ISSN:0143-1161    

DOI:10.1080/01431169608949035

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Daily snow depth data for 284 first-order hydromet stations located in the former Soviet Union have been made available for climatological analysis by the U.S.S.R. State Committee for Hydrometeorology. The data are compared with the snow depth product derived from Scanning Multichannel Microwave Radiometer (SMMR) passive microwave brightness temperatures for the year 1980. Results suggest some discrepancies between the two data sources. Anomalies are considered to emanate from a variety of sources. These may include: (a) problems comparing a point measurement to one averaged over a pixel area; (b) an algorithm bias given deep snow conditions; (c) geographical influences such as elevation and forest cover; and (d) presence of depth hoar.

ISSN:0143-1161    

DOI:10.1080/01431169608949036

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

ERS-1 SAR images have been used to monitor sea ice in the Canadian east coast and the Gulf of St. Lawrence since December 1992. Operational ice parameters were obtained, in near real-time, through visual image analysis. The information was incorporated in standard daily operational products. Further analysis was conducted later to evaluate the data utility. The images are remarkably useful in discriminating between new ice and water and in delineating ice edges. Structural information of ice surface is usually smeared. Distinction between young ice and first-year ice types, based on backscatter alone, is not reliable. Rules for image interpretation were developed. They are mainly based on structural information in images, ancillary data on weather, and recent and historical ice records. Limitations on data utilization are explained in relation to the sensor and orbit parameters. An insight into operational requirements and their relation to SAR observations is presented.

ISSN:0143-1161    

DOI:10.1080/01431169608949037

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

A methodology is developed for the prediction of river discharge and surface water quality (indexed by nitrogen loading) of a predominantly rural catchment using simple models in an integrated Geographical Information System (GIS). River discharge is predicted using the Soil Conservation Service (SCS) runoff Curve Number model, and surface water quality by the export coefficient model. Main input variable to these models is information on land-use along with ancillary information such as soils. Land-use is an important parameter that affects both discharge and water quality, and it can be derived from classification of remotely sensed images. Unlike conventional models, the models employed here do not require large amounts of data on several hydro-meteorological variables. The models are applied to a rural catchment in eastern England where major land-use changes have occurred in the recent past. Historical land-use data are derived from a variety of sources including maps, aerial photographs and remotely sensed satellite images for various dates ranging from 1931 to 1989. A GIS is a valuable means to enable large amounts of spatial data to be integrated, and to facilitate data manipulation for the specific application of the models. Results are validated using observed runoff and water quality records, and it is shown that the model predictions are of acceptable accuracy. This study demonstrated an application of a GIS to employ simple models to predict river discharge and water quality.

ISSN:0143-1161    

DOI:10.1080/01431169608949038

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

A sub-tropical intertidal wetland in Moreton Bay, Queensland, Australia (27°52'S, 153° 23'E) was physically modified in 1985 to manage a mosquito breeding problem. Monitoring before and after modification was done using field and remote sensing techniques. Images from large scale colour infrared aerial photography were analysed to evaluate impacts of the modification. Analysis was by subtracting and classifying digitized images taken before and after modification. The resulting ‘difference type images’ showed the types of change and their nature. These images indicated also the spatial extent of the changes. The site has become wetter as a result of increased tidal flushing, indicated by reduced spectral values. The area modified has changed less than the adjacent mangrove inlet which floods the area. Mangroves have increased in size and spatial extent, with increased spectral values generally. The changes are consistent with reported mangrove changes in other local areas and thus are unlikely to be a direct effect of runnelling.

ISSN:0143-1161    

DOI:10.1080/01431169608949039

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Coastal Zone Color Scanner (CZCS) pigment concentrations, sea surface temperature, and sea level from 1979 through to mid-1986 in the tropical Pacific are examined. The relationships among surface pigment concentration, sea surface temperature and sea level during the El Ni˜o/Southern Oscillation event of 1982-83 exhibit marked zonal variations. Sea level in the western and central Pacific decreased dramatically during the autumn of 1982 with both north-to-south and west-to-east time lags and corresponding increases in pigment concentrations. There was no apparent relationship between sea surface temperature and pigment in the Warm Pool. In contrast, sea surface temperature increases in the eastern Pacific along the Peruvian coast and the Galapagos Islands coincided with pronounced increases in sea level and decreases in surface pigment concentrations. Across the entire basin, pigment variability was linked to sea level height, and, presumably, thermocline depth with an inverse relationship between sea level and pigment occurring on both sides of the Pacific.

