scholarly journals Ionospheric anomaly due to seismic activities-III: correlation between night time VLF amplitude fluctuations and effective magnitudes of earthquakes in Indian sub-continent

2011 ◽  
Vol 11 (10) ◽  
pp. 2699-2704 ◽  
Author(s):  
S. Ray ◽  
S. K. Chakrabarti ◽  
S. K. Mondal ◽  
S. Sasmal
Keyword(s):  
Statistical Analysis ◽  
Signal Amplitude ◽  
Space Physics ◽  
Amplitude Fluctuation ◽  
Seismic Events ◽  
Time Data ◽  
Night Time ◽  
Amplitude Fluctuations ◽  
Time Fluctuation ◽  
Indian Centre

Abstract. We present the results of an analysis of year-long (2007) monitoring of night time data of the VLF signal amplitude from the Indian Navy station VTX at 18.2 kHz, received by the Indian Centre for Space Physics, Kolkata. We analyzed this data to find out the correlation, if any, between night time amplitude fluctuation and seismic events. We found, analyzing individual cases (with magnitudes >5) as well as statistical analysis (of all the events with effective magnitudes greater than 3.5), that night time fluctuation of the signal amplitude has the highest probability to be beyond the 2σ level about three days prior to seismic events. Thus, the night time fluctuation could be considered as a precursor to enhanced seismic activities.

scholarly journals Ionosperic anomaly due to seismic activities – Part 1: Calibration of the VLF signal of VTX 18.2 KHz station from Kolkata and deviation during seismic events

2009 ◽  
Vol 9 (4) ◽  
pp. 1403-1408 ◽  
Author(s):  
S. Sasmal ◽  
S. K. Chakrabarti
Keyword(s):  
Solar Activity ◽  
Calibration Curve ◽  
Solar Minimum ◽  
Seismic Event ◽  
Space Physics ◽  
Seismic Events ◽  
The Sun ◽  
Reference Signals ◽  
The Mean ◽  
Indian Centre

Abstract. VLF signals are long thought to give away important information about the lithosphere-ionosphere coupling. In order to establish co-relations, if any, between the ionospheric activities and the earthquakes, we need to understand what the reference signals are, throughout the year. The best opportunity to do this is during the period of solar minimum where the number of flares and sunspots are negligible and the data would be primarily affected by the sun and variation would be due to normal sunset and sunrise effects. In this paper, we present the result of the sunrise and sunset terminators as a function of the day of the year for a period of four years, viz, 2005–2008 when the solar activity was very low. The terminators are for the 18.2 KHz VTX signal of the Indian Navy as observed from Indian Centre for Space Physics receiving station located in Kolkata. A total of 624 days of data have been used to obtain the mean plot. Any deviation of observations from this so-called the standardized calibration curve would point to influences by terrestrial (such as earthquakes) and extra-terrestrial events (such as solar activities). We present examples of deviations which occur in a period of 16 months and show that the correlation with seismic events is significant and typically the highest deviation takes place up to a couple of days prior to the seismic event. Simultaneous observations of such deviations from more than one station could improve the predictability of earthquakes.

scholarly journals In-situ measurement of reactive hydrocarbons at Hohenpeissenberg with comprehensive gas chromatography (GCxGC-FID): use in estimating HO and NO<sub>3</sub>

2006 ◽  
Vol 6 (4) ◽  
pp. 8155-8188
Author(s):  
S. Bartenbach ◽  
J. Williams ◽  
C. Plass-Dülmer ◽  
H. Berresheim ◽  
J. Lelieveld
Keyword(s):  
Mean Value ◽  
Time Data ◽  
Night Time ◽  
Radical Species ◽  
Diurnal Cycles ◽  
Meteorological Observatory ◽  
Variate Analysis ◽  
The Relationship ◽  
Good Agreement

Abstract. During a field campaign at the Meteorological Observatory Hohenpeissenberg (MOHp) in July 2004, VOCs were measured using GCxGC-FID. Comparison to routinely made GC-MS measurements showed good agreement for a variety of anthropogenic and biogenic ambient VOCs ranging in concentration from below the detection limit (0.1 pmol mol−1) to 180 pmol mol−1. Pronounced diurnal cycles were found for both the biogenic and anthropogenic compounds, driven for the most part by the daily rise and fall of the boundary layer over the station. For the reactive compounds (lifetimes <2 days), a significant, non-zero dependency of the variability on lifetime was found, indicating that chemistry (as opposed to transport alone) was playing a role in determining the ambient VOC concentrations. The relationship was exploited using a single-variate analysis to derive a daytime mean value of HO (5.3±1.4×106 molecules cm−3), which compares well to that measured at the site, 3.2±2.3×106 molecules cm−3. The analysis was extended to the night time data to estimate concentrations for NO3 (1.47±0.2×108 molecules cm−3), which is not measured at the site. The feasibility of this approach for environments dominated by emissions of short-lived VOCs to estimate ambient levels of radical species is discussed.

scholarly journals Temperature trends at the Mauna Loa Observatory, Hawaii

2010 ◽  
Vol 6 (5) ◽  
pp. 1685-1699
Author(s):  
B. D. Malamud ◽  
D. L. Turcotte ◽  
C. S. B. Grimmond
Keyword(s):  
Linear Trend ◽  
Warming Trend ◽  
Time Of Day ◽  
Time Data ◽  
Night Time ◽  
Mauna Loa ◽  
Temperature Trends ◽  
Hourly Temperature ◽  
Local Standard ◽  
Temperature Records

Abstract. Observations at the Mauna Loa Observatory, Hawaii, established the systematic increase of anthropogenic CO2 in the atmosphere. For the same reasons that this site provides excellent globally averaged CO2 data, it may provide temperature data with global significance. Here, we examine hourly temperature records, averaged annually for 1977–2006, to determine linear trends as a function of time of day. For night-time data (22:00 to 06:00, LST (local standard time)) there is a near-uniform warming of 0.040 °C y−1. During the day, the linear trend shows a slight cooling of −0.013 °C y−1 at 12:00 (noon, LST). Overall, at Mauna Loa Observatory, there is a mean warming trend of 0.021 °C y−1. The dominance of night-time warming results in a relatively large annual decrease in the diurnal temperature range (DTR) of −0.050 °C y−1. These trends are consistent with the observed increases in the concentrations of CO2 and its role as a greenhouse gas, and indicate the possible relevance of the Mauna Loa temperature measurements to global warming.

