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.     

Ocean circulation studies in the vicinity of Southern Africa: Preliminary results using FGGE drifters and remote sensing

The three highly variable ocean circulation systems which meet south of South Africa have been studied by combining the use of satellite thermal infra-red imagery, hydrographic measurements and drifting buoys. We present a few preliminary examples where this method has been successful. These include the sources of the Agulhas Current, the influence of the Agulhas Current on the Cape upwelling region as well as the interaction of the Agulhas Current with the Subtropical Convergence. An example is also given of how a biological hypothesis concerning the recruitment of a rock lobster species at Vema Seamount has been supported by the analysis of the drifts of FGGE buoys in the South Atlantic Ocean.     

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.     

Nonlinear mixture model of mixed pixels in remote sensing satellite images based on Monte Carlo simulation

A nonlinear mixture model for the interpretation of mixed pixels in remote sensing satellite images is proposed. The proposed model is a Monte Carlo ray-tracing model that takes into account interactions among the ground cover materials (multiple reflections among the materials on the surface). The proposed model also takes into account topographic features (slope) of the ground surface. As an example, Top of the Atmosphere (TOA) radiance of mixed pixels of forested areas which are composed of grasses and trees are simulated with the proposed model and compared to actual remote sensing satellite data of ASTER/VNIR over these forested areas. It was found that the influence due to multiple scattering interactions between trees depends on the tree distance and ranges from 8% to 10%. It is also found that the proposed model is useful to interpret mixed pixels. Namely, it is suggested that actual reflectance of the trees is higher than apparent reflectance that is calculated with the satellite data. Also it is suggested that it is possible to estimate forest parameters such as tree distance, tree shape.     

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.     

Spatial and temporal monitoring of drought conditions using the satellite rainfall estimates and remote sensing optical and thermal measurements

Drought is an important natural disaster that causes devastating impacts on the ecosystem, livestock, environment, and society. So far, various remote-sensing methods have been developed to estimate drought conditions, each of which has advantages and restrictions. This study aims to monitor the real-time drought indices at the field scales via the integration of various earth observations. Our proposed method consists of two steps. In the first step, the relationships between long-term standardized precipitation indices (SPI) derived from PERSIANN-CDR rainfall data and two drought-dependent parameters derived from MODIS products, including normalized NDVI and soil-air temperature gradient, are obtained at the spatial resolution of PERSIANN-CDR grid (approximately 25 km). As the next step, the corresponding relationships are applied to estimate the drought index maps at the spatial resolution of MODIS products (1 km). Numerous analyses are carried out to evaluate the proposed method. The results revealed that, from various drought indices, including SPIs of different timescales (1, 3, 6, and 12-months), SPI-3 and SPI-6 are more appropriate to the proposed method in terms of correlation with temperature and vegetation parameters. The findings also demonstrate the competency of the proposed method in estimating SPI indices with average RMSE 0.67 and the average correlation coefficient of 0.74.     

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.     

Image restoration of the asymmetric point spread function of a high-resolution remote sensing satellite with time-delayed integration

The calibration and validation team of the Korea Aerospace Research Institute has calibrated and validated the image data of the KOMPSAT-2 since the launch of KOMPSAT-2 on July 28, 2006. The asymmetric phenomenon of the point spread function of the KOMPSAT-2 image data is evident in both the along and the across direction, most likely because KOMPSAT-2 has a 1 m ground sample distance high-resolution camera with time-delayed integration. Furthermore, because KOMPSAT-2 is in space, the KOMPSAT-2 image data has been corrected with good results by means of modulation transfer function compensation.     

Robust extension of the simple sea-surface irradiance model to handle cloudy conditions for the global ocean using satellite remote sensing data

Sea-surface solar radiation (abbreviated as photosynthetically available radiation, PAR) in the visible wavelength (400–700 nm) is an essential parameter to estimate marine primary productivity and understanding phytoplankton dynamics, upper ocean physics and biogeochemical processes. Although many remote-sensing models were developed to estimate daily PAR (DPAR) from ocean colour data, these models often produce biases in the DPAR products under cloudy-sky and complex atmospheric conditions due to the lack of parameterization to deal with the cloud cover conditions and insufficient in-situ DPAR data. This study presents an Extended Sea-surface Solar Irradiance Model (ESSIM) for estimating DPAR over the global ocean. The ESSIM uses the direct and diffuse components from the Simple sea-surface Solar Irradiance Model (SSIM) along with a new parameter to handle cloudy conditions. The ESSIM produced DPAR products with greater accuracy under both clear and cloudy conditions. Its performance was tested on the time-series MODIS-Aqua images and compared with the concurrent in-situ data and the results from two global models. Results showed that the DPAR values produced by ESSIM agree with in-situ data better than the global models for all-sky conditions (with a mean relative error of 11.267 %; a root mean square error of 5.563 Em^?2day^?1; and a mean net bias of 2.917 Em^?2day^?1). The ESSIM performed slightly better than the SSIM for clear conditions and the Frouin's Operational Algorithm (FOA) for all-sky conditions. As the new parameterization accounts for cloudy conditions, the ESSIM produced more accurate results for cloud cover conditions across latitudes (up to 60°). The time-series Level-3 binned MODIS-Aqua data (global gridded) also demonstrated that the ESSIM improved the accuracy of DPAR products and produced spatially and temporally consistent DPAR products over the global ocean regardless of the seasons and sky conditions.     