ISSN:0143-1161    

DOI:10.1080/01431169608949040

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

On a étudié la possibilité de suivre les mares temporaires du Sahel à l'aide des données au 1·1 km de résolution du Radiom`tre Avancé à Haute Résolution (AVHRR) des satellites de la série NOAA. Vingt et un mares du Niger Occidental titulaires de bonnes données de terrain furent choisis pour cette étude. Les données du Thematic Mapper (TM) de 1988 furent d'abord analysées afin de déterminer les superficies des dits lacs et les différences de température entre l'eau et la terre. Six scènes AVHRR prises pendant la saison séche de 1988-89 ont ensuite été étudiées. Il s'est avéré que dans la plupart des cas il est possible de suivre un lac tant que sa superficie reste supérieure à 10 ha. De plus, quand l'emplacement et la forme du lac sont déjà connus, la superficie du lac peut ˆtre estimée à partir des données de la bande 5 du AVHRR à environ 10ha près. La forte différence de température, d'environ 13°C, entre l'eau et la terre rend possible ce suivi et ces estimations.

ISSN:0143-1161    

DOI:10.1080/01431169608949041

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

In April-December 1989, June 1990 and July-October (1990-92), AVHRR/NOAA scenes from the north-east Atlantic (10-50° N and 0-30° W) and Mediterranean Alboran Sea were processed. The objective was to study the relationships between the upper ocean dynamics (synoptic and mesoscale fronts and vorticity) with skipjack tuna (Katsuwonus pelamisLinnaeus, 1758) and albacore tuna (Thunnus alalungaBonaterre, 1788) fishing ground locations by satellite-derived sea surface temperature (SST) maps and insitudata sets. Results show an analogy between the bioecological responses of both species to the large (SST seasonal drifts) and small-scale oceanographic events (eddy fields, as a consequence of their similar physiological response to all the anomalies at sea.

ISSN:0143-1161    

DOI:10.1080/01431169608949042

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

The sea level variability derived from repeating tracks of the Geosat altimeter data during the late phase (August-September) of the summer monsoon of 1988 revealed the presence of multiple meso-scale eddy features with clockwise and anti-clockwise rotation. During August, the prime eddy or the Great Whirl centred at 9·5° N, 53·5° E off northern Somalia and the southern gyre centred at 3°N, 51·5° E off southern Somalia, both are clearly identified with clockwise rotation. The region of lower sea levels off the central Somalia coast (between 6°N and 9°N) coincides with the cold water wedge formed by the offshore movement of the cold upwelled waters from the Somalia coast during the summer monsoon. By September the southern gyre weakens, while the prime eddy persists. The surface circulation is characterized by nearly meridional flows in the equatorial region. A strong narrow (˜ 100 km) southward jet-like flow is noticed south of 7° N between 53° and 54° E during September. In general, these circulation features are in agreement with the sea surface topography derived from the hydrographic data collected in this region during the same period on board theORV Sagar Kanya.

ISSN:0143-1161    

DOI:10.1080/01431169608949043

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

A relation between near surface level specific humidity (qa) and ERS-1/Along Track Scanning Radiometer's nadir and forward scan observations is proposed on the basis of radiative transfer simulations for tropical atmospheres, The simulation study shows that qacan be estimated within an r.m.s. error of 15 per cent when it is compared with the values derived from ship observations. As a case study analysis, we have applied the relation to an actual ERS-1/ATSR data dated 3 March 1992. The computed near-surface level specific humidity compared well with values derived from simultaneous ship observations and the r.m.s. error was found to be within 15 per cent.

ISSN:0143-1161    

DOI:10.1080/01431169608949044

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor