Dielectric properties and microwave remote sensing

The importance of the dielectric properties of earth, ocean and snow surfaces in microwave remote sensing is reviewed. Data on dielectric properties of materials in the microwave frequency range are very scarce and their behaviour is not fully understood. In this paper the need for dielectric properties of ocean and snow surfaces, the earth's surface and subsurface materials is discussed for the quantitative and qualitative interpretation of microwave remote sensing data of developing countries.     

The characterization of atmospheric spread functions affecting satellite remote sensing of the earth's surface

A Monte Carlo simulation program has been used to compute the signal contribution of surface elements outside the field of view of a satellite borne sensor in both the visible and infrared spectra for realistic atmospheric models. For azimuthally symmetric reflection the effect of an arbitrary surface albedo pattern can be represented by two spread functions, namely, 1) the ground-satellite spread function, and 2) the ground-ground spread function. Examples of computed spread functions are shown together with their Fourier correspondents, the modulation transfer functions. It has been shown that the central portions of the line spread functions behave as the inverse distance while the point spread functions always possess a region behaving as the inverse square of the radial distance. The median distance is shown to relate to the weighted molecular and aerosol scale height, and for large distances the spread functions become independent of the aerosol loading.     

Training opportunities in remote sensing in India

The paper deals with the Indian experience in training the resources scientists in the fast developing field of remote sensing and the facilities available for obtaining such training in India. The necessity of imparting training to the scientists at different levels is brought out. An outline of the training curriculum of a leading institution is described in some detail.     

Photopolarimetric sensing of planetary surfaces

Polarization measurements over the surfaces of the Moon, Mercury, Mars and Saturn's rings, and global data for the Galilean satellites, have been recorded with telescopes in France. A number of asteroids were measured by B. Zellner in USA. The curves of polarization are diagnostic of the micro-texture of the surface, and demonstrate that all the atmosphereless Solar System objects so far observed (except Callisto trailing hemisphere) have their surfaces covered with a regolith of fines, as for the Moon, which is produced by the cumulative effect of meteoroid impacts. For all the silicaceous objects down to a diameter of 700 km, namely Mars, Mercury, the Moon, Callisto (for the apex hemisphere), the mean grain sizes are no larger than 20um. The asteroids have coarser grained regoliths, apparently because of their smaller gravitational escape velocities. The C type asteroid surfaces, assumed to be carbon rich, appear finer grained than the silicaceous S types. The M astereroids assumed to be metallic, are also covered with small fragments, becuase metals loose their ductile properties at low temperature and behave at impact like brittle silicates. The trailing hemisphere of Callisto has a texture almost reminiscent of bare rocks. Orbital considerations to excluse significant impact effects, and a scenario for the past evolution of the satellite are implied.The planet Mars, with wind effects due to a tenuous atmosphere, several intense past volcanic episodes, a high tectonic activity and a permafrost underground has a more diversified surface regolith. A detailed analysis was achieved with photopolarimeters placed on board the soviet Mars Orbiter Spacecraft MARS-5.The Saturn's rings, anisotropic multiple scattering effects are observed and exhibit variations often in few days or weeks. Mutual interactions and gravitational forces are at work to produce organized structures, whereas disorganization forces occur and the competition produced ephemeral situations.     

Determination of reconnected flux via remote sensing

Magnetic reconnection is one of the most fundamental processes in the magnetosphere. We present here a simple method to determine the essential parameters of reconnection such as reconnected flux and location of the reconnection site out of single spacecraft data via remote sensing. On the basis of a time-dependent reconnection model, the dependence of the reconnected flux on the magnetic field z-component B_z is shown. The integral of B_z over time is proportional to the reconnected flux and depends on the distance between the reconnection site and the actual position where B_z is measured. This distance can be estimated from analysis of magnetic field B_z data. We apply our method to Cluster measurements in the Earth’s magnetotail.     

The use of remote sensing in global biosystem studies

Remote sensing techniques, if properly employed, offer definite advantages to studies of the Earth's environment and resources on a global scale. A remote sensing strategy is presented for selective sampling of the properties and changes in the atmosphere, the oceans and on land in support of global biosystems research as proposed by NASA, including mineral cycling, ocean and terrestrial productivity, perturbation effects and biospheric responses. It is shown that remote sensors on satellites and aircraft should be used to update existing data bases and to monitor areas of high productivity or rapid change, rather than attempting to produce a costly inventory of all biosphere resources and processes.     

Passive remote sensing of aerosols from space now and in the future

Aerosols modify scattered solar radiation leaving the atmosphere and this fact will be exploited to determine the aerosol optical depth. The interaction processes between solar radiation and aerosol particles are outlined. A quasi-linear relationship (‘conversion curves’) between the radiance at the satellite, L_sat, and the aerosol optical depth, a_Dλ, is found from both numerical and empirical studies. Because L_sat is not only controlled by a_Dλ, but also by a series of other atmospheric parameters (perturbing quantities), the concept of ‘favourable viewing conditions’ is presented, where the effects of the perturbing quantities are minimal. The paper ends with some lines of thought on a concept for a turbidity satellite.     

