Multi Satellite Research Articles

Study of Chlorophyll-a Enhancement Over the Northern Arabian Sea

Northern Arabian Sea is one of the most biologically rich region in the North Indian ocean during winter season. In the present study I wish to investigate the the dynamics behind the enrichment of Chlorophyll-a at the above region using multi satellite observations. Ocean Color Monitor (OCM) imageries are used to identify these areas along the west coast of India during February 2000 & 2001 and the mechanisms that can upwell nutrients to sustain the bloom are investigated using sea surface temperature and winds. The variability of Ekman pumping velocity along the northeast Arabian sea is 0.5 - 3.0x10 -6 m/s and the Ekman depth is 25 - 55m. Sea surface temperature was 1 0 C cooler in 2001 winter. This increased cooling resulted in more intense convection and vertical mixing.

Cyclone Persuade on Chlorophyll-A Enrichment in the Bay of Bengal

The response of phytoplankton chlorophyll generated by two cyclones with different intensities in the Bay of Bengal during pre monsoon season (May) during 2003-2004 was studied by multi satellite approach. Chlorophyll-a (Chl-a) concentration (0.5 mg/m3) increased with preceded by cooling (3.8°C) at the right ride of the track after the passage of cyclones. This is mainly due to the nutrient increase from vertical mixing and upwelling. The Chl-a enrichment is more during cyclone 01B compared with cyclone 02B, because of their intensities and movement.

Characteristics of recent dust storms over the Indian region using real time multi-satellite observations from the direct broadcast receiving system at IMD

In this study, observations from microwave satellites, visible and infrared instruments have been analyzed to detect dust storm over north and north–west part of India during 18–23 March 2012. This study investigated the approach to utilize the multi satellite data of Moderate Resolution Imaging Spectroradiometer (MODIS) on-board the Terra and Aqua satellite and the Advanced Microwave Sounding Unit (AMSU) on-board NOAA satellite to study the characteristics of dust storms from real time direct broadcast (DB) receiving system installed at three places of India Meteorological Department (IMD). The dust storm detection is based on the infrared brightness temperature (BT) difference between channels at 11 and 12μm and polarized BT difference between two channels of 89 and 23.8GHz. It is found that the significant differences between the BT of channel 89 and 23.8 can be used as a discriminator of identifying dust storm. The Total Ozone Mapping Spectroradiometer (TOMS) Aerosol Index (AI) and AMSU-A 23GHz channel BT from NOAA satellite over the north and north-west part of India have also been analyzed. The result indicated the characteristic behavior between BT and AI during the different phases of the dust storm. Finally, the occurrence of dust outbreaks has also been validated with sky radiometer of IMD, which confirms the presence of a dust storm over the Indian region. Further, the findings of the study and its approaches apply to the other dust storm cases which occurred during the months of April and June 2012. The integrated approach suggested the potential to use high resolution data of microwave as well as thermal–infrared using multi-satellite observations from real time direct broadcast system for the detection of severe, moderate or weak dust storms very well. The approach is found to be promising for operational application.

Detecting of Arasbaran Forest Changes Applying Image Processing Procedures and GIS Techniques

Nowadays, based on remote sensing procedure, satellite multi- temporal and multi- sensor images for change detection purposes are considered very important issues in optimal management of environmental and ecological resources. In the current study, some different image processing techniques have been accordingly applied in order to determine the rate of forest alterations in Arasbaran protected area. The study area is located in the Northwest of Iran and has been announced to be a component biosphere resource because of its unique fauna and flora by UNISCO organization in 1976. To achieve the main purpose of the study, all existing series of multi-satellite images, observed in years 1987, 1998, 2001, and 2005, have been steadily evaluated using ERDAS Imagine software to model the trend of forest changes in the region. According to the initial results, about 6146.9 hectares of the study area have been deforested throughout the past 18 years. Therefore, a logistic regression model was established among different environmental parameters (such as: distance to settlements, aspect, slope, rainfall, and elevation) to find the main causes of deforestation in the region. Different digital maps, which were created in a GIS setting, reveal that all above mentioned physiographic factors could affect the rate of deforestation in the area, but the distance from the settlements must be regarded as the most effective one. At the final stage, to predict the future trend of deforestation, an endangered map was produced, classifying the existing forests into three major categories such as: extra critical, critical, and vulnerable areas. All valuable results found by the current research could be documented in preventing procedure of the Arasbaran threatened woodlands in future environmental informatics management strategy.

