2024-03-29T15:15:05Z
https://jesphys.ut.ac.ir/?_action=export&rf=summon&issue=8032
فیزیک زمین و فضا
JESP
2538-371X
2538-371X
1395
42
4
Optimizing design of 3D seismic acquisition by CRS trace interpolation
Mehrdad
ُSoleimani
Amin
Roshandel Kahoo
Land seismic data acquisition in most of cases suffers from obstacles in fields which deviates geometry of the real acquired data from what was designed. These obstacles will cause gaps, narrow azimuth and offset limitation in the data. These shortcomings, not only prevents regular trace distribution in bins, but also distorts the subsurface image by reducing illumination of the target formation. However, there are some methods available that can compensate gaps in data due to field obstacles mainly by trace interpolation techniques. The common reflection surface (CRS) method which was previously introduced for seismic imaging in complex geological structures also could be used for trace interpolation to fill the gaps and increase fold of the data. In this study, we combined two different methods of trace interpolation and distribution in bins for solving the problem of gaps and low illumination of the target formation in a 3D seismic acquisition study area in SW Iran. After processing old 2D lines available from the same area, the CRS parameters were obtained for proper definition of the acquisition design. Then by combining the CRS trace interpolation scheme and trace distribution, possible gaps in the data was resolved and regular trace distribution in all bins and azimuths were achieved. Result showed increasing in redundancy in bins which will prevent occurring gaps in data in case of inevitable field obstacles. Result shows that this strategy could be used to construct lost traces and prevent further problem in seismic imaging.
Seismic acquisition
CRS
trace interpolation
seismic imaging
binning
2016
12
21
1
12
https://jesphys.ut.ac.ir/article_58886_7d849e39a886658dc9dd96a6cb34d280.pdf
فیزیک زمین و فضا
JESP
2538-371X
2538-371X
1395
42
4
Dynamics and Thermodynamics Analysis of Tropical Cyclone Haiyan
نفیسه
پگاه فر
پروین
غفاریان
Tropical cyclone Haiyan (TCH) that formed over the West Pacific Ocean during 3-11 November 2013 has been investigated using three datasets produced by Japan Meteorology Agency, ECMWF and NCEP. Strength of TCH has been studied using two synoptic parameters of 10-m wind velocity and mean sea level pressure (MSLP). Following, three dynamic parameters including vertical wind shear (VWSH) vector, helicity and potential vorticity (PV) together with the thermodynamic parameter of convective available potential energy (CAPE) have been calculated and analyzed during TCH life cycle. VWSH vector was analyzed in three classes of weak, moderate and strong shear, having northeasterly direction for the most of TCH lifetime. Moreover, the helicity parameter was intensified to the tornadic instability (at about 6 hours later than the time of maximum 10-m wind speed), and its anomaly was located in the downshear quadrants for the most of TCH life span. In addition, no significant PV anomaly was detected near TCH, but a subtropical PV anomaly was extended to the Philippines Islands before TCH eye reached this region. Also, CAPE parameter was intensified to the strong instability class at about 48 hours earlier than the time of maximum 10-m wind speed and its anomaly was equally displaced in both up- and downshear quadrants. Finally, it can be concluded that 30-hourly lag between the time of CAPE maximum value and VWSH one let TCH to be intensified to category 5.
Tropical Cyclone Haiyan
CAPE
Helicity
Potential vorticity
Vertical Wind Shear Vector
2016
12
21
13
26
https://jesphys.ut.ac.ir/article_58887_d1b3b09dd4b4a6a3120fb5b9ffe9377f.pdf
فیزیک زمین و فضا
JESP
2538-371X
2538-371X
1395
42
4
Simulation of entrainment near a density stratified layer: Laboratory experiment and LIDAR observation
مسعود
خوش سیما
عباسعلی
علی اکبری بیدختی
سمانه
ثابت قدم
In this paper a simple qualitative model of the growth of a mixed layer adjacent to a uniform layer with a stably stratified layer is presented. The depth variations of mixed layer can be estimated from direct measurements. The Entrainment of a stably stratified layer into a turbulent mixed layer in a confined region was studied in laboratory for different Richardson numbers. The internal waves generated at the interface propagate into the stratified fluid. The modal structure of these waves appears to interact with the turbulence processes near the interface creating a non-uniform entrainment rate usually in steps. This may be related to the vertical wave number of the dominant wave which is dependent on the depth of the stratified layer as well as the horizontal cross section of the tank. Also applicability of this work for the atmospheric boundary layer, its growth and the entrainment zone was considered as the aerosol backscattering from the convective boundary layer shows spatial variations due to non-uniform mixing of the naturally occurring aerosol near the entrainment zone.
