levels during normal daily activities with IOP levels during playing. Professional and amateur musicians of symphony and wind orchestras were invited to participate. A total of 42 participants, 9 with glaucoma, underwent a routine ophthalmologic examination. IOP measurements were taken before and immediately after 20 minutes of playing wind instruments. In addition, 6 participants underwent 24-hour IOP monitoring with the Triggerfish (Sensimed AG, Switzerland) sensing contact lens, during which they kept an activity logbook. Eleven professionals and 31 amateur musicians participated in the study. A total of 7 eyes of 6 patients underwent additional 24-hour IOP monitoring. Mean IOP before playing was 13.6±2.6 mm Hg, IOP change after playing was +1.5±2.2 mm Hg with a significant difference between professionals (2.5±1.5 mm Hg) and amateurs (1.1±2.3 mm Hg). There were no significant differences in IOP change between subjects with or without glaucoma. During 24-hour IOP monitoring there were slight increases in IOP while playing an instrument, but also during other activities and overnight. These latter IOP levels were similar or even higher than the IOP rise caused by playing a wind instrument. IOP often rises after playing wind instruments, but similar or even higher IOP levels seem to occur during common other daily activities or at night. These peaks may be relevant for glaucomatous field progression and treatment of glaucoma patients.

40 CFR 130.7 - Total maximum daily loads (TMDL) and individual water quality-based effluent limitations.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 21 2010-07-01 2010-07-01 false Total maximum daily loads (TMDL) and individual water quality-based effluent limitations. 130.7 Section 130.7 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) WATER PROGRAMS WATER QUALITY PLANNING AND MANAGEMENT § 130.7 Total...

40 CFR 130.7 - Total maximum daily loads (TMDL) and individual water quality-based effluent limitations.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 22 2011-07-01 2011-07-01 false Total maximum daily loads (TMDL) and individual water quality-based effluent limitations. 130.7 Section 130.7 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) WATER PROGRAMS WATER QUALITY PLANNING AND MANAGEMENT § 130.7 Total...

76 FR 30338 - Hill-Lake Gas Storage, LLC; Notice of Filing

Federal Register 2010, 2011, 2012, 2013, 2014

2011-05-25

... DEPARTMENT OF ENERGY Federal Energy Regulatory Commission [Docket No. PR11-110-000] Hill-Lake Gas Storage, LLC; Notice of Filing Take notice that on May 13, 2011, Hill-Lake Gas Storage, LLC filed to update its address and to clarify definitions for Maximum Daily Withdrawal Quantity and Maximum Daily...

Effects of setting angle on performance of fish-bionic wind wheel

NASA Astrophysics Data System (ADS)

Li, G. S.; Yang, Z. X.; Song, L.; Chen, Q.; Li, Y. B.; Chen, W.

2016-08-01

With the energy crisis and the increasing environmental pollutionmore and more efforts have been made about wind power development. In this paper, a new type of vertical axis named the fish-bionic wind wheel was proposed, and the outline of wind wheel was constructed by curve of Fourier fitting and polynomial equations. This paper attempted to research the relationship between the setting angle and the wind turbine characteristics by computational fluid dynamics (CFD) simulation. The results showed that the setting angle of the fish-bionic wind wheel has some significant effects on the efficiency of the wind turbine, Within the range of wind speed from 13m/s to 15m/s, wind wheel achieves the maximum efficiency when the setting angle is at 37 degree. The conclusion will work as a guideline for the improvement of wind turbine design.

Reattachment Zone Characterisation Under Offshore Winds With Flow Separation On The Lee Side Of Coastal Dunes

NASA Astrophysics Data System (ADS)

Delgado-Fernandez, I.; Jackson, D.; Cooper, J. A.; Baas, A. C.; Lynch, K.; Beyers, M.

2010-12-01

Airflow separation, lee-side eddies and secondary flows play an essential role on the formation and maintenance of sand dunes. Downstream from dune crests the flow surface layer detaches from the ground and generates an area characterised by turbulent eddies in the dune lee slope (the wake). At some distance downstream from the dune crest, flow separates into a reversed component directed toward the dune toe and an offshore “re-attached” component. This reattachment zone (RZ) has been documented in fluvial and desert environments, wind tunnel experiments and numerical simulations, but not yet characterised in coastal dunes. This study examines the extent and temporal evolution of the RZ and its implications for beach-dune interaction at Magilligan, Northern Ireland. Wind parameters were measured over a profile extending from an 11 m height dune crest towards the beach, covering a total distance of 65 m cross-shore. Data was collected using an array of nine ultrasonic anemometers (UAs) deployed in April-May 2010, as part of a larger experiment to capture airflow data under a range of incident wind velocities and offshore directions. UAs were located along the profile (5 m tower spacing) over the beach, which allowed a detailed examination of the RZ with empirical data. Numerical modelling using Computational Fluid Dynamics (CFD) software was also conducted with input data from anemometer field measurements, running over a surface mesh generated from LiDAR and DGPS surveys. Results demonstrate that there is a wind threshold of approximately 5-6 ms-1 under which no flow separation exists with offshore winds. As wind speed increases over the threshold, a flow reversal area is quickly formed, with the maximum extent of the RZ at approximately 3.5 dune heights (h). The maximum extent of the RZ increases up to 4.5h with stronger wind speeds of 8-10 ms-1 and remains relatively constant as wind speed further increases. This suggests that the spatial extent of the RZ is independent of incident wind speed and is located between 4-5h. The magnitude of the maximum extent of the RZ is similar to that simulated using CFD and is consistent with previous studies conducted in desert dunes and wind tunnel simulations for offshore winds blowing over tall and sharp-crested dunes. Ongoing analyses are being conducted to evaluate the effect of changing wind direction, dune height and shape.

Optimizing Wind And Hydropower Generation Within Realistic Reservoir Operating Policy

NASA Astrophysics Data System (ADS)

Magee, T. M.; Clement, M. A.; Zagona, E. A.

2012-12-01

Previous studies have evaluated the benefits of utilizing the flexibility of hydropower systems to balance the variability and uncertainty of wind generation. However, previous hydropower and wind coordination studies have simplified non-power constraints on reservoir systems. For example, some studies have only included hydropower constraints on minimum and maximum storage volumes and minimum and maximum plant discharges. The methodology presented here utilizes the pre-emptive linear goal programming optimization solver in RiverWare to model hydropower operations with a set of prioritized policy constraints and objectives based on realistic policies that govern the operation of actual hydropower systems, including licensing constraints, environmental constraints, water management and power objectives. This approach accounts for the fact that not all policy constraints are of equal importance. For example target environmental flow levels may not be satisfied if it would require violating license minimum or maximum storages (pool elevations), but environmental flow constraints will be satisfied before optimizing power generation. Additionally, this work not only models the economic value of energy from the combined hydropower and wind system, it also captures the economic value of ancillary services provided by the hydropower resources. It is recognized that the increased variability and uncertainty inherent with increased wind penetration levels requires an increase in ancillary services. In regions with liberalized markets for ancillary services, a significant portion of hydropower revenue can result from providing ancillary services. Thus, ancillary services should be accounted for when determining the total value of a hydropower system integrated with wind generation. This research shows that the end value of integrated hydropower and wind generation is dependent on a number of factors that can vary by location. Wind factors include wind penetration level, variability due to geographic distribution of wind resources, and forecast error. Electric power system factors include the mix of thermal generation resources, available transmission, demand patterns, and market structures. Hydropower factors include relative storage capacity, reservoir operating policies and hydrologic conditions. In addition, the wind, power system, and hydropower factors are often interrelated because stochastic weather patterns can simultaneously influence wind generation, power demand, and hydrologic inflows. One of the central findings is that the sensitivity of the model to changes cannot be performed one factor at a time because the impact of the factors is highly interdependent. For example, the net value of wind generation may be very sensitive to changes in transmission capacity under some hydrologic conditions, but not at all under others.

Erosive effects of the storms HELENA (1963) and HUGO (1989) on Basse-Terre island (Guadeloupe - Lesser Antilles Arc).

NASA Astrophysics Data System (ADS)

Le Bivic, Rejanne; Allemand, Pascal; Delacourt, Christophe; Quiquerez, Amélie

2014-05-01

Basse-Terre is a volcanic island which belongs to the archipelago of Guadeloupe located in the Lesser Antilles Arc (Caribbean Sea). As a mountainous region in the tropical belt, Basse-Terre is affected by intense sediment transport due to extreme meteorological events. During the last fifty years, eight major tropical storms and hurricanes with intense rainfalls induced landslides and scars in the weathered layers. The purpose of this study is to compare two major meteorological events within a period of 26 years (HELENA in 10/1963 and HUGO in 09/1989) in order to qualify the parameters responsible of the spatial distribution of landslides and scars. The storm HELENA affected Basse-Terre between the 23rd and the 25th of October, 1963. The maximal daily rainfall reached 300 mm in Baillif which is located on the leeward coast at the altitude of 650 m while the maximum wind velocity reached 50 km/h. A similar exceptional event happened when the hurricane HUGO slammed the island in September 17, 1989. The maximum daily rainfall recorded in Sainte-Rose (on the northern coast) was 250 mm while it reached 208 mm in Petit-Bourg and the maximum wind speed was 60 km/h. Aerial images were acquired by the IGN (French Geographical Institute) before and a few weeks after the extreme events: less than three months after the event HELENA and less than a month after the event HUGO. Those images have been orthorectified at a metric resolution and combined in a GIS with a 10 m resolution DEM. Scars and landslides were digitalized and their surface area and mean slope were measured for both HELENA and HUGO. This work confirms several results proposed by a previous study related to the HELENA event: (1) the landslides occurred mainly in the center of the island and (2) the slope is the main parameter for the initiation of landslides, since all of them occurred with a slope superior to 30°. Furthermore, the resiliency of the surface affected by the landslides induced by HELENA was studied from 1963 to 1989 through historical aerial images acquired by the IGN in 1963, 1969, 1984 and 1989. Landslide areas were covered with new vegetation within 6 years after a hurricane, due to the opportune weather conditions of heavy rainfalls and high temperature. The comparison between the landslides mapped after two similar events also shows that the zones affected by landslides are set apart. One can conclude that there are no weak zones which are likely to collapse during every meteorological event. These results are particularly relevant for landslide risk management.

Subsurface Assessment at McMurdo Station, Antarctica

DTIC Science & Technology

2017-02-01

collected at the T-site for design and construction of a foundation for a wind turbine (after Oswell et al. 2010...foundation for a wind turbine (after Oswell et al. 2010). 5.3 Surface snowmelt and frost susceptibility The gravelly sand with silts found in this...maximum unfrozen density with low moisture content. Compaction of fill materials for con- structing wind turbine foundations at the T-site commenced

Emergency department patient knowledge concerning acetaminophen (paracetamol) in over-the-counter and prescription analgesics.

PubMed

Fosnocht, D; Taylor, J R; Caravati, E M

2008-04-01

This study was designed to evaluate patient knowledge of the acetaminophen (paracetamol) content of commonly used pain medications and the maximum daily recommended dose of acetaminophen. A prospective, convenience sample of emergency department patients were enrolled. Data were recorded using a standardised questionnaire over 4 months. 1009 patients were enrolled. 492 patients (49%) did not know if Tylenol contained acetaminophen (paracetamol). The majority (66-90%) of patients did not know if Lortab, Vicodin, Percocet, non-aspirin pain reliever, ibuprofen, Motrin, or Advil contained acetaminophen. 568 patients (56%) reported not knowing the maximum daily dose of acetaminophen and only 71 patients (7%) reported the correct daily dose. Patient knowledge of the acetaminophen content of commonly used analgesic medications and its maximum recommended daily dose is limited. This may contribute to unintentional repeated supratherapeutic ingestion (RSTI) of acetaminophen, or overdose.

Quiet-Time Suprathermal (˜0.1 - 200 keV) Electrons in the Solar Wind

NASA Astrophysics Data System (ADS)

Wang, Linghua; Yang, Liu; Tao, Jiawei; Zong, Qiugang; Li, Gang; Wimmer-Schweingruber, Robert; He, Jiansen; Tu, Chuanyi; Bale, Stuart

2017-04-01

We present a statistical survey of the energy spectrum of solar wind suprathermal (˜0.1-200 keV) electrons measured by the WIND 3DP instrument at 1 AU during quiet times at the minimum and maximum of solar cycles 23 and 24. The observed energy spectrum of both (beaming) strahl and (isotropic) halo electrons at ˜0.1-1.5 keV generally fits to a Kappa distribution function with an index κ and effective temperature Teff, while the observed energy spectrum of nearly isotropic superhalo electrons at ˜20-200 keV generally fits to a power-law function, J ˜ E-β. We find a strong positive correlation between κ and Teff for both strahl and halo electrons, and a strong positive correlation between the strahl density and halo density. In both solar cycles, κ is larger at solar minimum than at solar maximum for both strahl and halo electrons. For the superhalo population, the spectral index β ranges from ˜1.6 to ˜3.7 and the integrated density nsup ranges from 10-8 cm-3 to 10-5 cm-3, with no clear association with the sunspot number. In solar cycle 23 (24), the distribution of β has a broad maximum between 2.4 and 2.8 (2.0 and 2.4). All the strahl, halo and superhalo populations show no obvious correlation with the solar wind core population. These results reflect the nature of the generation of solar wind suprathermal electrons.

Modelling storm development and the impact when introducing waves, sea spray and heat fluxes

NASA Astrophysics Data System (ADS)

Wu, Lichuan; Rutgersson, Anna; Sahlée, Erik

2015-04-01

In high wind speed conditions, sea spray generated due to intensity breaking waves have big influence on the wind stress and heat fluxes. Measurements show that drag coefficient will decrease in high wind speed. Sea spray generation function (SSGF), an important term of wind stress parameterization in high wind speed, usually treated as a function of wind speed/friction velocity. In this study, we introduce a wave state depended SSGG and wave age depended Charnock number into a high wind speed wind stress parameterization (Kudryavtsev et al., 2011; 2012). The proposed wind stress parameterization and sea spray heat fluxes parameterization from Andreas et al., (2014) were applied to an atmosphere-wave coupled model to test on four storm cases. Compared with measurements from the FINO1 platform in the North Sea, the new wind stress parameterization can reduce the forecast errors of wind in high wind speed range, but not in low wind speed. Only sea spray impacted on wind stress, it will intensify the storms (minimum sea level pressure and maximum wind speed) and lower the air temperature (increase the errors). Only the sea spray impacted on the heat fluxes, it can improve the model performance on storm tracks and the air temperature, but not change much in the storm intensity. If both of sea spray impacted on the wind stress and heat fluxes are taken into account, it has the best performance in all the experiment for minimum sea level pressure and maximum wind speed and air temperature. Andreas, E. L., Mahrt, L., and Vickers, D. (2014). An improved bulk air-sea surface flux algorithm, including spray-mediated transfer. Quarterly Journal of the Royal Meteorological Society. Kudryavtsev, V. and Makin, V. (2011). Impact of ocean spray on the dynamics of the marine atmospheric boundary layer. Boundary-layer meteorology, 140(3):383-410. Kudryavtsev, V., Makin, V., and S, Z. (2012). On the sea-surface drag and heat/mass transfer at strong winds. Technical report, Royal Netherlands Meteorological Institute.

Adaptive Gain-based Stable Power Smoothing of a DFIG

DOE PAGES

Muljadi, Eduard; Lee, Hyewon; Hwang, Min; ...

2017-11-01

In a power system that has a high wind penetration, the output power fluctuation of a large-scale wind turbine generator (WTG) caused by the varying wind speed increases the maximum frequency deviation, which is an important metric to assess the quality of electricity, because of the reduced system inertia. This paper proposes a stable power-smoothing scheme of a doubly-fed induction generator (DFIG) that can suppress the maximum frequency deviation, particularly for a power system with a high wind penetration. To do this, the proposed scheme employs an additional control loop relying on the system frequency deviation that operates in combinationmore » with the maximum power point tracking control loop. To improve the power-smoothing capability while guaranteeing the stable operation of a DFIG, the gain of the additional loop is modified with the rotor speed and frequency deviation. The gain is set to be high if the rotor speed and/or frequency deviation is large. Here, the simulation results based on the IEEE 14-bus system demonstrate that the proposed scheme significantly lessens the output power fluctuation of a WTG under various scenarios by modifying the gain with the rotor speed and frequency deviation, and thereby it can regulate the frequency deviation within a narrow range.« less

Adaptive Gain-based Stable Power Smoothing of a DFIG

DOE Office of Scientific and Technical Information (OSTI.GOV)

Muljadi, Eduard; Lee, Hyewon; Hwang, Min

In a power system that has a high wind penetration, the output power fluctuation of a large-scale wind turbine generator (WTG) caused by the varying wind speed increases the maximum frequency deviation, which is an important metric to assess the quality of electricity, because of the reduced system inertia. This paper proposes a stable power-smoothing scheme of a doubly-fed induction generator (DFIG) that can suppress the maximum frequency deviation, particularly for a power system with a high wind penetration. To do this, the proposed scheme employs an additional control loop relying on the system frequency deviation that operates in combinationmore » with the maximum power point tracking control loop. To improve the power-smoothing capability while guaranteeing the stable operation of a DFIG, the gain of the additional loop is modified with the rotor speed and frequency deviation. The gain is set to be high if the rotor speed and/or frequency deviation is large. Here, the simulation results based on the IEEE 14-bus system demonstrate that the proposed scheme significantly lessens the output power fluctuation of a WTG under various scenarios by modifying the gain with the rotor speed and frequency deviation, and thereby it can regulate the frequency deviation within a narrow range.« less

Polarization cancellation in the two-component winds from Wolf-Rayet stars

NASA Technical Reports Server (NTRS)

Taylor, M.; Cassinelli, J. P.

1992-01-01

In this paper we explore the possibility that there can be at least partial cancellation of the equatorial disk polarization as a result of scattering from the electrons that are present in the strong polar wind of WR stars. In order to achieve the cancellation necessary to explain the wavelength-dependent polarization, the polar wind must have a mass-loss rate that is near the maximum that is supported by radiation-driven wind theory. In addition, we find that it is possible to derive important new information regarding the relative column masses of the polar and equatorial winds.

An experimental analysis of electricity conservation procedures1

PubMed Central

Palmer, Michael H.; Lloyd, Margaret E.; Lloyd, Kenneth E.

1977-01-01

Daily electricity consumption of four families was recorded for 106 days. A reversal design, consisting of various experimental conditions interspersed between repeated baseline conditions, was used. During experimental conditions, daily prompts (written conservation slogans attached to front doors) and/or daily feedback (daily kilowatts consumed and daily cost information) were in effect. Maximum consumption occurred during the initial baseline; minimum consumption occurred during different experimental conditions for different families. The mean decrease from the maximum to the minimum for all families was 35%. Reversals in consumption were demonstrated in three families, although successive baselines tended to decrease. No clear differences in effectiveness between prompting and feedback conditions were apparent. The procedures used resulted in considerable dollar savings for the families. PMID:16795572

Drake Antarctic Agile Meteor Radar first results: Configuration and comparison of mean and tidal wind and gravity wave momentum flux measurements with Southern Argentina Agile Meteor Radar

NASA Astrophysics Data System (ADS)

Fritts, D. C.; Janches, D.; Iimura, H.; Hocking, W. K.; Bageston, J. V.; Leme, N. M. P.