Comparison of GPCP Monthly and Daily Precipitation Estimates with High-Latitude Gauge Observations

Abstract Monthly and daily products of the Global Precipitation Climatology Project (GPCP) are evaluated through a comparison with Finnish Meteorological Institute (FMI) gauge observations for the period January 1995–December 2007 to assess the quality of the GPCP estimates at high latitudes. At the monthly scale both the final GPCP combination satellite–gauge (SG) product is evaluated, along with the satellite-only multisatellite (MS) product. The GPCP daily product is scaled to sum to the monthly product, so it implicitly contains monthly-scale gauge influence, although it contains no daily gauge information. As expected, the monthly SG product agrees well with the FMI observations because of the inclusion of limited gauge information. Over the entire analysis period the SG estimates are biased low by 6% when the same wind-loss adjustment is applied to the FMI gauges as is used in the SG analysis. The interannual anomaly correlation is about 0.9. The satellite-only MS product has a lesser, but still reasonably good, interannual correlation (∼0.6) while retaining a similar bias due to the use of a climatological bias adjustment. These results indicate the value of using even a few gauges in the analysis and provide an estimate of the correlation error to be expected in the SG analysis over ocean and remote land areas where gauges are absent. The daily GPCP precipitation estimates compare reasonably well at the 1° latitude × 2° longitude scale with the FMI gauge observations in the summer with a correlation of 0.55, but less so in the winter with a correlation of 0.45. Correlations increase somewhat when larger areas and multiday periods are analyzed. The day-to-day occurrence of precipitation is captured fairly well by the GPCP estimates, but the corresponding precipitation event amounts tend to show wide variability. The results of this study indicate that the GPCP monthly and daily fields are useful for meteorological and hydrological studies but that there is significant room for improvement of satellite retrievals and analysis techniques in this region. It is hoped that the research here provides a framework for future high-latitude assessment efforts such as those that will be necessary for the upcoming satellite-based Global Precipitation Measurement (GPM) mission.

자동 궤도운용 시스템 개발

본 논문에서는 자동으로 궤도를 결정하고, 신뢰성을 판정한 후 임무계획, 위성추적, 위성위치 표시에 사용하도록 갱신하며, 안테나 추적을 위해 필요한 여러 가지 형태의 궤도데이터 파일을 생성하는 ‘자동 궤도운용 시스템 (KGS automated Operational Orbit Processing System, KOOPS)'의 개발 내용 및 실제 운용 결과를 기술하였다. 개발된 본 시스템은 다양한 형태의 궤도추적 데이터를 처리할 수 있으며, 각 위성 시스템에 따라 필요한 다양한 전처리 및 후처리 프로세스들을 각 위성 별로 개별적으로 설정할 수 있기 때문에 여러 기의 서로 다른 임무를 가진 “다중, 복합” 위성 궤도운용 시스템으로 적용이 가능하다. 아리랑 1호 및 아리랑 2호의 추적 및 임무계획을 위한 비행역학 시스템으로써 적용되어 운용한 결과, 임무운용의 효율성 및 안정성을 크게 높이고, 인력 소요를 대폭 줄이는 효과를 얻을 수 있었다. 본 시스템의 개발 과정과 실제 적용을 통해 얻은 경험은 향후 보다 효율적이고 자동화된 “통합지향형 범용” 비행역학 시스템 개발에 직접 활용될 수 있을 것으로 사료된다. This paper describes the development of an automated operational orbit processing system (KGS automated Operational Orbit Processing System, KOOPS), which can determine, evaluate, update, and generate the orbit data automatically. Developed system can be applied to the multi satellite mission operations as a generic satellite orbit processing system in that the KOOPS has a capability to process various kinds of tracking data and assign pre and post processes according to the satellite system respectively. Results of applying the KOOPS to the KOMPSAT-1 and KOMPSAT-2 mission operations show that man power is greatly reduced and the efficiency and stability of the mission operations are significantly increased. The experiences to develop the KOOPS and operate multi satellite missions using this system can be applied to enhance the multi and generic flight dynamics system further.