An influence of characteristics of amplitude fluctuation on detectability of alert sound of electric powered vehicles

2021 ◽  
Vol 263 (2) ◽  
pp. 4634-4640
Author(s):  
Nozomiko Yasui ◽  
Masanobu Miura ◽  
Tetsuya Shimamura
Keyword(s):  
Sine Wave ◽  
Amplitude Fluctuation ◽  
Amplitude Envelope ◽  
Complex Sound ◽  
Complex Sounds ◽  
Periodic Fluctuation ◽  
Modulation Wave ◽  
Amplitude Fluctuations ◽  
Actual Environment ◽  
Fluctuation Frequency

The motor sound on electric powered vehicle is quiet at low speeds. Thus, pedestrians have difficulty detecting the vehicles approaching them under urban noise. Although the vehicles were designed to play an alert sound to solve this problem, it has not been solved yet. Our previous studies found that characteristics of amplitude fluctuation, fluctuation frequency, non-periodic fluctuation and amplitude envelope, are effective to make them detect approaching vehicles. However, those studies were investigated under only a specific actual environment, weren't examined validity of detectability in those studies. Here, this paper investigates under another actual environment, examine the validity. Investigations were carried out by using synthesized complex sounds which were designed to have periodic and non-periodic amplitude fluctuations. Those complex sounds have characteristics of amplitude fluctuations in gasoline powered vehicle. Amplitude envelopes such as modulation wave in amplitude-modulated sound were set for deviations for time and amplitude, and amplitude-modulated complex sounds were synthesized using sine wave, sawtooth wave, and rectangle wave. Then, their effects on detectability by pedestrians were assessed in another actual environment. The results found that amplitude fluctuation enhances the ability with which people detect approaching electric powered vehicles in case of some complex sound.

scholarly journals Regional Poverty and Inequality in the Xiamen-Zhangzhou-Quanzhou City Cluster in China Based on NPP/VIIRS Night-Time Light Imagery

2020 ◽  
Vol 12 (6) ◽  
pp. 2547 ◽  
Author(s):  
Wenbin Pan ◽  
Hongming Fu ◽  
Peng Zheng
Keyword(s):  
Infrared Imaging ◽  
Spatial Scales ◽  
Principal Component ◽  
Regional Inequality ◽  
Theil Index ◽  
Poverty Index ◽  
Time Data ◽  
Night Time ◽  
Poverty And Inequality ◽  
City Cluster

Poverty and inequality remain outstanding challenges in many global regions. Understanding the underlying social and economic conditions is important in formulating poverty eradication strategies. Using Visible Infrared Imaging Radiometer Suite (VIIRS) Night-Time Light (NTL) images and multidimensional socioeconomic data between 2012 and 2018, this study measured regional poverty and inequality in the Xiamen-Zhangzhou-Quanzhou city cluster in the People’s Republic of China. Principal Component Analysis (PCA) and the Theil index decomposition method were used to establish an Integrated Poverty Index (IPI) and a regional inequality index, respectively. The results indicated that: (1) The poverty index is affected by the geographical location, policies, and resources of a district/county. A significant logarithmic correlation model between VIIRS Average Light Index (ALI) and IPI was established. (2) The Theil index derived from Gross Domestic Product (GDP) indicators showed that overall inequality and between-prefecture inequality declined, while within-prefecture inequality remained unchanged. In terms of the contributions to regional inequality, the contribution of within-prefecture inequality is the largest. The results indicated that Suomi National Polar Partnership/Visible Infrared Imaging Radiometer Suite (NPP/VIIRS) night-time data can help to perform district/county-level poverty assessments at small and medium spatial scales, although the evaluation effect on regional inequality is slightly lower.

The Statistical Analysis of Failure Time Data

Technometrics ◽  
2003 ◽  
Vol 45 (3) ◽  
pp. 265-266
Author(s):  
Laurence L George
Keyword(s):  
Statistical Analysis ◽  
Failure Time ◽  
Failure Time Data ◽  
Time Data

Anomalous enhancement in daytime 40-kHz signal amplitude accompanied by geomagnetic storms, earthquakes and meteor showers

1995 ◽  
Vol 13 (10) ◽  
pp. 1117-1123 ◽  
Author(s):  
B. K. De ◽  
S. K. Sarkar
Keyword(s):  
Geomagnetic Storms ◽  
Signal Strength ◽  
Signal Amplitude ◽  
Meteor Showers ◽  
Night Time ◽  
Low Latitude ◽  
After Effects ◽  
D Region

Abstract. Anomalous propagational characteristics, daytime signal levels greater than night-time, were observed. The amplitude records of a 40-kHz signal propagated over a distance of 5100 km from Sanwa, Japan to Calcutta along a low-latitude path show higher signal strength at midday compared to the midnight level on days preceded by principal geomagnetic storms, earthquakes and major meteor showers. This is explained by the increased ionization in the D-region following geophysical events. The storm after-effects only have a duration of a single day in this low-latitude path.

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