2012-01-01

A new generation meteor radar was installed at the Brazilian Antarctic Comandante Ferraz Base (62.1°S) in March 2010. This paper describes the motivations for the radar location, its measurement capabilities, and comparisons of measured mean winds, tides, and gravity wave momentum fluxes from April to June of 2010 and 2011 with those by a similar radar on Tierra del Fuego (53.8°S). Motivations for the radars include the “hotspot” of small-scale gravity wave activity extending from the troposphere into the mesosphere and lower thermosphere (MLT) centered over the Drake Passage, the maximum of the semidiurnal tide at these latitudes, and the lack of other MLT wind measurements in this latitude band. Mean winds are seen to be strongly modulated at planetary wave and longer periods and to exhibit strong coherence over the two radars at shorter time scales as well as systematic seasonal variations. The semidiurnal tide contributes most to the large-scale winds over both radars, with maximum tidal amplitudes during May and maxima at the highest altitudes varying from ˜20 to >70 ms-1. In contrast, the diurnal tide and various planetary waves achieve maximum winds of ˜10 to 20 ms-1. Monthly mean gravity wave momentum fluxes appear to reflect the occurrence of significant sources at lower altitudes, with relatively small zonal fluxes over both radars, but with significant, and opposite, meridional momentum fluxes below ˜85 km. These suggest gravity waves propagating away from the Drake Passage at both sites, and may indicate an important source region accounting in part for this “hotspot.”

Drake Antarctic Agile Meteor Radar (DrAAMER) First Results: Configuration and Comparison of Mean and Tidal Wind and Gravity Wave Momentum Flux Measurements with SAAMER

NASA Technical Reports Server (NTRS)

Fritts, D. C.; Janches, D.; Iimura, H.; Hocking, W. K.; Bageston, J. V.; Pene, N. M.

2011-01-01

A new-generation meteor radar was installed at the Brazilian Antarctic Comandante Ferraz Base (62.1degS) in March 2010. This paper describes the motivations for the radar location, its measurement capabilities, and comparisons of measured mean winds, tides, and gravity wave momentum fluxes from April to June of 2010 and 2011 with those by a similar radar on Tierra del Fuego (53.8degS). Motivations for the radars include the "hotspot" of small-scale gravity wave activity extending from the troposphere into the mesosphere and lower thermosphere (MLT) centered over the Drake Passage, the maximum of the semidiurnal tide at these latitudes, and the lack of other MLT wind measurements in this latitude band. Mean winds are seen to be strongly modulated at planetary wave and longer periods and to exhibit strong coherence over the two radars at shorter time scales as well as systematic seasonal variations. The semidiurnal tide contribute most to the large-scale winds over both radars, with maximum tidal amplitudes during May and maxima at the highest altitudes varying from approx.20 to >70 m/s. In contrast, the diurnal tide and various planetary waves achieve maximum winds of approx.10 to 20 m/s. Monthly-mean gravity wave momentum fluxes appear to reflect the occurrence of significant sources at lower altitudes, with relatively small zonal fluxes over both radars, but with significant, and opposite, meridional momentum fluxes below approx.85 km. These suggest gravity waves propagating away from the Drake Passage at both sites, and may indicate an important source region accounting in part for this "hotspot".

Optimization of Wind Turbine Airfoils/Blades and Wind Farm Layouts

NASA Astrophysics Data System (ADS)

Chen, Xiaomin

Shape optimization is widely used in the design of wind turbine blades. In this dissertation, a numerical optimization method called Genetic Algorithm (GA) is applied to address the shape optimization of wind turbine airfoils and blades. In recent years, the airfoil sections with blunt trailing edge (called flatback airfoils) have been proposed for the inboard regions of large wind-turbine blades because they provide several structural and aerodynamic performance advantages. The FX, DU and NACA 64 series airfoils are thick airfoils widely used for wind turbine blade application. They have several advantages in meeting the intrinsic requirements for wind turbines in terms of design point, off-design capabilities and structural properties. This research employ both single- and multi-objective genetic algorithms (SOGA and MOGA) for shape optimization of Flatback, FX, DU and NACA 64 series airfoils to achieve maximum lift and/or maximum lift to drag ratio. The commercially available software FLUENT is employed for calculation of the flow field using the Reynolds-Averaged Navier-Stokes (RANS) equations in conjunction with a two-equation Shear Stress Transport (SST) turbulence model and a three equation k-kl-o turbulence model. The optimization methodology is validated by an optimization study of subsonic and transonic airfoils (NACA0012 and RAE 2822 airfoils). In this dissertation, we employ DU 91-W2-250, FX 66-S196-V1, NACA 64421, and Flat-back series of airfoils (FB-3500-0050, FB-3500-0875, and FB-3500-1750) and compare their performance with S809 airfoil used in NREL Phase II and III wind turbines; the lift and drag coefficient data for these airfoils sections are available. The output power of the turbine is calculated using these airfoil section blades for a given B and lambda and is compared with the original NREL Phase II and Phase III turbines using S809 airfoil section. It is shown that by a suitable choice of airfoil section of HAWT blade, the power generated by the turbine can be significantly increased. Parametric studies are also conducted by varying the turbine diameter. In addition, a simplified dynamic inflow model is integrated into the BEM theory. It is shown that the improved BEM theory has superior performance in capturing the instantaneous behavior of wind turbines due to the existence of wind turbine wake or temporal variations in wind velocity. The dissertation also considers the Wind Farm layout optimization problem using a genetic algorithm. Both the Horizontal --Axis Wind Turbines (HAWT) and Vertical-Axis Wind Turbines (VAWT) are considered. The goal of the optimization problem is to optimally position the turbines within the wind farm such that the wake effects are minimized and the power production is maximized. The reasonably accurate modeling of the turbine wake is critical in determination of the optimal layout of the turbines and the power generated. For HAWT, two wake models are considered; both are found to give similar answers. For VAWT, a very simple wake model is employed. Finally, some preliminary investigation of shape optimization of 3D wind turbine blades at low Reynolds numbers is conducted. The optimization employs a 3D straight untapered wind turbine blade with cross section of NACA 0012 airfoils as the geometry of baseline blade. The optimization objective is to achieve maximum Cl/Cd as well as maximum Cl. The multi-objective genetic algorithm is employed together with the commercially available software FLUENT for calculation of the flow field using the Reynolds-Averaged Navier-Stokes (RANS) equations in conjunction with a one-equation Sparlart-Allmaras turbulence model. The results show excellent performance of the optimized wind turbine blade and indicate the feasibility of optimization on real wind turbine blades with more complex shapes in the future. (Abstract shortened by UMI.)

The large-scale modulation of cosmic rays in mid-1982: Its dependence on heliospheric longitude and radius

NASA Technical Reports Server (NTRS)

Pyle, K. R.; Simpson, J. A.

1985-01-01

Near solar maximum, a series of large radial solar wind shocks in June and July 1982 provided a unique opportunity to study the solar modulation of galactic cosmic rays with an array of spacecraft widely separated both in heliocentric radius and longitude. By eliminating hysteresis effects it is possible to begin to separate radial and azimuthal effects in the outer heliosphere. On the large scale, changes in modulation (both the increasing and recovery phases) propagate outward at close to the solar wind velocity, except for the near-term effects of solar wind shocks, which may propagate at a significantly higher velocity. In the outer heliosphere, azimuthal effects are small in comparison with radial effects for large-scale modulation at solar maximum.

The use of alternative pollutant metrics in time-series studies of ambient air pollution and respiratory emergency department visits.

PubMed

Darrow, Lyndsey A; Klein, Mitchel; Sarnat, Jeremy A; Mulholland, James A; Strickland, Matthew J; Sarnat, Stefanie E; Russell, Armistead G; Tolbert, Paige E

2011-01-01

Various temporal metrics of daily pollution levels have been used to examine the relationships between air pollutants and acute health outcomes. However, daily metrics of the same pollutant have rarely been systematically compared within a study. In this analysis, we describe the variability of effect estimates attributable to the use of different temporal metrics of daily pollution levels. We obtained hourly measurements of ambient particulate matter (PM₂.₅), carbon monoxide (CO), nitrogen dioxide (NO₂), and ozone (O₃) from air monitoring networks in 20-county Atlanta for the time period 1993-2004. For each pollutant, we created (1) a daily 1-h maximum; (2) a 24-h average; (3) a commute average; (4) a daytime average; (5) a nighttime average; and (6) a daily 8-h maximum (only for O₃). Using Poisson generalized linear models, we examined associations between daily counts of respiratory emergency department visits and the previous day's pollutant metrics. Variability was greatest across O₃ metrics, with the 8-h maximum, 1-h maximum, and daytime metrics yielding strong positive associations and the nighttime O₃ metric yielding a negative association (likely reflecting confounding by air pollutants oxidized by O₃). With the exception of daytime metric, all of the CO and NO₂ metrics were positively associated with respiratory emergency department visits. Differences in observed associations with respiratory emergency room visits among temporal metrics of the same pollutant were influenced by the diurnal patterns of the pollutant, spatial representativeness of the metrics, and correlation between each metric and copollutant concentrations. Overall, the use of metrics based on the US National Ambient Air Quality Standards (for example, the use of a daily 8-h maximum O₃ as opposed to a 24-h average metric) was supported by this analysis. Comparative analysis of temporal metrics also provided insight into underlying relationships between specific air pollutants and respiratory health.

Assessing the vulnerability of the transportation industry of Ukraine to future climate change

NASA Astrophysics Data System (ADS)

Khomenko, Inna

2017-04-01

Climate change will affect transportation primarily through increases in several types of weather and climate extremes. The impacts will vary by mode of transportation and region of the country, but they will be widespread and costly in both human and economic terms and will require significant changes in the planning, design, construction, operation, and maintenance of transportation systems. In the study impact of climate change on operation of road transport are analysed on the basis of RCP 4.5 and RCP 8.5 scenarios. Data contains series of daily mean, maximum and minimum temperature, daily liquid (or mixed) and solid precipitation, daily mean relative humidity and daily mean and maximum wind speed, obtained for the period of 2011 to 2050 for 28 cities distributed evenly across Ukraine. Spatial and temporal distributions of meteorological variables are obtained. The statistic characteristics obtained were compared with the correspondent climate normals and highway-related temporal changeability is determined. Frequency of freezing rain, wet snow, very hot days, droughts, fogs, ice-covered ground, slippery wet ground, ice and snow slippery coat are investigated. Climate and economic risks to the road transport network are assessed. Maps of spatial distribution of risk assessment are obtained. The results obtained show typical weather pattern is changed and climate and weather extreme influencing on operation of road transport are more frequent for the both scenarios, but for the RCP 8.5 scenario hazard weather occurs more often. During the period of 2011-2050 significant climate warming (by 2-3°C) is registered. Extreme temperatures are observed more frequently. High temperatures bring on growth in frequency of wildfires and heat waves. Annual precipitation amount decreases, except the western mountain and northern regions, where precipitation amount increase on 35%. Increase in temperature and decrease in precipitation can produce droughts in southern, eastern and central regions. But growth in precipitation in mountain region can cause flooding and landslides. Strong increase in mixed precipitation and significant reduction in ice and liquid precipitation take place for all territory of Ukraine. In the southern region ice precipitation is virtually vanished and observed only 2-3 days per year. Growth of mixed precipitation causes increase in severe weather events such as freezing precipitation, ice-covered ground and snow slippery coat.

Identification of anomalous motion of thunderstorms using daily rainfall fields

NASA Astrophysics Data System (ADS)

del Moral, Anna; Llasat, Maria Carmen; Rigo, Tomeu

2016-04-01

Adverse weather phenomena in Catalonia (NE of the Iberian Peninsula) is commonly associated to heavy rains, large hail, strong winds, and/or tornados, all of them caused by thunderstorms. In most of the cases with adverse weather, thunderstorms vary sharply their trajectories in a concrete moment, changing completely the motion directions that have previously followed. Furthermore, it is possible that a breaking into several cells may be produced, or, in the opposite, it can be observed a joining of different thunderstorms into a bigger system. In order to identify the main features of the developing process of thunderstorms and the anomalous motions that these may follow in some cases, this contribution presents a classification of the events using daily rainfall fields, with the purpose of distinguishing quickly anomalous motion of thunderstorms. The methodology implemented allows classifying the daily rainfall fields in three categories by applying some thresholds related with the daily precipitation accumulated values and their extension: days with "no rain", days with "potentially convective" rain and days with "non-potentially convective" rain. Finally, for those "potentially convective" daily rainfall charts, it also allows a geometrical identification and classification of all the convective structures into "ellipse" and "non-ellipse", obtaining then the structures with "normal" or "anomalous" motion pattern, respectively. The work is focused on the period 2008-2015, and presents some characteristics of the rainfall behaviour in terms of the seasonal distribution of convective rainfall or the geographic variability. It shows that convective structures are mainly found during late spring and summer, even though they can be recorded in any time of the year. Consequently, the maximum number of convective structures with anomalous motion is recorded between July and November. Furthermore, the contribution shows the role of the orography of Catalonia in the development of convective structures. This work has been developed in the framework of the Spanish project HOPE.

The Effect of Wind-Turbine Wakes on Summertime US Midwest Atmospheric Wind Profiles as Observed with Ground-Based Doppler Lidar

NASA Astrophysics Data System (ADS)

Rhodes, Michael E.; Lundquist, Julie K.

2013-07-01

We examine the influence of a modern multi-megawatt wind turbine on wind and turbulence profiles three rotor diameters (D) downwind of the turbine. Light detection and ranging (lidar) wind-profile observations were collected during summer 2011 in an operating wind farm in central Iowa at 20-m vertical intervals from 40 to 220 m above the surface. After a calibration period during which two lidars were operated next to each other, one lidar was located approximately 2D directly south of a wind turbine; the other lidar was moved approximately 3D north of the same wind turbine. Data from the two lidars during southerly flow conditions enabled the simultaneous capture of inflow and wake conditions. The inflow wind and turbulence profiles exhibit strong variability with atmospheric stability: daytime profiles are well-mixed with little shear and strong turbulence, while nighttime profiles exhibit minimal turbulence and considerable shear across the rotor disk region and above. Consistent with the observations available from other studies and with wind-tunnel and large-eddy simulation studies, measurable reductions in wake wind-speeds occur at heights spanning the wind turbine rotor (43-117 m), and turbulent quantities increase in the wake. In generalizing these results as a function of inflow wind speed, we find the wind-speed deficit in the wake is largest at hub height or just above, and the maximum deficit occurs when wind speeds are below the rated speed for the turbine. Similarly, the maximum enhancement of turbulence kinetic energy and turbulence intensity occurs at hub height, although observations at the top of the rotor disk do not allow assessment of turbulence in that region. The wind shear below turbine hub height (quantified here with the power-law coefficient) is found to be a useful parameter to identify whether a downwind lidar observes turbine wake or free-flow conditions. These field observations provide data for validating turbine-wake models and wind-tunnel observations, and for guiding assessments of the impacts of wakes on surface turbulent fluxes or surface temperatures downwind of turbines.

Voltage Impacts of Utility-Scale Distributed Wind

DOE Office of Scientific and Technical Information (OSTI.GOV)

Allen, A.

2014-09-01

Although most utility-scale wind turbines in the United States are added at the transmission level in large wind power plants, distributed wind power offers an alternative that could increase the overall wind power penetration without the need for additional transmission. This report examines the distribution feeder-level voltage issues that can arise when adding utility-scale wind turbines to the distribution system. Four of the Pacific Northwest National Laboratory taxonomy feeders were examined in detail to study the voltage issues associated with adding wind turbines at different distances from the sub-station. General rules relating feeder resistance up to the point of turbinemore » interconnection to the expected maximum voltage change levels were developed. Additional analysis examined line and transformer overvoltage conditions.« less

Evaluation of Noise Exposure Secondary to Wind Noise in Cyclists.

PubMed

Seidman, Michael D; Wertz, Anna G; Smith, Matthew M; Jacob, Steve; Ahsan, Syed F

2017-11-01

Objective Determine if the noise levels of wind exposure experienced by cyclists reach levels that could contribute to noise-induced hearing loss. Study Design Industrial lab research. Setting Industrial wind tunnel. Subjects and Methods A commercial-grade electric wind tunnel was used to simulate different speeds encountered by a cyclist. A single cyclist was used during the simulation for audiometric measurements. Microphones attached near the ears of the cyclist were used to measure the sound (dB sound pressure level) experienced by the cyclist. Loudness levels were measured with the head positioned at 15-degree increments from 0 degrees to 180 degrees relative to the oncoming wind at different speeds (10-60 mph). Results Wind noise ranged from 84.9 dB at 10 mph and increased proportionally with speed to a maximum of 120.3 dB at 60 mph. The maximum of 120.3 dB was measured at the downwind ear when the ear was 90 degrees away from the wind. Conclusions Wind noise experienced by a cyclist is proportional to the speed and the directionality of the wind current. Turbulent air flow patterns are observed that contribute to increased sound exposure in the downwind ear. Consideration of ear deflection equipment without compromising sound awareness for cyclists during prolonged rides is advised to avoid potential noise trauma. Future research is warranted and can include long-term studies including dosimetry measures of the sound and yearly pre- and postexposure audiograms of cyclists to detect if any hearing loss occurs with long-term cycling.

Power Smoothing and MPPT for Grid-connected Wind Power Generation with Doubly Fed Induction Generator

NASA Astrophysics Data System (ADS)

Kai, Takaaki; Tanaka, Yuji; Kaneda, Hirotoshi; Kobayashi, Daichi; Tanaka, Akio

Recently, doubly fed induction generator (DFIG) and synchronous generator are mostly applied for wind power generation, and variable speed control and power factor control are executed for high efficiently for wind energy capture and high quality for power system voltage. In variable speed control, a wind speed or a generator speed is used for maximum power point tracking. However, performances of a wind generation power fluctuation due to wind speed variation have not yet investigated for those controls. The authors discuss power smoothing by those controls for the DFIG inter-connected to 6.6kV distribution line. The performances are verified using power system simulation software PSCAD/EMTDC for actual wind speed data and are examined from an approximate equation of wind generation power fluctuation for wind speed variation.

The rationale and design features for the 40 by 80/80 by 120 foot wind tunnel

NASA Technical Reports Server (NTRS)

Mort, K. W.; Kelly, M. W.; Hickey, D. H.

1976-01-01

A substantial increase in the test capability of full scale wind tunnels is considered. In order to determine the most cost effective means for providing this desired increase in test capability, a series of design studies were conducted of various new facilities as well as of major modifications to the existing 40- by 80-foot wind tunnel. The most effective trade between test capability and facility cost was provided by repowering the existing 40 by 80 foot wind tunnel to increase the maximum speed from 200 knots to 300 knots and by the addition of a new 80- by 120-foot test section having a 110 knot maximum speed. The design of the facility is described with special emphasis on the unique features, such as the drive system which absorbs nearly four times the power without an increase in noise, and the large flow diversion devices required to interface the two test sections to a single drive.

77 FR 18809 - Clean Water Act Section 303(d): Proposed Withdrawal of Nine Total Maximum Daily Loads (TMDLs)

Federal Register 2010, 2011, 2012, 2013, 2014

2012-03-28

... withdrawal of nine final Total Maximum Daily Loads (TMDLs) for Chloride, Sulfate, and Total Dissolved Solids... 08040202-006 Bayou de L'Outre.... Chloride, Sulfate, TDS. 08040202-007 Bayou de L'Outre.... Chloride, Sulfate, TDS. 08040202-008 Bayou de L'Outre.... Chloride, Sulfate, TDS. The 2008 Arkansas Clean Water Act...

75 FR 43160 - Clean Water Act Section 303(d): Final Agency Action on One Arkansas Total Maximum Daily Load (TMDL)

Federal Register 2010, 2011, 2012, 2013, 2014

2010-07-23

... ENVIRONMENTAL PROTECTION AGENCY [FRL-9179-3 ] Clean Water Act Section 303(d): Final Agency Action on One Arkansas Total Maximum Daily Load (TMDL) AGENCY: Environmental Protection Agency (EPA). ACTION: Notice of availability. SUMMARY: This notice announces the final agency action on one TMDL established by...

Modeling maximum daily temperature using a varying coefficient regression model

Treesearch

Han Li; Xinwei Deng; Dong-Yum Kim; Eric P. Smith

2014-01-01

Relationships between stream water and air temperatures are often modeled using linear or nonlinear regression methods. Despite a strong relationship between water and air temperatures and a variety of models that are effective for data summarized on a weekly basis, such models did not yield consistently good predictions for summaries such as daily maximum temperature...

High-resolution vertical velocities and their power spectrum observed with the MAARSY radar - Part 1: frequency spectrum

NASA Astrophysics Data System (ADS)

Li, Qiang; Rapp, Markus; Stober, Gunter; Latteck, Ralph

2018-04-01

The Middle Atmosphere Alomar Radar System (MAARSY) installed at the island of Andøya has been run for continuous probing of atmospheric winds in the upper troposphere and lower stratosphere (UTLS) region. In the current study, we present high-resolution wind measurements during the period between 2010 and 2013 with MAARSY. The spectral analysis applying the Lomb-Scargle periodogram method has been carried out to determine the frequency spectra of vertical wind velocity. From a total of 522 days of observations, the statistics of the spectral slope have been derived and show a dependence on the background wind conditions. It is a general feature that the observed spectra of vertical velocity during active periods (with wind velocity > 10 m s-1) are much steeper than during quiet periods (with wind velocity < 10 m s-1). The distribution of spectral slopes is roughly symmetric with a maximum at -5/3 during active periods, whereas a very asymmetric distribution with a maximum at around -1 is observed during quiet periods. The slope profiles along altitudes reveal a significant height dependence for both conditions, i.e., the spectra become shallower with increasing altitudes in the upper troposphere and maintain roughly a constant slope in the lower stratosphere. With both wind conditions considered together the general spectra are obtained and their slopes are compared with the background horizontal winds. The comparisons show that the observed spectra become steeper with increasing wind velocities under quiet conditions, approach a spectral slope of -5/3 at a wind velocity of 10 m s-1 and then roughly maintain this slope (-5/3) for even stronger winds. Our findings show an overall agreement with previous studies; furthermore, they provide a more complete climatology of frequency spectra of vertical wind velocities under different wind conditions.

A 15-year climatology of wind pattern impacts on surface ozone in Houston, Texas

NASA Astrophysics Data System (ADS)

Souri, Amir Hossein; Choi, Yunsoo; Li, Xiangshang; Kotsakis, Alexander; Jiang, Xun

2016-06-01

Houston is recognized for its large petrochemical industrial facilities providing abundant radicals for tropospheric ozone formation. Fortunately, maximum daily 8-h average (MDA8) surface ozone concentrations have declined in Houston (- 0.6 ± 0.3 ppbv yr- 1) during the summers (i.e., May to September) of 2000 to 2014, possibly due to the reductions in precursor emissions by effective control policies. However, it is also possible that changes in meteorological variables have affected ozone concentrations. This study focused on the impact of long-term wind patterns which have the highest impact on ozone in Houston. The analysis of long-term wind patterns can benefit surface ozone studies by 1) providing wind patterns that distinctly changed ozone levels, 2) investigating the frequency of patterns and the respective changes and 3) estimating ozone trends in specific wind patterns that local emissions are mostly involved, thus separating emissions impacts from meteorology to some extent. To this end, the 900-hPa flow patterns in summers of 2000 to 2014 were clustered in seven classes (C1-C7) by deploying an unsupervised partitioning method. We confirm the characteristics of the clusters from a backward trajectory analysis, monitoring networks, and a regional chemical transport model simulation. The results indicate that Houston has experienced a statistically significant downward trend (- 0.6 ± 0.4 day yr- 1) of the cluster of weak easterly and northeasterly days (C4), when the highest fraction of ozone exceedances (MDA8 > 70 ppbv) occurred. This suggests that the reduction in ozone precursors was not the sole reason for the decrease in ozone exceedance days (- 1.5 ± 0.6 day yr- 1). Further, to examine the efficiency of control policies intended to reduce the amount of ozone, we estimated the trend of MDA8 ozone in C4 and C5 (weak winds) days when local emissions are primarily responsible for high ambient ozone levels. Both C4 and C5 show a large reduction in the 95th percentile and summertime trends mainly due to effective control strategies. Based on the 5th percentile daytime ozone for C1 (strong southeasterly wind) in coastal sites, this study found that the cleanest air masses that Houston received became more polluted during the summer of 2000-2014 by 1-3 ppbv. Though this study focused on Houston, the analysis method presented could generally be used to estimate ozone trends in other regions where surface ozone is dominantly influenced by both wind patterns and local emissions.

Reconstruction of the Indian monsoon variability and its environmental impacts over the northwestern Arabian Sea and its surrounding continents since the Last Glacial Maximum: Multi-proxy study of a marine core in the Gulf of Aden

NASA Astrophysics Data System (ADS)

Wiem, F.; Bassinot, F. C.; Lézine, A. M.

2016-12-01

Core MD92-1002 retrieved from the Gulf of Aden provides a unique paleoenvironmental and paleoclimatic record to study the evolution of continental and marine environments since 20 ka. Palynological analyses (pollen grains, spores, dinoflagellate cysts) were performed and data were combined with geochemical (δ18O, X-Ray Fluorescence) and sedimentological parameters (sedimentation rates, Total Organic Carbon (TOC)). Pollen grains reveal regional hyper-arid conditions during the glacial period, characterized by sparse vegetation cover of Saharo-Sindian origin. The abundance of steppic taxa associated with charcoal fragments suggests strong wind activity. Humidity tracers increased from 14.9 ka and reached their maximum between 9 and 7.5 ka. This maximum is characterized by the development of the tropical mangrove Rhizophora in the Gulf of Aden, reflecting tropical conditions with summer monsoon rains. The timing of events deduced from palynological records and continental data such as lacustrine and palustrine deposits and speleothems from Socotra and Oman, reveals a northward and westward shift of the Inter-Tropical Convergence Zone (ITCZ) summer position at the onset of the Holocene Humid Period (HHP). Dinoflagellate cyst assemblages suggest that the glacial period was characterized by weakened upwellings and well-ventilated bottom water. Primary productivity in the Gulf of Aden increased from 14.5 ka and reached its maximum during the glacial/interglacial transition between 12.6 and 10.8 ka. It took place about 3 ka earlier than the peak intensity of upwellings off the Oman margin, which is associated with the maximum of SW monsoonal winds. This singularity could be explained by the landlocked position of the gulf, at the junction between two orthogonal wind regimes during the boreal summer season (SW monsoon winds prevailing to the East of the Gulf, while NW winds blow along the main axis of the Red Sea to the West). TOC analysis reveals a Glacial-Interglacial variability that is largely decoupled from our reconstruction of surface productivity, suggesting that organic content is mainly controlled by preservation at the sea floor.

Effects of setting angle and chord length on performance of four blades bionic wind turbine

NASA Astrophysics Data System (ADS)

Yang, Z. X.; Li, G. S.; Song, L.; Bai, Y. F.

2017-11-01

With the energy crisis and the increasing environmental pollution, more and more efforts have been made about wind power development. In this paper, a four blades bionic wind turbine was proposed, and the outline of wind turbine was constructed by the fitted curve. This paper attempted to research the effects of setting angle and chord length on performance of four blades bionic wind turbine by computational fluid dynamics (CFD) simulation. The results showed that the setting angle and chord length of the bionic wind turbine has some significant effects on the efficiency of the wind turbine, and within the range of wind speed from 7 m/s to 15 m/s, the wind turbine achieved maximum efficiency when the setting angle is 31 degree and the chord length is 125 mm. The conclusion will work as a guideline for the improvement of wind turbine design

Effects of wind velocity and slope on flame properties

Treesearch

David R. Weise; Gregory S. Biging

1996-01-01

Abstract: The combined effects of wind velocity and percent slope on flame length and angle were measured in an open-topped, tilting wind tunnel by burning fuel beds composed of vertical birch sticks and aspen excelsior. Mean flame length ranged from 0.08 to 1.69 m; 0.25 m was the maximum observed flame length for most backing fires. Flame angle ranged from -46o to 50o...

Guidelines for Integrating Helicopter Assets into Emergency Planning

DTIC Science & Technology

1991-07-01

maximum. 35 TABLE 2 HELIPORT INFORMATION SOURCES Professional-and/or industry associations Airborne Law Enforcement Association ( ALEA ) 8060 Balboa Boulevard...Department of Transportation/ Federal Aviation Adminisration ATTN: Hugh Lyon (ASW-611C) Fort Worth, TX 76193-0611 81-624-5600 FAA Northwest Mountain ...indication of wind speed and direction. in areas with swirling or varying winds, such as near buildings or in mountainous areas, two or more wind

UDE-based control of variable-speed wind turbine systems

NASA Astrophysics Data System (ADS)

Ren, Beibei; Wang, Yeqin; Zhong, Qing-Chang

2017-01-01

In this paper, the control of a PMSG (permanent magnet synchronous generator)-based variable-speed wind turbine system with a back-to-back converter is considered. The uncertainty and disturbance estimator (UDE)-based control approach is applied to the regulation of the DC-link voltage and the control of the RSC (rotor-side converter) and the GSC (grid-side converter). For the rotor-side controller, the UDE-based vector control is developed for the RSC with PMSG control to facilitate the application of the MPPT (maximum power point tracking) algorithm for the maximum wind energy capture. For the grid-side controller, the UDE-based vector control is developed to control the GSC with the power reference generated by a UDE-based DC-link voltage controller. Compared with the conventional vector control, the UDE-based vector control can achieve reliable current decoupling control with fast response. Moreover, the UDE-based DC-link voltage regulation can achieve stable DC-link voltage under model uncertainties and external disturbances, e.g. wind speed variations. The effectiveness of the proposed UDE-based control approach is demonstrated through extensive simulation studies in the presence of coupled dynamics, model uncertainties and external disturbances under varying wind speeds. The UDE-based control is able to generate more energy, e.g. by 5% for the wind profile tested.

SOLAR WIND HEAVY IONS OVER SOLAR CYCLE 23: ACE/SWICS MEASUREMENTS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lepri, S. T.; Landi, E.; Zurbuchen, T. H.

2013-05-01

Solar wind plasma and compositional properties reflect the physical properties of the corona and its evolution over time. Studies comparing the previous solar minimum with the most recent, unusual solar minimum indicate that significant environmental changes are occurring globally on the Sun. For example, the magnetic field decreased 30% between the last two solar minima, and the ionic charge states of O have been reported to change toward lower values in the fast wind. In this work, we systematically and comprehensively analyze the compositional changes of the solar wind during cycle 23 from 2000 to 2010 while the Sun movedmore » from solar maximum to solar minimum. We find a systematic change of C, O, Si, and Fe ionic charge states toward lower ionization distributions. We also discuss long-term changes in elemental abundances and show that there is a {approx}50% decrease of heavy ion abundances (He, C, O, Si, and Fe) relative to H as the Sun went from solar maximum to solar minimum. During this time, the relative abundances in the slow wind remain organized by their first ionization potential. We discuss these results and their implications for models of the evolution of the solar atmosphere, and for the identification of the fast and slow wind themselves.« less

Wind friction parametrisation used in emission models for wastewater treatment plants: A critical review.

PubMed

Prata, Ademir A; Santos, Jane M; Timchenko, Victoria; Reis, Neyval C; Stuetz, Richard M

2017-11-01

Emission models are widely applied tools for estimating atmospheric emissions from wastewater treatment plants (WWTPs). The friction velocity u ∗ is a key variable for the modelling of emissions from passive liquid surfaces in WWTPs. This work evaluated different parametrisations of u ∗ for passive liquid surfaces at the scale of WWTP units, which present relatively small fetches, based on available wind friction and wave data measured at wind-wave tanks (fetches spanning from approximately 3 to 100 m, and wind speeds from 2 to 17 m s -1 ). The empirical correlation by Smith (1980; J. Phys. Oceanogr. 10, 709-726), which has been frequently adopted in air emission models (despite the fact that it was originally derived for the ocean) presented a general tendency to overestimate u ∗ , with significant (although not extreme) relative errors (mean and maximum errors of 13.5% and 36.6%, respectively); the use of Charnock's relation, with Charnock constant 0.010, performed in a very similar manner (mean and maximum errors of 13.3% and 37.8%, respectively). Better estimates of u ∗ were achieved by parametrisations based on the significant wave steepness. Simplified correlations between the wind drag and the non-dimensional fetch were obtained. An approach was devised, comprising the use of Charnock's relation (with Charnock constant 0.010) and of these simplified correlations, depending on the ranges of frequency of the peak waves, fetch and wind speed. The proposed approach predicted u ∗ with improved accuracy (mean, maximum and 95%-percentile relative errors of 6.6%, 16.7% and 13.9%, respectively), besides being able to incorporate the influence of the fetch in the wind drag, thus taking into account the size of the tanks in the WWTPs. Copyright © 2017 Elsevier Ltd. All rights reserved.

Upstream proton cyclotron waves at Venus near solar maximum

NASA Astrophysics Data System (ADS)

Delva, M.; Bertucci, C.; Volwerk, M.; Lundin, R.; Mazelle, C.; Romanelli, N.

2015-01-01

magnetometer data of Venus Express are analyzed for the occurrence of waves at the proton cyclotron frequency in the spacecraft frame in the upstream region of Venus, for conditions of rising solar activity. The data of two Venus years up to the time of highest sunspot number so far (1 Mar 2011 to 31 May 2012) are studied to reveal the properties of the waves and the interplanetary magnetic field (IMF) conditions under which they are observed. In general, waves generated by newborn protons from exospheric hydrogen are observed under quasi- (anti)parallel conditions of the IMF and the solar wind velocity, as is expected from theoretical models. The present study near solar maximum finds significantly more waves than a previous study for solar minimum, with an asymmetry in the wave occurrence, i.e., mainly under antiparallel conditions. The plasma data from the Analyzer of Space Plasmas and Energetic Atoms instrument aboard Venus Express enable analysis of the background solar wind conditions. The prevalence of waves for IMF in direction toward the Sun is related to the stronger southward tilt of the heliospheric current sheet for the rising phase of Solar Cycle 24, i.e., the "bashful ballerina" is responsible for asymmetric background solar wind conditions. The increase of the number of wave occurrences may be explained by a significant increase in the relative density of planetary protons with respect to the solar wind background. An exceptionally low solar wind proton density is observed during the rising phase of Solar Cycle 24. At the same time, higher EUV increases the ionization in the Venus exosphere, resulting in higher supply of energy from a higher number of newborn protons to the wave. We conclude that in addition to quasi- (anti)parallel conditions of the IMF and the solar wind velocity direction, the higher relative density of Venus exospheric protons with respect to the background solar wind proton density is the key parameter for the higher number of observable proton cyclotron waves near solar maximum.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hernandez, G.; Roble, R.G.; Ridley, E.C.

Nightime thermospheric winds and temperatures have been measured over Fritz Peak Observatory, Colorado (39.9 /sup 0/N, 105.5 /sup 0/W), with a high resolution Fabry-Perot spectrometer. The winds and temperatures are obtained from the Doppler shifts and line profiles of the (O 1) 15,867K (630 nm) line emission. Measurements made during two large geomagnetic storm periods near solar cycle maximum reveal a thermospheric response to the heat and momentum sources associated with these storms that is more complex than the ones measured near solar cycle minimum. In the earlier measurements made during solar cycle minimum, the winds to the north ofmore » Fritz Peak Observatory had an enhanced equatorward component and the winds to the south were also equatorward, usually with smaller velocities. The winds measured to the east and west of the observatory both had an enhanced westward wind component. For the two large storms near the present solar cycle maximum period converging winds are observed in each of the cardinal directions from Fritz Peak Observatory. These converging winds with speeds of hundreds of meters per second last for several hours. The measured neutral gas temperature in each of the directions also increases several hundred degrees Kelvin. Numerical experiments done with the NCAR thermospheric general circulation model (TGCM) suggest that the winds to the east and north of the station are driven by high-latitude heating and enhanced westward ion drag associated with magnetospheric convection. The cause of the enhanced poleward and eastward winds measured to the south and west of Fritz Peak Observatory, respectively, is not known. During geomagnetic quiet conditions the circulation is typically from the soutwest toward the northeast in the evening hours.« less

Surface ozone concentrations in Europe: Links with the regional-scale atmospheric circulation

NASA Astrophysics Data System (ADS)

Davies, T. D.; Kelly, P. M.; Low, P. S.; Pierce, C. E.

1992-06-01

Daily surface ozone observations from 1978 (1976 for some analyses) to 1988 for Bottesford (United Kingdom), Cabauw, Kloosterburen (The Netherlands), Hohenpeissenberg, Neuglobsow, Hamburg, and Arkona (Germany) are used to analyze links between surface ozone variations and the atmospheric circulation. A daily Europe-wide synoptic classification highlights marked differences between surface ozone/meteorology relationships in summer and winter. These relationships are characterized by correlations between daily surface ozone concentrations at each station and a local subregional surface pressure gradient (a wind speed index). Although there are geographical variations, which are explicable in terms of regional climatology, there are distinct annual cycles. In summer, the surface ozone/wind speed relationship exhibits the expected negative sign; however, in winter, the relationship is, in the main, strongly positive, especially at those stations which are more influenced by the vigorous westerlies. Spring and autumn exhibit negative, positive, or transitional (between summer and winter) behavior, depending on geographical position. It is suggested that these relationships reflect the importance of vertical exchange from the free troposphere to the surface in the nonsummer months. Composite surface pressure patterns and surface pressure anomaly (from the long-term mean) patterns associated with high surface ozone concentrations on daily and seasonal time scales are consistent with the surface ozone/wind speed relationships. Moreover, they demonstrate that high surface ozone concentrations, in a climatological time frame, can be associated with mean surface pressure patterns which have a synoptic reality and are robust. Such an approach may be useful in interpreting past variations in surface ozone and may help to isolate the effect of human activity. It is also possible that assessments can be made of the effect of projected future changes in the atmospheric circulation. This potential is illustrated by the fact that up to 65% of the interannual variance in 6-month mean surface ozone concentrations can be explained by the subregional wind speed index.

Diurnal and Seasonal Variations of Thermal Stratification and Vertical Mixing in a Shallow Fresh Water Lake

NASA Astrophysics Data System (ADS)

Yang, Yichen; Wang, Yongwei; Zhang, Zhen; Wang, Wei; Ren, Xia; Gao, Yaqi; Liu, Shoudong; Lee, Xuhui

2018-04-01

Among several influential factors, the geographical position and depth of a lake determine its thermal structure. In temperate zones, shallow lakes show significant differences in thermal stratification compared to deep lakes. Here, the variation in thermal stratification in Lake Taihu, a shallow fresh water lake, is studied systematically. Lake Taihu is a warm polymictic lake whose thermal stratification varies in short cycles of one day to a few days. The thermal stratification in Lake Taihu has shallow depths in the upper region and a large amplitude in the temperature gradient, the maximum of which exceeds 5°C m-1. The water temperature in the entire layer changes in a relatively consistent manner. Therefore, compared to a deep lake at similar latitude, the thermal stratification in Lake Taihu exhibits small seasonal differences, but the wide variation in the short term becomes important. Shallow polymictic lakes share the characteristic of diurnal mixing. Prominent differences on the duration and frequency of long-lasting thermal stratification are found in these lakes, which may result from the differences of local climate, lake depth, and fetch. A prominent response of thermal stratification to weather conditions is found, being controlled by the stratifying effect of solar radiation and the mixing effect of wind disturbance. Other than the diurnal stratification and convection, the representative responses of thermal stratification to these two factors with contrary effects are also discussed. When solar radiation increases, stronger wind is required to prevent the lake from becoming stratified. A daily average wind speed greater than 6 m s-1 can maintain the mixed state in Lake Taihu. Moreover, wind-induced convection is detected during thermal stratification. Due to lack of solar radiation, convection occurs more easily in nighttime than in daytime. Convection occurs frequently in fall and winter, whereas long-lasting and stable stratification causes less convection in summer.

Solar system plasma turbulence and intermittency at the maximum and minimum of the solar cycle

NASA Astrophysics Data System (ADS)

Echim, Marius M.

2015-04-01

We report on the analysis of turbulence properties of the solar wind and the planetary magnetosheaths of Venus and Earth at solar maximum (2000-2001) and minimum (1997-1998, 2007-2008) as revealed by Ulysses, Cluster and Venus Express. We provide an overview of the spectral and scaling properties of turbulence during the targeted time periods. A selection of Ulysses data reveals the spectral properties of the "pure" slow and "pure" fast solar wind turbulence, out of the ecliptic, at radial distances ranging between 1.3 and 5.4 AU. Venus Express and Cluster data contribute to the description of the solar wind turbulence at 0.72 AU and respectively 1 AU. The spectral analysis of magnetosheath data from Venus Express and Cluster reveals the properties of turbulence to be compared to solar wind turbulence. The statistical properties of plasma and magnetic field fluctuations exhibit features linked with intermittency revealed as non-Gaussian Probability Distribution Functions (PDFs) and scale dependent kurtosis. PDFs are computed for the solar wind data from Ulysses, Venus Express and Cluster, and complement the analysis based on second order corrrelation function. The same strategy is applied to study the intermittency of the magnetosheath turbulence of Venus and the Earth. The results of our thorough survey of data bases are organized in catalogues available on line: PSD and PDFs results are stored in three solar wind data bases (one for the solar maximum, 1999-2001, two for the solar minimum, 1997-1998 and respectively, 2007-2008), and two planetary databases (one for the solar maximum, 2000-2001, that includes PSDs and PDFs obtained in the terrestrial magnetosheath, and one for the solar minimum, 2007-2008, that includes PSDs and PDFs obtained in the terrestrial and Venus magnetosheaths). As an example of higher order analysis resulting from these results we discuss the similarities and differences between fast and slow wind turbulence and intermittency. We also discuss how the exploitation of data bases produced by the FP7 project STORM contribute to developing a (virtual) laboratory for studying solar system plasma turbulence and intermittency. Research supported by the European FP7 Programme (grant agreement 313038/STORM), and a national grant CNCS -UEFISCDI, project number PN-II-ID-PCE-2012-4-0418.

Wind effects on the migration routes of trans-Saharan soaring raptors: geographical, seasonal, and interspecific variation

PubMed Central

Vidal-Mateo, Javier; Mellone, Ugo; López-López, Pascual; La Puente, Javier De; García-Ripollés, Clara; Bermejo, Ana; Urios, Vicente

2016-01-01

Abstract Wind is among the most important environmental factors shaping birds’ migration patterns. Birds must deal with the displacement caused by crosswinds and their behavior can vary according to different factors such as flight mode, migratory season, experience, and distance to goal areas. Here we analyze the relationship between wind and migratory movements of three raptor species which migrate by soaring–gliding flight: Egyptian vulture Neophron percnopterus, booted eagle Aquila pennata, and short-toed snake eagle Circaetus gallicus. We analyzed daily migratory segments (i.e., the path joining consecutive roosting locations) using data recorded by GPS satellite telemetry. Daily movements of Egyptian vultures and booted eagles were significantly affected by tailwinds during both autumn and spring migrations. In contrast, daily movements of short-toed eagles were only significantly affected by tailwinds during autumn migration. The effect of crosswinds was significant in all cases. Interestingly, Egyptian vultures and booted eagles showed latitudinal differences in their behavior: both species compensated more frequently at the onset of autumn migration and, at the end of the season when reaching their wintering areas, the proportion of drift segments was higher. In contrast, there was a higher drift at the onset of spring migration and a higher compensation at the end. Our results highlight the effect of wind patterns on the migratory routes of soaring raptors, with different outcomes in relation to species, season, and latitude, ultimately shaping the loop migration patterns that current tracking techniques are showing to be widespread in many long distance migrants. PMID:29491895

F2 layer characteristics and electrojet strength over an equatorial station

NASA Astrophysics Data System (ADS)

Adebesin, B. O.; Adeniyi, J. O.; Adimula, I. A.; Reinisch, B. W.; Yumoto, K.

2013-09-01

The data presented in this work describes the diurnal and seasonal variation in hmF2, NmF2, and the electrojet current strength over an African equatorial station during a period of low solar activity. The F2 region horizontal magnetic element H revealed that the Solar quiet Sq(H) daily variation rises from early morning period to maximum around local noon and falls to lower values towards evening. The F2 ionospheric current responsible for the magnetic field variations is inferred to build up at the early morning hours, attaining maximum strength around 1200 LT. The Sq variation across the entire months was higher during the daytime than nighttime. This is ascribed to the variability of the ionospheric parameters like conductivity and winds structure in this region. Seasonal daytime electrojet (EEJ) current strength for June solstice, March and September equinoxes, respectively had peak values ranging within 27-35 nT (at 1400 LT) , 30-40 nT (at 1200 LT) and 35-45 nT (at 1500 LT). The different peak periods of the EEJ strength were attributed to the combined effects of the peak electron density and electric field. Lastly, the EEJ strength was observed to be higher during the equinoxes than the solstice period.

Methane distributions and transports in the nocturnal boundary layer at a rural station

NASA Astrophysics Data System (ADS)

Schäfer, Klaus; Zeeman, Matthias; Brosy, Caroline; Münkel, Christoph; Fersch, Benjamin; Mauder, Matthias; Emeis, Stefan

2016-10-01

To investigate the methane distributions and transports, the role of related atmospheric processes by determination of vertical profiles of wind, turbulence, temperature and humidity as well as nocturnal boundary layer (NBL) height and the quantification of methane emissions at local and plot scale the so-called ScaleX-campaign was performed in a pre-alpine observatory in Southern Germany from 01 June until 31 July 2015. The following measurements from the ground up to the free troposphere were performed: layering of the atmosphere by a ceilometer (Vaisala CL51); temperature, wind, turbulence profiles from 50 m up to 500 m by a Radio-Acoustic Sounding System (RASS, Metek GmbH); temperature, humidity profiles in situ by a hexacopter; methane farm emissions by two open-path laser spectrometers (Boreal GasFinder2); methane concentrations in situ (Los Gatos DLT-100) with tubes in 0.3 m agl and 5 sampling heads; and methane soil emissions by a big chamber (10 m length, 2.60 m width, up to 0.61 m height) with a plastic cover. The methane concentrations near the surface show a daily variation with a maximum and a frequent double-peak structure during night-time. Analysis of the variation of the nocturnal methane concentration together with the hexacopter and RASS data indicates that the first peak in the nocturnal methane concentration is probably due to local cooling and stabilization which keeps the methane emissions from the soil near the ground. The second peak seems to be due to advection of methane-enriched air which had formed in the environment of the nearby farm yards. These dairy farm emissions were determined by up-wind and down-wind open-path concentration measurements, turbulence data from an EC station nearby and Backward Lagrangian Simulation (WindTrax software). The methane fluxes at plot scale (big chamber) are characterized by emissions at water saturated grassland patches, by an exponential decrease of these emissions during grassland drying, and by an uptake of methane at dry grassland. Highest methane concentrations are found with lowest NBL heights which were determined from the ceilometer monitoring (correlation coefficient 0.56).

Determination of tropical cyclone surface pressure and winds from satellite microwave data

NASA Technical Reports Server (NTRS)

Kidder, S. Q.

1979-01-01

An approach to the problem of deducing wind speed and pressure around tropical cyclones is presented. The technique, called the Surface Wind Inference from Microwave data (SWIM technique, uses satellites microwave sounder data to measure upper tropospheric temperature anomalies which may then be related to surface pressure anomalies through the hydrostatic and radiative transfer equations. Surface pressure gradients outside of the radius of maximum wind are estimated for the first time. Future instruments may be able to estimate central pressure with + or - 0/1 kPa accuracy.

A high-temperature superconducting transformer with localized magnetic field

NASA Astrophysics Data System (ADS)

Volkov, E. P.; Dzhafarov, E. A.

2013-12-01

This paper describes a high-temperature superconducting transformer with a bar-type magnetic core and concentric windings with alternating layers, with single-channel and multi-channel arrangements. There is given the design concept of high-temperature superconducting windings of the transformer, made in the form of newly developed first-generation high-temperature superconducting ribbon wires, with localized magnetic field intended for producing maximum transport currents in the windings, as well as for reducing the consumption of a high-temperature superconducting material, cooling agent, and energy losses in these windings.

Outdoor temperature, precipitation, and wind speed affect physical activity levels in children: a longitudinal cohort study

PubMed Central

Edwards, Nicholas M.; Myer, Gregory D.; Kalkwarf, Heidi J.; Woo, Jessica G.; Khoury, Philip R.; Hewett, Timothy E.; Daniels, Stephen R.

2015-01-01

Objective Evaluate effects of local weather conditions on physical activity in early childhood. Methods Longitudinal prospective cohort study of 372 children, 3 years old at enrollment, drawn from a major US metropolitan community. Accelerometer-measured (RT3) physical activity was collected every 4 months over 5 years and matched with daily weather measures: day length, heating/cooling degrees (degrees mean temperature < 65°F or ≥ 65°F, respectively), wind, and precipitation. Mixed regression analyses, adjusted for repeated measures, were used to test the relationship between weather and physical activity. Results Precipitation and wind speed were negatively associated with total physical activity and moderate-vigorous physical activity (P<0.0001). Heating and cooling degrees were negatively associated with total physical activity and moderate-vigorous physical activity and positively associated with inactivity (all P<0.0001), independent of age, sex, race, BMI, day length, wind, and precipitation. For every 10 additional heating degrees there was a five-minute daily reduction in moderate-vigorous physical activity. For every additional 10 cooling degrees there was a 17-minute reduction in moderate-vigorous physical activity. Conclusions Inclement weather (higher/lower temperature, greater wind speed, more rain/snow) is associated with less physical activity in young children. These deleterious effects should be considered when planning physical activity research, interventions, and policies. PMID:25423667

Wind energy potential analysis in Al-Fattaih-Darnah

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tjahjana, Dominicus Danardono Dwi Prija, E-mail: danar1405@gmail.com; Salem, Abdelkarim Ali, E-mail: keemsalem@gmail.com; Himawanto, Dwi Aries, E-mail: dwiarieshimawanto@gmail.com

2016-03-29

In this paper the wind energy potential in Al-Fattaih-Darnah, Libya, had been studied. Wind energy is very attractive because it can provide a clean and renewable energy. Due mostly to the uncertainty caused by the chaotic characteristics of wind near the earth’s surface, wind energy characteristic need to be investigated carefully in order to get consistent power generation. This investigation was based on one year wind data measured in 2003. As a result of the analysis, wind speed profile and wind energy potential have been developed. The wind energy potential of the location is looked very promising to generate electricity.more » The annual wind speed of the site is 8.21 m/s and the wind speed carrying maximum energy is 7.97 m/s. The annual power density of the site is classified into class 3. The Polaris P50-500 wind turbine can produce 768.39 M Wh/year and has capacity factor of 17.54%.« less

Effects of lead structure in Bering Sea pack ice on the flight costs of wintering spectacled eiders

NASA Astrophysics Data System (ADS)

Bump, Joseph K.; Lovvorn, James R.

2004-10-01

In polar regions, sea ice is critical habitat for many marine birds and mammals. The quality of pack ice habitat depends on the duration and spacing of leads (openings in the ice), which determine access to water and air for diving endotherms, and how often and how far they must move as leads open and close. Recent warming trends have caused major changes in the extent and nature of sea ice at large scales used in climate models. However, no studies have analyzed lead structure in terms of habitat for ice-dependent endotherms, or effects of climate on ice habitat at scales relevant to their daily movements. Based on observations from an icebreaker and synthetic aperture radar (SAR) images, we developed methods to describe the dynamics and thermodynamics of lead structure relative to use by spectacled eiders ( Somateria fischeri) wintering in pack ice of the Bering Sea. By correlating lead structure with weather variables, we then used these methods to estimate changes in lead dynamics from 1945 to 2002, and effects of such changes on flight costs of the eiders. For 1991-1992, when images were available about every 3 days throughout winter, SAR images were divided among five weather regimes defined by wind speed, wind direction, and air temperature. Based on 12.5-m pixels, lead shape, compass orientation, and fetch across leads did not differ among the weather regimes. However, the five regimes differed in total area of open water, leads per unit area, and distance between leads. Lead duration was modeled based on air temperature, wind, and fetch. Estimates of mean daily flight time for eiders, based on lead duration and distance between neighboring leads, differed among regimes by 0 to 15 min. Resulting flight costs varied from 0 to 158 kJ day -1, or from 0% to 11% of estimated field metabolic rate. Over 57 winters (1945-2002), variation among years in mean daily flight time was most influenced by the north-south wind component, which determined pack divergence (lead opening) during northerly winds or pack convergence (lead closing) during southerly winds. Mean daily flight time and flight cost during winter did not differ among proposed periods of decadal-scale climate shifts in the North Pacific Ocean. Although leads in mobile pack ice constantly open and close with variations in wind, under most conditions in the Bering Sea there appeared to be a shifting-mosaic steady-state of lead availability. Long-term trends in the extent and timing of Bering Sea pack ice may have affected spectacled eiders more by altering foodweb processes than by changing flight costs relative to lead structure.

Fuselage ventilation due to wind flow about a postcrash aircraft

NASA Technical Reports Server (NTRS)

Stuart, J. W.

1980-01-01

Postcrash aircraft fuselage fire development, dependent on the internal and external fluid dynamics is discussed. The natural ventilation rate, a major factor in the internal flow patterns and fire development is reviewed. The flow about the fuselage as affected by the wind and external fire is studied. An analysis was performend which estimated the rates of ventilation produced by the wind for a limited idealized environmental configuration. The simulation utilizes the empirical pressure coefficient distribution of an infinite circular cylinder near a wall with its boundary later flow to represent the atmospheric boundary layer. The resulting maximum ventilation rate for two door size openings, with varying circumferential location in a common 10 mph wind was an order of magnitude greater than the forced ventilation specified in full scale fire testing. The parameter discussed are: (1) fuselage size and shape, (2) fuselage orientation and proximity to the ground, (3) fuselage-openings size and location, (4) wind speed and direction, and (5) induced flow of the external fire plume is recommended. The fire testing should be conducted to a maximum ventilation rate at least an order of magnitude greater than the inflight air conditioning rates.

Description of an 8 MW reference wind turbine

NASA Astrophysics Data System (ADS)

Desmond, Cian; Murphy, Jimmy; Blonk, Lindert; Haans, Wouter

2016-09-01

An 8 MW wind turbine is described in terms of mass distribution, dimensions, power curve, thrust curve, maximum design load and tower configuration. This turbine has been described as part of the EU FP7 project LEANWIND in order to facilitate research into logistics and naval architecture efficiencies for future offshore wind installations. The design of this 8 MW reference wind turbine has been checked and validated by the design consultancy DNV-GL. This turbine description is intended to bridge the gap between the NREL 5 MW and DTU 10 reference turbines and thus contribute to the standardisation of research and development activities in the offshore wind energy industry.

76 FR 79579 - Approval and Promulgation of Implementation Plans and Designation of Areas for Air Quality...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-12-22

... posting of the availability of the submittal on EPA's Adequacy Web site (at http://www.epa.gov/otaq... average annual fourth-highest daily maximum 8-hour average ozone concentration), if it had a 1-hour design... ozone standard is attained when the three-year average of the annual fourth-highest daily maximum 8-hour...

A Procedure for Setting Environmentally Safe Total Maximum Daily Loads (TMDLs) for Selenium

Treesearch

A. Dennis Lemly

2002-01-01

This article presents a seven-step procedure for developing environmentally safe total maximum daily loads (TMDLs) for selenium. The need for this information stems from recent actions taken by the U.S. Environmental Protection Agency (EPA) that may require TMDLs for selenium and other contaminants that are impairing water bodies. However, there is no technical...

The phenology of cherry blossom (Prunus yedoensis ``Somei-yoshino'') and the geographic features contributing to its flowering

NASA Astrophysics Data System (ADS)

Ohashi, Yukitaka; Kawakami, Hiroshi; Shigeta, Yoshinori; Ikeda, Hiroshi; Yamamoto, Nobuko

2012-09-01

We investigated relationships between the flowering phenology of Prunus yedoensis "Somei-yoshino" (cherry blossom) and the local temperatures in Japan. Our observations were carried out across the Okayama Plain, which included Okayama City (about 700,000 inhabitants), from the winter of 2008 to the spring of 2009. Local air temperature (AT) and the globe temperature (GT) were recorded at the tree height. The flowering dates (FDs) of P. yedoensis were earliest in the central commercial area (located at the center of the plain), followed by the north residential area (further inland), and finally the south residential area (seaward). The recorded FDs were related to the period-averaged daily maximum/minimum AT and GT, and the phenologically effective AT and GT defined in this study. Of these parameters, the phenologically effective GTs correlated most with the FDs. Since the GT is determined by AT, solar and infrared radiations, and wind speed, our previous result suggests that a combination of these three components surrounding the tree is more important for budding and flowering than is AT alone. The supposition is supported by the flowering of P. yedoensis being the latest at the coastal region of the Okayama Plain where the AT were higher than at the inland region, excluding the urban area; it is probably caused by stronger winds there than at the other sites.

Partial differential equation methods for stochastic dynamic optimization: an application to wind power generation with energy storage.

PubMed

Johnson, Paul; Howell, Sydney; Duck, Peter

2017-08-13

A mixed financial/physical partial differential equation (PDE) can optimize the joint earnings of a single wind power generator (WPG) and a generic energy storage device (ESD). Physically, the PDE includes constraints on the ESD's capacity, efficiency and maximum speeds of charge and discharge. There is a mean-reverting daily stochastic cycle for WPG power output. Physically, energy can only be produced or delivered at finite rates. All suppliers must commit hourly to a finite rate of delivery C , which is a continuous control variable that is changed hourly. Financially, we assume heavy 'system balancing' penalties in continuous time, for deviations of output rate from the commitment C Also, the electricity spot price follows a mean-reverting stochastic cycle with a strong evening peak, when system balancing penalties also peak. Hence the economic goal of the WPG plus ESD, at each decision point, is to maximize expected net present value (NPV) of all earnings (arbitrage) minus the NPV of all expected system balancing penalties, along all financially/physically feasible future paths through state space. Given the capital costs for the various combinations of the physical parameters, the design and operating rules for a WPG plus ESD in a finite market may be jointly optimizable.This article is part of the themed issue 'Energy management: flexibility, risk and optimization'. © 2017 The Author(s).

Assessing the accuracy of ANFIS, EEMD-GRNN, PCR, and MLR models in predicting PM2.5

NASA Astrophysics Data System (ADS)

Ausati, Shadi; Amanollahi, Jamil

2016-10-01

Since Sanandaj is considered one of polluted cities of Iran, prediction of any type of pollution especially prediction of suspended particles of PM2.5, which are the cause of many diseases, could contribute to health of society by timely announcements and prior to increase of PM2.5. In order to predict PM2.5 concentration in the Sanandaj air the hybrid models consisting of an ensemble empirical mode decomposition and general regression neural network (EEMD-GRNN), Adaptive Neuro-Fuzzy Inference System (ANFIS), principal component regression (PCR), and linear model such as multiple liner regression (MLR) model were used. In these models the data of suspended particles of PM2.5 were the dependent variable and the data related to air quality including PM2.5, PM10, SO2, NO2, CO, O3 and meteorological data including average minimum temperature (Min T), average maximum temperature (Max T), average atmospheric pressure (AP), daily total precipitation (TP), daily relative humidity level of the air (RH) and daily wind speed (WS) for the year 2014 in Sanandaj were the independent variables. Among the used models, EEMD-GRNN model with values of R2 = 0.90, root mean square error (RMSE) = 4.9218 and mean absolute error (MAE) = 3.4644 in the training phase and with values of R2 = 0.79, RMSE = 5.0324 and MAE = 3.2565 in the testing phase, exhibited the best function in predicting this phenomenon. It can be concluded that hybrid models have accurate results to predict PM2.5 concentration compared with linear model.