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.     

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.     

Different atmospheric effects in remote sensing of uniform and nonuniform surfaces

The atmospheric effect on the radiance of sunlight scattered from the Earth-atmosphere system is greatly dependent on the surface reflectance pattern, the contrast between adjacent fields, and the optical properties of the atmosphere. In addition, the atmospheric effect is described by the range and magnitude of the adjacency effects, the atmospheric modulation transfer function, and the apparent spatial resolution of remotely sensed imagery. This paper discusses the atmospheric effect on classification of surface features and shows that surface nonuniformity can be used for developing procedures to remove the atmospheric effect from the satellite imagery.     

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.     

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.     

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.     

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.     

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.     

Using the MIR bands in vegetation indices for the estimation of grassland biophysical parameters from satellite remote sensing in the Alps region of Trentino (Italy)

Development of new methods for estimating biophysical parameters can be considered one of the most important targets for the improvement of grassland parameters estimation at full canopy cover. In fact, accurate assessment methods of biophysical characteristics of vegetation are needed in order to avoid the uncertainties of carbon terrestrial sinks.

Remote sensing is a valid tool for scaling up ecosystem measurements towards landscape levels serving a wide range of applications, many of them being related to carbon-cycle models. The aim of this study was to test the suitability of satellite platform sensors in estimating grassland biophysical parameters such as LAI, biomass, phytomass, and Green herbage ratio (GR). Also, we wanted to compare some of the most common NIR and red/green-based vegetation indices with ones that also make use of the MIR band, in relation to their ability to predict grassland biophysical parameters.

Ground-truth measurements were taken on July 2003 and 2004 on the Monte Bondone plateau (Italian Alps, Trento district) in grasslands varying in land use and management intensities. From satellite platforms, an IRS-1C-LISS III image (18/07/2003; 25 m resolution in the visible-NIR and 70 m resolution in the MIR) and a SPOT 5 image (27/07/2004, 10 m resolution in the visible-NIR and MIR) were used.

LAI, biomass, and phytomass measurements showed logarithmic relationships with the investigated NIR and red/green-based indices. GreenNDVI showed the highest R² values (0.59, IRS 2003; 0.60, SPOT 2004). Index saturation occurred above approximately 100–150 g m⁻² of biomass (LAI 1.5–2). On the other hand, GR relationships were shown to be linear. MIR-based indices performed better than NIR and red/green-based ones in estimating biophysical variables, with no saturation effect. Biomass showed a linear regression with Canopy Index (MIR/green ratio) and with the Normalised Canopy Index (NCI) calculated as a normalised difference between MIR and green bands (IRS: R² = 0.91 and 0.90, respectively. SPOT: R² = 0.63 and 0.64). Similar correlations could also be found for LAI and phytomass, and GR predictability was shown to be higher than NDVI and GreenNDVI. According to these results obtained in the investigated areas, phytomass, biomass, LAI, and GR are linearly correlated with the investigated MIR band indices and as a result, these parameters could be estimated from the adopted satellite platforms with limited saturation problems.     

Building capacity in the basic space sciences in Southern Africa: Experiences and prospects

The basic space sciences and their supporting technologies underpin the ability of a country to utilise space applications programmes for development. By whatever measure is employed, Africa is under-represented in the international space science community. This paper reviews lessons learnt over the past 8 years with regard to sustainable capacity building in the region. At present there are a number of role-players in the space arena engaged in various capacity-building initiatives. We advocate that the emphasis of these initiatives should shift from fairly isolated capacity-building activities to comprehensive regional capacity-building programmes developed jointly by the different role-players. In order to develop such coordinated programmes, the establishment of a capacity-building forum involving the space community, the development sector and the developing countries in a region, is proposed.