Atmospheric mixed layer depth
Entrainment zone
Laboratory experiments
2016
12
21
27
34
https://jesphys.ut.ac.ir/article_58888_e780bdc21c76e65d0e63b2979a22273f.pdf
فیزیک زمین و فضا
JESP
2538-371X
2538-371X
1395
42
4
Evaluation of Groundwater Vulnerability Using Data Mining Technique in Hashtgerd Plain
Saman
Javadi
S. Mehdy
Hashemy
Groundwater vulnerability assessment would be one of the effective informative methods to provide a basis for determining source of pollution. Vulnerability maps are employed as an important solution in order to handle entrance of pollution into the aquifers. A common way to develop groundwater vulnerability map is DRASTIC. Meanwhile, application of the method is not easy for any aquifer due to choosing appropriate constant values of weights and ranks. Clustering technique would be an influential method for regionalization of groundwater flow zone to facilitate vulnerability assessment of groundwater aquifers. In this study, a new approach using k-means clustering is applied to make vulnerability maps. Four features of depth to groundwater, hydraulic conductivity, recharge value and vadose zone were considered at the same time as features of clustering. Five regions are recognized out of the Hashtgerd plain. Each zone corresponds to a different level of vulnerability. The results show that clustering provides a realistic vulnerability map so that, Pearson’s correlation coefficients between nitrate concentrations and clustering vulnerability is 72%.
Groundwater
Vulnerability assessment
Clustering
Data Mining
2016
12
21
35
41
https://jesphys.ut.ac.ir/article_57743_cc06d3729e330c4e0c27fe5b53acae70.pdf
فیزیک زمین و فضا
JESP
2538-371X
2538-371X
1395
42
4
Observation of vertical electron density profile in inospheric E-layer during Indian-Ocean earthquake on December 2004 using CHAMP satellite
Siti Harwani
Md Yusoff
Lim
Hwee San
Yoon
Tiem Leong
This paper describes the observation and analysis of vertical electron density before major earthquake above the Sumatra-Malaysia region during Indian Ocean major earthquake in 2004 in Aceh, Sumatra. The electron density profile in E-layer of ionosphere a few days before earthquake and a few hours after earthquake have been observed using the data from the CHAMP satellite. The data obtained from the CHAMP satellite based on GPS radio occultation technique, starting from 21st Dec, 2004 until 27th Dec, 2004, between 90 - 120 km altitude ranges. It is shown that significant anomaly can be detected as early as 3 days before the major earthquake above the preparation zone of earthquake epicentre through significant disturbances of the electron concentration in the ionosphere. In addition, the electron density in the ionosphere above the earthquake epicentre is observed to be very high during 8 hours before earthquake occurred. After a day of the earthquake occurrence, it is observed that the electron density decreases and the ionospheric region become more stable.
earthquake
CHAMP satellite
Ionosphere
electron density
2016
12
21
43
47
https://jesphys.ut.ac.ir/article_58891_76dc365257d9b4f762a31b3eba9315b8.pdf
فیزیک زمین و فضا
JESP
2538-371X
2538-371X
1395
42
4
Spatial analysis and investigation of Tele-connection patterns with drought in central Iran
مهران
فاطمی
کمال
امیدوار
ابراهیم
مسگری
مهدی
نارنگی فرد
This study, adopting an environmental approach to atmospheric circulation, estimates drought periods over a 20-year period (1992-2011) in 21 synoptic stations in Kerman, Yazd and Isfahan provinces, which share a long-term statistical period, using Standardized Precipitation Index (SPI). The data pertinent to 18 teleconnection patterns were derived and compared with climatic data of provinces under study and the relationship between major droughts in the region and these patterns was evaluated in accordance with correlation methods and multivariate regression model. According to the results, a total of 37.42% of annual SPI variation in Isfahan province, 51.09 % of SPI variation in Kerman province and 42.17% of SPI variation in Yazd province can be explained by the above patterns. Finally, the multivariate Scandinavia pattern (SCA) in Isfahan, East Atlantic (EA) pattern in Kerman and Tropical Southern Atlantic (TSA) pattern in Yazd were found to be the most effective patterns in explaining annual SPI changes in central Iran.