Foehn-induced effects on local dust pollution, frontal clouds and solar radiation in the Dead Sea valley

NASA Astrophysics Data System (ADS)

Kishcha, Pavel; Starobinets, Boris; Savir, Amit; Alpert, Pinhas; Kaplan, Michael

2018-06-01

Despite the long history of investigation of foehn phenomena, there are few studies of the influence of foehn winds on air pollution and none in the Dead Sea valley. For the first time the foehn phenomenon and its effects on local dust pollution, frontal cloudiness and surface solar radiation were analyzed in the Dead Sea valley, as it occurred on 22 March 2013. This was carried out using both numerical simulations and observations. The foehn winds intensified local dust emissions, while the foehn-induced temperature inversion trapped dust particles beneath this inversion. These two factors caused extreme surface dust concentration in the western Dead Sea valley. The dust pollution was transported by west winds eastward, to the central Dead Sea valley, where the speed of these winds sharply decreased. The transported dust was captured by the ascending airflow contributing to the maximum aerosol optical depth (AOD) over the central Dead Sea valley. On the day under study, the maximum surface dust concentration did not coincide with the maximum AOD: this being one of the specific effects of the foehn phenomenon on dust pollution in the Dead Sea valley. Radar data showed a passage of frontal cloudiness through the area of the Dead Sea valley leading to a sharp drop in noon solar radiation. The descending airflow over the downwind side of the Judean Mountains led to the formation of a cloud-free band followed by only the partial recovery of solar radiation because of the extreme dust pollution caused by foehn winds.

Tornado and extreme wind design criteria for nuclear power plants

DOE Office of Scientific and Technical Information (OSTI.GOV)

None

1973-12-01

Nuclear power plant design criteria for tornadoes and extreme winds are presented. Data, formulas, and procedures for determining maximum wind loading on structures and parts of structures are included. Extreme wind loading is applied to structures using methods and procedures consistent with ANSI Building Code A58.1- 1972. The design wind velocities specified generally exceed 100-year recurrent interval winds. Tornado wind loading is applied to structures using procedures paralleling those for extrene winds with additional criteria resulting from the atmospheric pressure change accompanying tornadoes and tornado missile inipact effects. Tornado loading for the 48 contiguous United States is specified for twomore » major zones separated by the Continental Divide. A cross reference listing items related to Atomic Energy Commission Safety Analysis Report format is provided. Development supporting tornado criteria is included. (auth)« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Belu, Radian; Koracin, Darko

The main objective of the study was to investigate spatial and temporal characteristics of the wind speed and direction in complex terrain that are relevant to wind energy assessment and development, as well as to wind energy system operation, management, and grid integration. Wind data from five tall meteorological towers located in Western Nevada, USA, operated from August 2003 to March 2008, used in the analysis. The multiannual average wind speeds did not show significant increased trend with increasing elevation, while the turbulence intensity slowly decreased with an increase were the average wind speed. The wind speed and direction weremore » modeled using the Weibull and the von Mises distribution functions. The correlations show a strong coherence between the wind speed and direction with slowly decreasing amplitude of the multiday periodicity with increasing lag periods. The spectral analysis shows significant annual periodicity with similar characteristics at all locations. The relatively high correlations between the towers and small range of the computed turbulence intensity indicate that wind variability is dominated by the regional synoptic processes. Knowledge and information about daily, seasonal, and annual wind periodicities are very important for wind energy resource assessment, wind power plant operation, management, and grid integration.« less

PI Passivity-Based Control for Maximum Power Extraction of a Wind Energy System with Guaranteed Stability Properties

NASA Astrophysics Data System (ADS)

Cisneros, Rafael; Gao, Rui; Ortega, Romeo; Husain, Iqbal

2016-10-01

The present paper proposes a maximum power extraction control for a wind system consisting of a turbine, a permanent magnet synchronous generator, a rectifier, a load and one constant voltage source, which is used to form the DC bus. We propose a linear PI controller, based on passivity, whose stability is guaranteed under practically reasonable assumptions. PI structures are widely accepted in practice as they are easier to tune and simpler than other existing model-based methods. Real switching based simulations have been performed to assess the performance of the proposed controller.

BOREAS AES READAC Surface Meteorological Data

NASA Technical Reports Server (NTRS)

Atkinson, G. Barrie; Funk, Barry; Hall, Forrest G. (Editor); Knapp, David E. (Editor)

2000-01-01

Canadian AES personnel collected and processed data related to surface atmospheric meteorological conditions over the BOREAS region. This data set contains 15-minute meteorological data from one READAC meteorology station in Hudson Bay, Saskatchewan. Parameters include day, time, type of report, sky condition, visibility, mean sea level pressure, temperature, dewpoint, wind, altimeter, opacity, minimum and maximum visibility, station pressure, minimum and maximum air temperature, a wind group, precipitation, and precipitation in the last hour. The data were collected non-continuously from 24-May-1994 to 20-Sep-1994. The data are provided in tabular ASCII files, and are classified as AFM-Staff data.

Banner clouds observed at Mount Zugspitze

NASA Astrophysics Data System (ADS)

Wirth, V.; Kristen, M.; Leschner, M.; Reuder, J.; Schween, J. H.

2012-04-01

Systematic observations of banner clouds at Mount Zugspitze in the Bavarian Alps are presented and discussed. One set of observations draws on daily time lapse movies, which were taken over several years at this mountain. Identifying banner clouds with the help of these movies and using simultaneous observations of standard variables at the summit of the mountain provides climatological information regarding the banner clouds. In addition, a week-long measurement campaign with an entire suite of instruments was carried through yielding a comprehensive set of data for two specific banner cloud events. The duration of banner cloud events has a long-tailed distribution with a mean of about 40 min. The probability of occurrence has both a distinct diurnal and a distinct seasonal cycle, with a maximum in the afternoon and in the warm season, respectively. These cycles appear to correspond closely to analogous cycles of relative humidity, which maximize in the late afternoon and during the warm season. In addition, the dependence of banner cloud occurrence on wind speed is weak. Both results suggest that moisture conditions are a key factor for banner cloud occurrence. The distribution of wind direction during banner cloud events slightly deviates from climatology, suggesting an influence from the specific Zugspitz orography. The two banner cloud events during the campaign have a number of common features: the windward and the leeward side are characterized by different wind regimes, however, with mean upward flow on both sides; the leeward air is both moister and warmer than the windward air; the background atmosphere has an inversion just above the summit of Mt. Zugspitze; the lifting condensation level increases with altitude. The results are discussed, and it is argued that they are consistent with previous Large Eddy Simulations using idealized orography.

Bannerclouds observed at Mount Zugspitze

NASA Astrophysics Data System (ADS)

Wirth, V.; Kristen, M.; Leschner, M.; Reuder, J.; Schween, J. H.

2011-10-01

Systematic observations of banner clouds at Mount Zugspitze in the Bavarian Alps are presented and discussed. One set of observations draws on daily time lapse movies, which were taken over several years at this mountain. Identifying banner clouds with the help of these movies and using simultaneous observations of standard variables at the summit of the mountain provides climatological information regarding the banner clouds. In addition, a week-long measurement campaign with an entire suite of instruments was carried through yielding a comprehensive set of data for two specific banner cloud events. The duration of banner cloud events has a long-tailed distribution with a mean of about 40 min. The probability of occurrence has both a distinct diurnal and seasonal cycle, with a maximum in the afternoon and in the warm season, respectively. These cycles appear to correspond closely to analogous cycles of relative humidity, which maximizes in the late afternoon and during the warm season. In addition, the dependence of banner cloud occurrence on wind speed is weak. Both results suggest that moisture conditions are a key factor for banner cloud occurrence. The distribution of wind direction during banner cloud events slightly deviates from climatology, suggesting an influence from the specific Zugspitz orography. The two banner cloud events during the campaign have a number of common features: the windward and the leeward side are characterized by a different wind regime, however, with mean upward flow on both sides; the leeward air is both moister and warmer than the windward air; the background atmosphere has an inversion just above the summit of Mt. Zugspitze; the lifting condensation level is an increasing function with altitude. The results are discussed, and it is argued that they are consistent with previous Large Eddy Simulations using idealized orography.

Windstorms and Insured Loss in the UK: Modelling the Present and the Future

NASA Astrophysics Data System (ADS)

Hewston, R.; Dorling, S.; Viner, D.

2006-12-01

Worldwide, the costs of catastrophic weather events have increased dramatically in recent years, with average annual insured losses rising from a negligible level in 1950 to over $10bn in 2005 (Munich Re 2006). When losses from non-catastrophic weather related events are included this figure is doubled. A similar trend is exhibited in the UK with claims totalling over £6bn for the period 1998-2003, more than twice the value for the previous five years (Dlugolecki 2004). More than 70% of this loss is associated with storms. Extratropical cyclones are the main source of wind damage in the UK. In this research, a windstorm model is constructed to simulate patterns of insured loss associated with wind damage in the UK. Observed daily maximum wind gust speeds and a variety of socioeconomic datasets are utilised in a GIS generated model, which is verified against actual domestic property insurance claims data from two major insurance providers. The increased frequency and intensity of extreme events which are anticipated to accompany climate change in the UK will have a direct affect on general insurance, with the greatest impact expected to be on property insurance (Dlugolecki 2004). A range of experiments will be run using Regional Climate Model output data, in conjunction with the windstorm model, to simulate possible future losses resulting from climate change, assuming no alteration to the vulnerability of the building stock. Losses for the periods 2020-2050 and 2070- 2100 will be simulated under the various IPCC emissions scenarios. Munich Re (2006). Annual Review: Natural Catastrophes 2005. Munich, Munich Re: 52. Dlugolecki, A. (2004). A Changing Climate for Insurance - A summary report for Chief Executives and Policymakers, Association of British Insurers

Aerodynamic profiling of terminal building using computational fluid dynamics approach

NASA Astrophysics Data System (ADS)

Vidhya, S.; Pradeep Kumar, R.; Hareesh, M.; Sekar, S. K.

2017-11-01

A case study of isolated building is studied using ANSYS CFX and SAP2000. The plan idea of 30m by 60m is chosen for terminal building. The model is subjected to different wind incidence from 0° to 90° and 45° with 30° interval for 55m/s wind speed. By using tributary area method, the forces at the each mesh node are summed up to get corresponding wind force at that joint within that area. The best effective structural system is determined by designing the structure for each wind incidence. Wind analysis and design is carried out for increasing wind speed above 55m/s to identify the collapse pattern of structure. External supporting members are suggested to withstand that maximum wind speed.

Multivariate Regression Analysis of Winter Ozone Events in the Uinta Basin of Eastern Utah, USA

NASA Astrophysics Data System (ADS)

Mansfield, M. L.

2012-12-01

I report on a regression analysis of a number of variables that are involved in the formation of winter ozone in the Uinta Basin of Eastern Utah. One goal of the analysis is to develop a mathematical model capable of predicting the daily maximum ozone concentration from values of a number of independent variables. The dependent variable is the daily maximum ozone concentration at a particular site in the basin. Independent variables are (1) daily lapse rate, (2) daily "basin temperature" (defined below), (3) snow cover, (4) midday solar zenith angle, (5) monthly oil production, (6) monthly gas production, and (7) the number of days since the beginning of a multi-day inversion event. Daily maximum temperature and daily snow cover data are available at ten or fifteen different sites throughout the basin. The daily lapse rate is defined operationally as the slope of the linear least-squares fit to the temperature-altitude plot, and the "basin temperature" is defined as the value assumed by the same least-squares line at an altitude of 1400 m. A multi-day inversion event is defined as a set of consecutive days for which the lapse rate remains positive. The standard deviation in the accuracy of the model is about 10 ppb. The model has been combined with historical climate and oil & gas production data to estimate historical ozone levels.

Assessing values of air quality and visibility at risk from wildland fires.

Treesearch

Sue A. Ferguson; Steven J. McKay; David E. Nagel; Trent Piepho; Miriam L. Rorig; Casey Anderson; Lara Kellogg

2003-01-01

To assess values of air quality and visibility at risk from wildland fire in the United States, we generated a 40-year database that includes twice daily values of wind, mixing height, and a ventilation index that is the product of windspeed and mixing height. The database provides the first nationally consistent map of surface wind and ventilation index. In addition,...

Project demonstration of wind turbine electricity: Interconnecting a northern Michigan fruit farm with a major utility

NASA Astrophysics Data System (ADS)

Amon, D. M.

1982-10-01

A project to interconnect a farm wind turbine with a utility is reported. Included are a summary of accomplishments and daily major events, correspondence relevant to the project (letters explaining the delay of installation, extending the period of performance, tax credits, net energy sellback legislation, etc.), publicity, legal aspects, maintenance and repair, analysis of test data, and accounting.

High resolution vertical profiles of wind, temperature and humidity obtained by computer processing and digital filtering of radiosonde and radar tracking data from the ITCZ experiment of 1977

NASA Technical Reports Server (NTRS)

Danielson, E. F.; Hipskind, R. S.; Gaines, S. E.

1980-01-01

Results are presented from computer processing and digital filtering of radiosonde and radar tracking data obtained during the ITCZ experiment when coordinated measurements were taken daily over a 16 day period across the Panama Canal Zone. The temperature relative humidity and wind velocity profiles are discussed.

Hourly temporal distribution of wind

NASA Astrophysics Data System (ADS)

Deligiannis, Ilias; Dimitriadis, Panayiotis; Koutsoyiannis, Demetris

2016-04-01

The wind process is essential for hydrometeorology and additionally, is one of the basic renewable energy resources. Most stochastic forecast models are limited up to daily scales disregarding the hourly scale which is significant for renewable energy management. Here, we analyze hourly wind timeseries giving emphasis on the temporal distribution of wind within the day. We finally present a periodic model based on statistical as well as hydrometeorological reasoning that shows good agreement with data. Acknowledgement: This research is conducted within the frame of the undergraduate course "Stochastic Methods in Water Resources" of the National Technical University of Athens (NTUA). The School of Civil Engineering of NTUA provided moral support for the participation of the students in the Assembly.

Changes to Sub-daily Rainfall Patterns in a Future Climate

NASA Astrophysics Data System (ADS)

Westra, S.; Evans, J. P.; Mehrotra, R.; Sharma, A.

2012-12-01

An algorithm is developed for disaggregating daily rainfall into sub-daily rainfall 'fragments' (continuous high temporal-resolution rainfall sequences whose total depth sums to the daily rainfall amount) under a future, warmer climate. The basis of the algorithm is to re-sample sub-daily fragments from the historical record conditional on the total daily rainfall amount and a range of temperature-based atmospheric predictors. The logic is that as the atmosphere warms, future rainfall patterns will be more reflective of historical rainfall patterns which occurred on warmer days at the same location, or at locations which have an atmospheric temperature profile more representative of expected future atmospheric conditions. It was found that the daily to sub-daily scaling relationship varied significantly by season and by location, with rainfall patterns on warmer seasons or at warmer locations typically exhibiting higher rainfall intensity occurring over shorter periods within a day, compared with cooler seasons and locations. Importantly, by regressing against temperature-based atmospheric covariates, this effect was substantially reduced, suggesting that the approach also may be valid when extrapolating to a future climate. An adjusted method of fragments algorithm was then applied to nine stations around Australia, with the results showing that when holding total daily rainfall constant, the maximum intensity of short duration rainfall increased by a median of about 5% per degree for the maximum 6 minute burst, and 3.5% for the maximum one hour burst, whereas the fraction of the day with no rainfall increased by a median of 1.5%. This highlights that a large proportion of the change to the distribution of rainfall is likely to occur at sub-daily timescales, with significant implications for many hydrological systems.

Stable plume rise in a shear layer.

PubMed

Overcamp, Thomas J

2007-03-01

Solutions are given for plume rise assuming a power-law wind speed profile in a stably stratified layer for point and finite sources with initial vertical momentum and buoyancy. For a constant wind speed, these solutions simplify to the conventional plume rise equations in a stable atmosphere. In a shear layer, the point of maximum rise occurs further downwind and is slightly lower compared with the plume rise with a constant wind speed equal to the wind speed at the top of the stack. If the predictions with shear are compared with predictions for an equivalent average wind speed over the depth of the plume, the plume rise with shear is higher than plume rise with an equivalent average wind speed.

Statistical and Spectral Analysis of Wind Characteristics Relevant to Wind Energy Assessment Using Tower Measurements in Complex Terrain

DOE PAGES

Belu, Radian; Koracin, Darko

2013-01-01

The main objective of the study was to investigate spatial and temporal characteristics of the wind speed and direction in complex terrain that are relevant to wind energy assessment and development, as well as to wind energy system operation, management, and grid integration. Wind data from five tall meteorological towers located in Western Nevada, USA, operated from August 2003 to March 2008, used in the analysis. The multiannual average wind speeds did not show significant increased trend with increasing elevation, while the turbulence intensity slowly decreased with an increase were the average wind speed. The wind speed and direction weremore » modeled using the Weibull and the von Mises distribution functions. The correlations show a strong coherence between the wind speed and direction with slowly decreasing amplitude of the multiday periodicity with increasing lag periods. The spectral analysis shows significant annual periodicity with similar characteristics at all locations. The relatively high correlations between the towers and small range of the computed turbulence intensity indicate that wind variability is dominated by the regional synoptic processes. Knowledge and information about daily, seasonal, and annual wind periodicities are very important for wind energy resource assessment, wind power plant operation, management, and grid integration.« less

Tools for the trade

NASA Technical Reports Server (NTRS)

Gillman, Wallace M.

1990-01-01

A brief review is given of daily operations in the airline business, with emphasis on the decisions made by pilots and the information used to make those decisions. Various wind shears are discussed as they affect daily operations. The discussion of tools focuses on airborne reactive and predictive systems. The escape maneuver used to fly out of a severe windshear is from a pilot's point of view.

Long-period variations of wind parameters in the mesopause region and the solar cycle dependence

NASA Technical Reports Server (NTRS)

Greisiger, K. M.; Schminder, R.; Kuerschner, D.

1987-01-01

The solar cycle dependence of wind parameters below 100 km on the basis of long term continuous ionospheric drift measurements in the low frequency range is discussed. For the meridional prevailing wind no significant variation was found. The same comparison as for winter was done for summer where the previous investigations gave no correlation. Now the radar meteor wind measurement values, too, showed a significant negative correlation of the zonal prevailing wind with solar activity for the years 1976 to 1983. The ionospheric drift measurement results of Collm have the same tendency but a larger dispersion due to the lower accuracy of the harmonic analysis because of the shorter daily measuring interval in summer. Continuous wind observations in the upper mesopause region over more than 20 years revealed distinct long term variations, the origin of which cannot be explained with the present knowledge.

Wind energy and Turkey.

PubMed

Coskun, Aynur Aydin; Türker, Yavuz Özhan

2012-03-01

The global energy requirement for sustaining economic activities, meeting social needs and social development is increasing daily. Environmentally friendly, renewable energy resources are an alternative to the primary non-renewable energy resources, which devastate ecosystems in order to meet increasing demand. Among renewable energy sources such as hydropower, biopower, geothermal power and solar power, wind power offers distinct advantages to Turkey. There is an increasing tendency toward wind globally and the European Union adjusted its legal regulations in this regard. As a potential EU Member state, Turkey is going through a similar process. The number of institutional and legal regulations concerning wind power has increased in recent years; technical infrastructure studies were completed, and some important steps were taken in this regard. This study examines the way in which Turkey has developed support for wind power, presents a SWOT analysis of the wind power sector in Turkey and a projection was made for the concrete success expected to be accomplished in the future.

Linking playa surface dust emission potential to feedbacks between surface moisture and salt crust expansion through high resolution terrestrial laser scanning measurements

NASA Astrophysics Data System (ADS)

Nield, J. M.; King, J.; Wiggs, G.

