Short term tidal variability in stratosphere using ERA-interim and CMAM temperature data and comparison with satellite retrievals

2021 ◽  
Author(s):  
Subhajit Debnath ◽  
Uma Das
Keyword(s):  
Middle Atmosphere ◽  
Window Size ◽  
Temperature Data ◽  
Short Term ◽  
Transform Method ◽  
Data Set ◽  
Linear Interaction ◽  
Non Linear ◽  
Tidal Variability ◽  
Short Term Variability

<p>A short term variability of migrating and non migrating tide is investigated in the stratosphere from the regular Canadian Middle Atmosphere Model (CMAM) and reanalysis ERA-interim temperature and wind dataset during winter of 2006 to 2010. Short term variability of tides is examined by ±10 day’s window size from Earth’s surface to 1hPa pressure level. To examine the short term variability of migrating and non migrating tide in stratosphere, we applied the fast fourier transform method to the CMAM30 and ERA-interim observation. The results reveal that tide changes with amplitude of 1-2K regularly on short timescales (21days) in stratosphere. Similar variability occurs in ERA-interim reanalysis observation. Non-migrating tide DS0 shows strong winter features with finer variation during 2009 and 2010 at 65°N. The short term variability of DE3 tide in stratosphere during 2008 and 2010 may be driven by zonal mean wind and non linear interaction with planetary wave. Amplitude of DW1 shows day to day variabilities clearly during winter of 2006, 2008 and 2009 at 0.7hPa over the equator and mid-latitude while the peak of DW1 is absent at 1hPa and 10hPa from CMAM temperature data set. Short term tidal variability in the stratosphere is not related to a single source. It depends on ozone density, zonal mean wind, and wave-wave non linear interactions. By using smaller window size, short term variabilities and finer variation of non migrating tides and SPW1 are understood. These results will be compared to results from satellite temperature data set, particularly FORMOSAT-3/COMSIC, for investigating short term tidal variability in the stratosphere.</p>

scholarly journals Forcing mechanisms of the 6 h tide in the mesosphere/lower thermosphere

2018 ◽  
Vol 16 ◽  
pp. 141-147 ◽  
Author(s):  
Christoph Jacobi ◽  
Christoph Geißler ◽  
Friederike Lilienthal ◽  
Amelie Krug
Keyword(s):  
Middle Atmosphere ◽  
Lower Thermosphere ◽  
Radar Data ◽  
Radiation Absorption ◽  
Semidiurnal Tide ◽  
Bispectral Analysis ◽  
Solar Forcing ◽  
Linear Interaction ◽  
Non Linear ◽  
Forcing Mechanisms

Abstract. Solar tides such as the diurnal and semidiurnal tide, are forced in the lower and middle atmosphere through the diurnal cycle of solar radiation absorption. This is also the case with higher harmonics like the quarterdiurnal tide (QDT), but for these also non-linear interaction of tides such as the self-interaction of the semidiurnal tide, or the interaction of terdiurnal and diurnal tides, are discussed as possible forcing mechanism. To shed more light on the sources of the QDT, 12 years of meteor radar data at Collm (51.3∘ N, 13∘ E) have been analyzed with respect to the seasonal variability of the QDT at 82–97 km altitude, and bispectral analysis has been applied. The results indicate that non-linear interaction, in particular self-interaction of the semidiurnal tide probably plays an important role in winter, but to a lesser degree in summer. Numerical modelling of 6 h amplitudes qualitatively reproduces the gross seasonal structure of the observed 6 h wave at Collm. Model experiments with removed tidal forcing mechanisms lead to the conclusion that, although non-linear tidal interaction is one source of the QDT, the major forcing mechanism is direct solar forcing of the 6 h tidal components.

scholarly journals Migrating and Non-Migrating Tides Observed in the Stratosphere from FORMOSAT-3/COSMIC Temperature Retrievals

2019 ◽  
Author(s):  
Uma Das ◽  
William Ward ◽  
Chen Jeih Pan ◽  
Sanat Kumar Das
Keyword(s):  
Planetary Wave ◽  
Middle Atmosphere ◽  
High Latitudes ◽  
Short Term ◽  
The Mean ◽  
Tidal Variability ◽  
Using Data ◽  
Stationary Planetary Wave ◽  
Linear Interactions ◽  
Winter Hemisphere