Responses to satellite remote sensing opportunities in East and Southern Africa

Since 1978 the U.S. Agency for International Development (USAID) has funded a regional remote sensing project for East and Southern Africa. The project, hosted by the Regional Centre for Services in Surveying Mapping and Remote Sensing, has provided a programme of training courses, user services and project support. This included the equipping and establishment of a photo-laboratory complex for processing Landsat images and the provision of advice and support for agencies undertaking natural resources analysis.Response to the training programme has been very good. Courses are usually over subscribed and there is a continued demand for training. Assessments of the courses by participants are highly positive and the courses have featured consultants of international calibre. Requests for follow-up courses, and for specialist group training indicate a strong response to this training activity. User services are active, consultations with staff, use of the browse file and interpretation equipment and the purchase of data for project work all produce an average demand of 12 active enquiries per working week. The photo-laboratory is particularly active and demand for products exceeds available capacity.Project work is now being supported but limited resources restrict the range and amount of project activity. Response to the opportunities offered for projects has been favourable and this activity is ripe for expansion. The difficulty in expanding to meet the expressed demand is primarily financial. The east and southern Africa region is not economically strong and has a great need for natural resources data for development work and planning. The responses to satellite remote sensing opportunities will be limited by these financial constraints which effectively means by the level of international aid directed to this activity. For such aid to be effective it must be coordinated and firmly attached to the region. Such coordinated aid programmes would avoid fragmentation of distribution and applications work. Fragmentation could seriously disrupt the present growth in natural resources activity based on remote sensing data from satellites. The lack of financing for a regional ground receiving station is also a significant limiting factor.     

GNSS reflectometry and remote sensing: New objectives and results

The Global Navigation Satellite System (GNSS) has been a very powerful and important contributor to all scientific questions related to precise positioning on Earth’s surface, particularly as a mature technique in geodesy and geosciences. With the development of GNSS as a satellite microwave (L-band) technique, more and wider applications and new potentials are explored and utilized. The versatile and available GNSS signals can image the Earth’s surface environments as a new, highly precise, continuous, all-weather and near-real-time remote sensing tool. The refracted signals from GNSS radio occultation satellites together with ground GNSS observations can provide the high-resolution tropospheric water vapor, temperature and pressure, tropopause parameters and ionospheric total electron content (TEC) and electron density profile as well. The GNSS reflected signals from the ocean and land surface could determine the ocean height, wind speed and wind direction of ocean surface, soil moisture, ice and snow thickness. In this paper, GNSS remote sensing applications in the atmosphere, oceans, land and hydrology are presented as well as new objectives and results discussed.     

A decade of remote sensing in India — Some salient results

Remote sensing activities in India over the past decade are briefly described in the paper; some important application areas are explained. Some results are highlighted. Activities in India for building remote sensing spacecraft, sensors and ground segment are summarised. Some facilities in India for remote sensing applications including low cost interpretative equipment developed are described. The paper also outlines the Indian Remote Sensing Satellite (IRS) series, the first of which is presently under development for launch in 1986 and the National Natural Resources Management System (NNRMS) under evolution.     

Low cost training in remote sensing applications for developing countries

This presentation introduces the Polish Remote Sensing Centre /OPOLiS/, which offers various types of training possibilities in remote sensing techniques and applications. It deals with a wide range of applications and experiences reached by OPOLiS for various branches of national economy, as well as introduction to analog and digital satellite data processing possibilities with the existing equipment.The offered training possibilities include analog and digital data handling and its interpretation such as visual and computer assisted integration of multiple data sets, as well as image processing, enhancements, mosaics etc.It also includes training and applications of interpretations results for exploration of minerals, energy, and ground water resources, as well as inventories, monitoring and forecasting for agriculture, forest, and natural environmental purposes.The cost factor of the offered training possibilities includes a reasonable input from the Polish Government, which results in low cost input by the participants from developing countries. It also accepts the participation fee in non - convertible currency.     

The application of remote sensing techniques to regional geological survey in China

Information is provided on the applications of remote sensing to regional geological survey and mapping on medium and small scale over recent years in China. The work began from establishing interpretation key for strata, magmatic rocks and regional structures. Preliminary results have been obtained. It is explained through case histories in Sichuan Province and Xinjiang Uygur Autonomous Region. By means of remote sensing the time of compilation has been shortened and the cost was reduced, the accuracy and quality of geological maps was improved, and abundant basic geological data were provided for exploration. In addition, prediction of various ore targets were defined along with new ideas for geological scientific research.     

Remote sensing of the atmospheric from scientific stations “Salyut”

A review of the four-channel teleradiometer “Micron” calibration and data processing techniques has been presented. The sensor validation of the space-borne teleradiometer “Micron” was based on the following: the preflight absolute calibration with the state certificated standard, the secondary onboard standard (miniature filament lamp), the inflight measurements of the Moon's brightness. The procedure of the extinction coefficient determination from the daytime horizon profiles has been developed. The validity of the used techniques was estimated by carring out model calculations. An optimal measuring procedure has been recommended. The proposed simple techniques are used for processing the space measured horizon brightness data. The results have been compared with the earlier published ones.     