2012-12-01

The dust emissivity of salt pans (or playas) can be significant but is controlled by interactions between wind erosivity, surface moisture, salt chemistry and crust morphology. These surface properties influence the aeolian transport threshold and can be highly variable over both short temporal and spatial scales. In the past, field studies have been hampered by practical difficulties in accurately measuring properties controlling sediment availability at the surface in high resolution. Studies typically therefore, have investigated large scale monthly or seasonal change using remote sensing and assume a homogeneous surface when predicting dust emissivity. Here we present the first high resolution measurements (sub-cm) of salt crust expansion related to changes in diurnal moisture over daily and weekly time periods using terrestrial laser scanning (TLS, ground-based LiDAR) on Sua Pan, Botswana. The TLS measures both elevation and relative surface moisture change simultaneously, without disturbing the surface. Measurement sequences enable the variability in aeolian sediment availability to be quantified along with temporal feedbacks associated with crust degradation. On crusts with well-developed polygon ridges (high aerodynamic and surface roughness), daily surface expansion was greater than 30mm. The greatest surface change occurred overnight on the upper, exposed sections of the ridges, particularly when surface temperatures dropping below 10°C. These areas also experienced the greatest moisture variation and became increasingly moist overnight in response to an increase in relative humidity. In contrast, during daylight hours, the ridge areas were drier than the lower lying inter-ridge areas. Positive feedbacks between surface topography and moisture reinforced the maximum diurnal moisture variation at ridge peaks, encouraging crust thrusting due to overnight salt hydration, further enhancing the surface, and therefore, aerodynamic roughness. These feedbacks between surface roughness and moisture have implications for dust emissivity because crust expansion increases fluff production which is one of the main dust source materials. Further, increased roughness can locally increase wind erosivity and the potential evaporation of ridge areas. Crust thrusting also weakens the ridge peaks, developing cracked surfaces and exposing the sediment supply source below. These fast acting processes can have a major influence on wind erosion variability and dust emissivity from key dust source regions.; a-d) Elevation change overnight. e-f) Elevation change over 6 days.

40 CFR 432.105 - New source performance standards (NSPS).

Code of Federal Regulations, 2013 CFR

2013-07-01

...: Performance Standards [NSPS] Regulatedparameter Maximum daily Maximum monthly avg. Ammonia (as N) 1 0.14 0.07... No maximum monthly average limitation. 4 May be measured as hexane extractable material (HEM). 5 mg/L...

40 CFR 432.105 - New source performance standards (NSPS).

Code of Federal Regulations, 2012 CFR

2012-07-01

...: Performance Standards [NSPS] Regulatedparameter Maximum daily Maximum monthly avg. Ammonia (as N) 1 0.14 0.07... No maximum monthly average limitation. 4 May be measured as hexane extractable material (HEM). 5 mg/L...

40 CFR 432.105 - New source performance standards (NSPS).

Code of Federal Regulations, 2014 CFR

2014-07-01

...: Performance Standards [NSPS] Regulatedparameter Maximum daily Maximum monthly avg. Ammonia (as N) 1 0.14 0.07... No maximum monthly average limitation. 4 May be measured as hexane extractable material (HEM). 5 mg/L...

Descriptive Statistics and Cluster Analysis for Extreme Rainfall in Java Island

NASA Astrophysics Data System (ADS)

E Komalasari, K.; Pawitan, H.; Faqih, A.

2017-03-01

This study aims to describe regional pattern of extreme rainfall based on maximum daily rainfall for period 1983 to 2012 in Java Island. Descriptive statistics analysis was performed to obtain centralization, variation and distribution of maximum precipitation data. Mean and median are utilized to measure central tendency data while Inter Quartile Range (IQR) and standard deviation are utilized to measure variation of data. In addition, skewness and kurtosis used to obtain shape the distribution of rainfall data. Cluster analysis using squared euclidean distance and ward method is applied to perform regional grouping. Result of this study show that mean (average) of maximum daily rainfall in Java Region during period 1983-2012 is around 80-181mm with median between 75-160mm and standard deviation between 17 to 82. Cluster analysis produces four clusters and show that western area of Java tent to have a higher annual maxima of daily rainfall than northern area, and have more variety of annual maximum value.

Floods of May 1978 in southeastern Montana and northeastern Wyoming

USGS Publications Warehouse

Parrett, Charles; Carlson, D.D.; Craig, G.S.; Chin, E.H.

1984-01-01

Heavy rain and some snow fell on previously saturated ground over southeastern Montana and northeastern Wyoming during May 16-19, 1978. The maximum amount of 7.60 inches within a 72-hour period observed at Lame Deer, Montana, set a record for the month of May in that region. Heavy flooding occurred in the drainages of the Yellowstone River and its tributaries as well as the Belle Fourche, Cheyenne, and North Platte Rivers. The previous maximum flood of record was exceeded at 48 gaged sites, and the 1-percent chance flood was equaled or exceeded at 24 sites. Flood damage was extensive, exceeding $33 million. Nineteen counties in the two States were declared major disaster areas. Mean daily suspended-sediment discharges exceeded previously recorded maximum mean daily values at four sites on the Powder River. The maximum daily suspended-sediment discharge of 2,810,000 tons per day occurred on May 20 at the Site Powder River near Arvada, Wyoming. (USGS)

Impacts of wind stilling on solar radiation variability in China

PubMed Central

Lin, Changgui; Yang, Kun; Huang, Jianping; Tang, Wenjun; Qin, Jun; Niu, Xiaolei; Chen, Yingying; Chen, Deliang; Lu, Ning; Fu, Rong

2015-01-01

Solar dimming and wind stilling (slowdown) are two outstanding climate changes occurred in China over the last four decades. The wind stilling may have suppressed the dispersion of aerosols and amplified the impact of aerosol emission on solar dimming. However, there is a lack of long-term aerosol monitoring and associated study in China to confirm this hypothesis. Here, long-term meteorological data at weather stations combined with short-term aerosol data were used to assess this hypothesis. It was found that surface solar radiation (SSR) decreased considerably with wind stilling in heavily polluted regions at a daily scale, indicating that wind stilling can considerably amplify the aerosol extinction effect on SSR. A threshold value of 3.5 m/s for wind speed is required to effectively reduce aerosols concentration. From this SSR dependence on wind speed, we further derived proxies to quantify aerosol emission and wind stilling amplification effects on SSR variations at a decadal scale. The results show that aerosol emission accounted for approximately 20% of the typical solar dimming in China, which was amplified by approximately 20% by wind stilling. PMID:26463748

Climatic change on the Gulf of Fonseca (Central America) using two-step statistical downscaling of CMIP5 model outputs

NASA Astrophysics Data System (ADS)

Ribalaygua, Jaime; Gaitán, Emma; Pórtoles, Javier; Monjo, Robert

2018-05-01

A two-step statistical downscaling method has been reviewed and adapted to simulate twenty-first-century climate projections for the Gulf of Fonseca (Central America, Pacific Coast) using Coupled Model Intercomparison Project (CMIP5) climate models. The downscaling methodology is adjusted after looking for good predictor fields for this area (where the geostrophic approximation fails and the real wind fields are the most applicable). The method's performance for daily precipitation and maximum and minimum temperature is analysed and revealed suitable results for all variables. For instance, the method is able to simulate the characteristic cycle of the wet season for this area, which includes a mid-summer drought between two peaks. Future projections show a gradual temperature increase throughout the twenty-first century and a change in the features of the wet season (the first peak and mid-summer rainfall being reduced relative to the second peak, earlier onset of the wet season and a broader second peak).

Climatic context and ecological implications of summer fog decline in the coast redwood region

PubMed Central

Johnstone, James A.; Dawson, Todd E.

2010-01-01

Biogeographical, physiological, and paleoecological evidence suggests that the coast redwood [Sequoia sempervirens (D. Don) Endl.] is closely associated with the presence of summer marine fog along the Pacific coast of California. Here we present a novel record of summer fog frequency in the coast redwood region upon the basis of direct hourly measurements of cloud ceiling heights from 1951 to 2008. Our analysis shows that coastal summer fog frequency is a remarkably integrative measure of United States Pacific coastal climate, with strong statistical connections to the wind-driven upwelling system of the California Current and the broad ocean temperature pattern known as the Pacific Decadal Oscillation. By using a long-term index of daily maximum land temperatures, we infer a 33% reduction in fog frequency since the early 20th century. We present tree physiological data suggesting that coast redwood and other ecosystems along the United States west coast may be increasingly drought stressed under a summer climate of reduced fog frequency and greater evaporative demand. PMID:20160112

Estimating cumulative effects of clearcutting on stream temperatures

USGS Publications Warehouse

Bartholow, J.M.

2000-01-01

The Stream Segment Temperature Model was used to estimate cumulative effects of large-scale timber harvest on stream temperature. Literature values were used to create parameters for the model for two hypothetical situations, one forested and the other extensively clearcut. Results compared favorably with field studies of extensive forest canopy removal. The model provided insight into the cumulative effects of clearcutting. Change in stream shading was, as expected, the most influential factor governing increases in maximum daily water temperature, accounting for 40% of the total increase. Altered stream width was found to be more influential than changes to air temperature. Although the net effect from clearcutting was a 4oC warming, increased wind and reduced humidity tended to cool the stream. Temperature increases due to clearcutting persisted 10 km downstream into an unimpacted forest segment of the hypothetical stream, but those increases were moderated by cooler equilibrium conditions downstream. The model revealed that it is a complex set of factors, not single factors such as shade or air temperature, that governs stream temperature dynamics.

Climatic context and ecological implications of summer fog decline in the coast redwood region.

PubMed

Johnstone, James A; Dawson, Todd E

2010-03-09

Biogeographical, physiological, and paleoecological evidence suggests that the coast redwood [Sequoia sempervirens (D. Don) Endl.] is closely associated with the presence of summer marine fog along the Pacific coast of California. Here we present a novel record of summer fog frequency in the coast redwood region upon the basis of direct hourly measurements of cloud ceiling heights from 1951 to 2008. Our analysis shows that coastal summer fog frequency is a remarkably integrative measure of United States Pacific coastal climate, with strong statistical connections to the wind-driven upwelling system of the California Current and the broad ocean temperature pattern known as the Pacific Decadal Oscillation. By using a long-term index of daily maximum land temperatures, we infer a 33% reduction in fog frequency since the early 20th century. We present tree physiological data suggesting that coast redwood and other ecosystems along the United States west coast may be increasingly drought stressed under a summer climate of reduced fog frequency and greater evaporative demand.

On the role of successive downstream development in East Asian polar air outbreaks

NASA Technical Reports Server (NTRS)

Jung, C. H.; Hitchman, M. H.

1982-01-01

Common features were drawn from 16 events of wintertime migration of cold Siberian air moving southeastward across the east Asia coast, accompanied by strong northerly winds. Criteria for including an event as an instance of a typical synoptic scale occurrence comprised a surface pressure gradient over Korea exceeding 2.5 mb/100 km, and a drop in the daily mean temperature of over 5 C in one day. The events were required to have at least a 10 day separation. A sequence of events was discerned, including the formation of troughs and ridges over the western north Atlantic 6-7 days before an event, their development and decay downstream from one another across the Eurasian continent, and then an outbreak of polar weather. The troughs and ridges displayed maximum amplitude in the same places in the majority of cases studied, with the center moving along a curved trajectory of the 300 mb flow at nearly 30 deg longitudinally every day.

Idealized Numerical Modeling Experiments of the Diurnal Cycle of Tropical Cyclones

NASA Astrophysics Data System (ADS)

Navarro, Erika L.

Numerical experiments are performed to evaluate the role of the daily cycle of radiation on axisymmetric hurricane structure. Although a diurnal response in the high cloudiness of tropical cyclones (TCs) has been well documented in the past, the impact to storm structure and intensity remains unknown. Previous modeling work attributes differences in results to experimental setup (e.g., initial and boundary conditions) as well as to radiative parameterization schemes. Here, a numerically-simulated TC in a statistical steady-state is examined to quantify the TC response to the daily cycle of radiation, and a modified, Sawyer-Eliassen approach is applied to evaluate the dynamical mechanism. Fourier analysis in time reveals a spatially coherent pattern in the temperature, wind, and latent heating tendency fields that is statistically significant at the 95% level. This signal accounts for up to 62% of the variance in the temperature field of the upper troposphere, and is mainly concentrated in the TC outflow layer. Composite analysis reveals a cycle in the storm intensity in the low-levels, which lags a periodic response in the latent heating tendency by 6 h. Average magnitudes of the azimuthal wind anomalies near the radius of maximum wind (RMW) are 1 m/s and account for 21% of the overall variance. A hypothesis is drawn from these results that the TC diurnal cycle is comprised of two distinct, periodic circulations: (1) a radiatively-driven circulation in the TC outflow layer due to absorption of solar radiation, and (2) a convectively-driven circulation in the lower and middle troposphere due to anomalous latent heating from convection. These responses are coupled and are periodic with respect to the diurnal cycle. Using a modified, Sawyer-Eliassen approach for time-varying heating, these hypotheses are evaluated to determine the impact of periodic diurnal heating on a balanced vortex. Periodic heating near the top of the vortex produces a local overturning circulation in the region of heating that manifests as inertia-buoyancy waves in the storm environment. Periodic heating in the lower troposphere drives an overturning circulation that resembles the Sawyer-Eliassen solution. This low-level heating induces a positive perturbation azimuthal wind response of 4 m/s near the RMW, which lags the maximum in streamfunction by 6 h. Comparison of these solutions to the numerically-simulated TC reveals a close correspondence of results, suggesting that the axisymmetric TC diurnal cycle is a balanced response driven by periodic heating. The sensitivity of these results to the length of the diurnal period and the vortex intensity are evaluated using the modified, Sawyer-Eliassen approach. Although the true diurnal period is fixed in nature, these experiments allow for the relationship between the magnitude and structure of the TC diurnal signal to the length of the diurnal period to be explored. Results demonstrate that the TC diurnal cycle exhibits large variance, even for the same heating distributions. High-frequency forcing projects mainly onto inertia-buoyancy waves, while low-frequency produces a balanced response resembling the Sawyer-Eliassen solution. Comparison to two, numerically simulated TCs with modified diurnal periods show similar results. In addition, stronger diurnal signals are observed for stronger vortices, suggesting a dependence of the TC diurnal signal on the underlying state of the vortex. These results imply that the magnitude and structure of the TC diurnal signal in nature varies throughout the storm lifetime, and is a function of the structure and intensity of the vortex.

Approximate Co-Location of Precipitation and Low-Level Westerlies in Tropical Monthly Means

NASA Technical Reports Server (NTRS)

Choa, Winston C.; Chen, Baode

1999-01-01

In summer monsoon regions the monthly mean precipitation regions coincide approximately well with regions of westerlies at low-levels. An included chart shows a 15-year (1979-1993) mean August 850 hPa zonal wind from NCEP/NCAR reanalysis dataset and Xie-Arkin precipitation. It shows a region of westerlies covering most of Northern Indian Ocean and extending to northwestern Pacific. This region coincides well with the region with precipitation greater than 6 mm/day. Obviously the coincidence is not exact; the region of larges; zonal wind in the Arabian Sea is in a region of relatively low precipitation and is far from the region of maximum precipitation in Bay of Bengal. Also, in a zonally averaged sense between 40E and 140E, the latitude of maximum precipitation is slightly higher than that of the maximum zonal wind. Low-level westerlies are also found in regions west of Central America and in western Africa north of the equator. These regions are also closely associated with precipitation centers. Across equator from these westerlies regions there are regions of strong easterlies. Also, on their poleward side the westerly regions are flanked by weaker easterly regions. In February, similar observation can be found in the Australian monsoon area and in South America monsoon region; again the regions of westerlies coincide well with regions of maximum precipitation. As in the northern hemisphere, the maximum precipitation is found to the cast of the maximum zonal wind. The two maxima lie almost at the same latitude with that of the westerlies slightly closer to the equator. In the non-monsoon seasons the low- level westerlies can also be found in the tropical precipitation regions, the longitudinal range of the westerlies is undiminished and the speed of the westerlies is not much weaker than that found in February. The interpretation of these observational facts is the goal of this investigation. The approach taken is numerical simulation with the Goddard Earth Observation Systems atmospheric general circulation model, and its aqua-planet version, combined with theoretical arguments.

A 7.5-Year Dataset of SSM/I-Derived Surface Turbulent Fluxes Over Global Oceans

NASA Technical Reports Server (NTRS)

Chou, Shu-Hsien; Shie, Chung-Lin; Atlas, Robert M.; Ardizzone, Joe; Nelkin, Eric; Einaudi, Franco (Technical Monitor)

2001-01-01

The surface turbulent fluxes of momentum, latent heat, and sensible heat over global oceans are essential to weather, climate and ocean problems. Wind stress is the major forcing for driving the oceanic circulation, while Evaporation is a key component of hydrological cycle and surface heat budget. We have produced a 7.5-year (July 1987-December 1994) dataset of daily, individual monthly-mean and climatological (1988-94) monthly-mean surface turbulent fluxes over the global oceans from measurements of the Special Sensor Microwave/Imager (SSM/I) on board the US Defense Meteorological Satellite Program F8, F10, and F11 satellites. It has a spatial resolution of 2.0x2.5 latitude-longitude. Daily turbulent fluxes are derived from daily data of SSM/I surface winds and specific humidity, National Centers for Environmental Prediction (NCEP) sea surface temperatures, and European Centre for Medium-Range Weather Forecasts (ECMWF) air-sea temperature differences, using a stability-dependent bulk scheme. The retrieved instantaneous surface air humidity (with a 25-km resolution) IS found to be generally accurate as compared to the collocated radiosonde observations over global oceans. The surface wind speed and specific humidity (latent heat flux) derived from the F10 SSM/I are found to be -encrally smaller (larger) than those retrieved from the F11 SSM/I. The F11 SSM/I appears to have slightly better retrieval accuracy for surface wind speed and humidity as compared to the F10 SSM/I. This difference may be due to the orbital drift of the F10 satellite. The daily wind stresses and latent heat fluxes retrieved from F10 and F11 SSM/Is show useful accuracy as verified against the research quality in si -neasurerrients (IMET buoy, RV Moana Wave, and RV Wecoma) in the western Pacific warm pool during the TOGA COARE Intensive observing period (November 1992-February 1993). The 1988-94 seasonal-mean turbulent fluxes and input variables derived from FS and F11 SSM/Is show reasonable patterns related to seasonal variations of atmospheric general circulation. This dataset of SSM/I-derived turbulent fluxes is useful for climate studies, forcing of ocean models, and validation of coupled ocean-atmosphere global models and can be accessed through the NASA/GSFC Distributed Active Archive Center.

QUIET-TIME SUPRATHERMAL (∼0.1–1.5 keV) ELECTRONS IN THE SOLAR WIND

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tao, Jiawei; Wang, Linghua; Zong, Qiugang

2016-03-20

We present a statistical survey of the energy spectrum of solar wind suprathermal (∼0.1–1.5 keV) electrons measured by the WIND 3DP instrument at 1 AU during quiet times at the minimum and maximum of solar cycles 23 and 24. After separating (beaming) strahl electrons from (isotropic) halo electrons according to their different behaviors in the angular distribution, we fit the observed energy spectrum of both strahl and halo electrons at ∼0.1–1.5 keV to a Kappa distribution function with an index κ and effective temperature T{sub eff}. We also calculate the number density n and average energy E{sub avg} of strahl andmore » halo electrons by integrating the electron measurements between ∼0.1 and 1.5 keV. We find a strong positive correlation between κ and T{sub eff} for both strahl and halo electrons, and a strong positive correlation between the strahl n and halo n, likely reflecting the nature of the generation of these suprathermal electrons. In both solar cycles, κ is larger at solar minimum than at solar maximum for both strahl and halo electrons. The halo κ is generally smaller than the strahl κ (except during the solar minimum of cycle 23). The strahl n is larger at solar maximum, but the halo n shows no difference between solar minimum and maximum. Both the strahl n and halo n have no clear association with the solar wind core population, but the density ratio between the strahl and halo roughly anti-correlates (correlates) with the solar wind density (velocity)« less

Autonomous Electrothermal Facility for Oil Recovery Intensification Fed by Wind Driven Power Unit

NASA Astrophysics Data System (ADS)

Belsky, Aleksey A.; Dobush, Vasiliy S.