Outer loop power control in CDMA satellite systems with on-board power constraints

This paper aims at clarifying the role of the outer loop power control for CDMA satellite systems with on-board power constraints. If the inner loop of the power control is perfect, the channel turns into a AWGN channel and there is no need of the outer loop. In satellite CDMA systems, due to the longer propagation delay with respect to a terrestrial system, the inner loop of power control is only partly able to track power variations due to fast fading. Moreover, the Rice factor, which characterizes the channel statistics, can widely vary even if the user does not move but just because of the change of the elevation angle. Because of that, a wide range of target SNIR (and larger than in typical terrestrial systems) may be necessary to get the same BER performance. Therefore, the outer loop power control turns out to be essential to minimize the dynamic of the power link margins and avoid capacity degradations induced by the systematic use of static link margins. A semi-analytical model for the capacity evaluation has been developed, which is specifically intended for the power-limited satellite-to-mobile link with multi satellite reception. We found that the capacity gain with respect to a pure SNIR-based strategy (i.e., only inner loop) can reach the 40% of the total capacity in a single reception scheme. A smaller, but still noticeable capacity gain of the order of 20 - 30% is observed in presence of satellite diversity. Therefore, any dimensioning of CDMA satellite systems should not neglect this component of the power control.

Outer loop power control in CDMA systems with on-board power constraints

This paper aims at clarifying the role of the outer loop power control for CDMA satellite systems with on-board power constraints. If the inner loop of the power control is perfect, the channel turns into a AWGN channel and there is no need of the outer loop. In satellite CDMA sytsems, due to the longer propagation delay with respect to a terrestrial system, the inner loop of power control is only partly able to track power variations due to fast fading. Moreover, the Rice factor, which characterizes the channel statistics, can widely vary even if the user does not move but just because of the change of the elevation angle. Because of that, a wide range of target SNIR (and larger than in typical terrestrial systems) may be necessary to get the same BER performance. Therefore, the outer loop power control turns out to be essential to minimize the dynamic of the power link margins and avoid capacity degradations induced by the systematic use of static link margins. A semi-analytical model for the capacity evaluation has been developed, which is specifically intended for the power-limited satellite-to-mobile link with multi satellite reception. We found that the capacity gain with respect to pure SNIR-based strategy (i.e. only inner loop) can reach the 40% of the total capacity in a single reception scheme. A smaller, but still noticeable capacity gain of the order of 20-30% is observed in the presence of satellite diversity. Therefore, any dimensioning of CDMA satellite systems should neglet this component of the power control.

Remote Sensing Research Priorities in Tropical Dry Forest Environments

ABSTRACTSatellite multi– and hyper‐spectral sensors have evolved over the past three decades into powerful monitoring tools for ecosystem processes. Research in temperate environments, however, has tended to keep pace with new remote sensing technologies more so than in tropical environments. Here, we identify what we consider to be three priority areas for remote sensing research in Neotropical dry forests. The first priority is the use of improved sensor capabilities, which should allow for better characterization of tropical secondary forests than has been achieved. Secondary forests are of key interest due to their potential for sequestering carbon in relatively short periods of time. The second priority is the need to characterize leaf area index (LAI) and other biophysical variables by means of bidirectional reflectance function models. These biophysical parameters have importance linkages with net primary productivity and may be estimated through remote sensing. The third priority is to identify tree species using hyper‐spectral imagery, which represents an entirely new area of research for tropical forests that could have powerful applications in biodiversity conservation.RESUMENEn las últimas tres decadas, los sensores satelitales multi e hiper‐espectrales han evolucionado hasta convertirse en importantes herramientas para el monitoreo de los ecosistemas. La investigación en los ecosistemas templados y boreales ha seguido el paso de los avances en los sistemas de percepción remota, mientras que en los sistemas tropicales existe un desface significative. En este articulo identificamos y revisamos tres prioridades básicas en la investigación basada en sensores remotos de las regiones neotropicales del bosque seco. Estas prioridades están relacionadas con el monitoreo de bosques secundarios, el desarrollo de estudios relacionados con la cuantificación del área foliar por médio de métodos ópticos y finalmente el desarrollo de técnicas, que ligadas a información hiper‐espectral, puedan ser utilizadas para la identificación de especies de árboles en zonas tropicales. Esta última prioridad representa una nueva área de investigación en los bosques tropicales con importantes connotaciones para la conservación de la biodiversidad boilógica.