Selected examples of profitable applications of remote sensing for resources inventories and monitoring

The Remote Sensing Centre of the Institute of Geodesy and Cartography in Warsaw has been operating since 1976. It has multi-disciplinary character; carries out scientific research, elaborates technologies of remote sensing investigations, applies remote sensing methods for solving various practical problems, coordinates national activities in this field, developes and disseminates remote sensing knowledge at both national and international levels offering various types of specialized training.The authors discuss the role of remote sensing investigations in the process of development planning. Examples of projects executed at the Remote Sensing Centre and concerning topographic and land use mapping, geological investigations, agricultural crop area determination, forest research, environmental monitoring and studies of climatic conditions in urban environment are described and extensively discussed in the paper. The authors emphasize these areas of the application of remote sensing and these interpretation techniques which are of potential interest for the developing countries.     

Feasibility study of ocean color remote sensing for detecting ballast water

The paper describes the feasibility of ballast water detection with SeaWiFS-derived diffuse attenuation coefficients and the corresponding number of in situ plankton cell density along the ship’s routes. Onboard sampling of the ballast water have been carried out by the LNG carrier of 110,000 gross tons during the six cruises between Japan and Qatar from May 2002 to July 2003. SeaWiFS images of the ballast water exchange areas along the ship’s route were acquired and processed by using SeaDAS. Based on the plankton analysis of the sampled ballast water, phytoplankton and zooplankton species were identified and their numbers of cell were counted for each ballast water exchange. It is found out that the observed cell density is highly correlated with the corresponding SeaWiFS-derived diffuse attenuation coefficient at 490 nm (K(490)). By using this correlation the criterion of 10 cells/ml imposed by IMO regulations corresponds to 0.24 m⁻¹ of K(490). It is expected that this value of K(490) will be the criterion of future satellite-based ballast water quality standard.     

Estimation of stress and its use in evaluation of landslide prone regions using remote sensing data

Recently, use of remote sensing data for determining the orientation of stress has been demonstrated. The present study deals with the estimation of stress pattern in the part of the Himalayan region which shows the ongoing neo-tectonic activities. The study area falls into a tectonically active zone of the Central-Himalaya, with a complex geotectonic set-up confined by a number of faults. Efforts have been made to evaluate the technique as a fast algorithm for quick and time limited analysis of linear feature from which the orientation of the lineaments are estimated by using remote sensing data. Further, the estimation of stress and the lineament analysis have been used in mapping of landslide prone areas. Terrain information such as land cover, geology, lineament, faults, mega faults, geomorphology and drainage has been derived from the satellite imageries, and the existing thematic information has been updated to enable the quantification of landslide causative parameters. Spatial and temporal multi-layered information have been used for landslides hazard susceptibility analysis. The qualitative hazard analysis has been carried out using the map overlying techniques in GIS environment along the central part of Himalayan region. It has been observed that the high potential zones have been found to have very high lineament density, moderate to low drainage density and high slope areas of the terrain. On the basis of the geological and morphological analysis, it is further suggested that the combined impacts of the crushed nature of bed rock (due to the neo-tectonic activities), heavy rainfall and lack of vegetation cover cause persistent recurrence of landslides along this region. The role of earthquake on induction of landslides will be presented.     

The role of the society of Latin American specialists on remote sensing (SELPER) in the analysis and actions related to the main advances and needs of spatial remote sensing for Latin America

The existence of SELPER (Sociedad de Especialistas Latinoamericanos en Percepción Remota / Society of Latinamerican Specialists on Remote Sensing) has filled a great gap among latinamerican countries. SELPER was formed in 1980 and several important activities, having international support, have been performed and are planned in the near future. SELPER consolidation will help develop several important regional cooperation programs and the next years look very promisory in this sense. Different steps are planned but the most important is related with the formation of such a Latin American Council on Remote Sensing, having official support from different countries of the region; SELPER can help this important objective. Main advances and needs are summarized in this paper and it is possible to conclude that SELPER will be important for regional and inter-regional scientific and technical cooperation on remote sensing.     

Recent ozone investigations over Bulgaria by remote sensing: Ground-based and satellite data

This presentation deals with the recent investigations of the dynamics of the total ozone content (TOC) and of the lower troposphere ozone over Bulgaria, South-Eastern Europe.     

Selection of spectral bands for Indian remote sensing satellite (IRS)

Indian Space Research Organisation (ISRO) plans to launch a Remote Sensing Satellite around 1985 for acquiring resources information in the visible and near infrared region. For this a number of projects under Joint Experiments Program (JEP) were taken up between ISRO and various departments under Government of India to define the mission parameters including the spectral bands. This paper presents the results obtained in the selection of spectral bands and their widths for IRS program.