Abstract. FORMOSAT-3/COSMIC temperature data during 2009 to 2010 are analysed for tides in the middle atmosphere from ~ 10 to 50 km. COSMIC is a set of six micro satellites in near sun synchronous orbits with 30° orbital separations and provides good phase space sampling of tides. Short term tidal variability is deduced by considering ± 10 days' data together. The DW1 tide is found to peak over the equator at 30 km. It maximises and slightly shifts poleward during winters and thus is attributed to ozone absorption. Over mid and high latitudes, DW1 and the non-migrating tides DS0 and DW2 are intermittent in nature. Numerical experiments in the current study show that these could be a result of aliasing as they are found to occur at times of steep rise or fall in the mean temperature, particularly during the SSW of 2010. Further, stationary planetary wave components are found to be of very large amplitudes in the northern hemispheres reaching 18 K at 30 km over 65° N. By using data from COSMIC over shorter durations, aliasing between SPW and non-migrating tides is reduced and thus results in the large amplitudes of the former. This study clearly indicates that non-linear interactions are not a very important source of generation of the non migrating tides in the high latitude winter hemisphere. There is also a modulation of SPW1 by ~ 60 days in the high latitudes, which was not seen earlier.

scholarly journals Migrating and non-migrating tides observed in the stratosphere from FORMOSAT-3/COSMIC temperature retrievals

2020 ◽  
Vol 38 (2) ◽  
pp. 421-435 ◽  
Author(s):  
Uma Das ◽  
William E. Ward ◽  
Chen Jeih Pan ◽  
Sanat Kumar Das
Keyword(s):  
Planetary Wave ◽  
Middle Atmosphere ◽  
High Latitudes ◽  
Sudden Stratospheric Warming ◽  
Short Term ◽  
The Mean ◽  
Tidal Variability ◽  
Using Data ◽  
Stationary Planetary Wave ◽  
Linear Interactions

Abstract. Formosa Satellite-3 and Constellation Observing System for Meteorology, Ionosphere and Climate (FORMOSAT-3/COSMIC) temperature data during October 2009–December 2010 are analysed for tides in the middle atmosphere from ∼10 to 50 km. COSMIC is a set of six micro-satellites in near-Sun-synchronous orbits with 30∘ orbital separations that provides good phase space sampling of tides. Short-term tidal variability is deduced by considering ±10 d data together. The migrating diurnal (DW1) tide is found to peak over the Equator at 30 km. It maximises and slightly shifts poleward during winters. Over middle and high latitudes, DW1 and the non-migrating diurnal tides with wavenumber 0 (DS0) and wavenumber 2 (DW2) are intermittent in nature. Numerical experiments in the current study show that these could be a result of aliasing as they are found to occur at times of a steep rise or fall in the mean temperature, particularly during the sudden stratospheric warming (SSW) of 2010. Further, the stationary planetary wave component of wavenumber 1 (SPW1) is found to be of very large amplitudes in the Northern Hemisphere, reaching 18 K at 30 km over 65∘ N. By using data from COSMIC over shorter durations, it is shown that aliasing between stationary planetary wave and non-migrating tides is reduced and thus results in the large amplitudes of the former. This study clearly indicates that non-linear interactions are not a very important source for the generation of non-migrating tides in the middle- and high-latitude winter stratosphere. There is also a modulation of SPW1 by a ∼60 d oscillation in the high latitudes, which was not seen earlier.

scholarly journals A comparative study of winds and tidal variability in the mesosphere/lower-thermosphere region over Bulgaria and the UK

2000 ◽  
Vol 18 (10) ◽  
pp. 1304-1315 ◽  
Author(s):  
D. Pancheva ◽  
P. Mukhtarov ◽  
N. J. Mitchell ◽  
A. G. Beard ◽  
H. G. Muller
Keyword(s):  
Middle Atmosphere ◽  
Spatial Scales ◽  
Lower Thermosphere ◽  
Planetary Waves ◽  
Wave Number ◽  
Linear Interaction ◽  
Zonal Wave Number ◽  
Tidal Variability ◽  
Cross Wavelet Analysis ◽  
The Uk

Abstract. Meteor radars located in Bulgaria and the UK have been used to simultaneously measure winds in the mesosphere/lower-thermosphere region near 42.5°N, 26.6°E and 54.5°N, 3.9°W, respectively, over the period January 1991 to June 1992. The data have been used to investigate planetary waves and diurnal and semidiurnal tidal variability over the two sites. The tidal amplitudes at each site exhibit fluctuations as large as 300% on time scales from a few days to the intra-seasonal, with most of the variability being at intra-seasonal scales. Spectral and cross-wavelet analysis reveals closely related tidal variability over the two sites, indicating that the variability occurs on spatial scales large compared to the spacing between the two radars. In some, but not all, cases, periodic variability of tidal amplitudes is associated with simultaneously present planetary waves of similar period, suggesting the variability is a consequence of non-linear interaction. Calculation of the zonal wave number of a number of large amplitude planetary waves suggests that during summer 1991 the 2-day wave had a zonal wave number of 3, but that during January–February 1991 it had a zonal wave number of 4.Key words: Meteorology and atmospheric dynamics (middle atmosphere dynamics; waves and tides)