2017-10-01

This paper describes the structure of autonomous facility fed by wind driven power unit for intensification of viscous and heavy crude oil recovery by means of heat impact on productive strata. Computer based service simulation of this facility was performed. Operational energy characteristics were obtained for various operational modes of facility. The optimal resistance of heating element of the downhole heater was determined for maximum operating efficiency of wind power unit.

Scientific Analysis of Data for the ISTP/SOLARMAX Programs

NASA Technical Reports Server (NTRS)

Lazarus, Alan J.

2001-01-01

This Grant supplemented our work on data analysis from the Wind spacecraft which was one of the ISTRIA fleet of spacecraft. It was targeted at observations related to the time of solar maximum in 2000. The work we proposed to do under this grant included comparison of solar wind parameters obtained from different spacecraft in order to establish correlation lengths appropriate to the solar wind and also to compare parameters to explore solar cycle effects.

Influence of Reynolds Number on Multi-Objective Aerodynamic Design of a Wind Turbine Blade.

PubMed

Ge, Mingwei; Fang, Le; Tian, De

2015-01-01

At present, the radius of wind turbine rotors ranges from several meters to one hundred meters, or even more, which extends Reynolds number of the airfoil profile from the order of 105 to 107. Taking the blade for 3MW wind turbines as an example, the influence of Reynolds number on the aerodynamic design of a wind turbine blade is studied. To make the study more general, two kinds of multi-objective optimization are involved: one is based on the maximum power coefficient (CPopt) and the ultimate load, and the other is based on the ultimate load and the annual energy production (AEP). It is found that under the same configuration, the optimal design has a larger CPopt or AEP (CPopt//AEP) for the same ultimate load, or a smaller load for the same CPopt//AEP at higher Reynolds number. At a certain tip-speed ratio or ultimate load, the blade operating at higher Reynolds number should have a larger chord length and twist angle for the maximum Cpopt//AEP. If a wind turbine blade is designed by using an airfoil database with a mismatched Reynolds number from the actual one, both the load and Cpopt//AEP will be incorrectly estimated to some extent. In some cases, the assessment error attributed to Reynolds number is quite significant, which may bring unexpected risks to the earnings and safety of a wind power project.

[Observation on atmospheric pollution in Xianghe during Beijing 2008 Olympic Games].

PubMed

Pan, Yue-Peng; Wang, Yue-Si; Hu, Bo; Liu, Quan; Wang, Ying-Hong; Nan, Wei-Dong

2010-01-01

There is a concern that much of the atmospheric pollution experienced in Beijing is regional in nature and not attributable to local sources. The objective of this study is to examine the contribution of sources outside Beijing to atmospheric pollution levels during Beijing 2008 Olympic Games. The observations of SO2, NO(x), O3, PM2.5 and PM10 were conducted from June 1 to September 30, 2008 in Xianghe, a rural site about 70 km southeast of Beijing. Sources and transportation of atmospheric pollution during the experiment were discussed with surface meteorology data and backward trajectories calculated using HYSPLIT model. The results showed that the daily average maximum (mean +/- standard deviation) concentrations of SO2, NO(x), O3, PM2.5, and PM10 during observation reached 84.4(13.4 +/- 15.2), 43.3 (15.9 +/- 9.1), 230 (82 +/- 38), 184 (76 +/- 42) and 248 (113 +/- 52) microg x m(-3), respectively. In particular, during the pollution episodes from July 20 to August 12, the hourly average concentration of O3 exceeded the National Ambient Air Quality Standard II for 46 h (9%), and the daily average concentration of PM10 exceeded the Standard for 11 d (46%); PM2.5 exceeded the US EPA Standard for 18 d (75%). The daily average concentrations of SO2, NO(x), O3, PM2.5 and PM10 decreased from 27.7, 18.6, 96, 90, 127 microg x m(-3) in June-July to 5.8, 13.2, 80, 60, 106 microg x m(-3) during Olympic Games (August-September), respectively. The typical diurnal variations of NO(x), PM2.5 and PM10 were similar, peaking at 07:00 and 20:00, while the maximum of O3 occurred between 14:00 to 16:00 local time. The findings also suggested that the atmospheric pollution in Xianghe is related to local emission, regional transport as well as the meteorological conditions. Northerly wind and precipitation are favorable for diffusion and wet deposition of pollutants, while sustained south flows make the atmospheric pollution more serious. The lead-lag correlation analysis during the pollution episodes from July 20 to August 12 showed that there are about 6-10 h (0.57 < r < 0.65, p = 0.01) of hourly average PM2.5 in Beijing lagging Xianghe, reaching the maximum at 8 h, which indicates that the real-time atmospheric PM2.5 database of Xianghe might provides early warning for the Beijing PM2.5 pollution events.

Experimental studies of Savonius wind turbines with variations sizes and fin numbers towards performance

NASA Astrophysics Data System (ADS)

Utomo, Ilham Satrio; Tjahjana, Dominicus Danardono Dwi Prija; Hadi, Syamsul

2018-02-01

The use of renewable energy in Indonesia is still low. Especially the use of wind energy. Wind turbine Savonius is one turbine that can work with low wind speed. However, Savonius wind turbines still have low efficiency. Therefore it is necessary to modify. Modifications by using the fin are expected to increase the positive drag force by creating a flow that can enter the overlap ratio of the gap. This research was conducted using experimental approach scheme. Parameters generated from the experiment include: power generator, power coefficient, torque coefficient. The experimental data will be collected by variation of fin area, horizontal finning, at wind speed 3 m/s - 4,85 m/s. Experimental results show that with the addition of fin can improve the performance of wind turbine Savonius 11%, and by using the diameter of 115 mm fin is able to provide maximum performance in wind turbine Savonius.

Quality Control of Wind Data from 50-MHz Doppler Radar Wind Profiler

NASA Technical Reports Server (NTRS)

Vacek, Austin

2016-01-01

Upper-level wind profiles obtained from a 50-MHz Doppler Radar Wind Profiler (DRWP) instrument at Kennedy Space Center are incorporated in space launch vehicle design and day-of-launch operations to assess wind effects on the vehicle during ascent. Automated and manual quality control (QC) techniques are implemented to remove spurious data in the upper-level wind profiles caused from atmospheric and non-atmospheric artifacts over the 2010-2012 period of record (POR). By adding the new quality controlled profiles with older profiles from 1997-2009, a robust database will be constructed of upper-level wind characteristics. Statistical analysis will determine the maximum, minimum, and 95th percentile of the wind components from the DRWP profiles over recent POR and compare against the older database. Additionally, this study identifies specific QC flags triggered during the QC process to understand how much data is retained and removed from the profiles.

Quality Control of Wind Data from 50-MHz Doppler Radar Wind Profiler

NASA Technical Reports Server (NTRS)

Vacek, Austin

2015-01-01

Upper-level wind profiles obtained from a 50-MHz Doppler Radar Wind Profiler (DRWP) instrument at Kennedy Space Center are incorporated in space launch vehicle design and day-of-launch operations to assess wind effects on the vehicle during ascent. Automated and manual quality control (QC) techniques are implemented to remove spurious data in the upper-level wind profiles caused from atmospheric and non-atmospheric artifacts over the 2010-2012 period of record (POR). By adding the new quality controlled profiles with older profiles from 1997-2009, a robust database will be constructed of upper-level wind characteristics. Statistical analysis will determine the maximum, minimum, and 95th percentile of the wind components from the DRWP profiles over recent POR and compare against the older database. Additionally, this study identifies specific QC flags triggered during the QC process to understand how much data is retained and removed from the profiles.

Influence of omni-directional guide vane on the performance of cross-flow rotor for urban wind energy

NASA Astrophysics Data System (ADS)

Wicaksono, Yoga Arob; Tjahjana, Dominicus Danardono Dwi Prija; Hadi, Syamsul

2018-02-01

Vertical axis wind turbine like cross-flow rotor have some advantage there are, high self-starting torque, low noise, and high stability; so, it can be installed in the urban area to produce electricity. But, the urban area has poor wind condition, so the cross-flow rotor needs a guide vane to increase its performance. The aim of this study is to determine experimentally the effect of Omni-Directional Guide Vane (ODGV) on the performance of a cross-flow wind turbine. Wind tunnel experiment has been carried out for various configurations. The ODGV was placed around the cross-flow rotor in order to increase ambient wind environment of the wind turbine. The maximum power coefficient is obtained as Cpmax = 0.125 at 60° wind direction. It was 21.46% higher compared to cross-flow wind turbine without ODGV. This result showed that the ODGV able to increase the performance of the cross-flow wind turbine.

A nonlinear dynamics approach for incorporating wind-speed patterns into wind-power project evaluation.

PubMed

Huffaker, Ray; Bittelli, Marco

2015-01-01

Wind-energy production may be expanded beyond regions with high-average wind speeds (such as the Midwest U.S.A.) to sites with lower-average speeds (such as the Southeast U.S.A.) by locating favorable regional matches between natural wind-speed and energy-demand patterns. A critical component of wind-power evaluation is to incorporate wind-speed dynamics reflecting documented diurnal and seasonal behavioral patterns. Conventional probabilistic approaches remove patterns from wind-speed data. These patterns must be restored synthetically before they can be matched with energy-demand patterns. How to accurately restore wind-speed patterns is a vexing problem spurring an expanding line of papers. We propose a paradigm shift in wind power evaluation that employs signal-detection and nonlinear-dynamics techniques to empirically diagnose whether synthetic pattern restoration can be avoided altogether. If the complex behavior of observed wind-speed records is due to nonlinear, low-dimensional, and deterministic system dynamics, then nonlinear dynamics techniques can reconstruct wind-speed dynamics from observed wind-speed data without recourse to conventional probabilistic approaches. In the first study of its kind, we test a nonlinear dynamics approach in an application to Sugarland Wind-the first utility-scale wind project proposed in Florida, USA. We find empirical evidence of a low-dimensional and nonlinear wind-speed attractor characterized by strong temporal patterns that match up well with regular daily and seasonal electricity demand patterns.

Disaggregating from daily to sub-daily rainfall under a future climate

NASA Astrophysics Data System (ADS)

Westra, S.; Evans, J.; Mehrotra, R.; Sharma, A.

2012-04-01

We describe an algorithm for disaggregating daily rainfall into sub-daily rainfall 'fragments' (continuous fine-resolution rainfall sequences whose total depth sums to the daily rainfall amount) under a future, warmer climate. The basis of the algorithm is re-sample sub-daily fragments from the historical record conditional on the total daily rainfall amount and a range of atmospheric predictors representative of the future climate. The logic is that as the atmosphere warms, future rainfall patterns will be more reflective of historical rainfall patterns which occurred on warmer days at the same location, or at locations which have an atmospheric profile more reflective of expected future conditions. When looking at the scaling from daily to sub-daily rainfall over the historical record, it was found that the relationship varied significantly by season and by location, with rainfall patterns on warmer seasons or at warmer locations typically showing more intense rain falling over shorter periods compared with cooler seasons and stations. Importantly, by regressing against atmospheric covariates such as temperature this effect was almost entirely eliminated, providing a basis for suggesting the approach may be valid when extrapolating sub-daily sequences to a future climate. The method of fragments algorithm was then applied to nine stations around Australia, and showed that when holding the total daily rainfall constant, the maximum intensity of a short duration (6 minute) rainfall increased by between 4.1% and 13.4% per degree change in temperature for the maximum six minute burst, between 3.1% and 6.8% for the maximum one hour burst, and between 1.5% and 3.5% for the fraction of the day with no rainfall. This highlights that a large proportion of the change to the distribution of precipitation in the future is likely to occur at sub-daily timescales, with significant implications for many hydrological systems.

Concentration-response of short-term ozone exposure and hospital admissions for asthma in Texas.

PubMed

Zu, Ke; Liu, Xiaobin; Shi, Liuhua; Tao, Ge; Loftus, Christine T; Lange, Sabine; Goodman, Julie E

2017-07-01

Short-term exposure to ozone has been associated with asthma hospital admissions (HA) and emergency department (ED) visits, but the shape of the concentration-response (C-R) curve is unclear. We conducted a time series analysis of asthma HAs and ambient ozone concentrations in six metropolitan areas in Texas from 2001 to 2013. Using generalized linear regression models, we estimated the effect of daily 8-hour maximum ozone concentrations on asthma HAs for all ages combined, and for those aged 5-14, 15-64, and 65+years. We fit penalized regression splines to evaluate the shape of the C-R curves. Using a log-linear model, estimated risk per 10ppb increase in average daily 8-hour maximum ozone concentrations was highest for children (relative risk [RR]=1.047, 95% confidence interval [CI]: 1.025-1.069), lower for younger adults (RR=1.018, 95% CI: 1.005-1.032), and null for older adults (RR=1.002, 95% CI: 0.981-1.023). However, penalized spline models demonstrated significant nonlinear C-R relationships for all ages combined, children, and younger adults, indicating the existence of thresholds. We did not observe an increased risk of asthma HAs until average daily 8-hour maximum ozone concentrations exceeded approximately 40ppb. Ozone and asthma HAs are significantly associated with each other; susceptibility to ozone is age-dependent, with children at highest risk. C-R relationships between average daily 8-hour maximum ozone concentrations and asthma HAs are significantly curvilinear for all ages combined, children, and younger adults. These nonlinear relationships, as well as the lack of relationship between average daily 8-hour maximum and peak ozone concentrations, have important implications for assessing risks to human health in regulatory settings. Copyright © 2017. Published by Elsevier Ltd.

First annual register of allergenic pollen in Talca, Chile.

PubMed

Mardones, P; Grau, M; Araya, J; Córdova, A; Pereira, I; Peñailillo, P; Silva, R; Moraga, A; Aguilera-Insunza, R; Yepes-Nuñez, J J; Palomo, I

2013-01-01

There are no data on atmospheric pollen in Talca. In the present work, our aim is to describe the amount of pollen grain in the atmosphere of the city of Talca likely to cause pollinosis of its inhabitants. A volumetric Hirst sampler (Burkard seven-day recording device) was used to study pollen levels. It was placed in the centre of Talca from May 2007 to April 2008. The highest airborne presence of pollen, as measured in weekly averages, was Platanus acerifolia with a maximum weekly daily average of 203 grains/m³ registered during September and October. The second highest was Acer pseudoplatanus with a maximum weekly daily average of 116 grains/m³. Populus spp. had a maximum weekly daily average 103 grains/m³. Olea europaea reached 19 grains/m³ in November. Grasses presented high levels of pollen counts with a maximum weekly daily average of 27 grains/m³ from the end of August until the end of January. Pollens of Plantago spp. Rumex acetosella and Chenopodium spp. had a similar distribution and were present from October to April with maximum weekly daily average of 7 grains/m³, 7 grains/m³ and 3 grains/m³ respectively. Significant concentrations of Ambrosia artemisiifolia were detected from February until April. The population of Talca was exposed to high concentrations of allergenic pollen, such as P. acerifolia, A. pseudoplatanus, and grasses in the months of August through November. The detection of O. europaea and A. artemisiifolia is important as these are emergent pollens in the city of Talca. Aerobiological monitoring will provide the community with reliable information about the level of allergenic pollens, improving treatment and quality of life of patients with respiratory allergy. Copyright © 2011 SEICAP. Published by Elsevier Espana. All rights reserved.

Influence of intravenous opioid dose on postoperative ileus.

PubMed

Barletta, Jeffrey F; Asgeirsson, Theodor; Senagore, Anthony J

2011-07-01

Intravenous opioids represent a major component in the pathophysiology of postoperative ileus (POI). However, the most appropriate measure and threshold to quantify the association between opioid dose (eg, average daily, cumulative, maximum daily) and POI remains unknown. To evaluate the relationship between opioid dose, POI, and length of stay (LOS) and identify the opioid measure that was most strongly associated with POI. Consecutive patients admitted to a community teaching hospital who underwent elective colorectal surgery by any technique with an enhanced-recovery protocol postoperatively were retrospectively identified. Patients were excluded if they received epidural analgesia, developed a major intraabdominal complication or medical complication, or had a prolonged workup prior to surgery. Intravenous opioid doses were quantified and converted to hydromorphone equivalents. Classification and regression tree (CART) analysis was used to determine the dosing threshold for the opioid measure most associated with POI and define high versus low use of opioids. Risk factors for POI and prolonged LOS were determined through multivariate analysis. The incidence of POI in 279 patients was 8.6%. CART analysis identified a maximum daily intravenous hydromorphone dose of 2 mg or more as the opioid measure most associated with POI. Multivariate analysis revealed maximum daily hydromorphone dose of 2 mg or more (p = 0.034), open surgical technique (p = 0.045), and days of intravenous narcotic therapy (p = 0.003) as significant risk factors for POI. Variables associated with increased LOS were POI (p < 0.001), maximum daily hydromorphone dose of 2 mg or more (p < 0.001), and age (p = 0.005); laparoscopy (p < 0.001) was associated with a decreased LOS. Intravenous opioid therapy is significantly associated with POI and prolonged LOS, particularly when the maximum hydromorphone dose per day exceeds 2 mg. Clinicians should consider alternative, nonopioid-based pain management options when this occurs.

Fuzzy regulator design for wind turbine yaw control.

PubMed

Theodoropoulos, Stefanos; Kandris, Dionisis; Samarakou, Maria; Koulouras, Grigorios

2014-01-01

This paper proposes the development of an advanced fuzzy logic controller which aims to perform intelligent automatic control of the yaw movement of wind turbines. The specific fuzzy controller takes into account both the wind velocity and the acceptable yaw error correlation in order to achieve maximum performance efficacy. In this way, the proposed yaw control system is remarkably adaptive to the existing conditions. In this way, the wind turbine is enabled to retain its power output close to its nominal value and at the same time preserve its yaw system from pointless movement. Thorough simulation tests evaluate the proposed system effectiveness.

A simple, analytical, axisymmetric microburst model for downdraft estimation

NASA Technical Reports Server (NTRS)

Vicroy, Dan D.

1991-01-01

A simple analytical microburst model was developed for use in estimating vertical winds from horizontal wind measurements. It is an axisymmetric, steady state model that uses shaping functions to satisfy the mass continuity equation and simulate boundary layer effects. The model is defined through four model variables: the radius and altitude of the maximum horizontal wind, a shaping function variable, and a scale factor. The model closely agrees with a high fidelity analytical model and measured data, particularily in the radial direction and at lower altitudes. At higher altitudes, the model tends to overestimate the wind magnitude relative to the measured data.

Profitability Analysis of Residential Wind Turbines with Battery Energy Storage

NASA Astrophysics Data System (ADS)

She, Ying; Erdem, Ergin; Shi, Jing

Residential wind turbines are often accompanied by an energy storage system for the off-the-grid users, instead of the on-the-grid users, to reduce the risk of black-out. In this paper, we argue that residential wind turbines with battery energy storage could actually be beneficial to the on-the-grid users as well in terms of monetary gain from differential pricing for buying electricity from the grid and the ability to sell electricity back to the grid. We develop a mixed-integer linear programming model to maximize the profit of a residential wind turbine system while meeting the daily household electricity consumption. A case study is designed to investigate the effects of differential pricing schemes and sell-back schemes on the economic output of a 2-kW wind turbine with lithium battery storage. Overall, based on the current settings in California, a residential wind turbine with battery storage carries more economical benefits than the wind turbine alone.

The relationship between mortality caused by cardiovascular diseases and two climatic factors in densely populated areas in Norway and Ireland.