Tele-connection
Standardized Precipitation Index
Kriging
Correlation and Regression Models
Central Iran
2016
12
21
49
61
https://jesphys.ut.ac.ir/article_58915_2a261ca9d2b05a0bea179916f712f902.pdf
فیزیک زمین و فضا
JESP
2538-371X
2538-371X
1395
42
4
On the source of plasma density and electric field perturbations in PMSE and PMWE regions
علیرضا
محمودیان
Alireza
Mohebalhojeh
مجید
مزرعهفراهانی
Wayne
Scales
تشکیل ابرهای مسسفری در فصل تابستان و در ارتفاع ۸۰ تا ۹۰ کیلومتری از سطح زمین در نواحی قطبی دارای اهمیت بسیار زیادی می باشند. ارتباط مستقیم بین افزایش مشاهده این ابرها و پدیده گرم شدن کره زمین از دلایل اصلی اهمیت مطالعه این ناحیه می باشد. طبق تحقیقات انجام شده افزایش گازهای گلخانه ای باعث کاهش دما در این ناحیه از جو می شود. از طرف دیگر افزایش گاز متان و فرایند تجزیه آن توسط نور خورشید نیز باعث افزایش مولکول های آب در ناحیه مسسفیر قطبی شده که در حدود ۳ تا ۱۰ روز عمر مفید دارند. لذا پدیده گرم شدن زمین در این ناحیه از جو، فضای مناسبی را برای تشکیل ذرات یخ بر روی هسته های غبار حاضر در این ناحیه فراهم می سازد. ذرات یخ کوچکتر در فصل تابستان قابلیت انعکاس سیگنال راداری در باندهای فرکانسی مختلف را داشته که به معروف هستند. دلیل ناپایداری های حاضر در این ناحیه که باعث پراکندگی سیگنال راداری می شود همچنان نامشخص است. هدف اصلی این مقاله بررسی اثر امواج گرانی بر لایه های پلاسما و غبار معلق در ناحیه مسسفیر و در ارتفاع ۸۰ تا ۹۰ کیلومتری از سطح زمین می باشد. ناپایداری های ایجاد شده در لایه پلاسما باعث پراکندگی سیگنال های راداری در باند های فرکانسی مختلف شده و باعث اختلال در عملکرد سیستم های مخابراتی میشود. این مقاله به بررسی پارامترهای امواج گرانی و تاثیر آن بر دامنه ناپایداری های ایجاد شده در لایه پلاسما می پردازد.
ابرهای مسسفری
پراکندگی سیگنال راداری
ناپایداری پلاسما
2016
12
21
63
71
https://jesphys.ut.ac.ir/article_58921_b770e138fd149fe142b6245ab1c19b29.pdf
فیزیک زمین و فضا
JESP
2538-371X
2538-371X
1395
42
4
Self-Consistent hot spot tracing particles by kinetic simulations: With the emphasis on Cusp particle entry
محمدجواد
کلایی
امین
اسماعیلی
One of the most important advantages of particle simulation as compared to fluid simulation is the capacity for working with and tracing particles. In particle simulations, the test particle method is usually used to get some idea of the behavior of plasma or other substances. In this method, first, a small number of particles are injected into the frame of static electromagnetic fields. Then, movement of particles is investigated using the pattern of the electromagnetic fields. This method is useful; however, as it is needed to work with non self-consistent fields, it lacks precision. In this work, we adapted the particle simulations method, adding the flexibility of working with self-consistent fields that come directly from the simulation. Here we have tried to investigate particle entry from the solar wind with northward Interplanetary Magnetic Field (IMF) to the magnetospheric cusp. As our initial results show, self-consistent path of particles does not follow the magnetic field lines going to the cusp that is slightly in contrast to the conventional non self-consistent results from test particle method.
self-consistent hot spot tracing
cusp particle entry
test particles method
IMF
Solar wind
Magnetosphere
2016
12
21
73
79
https://jesphys.ut.ac.ir/article_60291_38b0ec911d887f766a1bee408b26b3d1.pdf