Investigations of the hot plasma pressure gradients and the configuration of magnetospheric currents from interball

One of the main aspects of the multi satellite INTERBALL program is connected with the experimental determination of the hot plasma pressure distribution inside the magnetosphere and the solution of the well known problem of the inner magnetosphere substorm onset. The main results of the experimental observations, the structure of high latitude currents and the modeling of the magnetospheric processes are discussed. Observations of particles in a wide energy range from tens of eV to Mev energies give the possibility to construct the full distribution function and to calculate plasma pressure. Quiet time plasma pressure profiles show the regularity and the increase of the pressure with the decrease of the geocentric distance. The observed region of plasma pressure plateau means the existence of nearly zero transverse and field-aligned current regions. The existence of such a region gives the possibility to explain the observed gap between Region 1 and Region 2 currents. Investigations of the fluctuations of the plasma bulk velocity inside the plasma sheet support the existence of plasma sheet turbulence. The existence of plasma sheet turbulence explains the inner magnetosphere substorm onset as only stable before substorm plasma region can become unstable. The introduction of the turbulent transport in the model of the plasma sheet and the theory of the plasma sheet with medium-scale turbulence are discussed

Monitoring of vegetation growth along Wadi Al-Rumah, KSA using C-band of Radarsat, L-band of JERS-1 and comparison with LandsatTM data

Synoptic interpretation using multi sensor data — this is the keywork applied to our research to understand deeply the phenomena on the Earth surface. Many approaches so far included the digital method using the single sensor data with the mathematical evaluation, and those were believed to be the best to define the ground phenomena, so first we would like to know what is the synoptic view of the Earth surface from various aspects. From this point of view, we intensify the synoptic interpretation with multi satellite sensor data and multi ground based investigation phenomena. Actual target of the study is to understand the time-sequential variation of the vegetation growth along Wadi Al-Rumah area. One-month observation images by Radarsat and Landsat/TM show the growing stages of the wheat and the alfalfa. JERS-1/SAR data indicates the location of the forest of date. In Saudi Arabia, the date is the most important tree from ancient times, also in our test domain, the detection of date trees is essentially important.

Statistical Angle-of-arrival and Doppler Method for GPS radio interferometry of TIDs

Abstract A Statistical Angle-of-arrival and Doppler Method for GPS radio interferometry (SADM-GPS) is proposed for determining the characteristics of the Travelling Ionospheric Disturbances (TIDs) by measuring variations of GPS phase derivatives with respect to time and spatial coordinates. These data are used to calculate corresponding values of the velocity vector, in view of a correction for satellite motion based on current information available regarding the angular coordinates of the satellites. Through a computer simulation it was shown that multi satellite GPS radio interferometry in conjunction with the SADM-GPS algorithm allows for detecting and measuring the velocity vector of TIDs in virtually the entire azimuthal range of possible TID propagation directions.

A global high resolution mean sea surface from multi mission satellite altimetry

Satellite altimetry from the GEOSAT and the ERS-1 geodetic missions provide altimeter data with a very dense coverage. Hence, the heights of the sea surface may be recovered very detailed. Satellite altimetry from the 35 days repeat cycle mission of the ERS satellites and, especially, from the 10 days repeat cycle TOPEX/POSEIDON satellite mission provide repeated height observations, so that the mean sea surface heights along the ground tracks can be recovered very accurately. In this study a global high resolution mean sea surface (18 by 18 degrees) is constructed using satellite altimetry from those four missions. The mean sea surface fits the TOPEX/POSEIDON mean sea surface heights within 5 cm and the slopes fit within 2.5 mm per km.

The use of 3-D mapping in geological research and risks analysis: evaluation of a water supply project in the Kathmandu-Melamchi Area

Using 2-D and 3-D multi satellite data (SPOT and LANDSAT TM) in a GIS allows us to produce 3-D digital elevation maps (DEM) through the techniques of remote sensing (RS) analysis and computer aided mapping. In the field of geotechnical research, since 1992, some works have been made in cooperation with ICIMOD-MENRIS, the department of Mines and Geology in Nepal, and the bilateral cooperation from both France and Germany. The use of 2-D and 3-D digital maps to geological and geotechnical research and risks analysis, concerns here the evaluation of the new water supply project Kathmandu-Melamchi proposed by WHO-UNDP and the World Bank.

Combined spectral and spatial processing of ERTS imagery data

In addition to spectral features, texture is an important spatial feature used in identifying objects or regions of interest in an image. Although texture is relatively easy for human observers to recognize and describe in empirical terms, it has been extremely refractory to precise definition and analysis by digital computers. This paper describes a procedure for extracting some easily computable features for the texture of blocks of digital image data and illustrates the applications of combined textural (spatial) and spectral features for identifying the land use categories of blocks of ERTS MSS (Earth Resources Technology Satellite Multi Spectral Scanner) data. The land use classification algorithm based on textural and spectral features was developed and tested using 614 image blocks of 64 × 64 resolution cells derived from an ERTS image over the Monterrey Bay area of the California coast line. The algorithm was applied on a training set of 314 blocks and tested on a set of 310 blocks. The overall accuracy of the classifier was found to be 83.5% on seven land use categories.