PubMed

Eng, H; Mercer, J B

2000-10-01

Seasonal variations in mortality due to cardiovascular disease have been demonstrated in many countries, with the highest levels occurring during the coldest months of the year. It has been suggested that this can be explained by cold climate. In this study, we examined the relationship between mortality and two different climatic factors in two densely populated areas (Dublin, Ireland and Oslo/Akershus, Norway). Meteorological data (mean daily air temperatures and wind speed) and registered daily mortality data for three groups of cardiovascular disease for the period 1985-1994 were obtained for the two respective areas. The daily mortality ratio for both men and women of 60 years and older was calculated from the mortality data. The wind chill temperature equivalent was calculated from the Siple and Passels formula. The seasonal variations in mortality were greater in Dublin than in Oslo/Akershus, with mortality being highest in winter. This pattern was similar to that previously shown for the two respective countries as a whole. There was a negative correlation between mortality and both air temperature and wind chill temperature equivalent for all three groups of diseases. The slopes of the linear regression lines describing the relationship between mortality and air temperature were a lot steeper for the Irish data than for the Norwegian data. However, the difference between the steepness of the linear regression lines for the relationship between mortality and wind chill temperature equivalent was considerably less between the two areas. This can be explained by the fact that Dublin is a much windier area than Oslo/Akershus. The results of this study demonstrate that the inclusion of two climatic factors rather than just one changes the impression of the relationship between climate and cardiovascular disease mortality.

40 CFR 53.63 - Test procedure: Wind tunnel inlet aspiration test.

Code of Federal Regulations, 2010 CFR

2010-07-01

... the sampler inlet opening centered in the sampling zone. To meet the maximum blockage limit of § 53.62(c)(1) or for convenience, part of the test sampler may be positioned external to the wind tunnel... = reference method sampler volumetric flow rate; and t = sampling time. (iii) Remove the reference method...

33 CFR 164.35 - Equipment: All vessels.

Code of Federal Regulations, 2010 CFR

2010-07-01

... to alter course 90 degrees with maximum rudder angle and constant power settings, for either full and...: (i) Calm weather—wind 10 knots or less, calm sea; (ii) No current; (iii) Deep water conditions—water...: (1) Calm weather—wind 10 knots or less, calm sea; (2) No current; (3) Water depth twice the vessel's...

40 CFR 205.174 - Remedial orders.

Code of Federal Regulations, 2010 CFR

2010-07-01

... power (maximum rated RPM) is developed; and (B) Response characteristics such that, when closing RPM is...-state accuracy of within ±10% at 20 km/h (12.4 mph). (5) A microphone wind screen which does not affect... microphone wind screen must be used. The sound level meter must be calibrated with the acoustic calibrator as...

46 CFR 35.20-40 - Maneuvering characteristics-T/OC.

Code of Federal Regulations, 2011 CFR

2011-10-01

... degrees with maximum rudder angle and constant power settings. (2) The time and distance to stop the... for the normal load and normal ballast condition for: (1) Calm weather—wind 10 knots or less, calm sea... conditions, upon which the maneuvering information is based, are varied: (1) Calm weather—wind 10 knots or...

33 CFR 164.35 - Equipment: All vessels.

Code of Federal Regulations, 2011 CFR

2011-07-01

... to alter course 90 degrees with maximum rudder angle and constant power settings, for either full and...: (i) Calm weather—wind 10 knots or less, calm sea; (ii) No current; (iii) Deep water conditions—water...: (1) Calm weather—wind 10 knots or less, calm sea; (2) No current; (3) Water depth twice the vessel's...

On the asymmetric distribution of shear-relative typhoon rainfall

NASA Astrophysics Data System (ADS)

Gao, Si; Zhai, Shunan; Li, Tim; Chen, Zhifan

2018-02-01

The Tropical Rainfall Measuring Mission (TRMM) 3B42 precipitation, the National Centers for Environmental Prediction (NCEP) Final analysis and the Regional Specialized Meteorological Center (RSMC) Tokyo best-track data during 2000-2015 are used to compare spatial rainfall distribution associated with Northwest Pacific tropical cyclones (TCs) with different vertical wind shear directions and investigate possible mechanisms. Results show that the maximum TC rainfall are all located in the downshear left quadrant regardless of shear direction, and TCs with easterly shear have greater magnitudes of rainfall than those with westerly shear, consistent with previous studies. Rainfall amount of a TC is related to its relative position and proximity from the western Pacific subtropical high (WPSH) and the intensity of water vapor transport, and low-level jet is favorable for water vapor transport. The maximum of vertically integrated moisture flux convergence (MFC) are located on the downshear side regardless of shear direction, and the contribution of wind convergence to the total MFC is far larger than that of moisture advection. The cyclonic displacement of the maximum rainfall relative to the maximum MFC is possibly due to advection of hydrometeors by low- and middle-level cyclonic circulation of TCs. The relationship between TC rainfall and the WPSH through water vapor transport and vertical wind shear implies that TC rainfall may be highly predictable given the high predictability of the WPSH.

Operational wind shear detection and warning - The 'CLAWS' experience at Denver and future objectives

NASA Technical Reports Server (NTRS)

Mccarthy, John; Wilson, James W.; Hjelmfelt, Mark R.

1986-01-01

An operational wind shear detection and warning experiment was conducted at Denver's Stapleton International Airport in summer 1984. Based on meteorological interpretation of scope displays from a Doppler weather radar, warnings were transmitted to the air traffic control tower via voice radio. Analyses of results indicated real skill in daily microburst forecasts and very short-term (less than 5-min) warnings. Wind shift advisories with 15-30 min forecasts, permitted more efficient runway reconfigurations. Potential fuel savings were estimated at $875,000/yr at Stapleton. The philosophy of future development toward an automated, operational system is discussed.

Solar wind velocity and daily variation of cosmic rays

NASA Technical Reports Server (NTRS)

Ahluwalia, H. S.; Riker, J. F.

1985-01-01

Recently parameters applicable to the solar wind and the interplanetary magnetic field (IMF) have become much better defined. Superior quality of data bases that are now available, particularly for post-1971 period, make it possible to believe the long-term trends in the data. These data are correlated with the secular changes observed in the diurnal variation parameters obtained from neutron monitor data at Deep River and underground muon telescope data at Embudo (30 MEW) and Socorro (82 MWE). The annual mean amplitudes appear to have large values during the epochs of high speed solar wind streams. Results are discussed.

A new method for evaluating impacts of data assimilation with respect to tropical cyclone intensity forecast problem

NASA Astrophysics Data System (ADS)

Vukicevic, T.; Uhlhorn, E.; Reasor, P.; Klotz, B.

2012-12-01

A significant potential for improving numerical model forecast skill of tropical cyclone (TC) intensity by assimilation of airborne inner core observations in high resolution models has been demonstrated in recent studies. Although encouraging , the results so far have not provided clear guidance on the critical information added by the inner core data assimilation with respect to the intensity forecast skill. Better understanding of the relationship between the intensity forecast and the value added by the assimilation is required to further the progress, including the assimilation of satellite observations. One of the major difficulties in evaluating such a relationship is the forecast verification metric of TC intensity: the maximum one-minute sustained wind speed at 10 m above surface. The difficulty results from two issues : 1) the metric refers to a practically unobservable quantity since it is an extreme value in a highly turbulent, and spatially-extensive wind field and 2) model- and observation-based estimates of this measure are not compatible in terms of spatial and temporal scales, even in high-resolution models. Although the need for predicting the extreme value of near surface wind is well justified, and the observation-based estimates that are used in practice are well thought of, a revised metric for the intensity is proposed for the purpose of numerical forecast evaluation and the impacts on the forecast. The metric should enable a robust observation- and model-resolvable and phenomenologically-based evaluation of the impacts. It is shown that the maximum intensity could be represented in terms of decomposition into deterministic and stochastic components of the wind field. Using the vortex-centric cylindrical reference frame, the deterministic component is defined as the sum of amplitudes of azimuthal wave numbers 0 and 1 at the radius of maximum wind, whereas the stochastic component is represented by a non-Gaussian PDF. This decomposition is exact and fully independent of individual TC properties. The decomposition of the maximum wind intensity was first evaluated using several sources of data including Step Frequency Microwave Radiometer surface wind speeds from NOAA and Air Force reconnaissance flights,NOAA P-3 Tail Doppler Radar measurements, and best track maximum intensity estimates as well as the simulations from Hurricane WRF Ensemble Data Assimilation System (HEDAS) experiments for 83 real data cases. The results confirmed validity of the method: the stochastic component of the maximum exibited a non-Gaussian PDF with small mean amplitude and variance that was comparable to the known best track error estimates. The results of the decomposition were then used to evaluate the impact of the improved initial conditions on the forecast. It was shown that the errors in the deterministic component of the intensity had the dominant effect on the forecast skill for the studied cases. This result suggests that the data assimilation of the inner core observations could focus primarily on improving the analysis of wave number 0 and 1 initial structure and on the mechanisms responsible for forcing the evolution of this low-wavenumber structure. For the latter analysis, the assimilation of airborne and satellite remote sensing observations could play significant role.

A Solar Cycle Prediction Puzzle's PossibleExplanation?

NASA Astrophysics Data System (ADS)

Luhmann, Janet

2007-05-01

A long-standing and intriguing puzzle of the last few decades has been Joan Feynman's (1982) discovery that the solar cycle (sunspot number) maximum trends follow the level of geomagnetic activity during the prior minimum phase. Recently Hathaway (GRL 33, 2006) used this relationship to make a prediction of the size of the next solar maximum. But the physical reason why this should work at all remains a matter of speculation. Although it has been suggested that geomagnetic activity around solar minimum is determined by the terrestrial magnetosphere's response to high speed solar wind streams which seem to often characterize the declining phase of the cycle, why should the occurrence of these streams portend the new solar maximum? Our improving understanding of solar wind sources may hold the key, and also tell us something useful about the solar dynamo.

Throughfall under a teak plantation in Thailand: a multifactorial analysis on the effects of canopy phenology and meteorological conditions

NASA Astrophysics Data System (ADS)

Tanaka, N.; Levia, D. F., Jr.; Igarashi, Y.; Nanko, K.; Yoshifuji, N.; Tanaka, K.; Chatchai, T.; Suzuki, M.; Kumagai, T.

2014-12-01

Teak (Tectona grandis Linn. f.) plantations cover vast areas throughout Southeast Asia and are of great economic importance. This study has sought to increase our understanding of throughfall inputs under teak by analyzing the abiotic and biotic factors governing throughfall amounts and throughfall ratios in relation to three canopy phenophases (leafless, leafing, and leafed). There is no rain during the brief leaf senescence phenophase. Daily data was available for both throughfall volumes and depths as well as leaf area index. Detailed meteorological data were available in situ every ten minutes. Leveraging this high-resolution field data, we employed boosted regression trees (BRT) analysis to identify the primary controls on throughfall amount and ratio during each of the three canopy phenophases. Whereas throughfall amounts were always dominated by the magnitude of rainfall (as expected), throughfall ratios were governed by a suite of predictor variables during each phenophase. The BRT analysis demonstrated that throughfall ratio in the leafless phase was most influenced (in descending order of importance) by air temperature, rainfall amount, maximum wind speed, and rainfall intensity. Throughfall ratio in the leafed phenophase was dominated by rainfall amount which exerted 54.0% of the relative influence. The leafing phenophase was an intermediate case where rainfall amount, air temperature, and vapor pressure deficit were most important. Our results highlight the fact that throughfall ratios are differentially influenced by a suite of meteorological variables during leafless, leafing, and leafed phenophases. Abiotic variables (rainfall amount, air temperature, vapor pressure deficit, and maximum wind speed) trumped leaf area index and stand density in their effect on throughfall ratio. The leafing phenophase, while transitional in nature and short in duration, has a detectable and unique impact on water inputs to teak plantations. Further work is clearly needed to better gauge the importance of the leaf emergence period to the stemflow hydrology and forest biogeochemistry of teak plantations.

Forest trees filter chronic wind-signals to acclimate to high winds.

PubMed

Bonnesoeur, Vivien; Constant, Thiéry; Moulia, Bruno; Fournier, Meriem

2016-05-01

Controlled experiments have shown that trees acclimate thigmomorphogenetically to wind-loads by sensing their deformation (strain). However, the strain regime in nature is exposed to a full spectrum of winds. We hypothesized that trees avoid overreacting by responding only to winds which bring information on local climate and/or wind exposure. Additionally, competition for light dependent on tree social status also likely affects thigmomorphogenesis. We monitored and manipulated quantitatively the strain regimes of 15 pairs of beech (Fagus sylvatica) trees of contrasting social status in an acclimated stand, and quantified the effects of these regimes on the radial growth over a vegetative season. Trees exposed to artificial bending, the intensity of which corresponds to the strongest wind-induced strains, enhanced their secondary growth by at least 80%. Surprisingly, this reaction was even greater - relatively - for suppressed trees than for dominant ones. Acclimated trees did not sense the different types of wind events in the same way. Daily wind speed peaks due to thermal winds were filtered out. Thigmomorphogenesis was therefore driven by intense storms. Thigmomorphogenesis is also likely to be involved in determining social status. © 2016 The Authors. New Phytologist © 2016 New Phytologist Trust.

A MODEL FOR THERMAL PHASE VARIATIONS OF CIRCULAR AND ECCENTRIC EXOPLANETS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cowan, Nicolas B.; Agol, Eric, E-mail: n-cowan@northwestern.edu

2011-01-10

We present a semi-analytic model atmosphere for close-in exoplanets that captures the essential physics of phase curves: orbital and viewing geometry, advection, and re-radiation. We calibrate the model with the well-characterized transiting planet, HD 189733b, then compute light curves for seven of the most eccentric transiting planets: Gl 436b, HAT-P-2b, HAT-P-11b, HD 17156b, HD 80606b, WASP-17b, and XO-3b. We present phase variations for a variety of different radiative times and wind speeds. In the limit of instant re-radiation, the light-curve morphology is entirely dictated by the planet's eccentricity and argument of pericenter: the light curve maximum leads or trails themore » eclipse depending on whether the planet is receding from or approaching the star at superior conjunction, respectively. For a planet with non-zero radiative timescales, the phase peak occurs early for super-rotating winds, and late for sub-rotating winds. We find that for a circular orbit, the timing of the phase variation maximum with respect to superior conjunction indicates the direction of the dominant winds, but cannot break the degeneracy between wind speed and radiative time. For circular planets the phase minimum occurs half an orbit away from the phase maximum-despite the fact that the coolest longitudes are always near the dawn terminator-and therefore does not convey any additional information. In general, increasing the advective frequency or the radiative time has the effect of reducing the peak-to-trough amplitude of phase variations, but there are interesting exceptions to these trends. Lastly, eccentric planets with orbital periods significantly longer than their radiative time exhibit 'ringing', whereby the hot spot generated at periastron rotates in and out of view. The existence of ringing makes it possible to directly measure the wind speed (the frequency of the ringing) and the radiative time constant (the damping of the ringing).« less

Solar cycle dependence of the heliospheric shape deduced from a global MHD simulation of the interaction process between a nonuniform time-dependent solar wind and the local interstellar medium

NASA Astrophysics Data System (ADS)

Tanaka, T.; Washimi, H.

1999-06-01

The global structure of the solar wind/very local interstellar medium interaction is studied from a fully three-dimensional time-dependent magnetohydrodynamic model, in which the solar wind speed increases from 400 to 800 km/s in going from the ecliptic to pole and the heliolatitude of the low-high-speed boundary changes from 30° to 80° in going from the solar minimum to solar maximum. In addition, the interplanetary magnetic field (IMF) changes its polarity at the solar maximum. As a whole, the shapes of the terminal shock (TS) and heliopause (HP) are elongated along the solar polar axis owing to a high solar wind ram pressure over the poles. In the ecliptic plane, the heliospheric structure changes little throughout a solar cycle. The TS in this plane shows a characteristic bullet-shaped structure. In the polar plane, on the other hand, the shape of the TS exhibits many specific structures according to the stage of the solar cycle. These structures include the polygonal configuration of the polar TS seen around the solar minimum, the mesa- and terrace-shaped TSs in the high- and low-speed solar wind regions seen around the ascending phase, and the chimney-shaped TS in the high-speed solar wind region seen around the solar maximum. These structures are formed from different combinations of right-angle shock, oblique shock, and steep oblique shock so as to transport the heliosheath plasma most efficiently toward the heliotail (HT). In the HT, the hot and weakly-magnetized plasma from the high-heliolatitude TS invades as far as the ecliptic plane. A weakly time-dependent recirculation flow in the HT is a manifestation of invading flow. Distributions of magnetic field in the HT, which are a pile-up of the compressed MF over several solar cycles, are modified by the flow from high-heliolatitude.

Total maximum daily loads, sediment budgets, and tracking restoration progress of the north coast watersheds

Treesearch

Matthew S. Buffleben

2012-01-01

One of the predominate water quality problems for northern coastal California watersheds is the impairment of salmonid habitat. Most of the North Coast watersheds are listed as “impaired” under section 303(d) of Clean Water Act. The Clean Water Act requires states to address impaired waters by developing Total Maximum Daily Loads (TMDLs) or implementing...

Spatiotemporal Divergence of the Warming Hiatus over Land Based on Different Definitions of Mean Temperature

PubMed Central

Zhou, Chunlüe; Wang, Kaicun

2016-01-01

Existing studies of the recent warming hiatus over land are primarily based on the average of daily minimum and maximum temperatures (T2). This study compared regional warming rates of mean temperature based on T2 and T24 calculated from hourly observations available from 1998 to 2013. Both T2 and T24 show that the warming hiatus over land is apparent in the mid-latitudes of North America and Eurasia, especially in cold seasons, which is closely associated with the negative North Atlantic Oscillation (NAO) and Arctic Oscillation (AO) and cold air propagation by the Arctic-original northerly wind anomaly into mid-latitudes. However, the warming rates of T2 and T24 are significantly different at regional and seasonal scales because T2 only samples air temperature twice daily and cannot accurately reflect land-atmosphere and incoming radiation variations in the temperature diurnal cycle. The trend has a standard deviation of 0.43 °C/decade for T2 and 0.41 °C/decade for T24, and 0.38 °C/decade for their trend difference in 5° × 5° grids. The use of T2 amplifies the regional contrasts of the warming rate, i.e., the trend underestimation in the US and overestimation at high latitudes by T2. PMID:27531421

Satellite Observations of Enhanced Tropospheric Ozone Associated with Biomass Burning in Africa and Madagascar

NASA Technical Reports Server (NTRS)

Aikin, A. C.; Ziemke, J. R.; Thorpe, A.; Einaudi, Franco (Technical Monitor)

2000-01-01

Tropospheric ozone over Africa and Madagascar is enhanced by 10 to 15 DU in October. This maximum coincides with the time of maximum biomass area burning in Africa and Madagascar. Ozone observations were made from 1979 to 1999 using the TOMS tropospheric ozone convective cloud differential method. As a result of easterly trade winds, ozone originating on Madagascar is transported to the west over the Mozambique Channel. In El Nino years higher level westerly winds descend to transport low level ozone easterly. This results in African continental ozone being transported east of Madagascar. Long range transport of African ozone is observed during El Nino periods.

Dose and Dose Risk Caused by Natural Phenomena - Proposed Powder Metallurgy Core Manufacturing Facility

DOE Office of Scientific and Technical Information (OSTI.GOV)

Holmes, W.G.

2001-08-16

The offsite radiological effects from high velocity straight winds, tornadoes, and earthquakes have been estimated for a proposed facility for manufacturing enriched uranium fuel cores by powder metallurgy. Projected doses range up to 30 mrem/event to the maximum offsite individual for high winds and up to 85 mrem/event for very severe earthquakes. Even under conservative assumptions on meteorological conditions, the maximum offsite dose would be about 20 per cent of the DOE limit for accidents involving enriched uranium storage facilities. The total dose risk is low and is dominated by the risk from earthquakes. This report discusses this test.