MULTIVARIATE TIME-VARYING AUTOREGRESSIVE MODELING OF FETAL SYMPATHO-VAGAL BALANCE THROUGH GESTATION

2013 ◽  
Vol 25 (01) ◽  
pp. 1350014 ◽  
Author(s):  
D. Gutiérrez
Keyword(s):  
High Specificity ◽  
Time Varying ◽  
Autoregressive Modeling ◽  
Short Term ◽  
Data Set ◽  
Varying Coefficients ◽  
Non Invasive ◽  
Time Varying Coefficients ◽  
The Time Domain ◽  
Short Term Variability

A processing framework is proposed to model relative changes in fetal sympatho-vagal balance at equally spaced gestational periods. The proposed method is based on a multivariable time-varying autoregression (TVAR) of the beat-to-beat time differences obtained from non-invasive fetal electrocardiographic (ECG) or magnetocardiographic (MCG) measurements. In order to quantify the sympatho-vagal balance at each measured gestational period, the ratio between the standard deviation of normal-to-normal (SDNN) beat intervals and the sum of absolute differences (SAD) is computed. While the SDNN quantifies the overall variability of the sympathetic and vagal systems, the SAD enhances short-term variability components related to vagal control, then the ratio of these two compares with high specificity the overall variability against the short-term vagal component in the time domain. The SDNN/SAD ratio is used to form a new data set by removing short-term variability events, then leaving only those corresponding to longer-term sympatho-vagal balance. The new data set is then analyzed as a dynamical system by fitting it to a suitable multivariate TVAR, and relative changes in the sympatho-vagal balance through the analyzed gestational periods are assumed to be related to the dynamics of the time-varying coefficients of the TVAR. In order to demonstrate the applicability of the proposed method, simulated and real fetal E/MCG data are analyzed. The results show that the modeling approach is able to infer the expected trend seen through sympatho-vagal development.

Non-Linear Interaction of MHD Waves with Small-Scale Ionospheric Irregularities

2004 ◽  
Vol 61 (7-12) ◽  
pp. 1055-1071
Author(s):  
N. N. Gerasimova ◽  
V. G. Sinitsin ◽  
Yu. M. Yampolski
Keyword(s):  
Ionospheric Irregularities ◽  
Mhd Waves ◽  
Small Scale ◽  
Linear Interaction ◽  
Non Linear

Short-Term Flood Prediction System

2014 ◽  
Vol 13 (1) ◽  
Author(s):  
Konrad Nering
Keyword(s):  
Flash Floods ◽  
Prediction System ◽  
Short Term ◽  
Data Set ◽  
Flood Prediction ◽  
Full Operation

AbstractThis paper describes a fully functional short-term flood prediction system. Its effect has been tested on watershed of Lubieńka river in Małopolska. To use this system it must have a data set also described in this paper. A modification of the system to adopt for predicting flash floods was described. Full operation of the system is shown on example of real flood on Lubieńka river in June 2011.

QSAR Study of PARP Inhibitors by GA-MLR, GA-SVM and GA-ANN Approaches

2020 ◽  
Vol 16 (8) ◽  
pp. 1088-1105
Author(s):  
Nafiseh Vahedi ◽  
Majid Mohammadhosseini ◽  
Mehdi Nekoei
Keyword(s):  
Present Report ◽  
Principal Component ◽  
Parp Inhibitors ◽  
Support Vector ◽  
Ann Model ◽  
Statistical Parameters ◽  
Qsar Study ◽  
Data Set ◽  
Test Set ◽  
Non Linear

Background: The poly(ADP-ribose) polymerases (PARP) is a nuclear enzyme superfamily present in eukaryotes. Methods: In the present report, some efficient linear and non-linear methods including multiple linear regression (MLR), support vector machine (SVM) and artificial neural networks (ANN) were successfully used to develop and establish quantitative structure-activity relationship (QSAR) models capable of predicting pEC50 values of tetrahydropyridopyridazinone derivatives as effective PARP inhibitors. Principal component analysis (PCA) was used to a rational division of the whole data set and selection of the training and test sets. A genetic algorithm (GA) variable selection method was employed to select the optimal subset of descriptors that have the most significant contributions to the overall inhibitory activity from the large pool of calculated descriptors. Results: The accuracy and predictability of the proposed models were further confirmed using crossvalidation, validation through an external test set and Y-randomization (chance correlations) approaches. Moreover, an exhaustive statistical comparison was performed on the outputs of the proposed models. The results revealed that non-linear modeling approaches, including SVM and ANN could provide much more prediction capabilities. Conclusion: Among the constructed models and in terms of root mean square error of predictions (RMSEP), cross-validation coefficients (Q2 LOO and Q2 LGO), as well as R2 and F-statistical value for the training set, the predictive power of the GA-SVM approach was better. However, compared with MLR and SVM, the statistical parameters for the test set were more proper using the GA-ANN model.

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