摘要:

Analyses of mesoscale horizontal distributions of temperature were performed for an area of the North Atlantic using data from the NOAA-7 and NOAA-6 Advanced Very High Resolution Radiometer (AVHRR). The zonal and meridianal variance spectra have.slopes between —1.4 and —2.5 with a clear maximum at -2.0. This is also true for the direction-dependent structure functions. The isotropic part of the variance spectra has a mean slope of —2.2±0.17 at scales of 10— 100km; this lies between the slopes of -1 and —3 predicted by the theories of two-dimensional and geostrophic turbulence. A comparison between measurements and theories is difficult because of the insufficient applicability of these theories to boundary layers. Moreover, in some cases there are significant maxima in the variance spectra at scales between 50 km and 250 km.

ISSN:0143-1161    

DOI:10.1080/01431168908903918

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

A comparison is made betweenin situmeasurements of sea surface temperature (SST) in the north-east Atlantic Ocean, obtained during Cruise 145 of RRSDiscovery, and SSTs derived from several overpasses of the Advanced Very High Resolution Radiometer on the NOAA-7 satellite during the same period in March 1984. The objective of the analysis was to test the ability of the satellite to map the detailed features of SST structure and to examine the performance of atmospheric correction and temperature calibration procedures in this context. Gross comparison between all the cloud-free ship and satellite data confirms agreement normally within 1 degC. More detailed comparison of SST structure along the cruise tracks shows that the satellite data are able to identify features with a resolution of 0.3°C.

ISSN:0143-1161    

DOI:10.1080/01431168908903919

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

A comparison is made between the measurements of sea surface temperature (SST), obtained using an infrared radiometer mounted on a vessel of the British Antarctic Survey, and from a conventional Meteorological Office rubber bucket with mercury thermometer. These measurements are used to investigate the size and variability of the oceanic skin effect from the tropical Atlantic to the waters of Antarctica. The implication of the skin effect on the validation of satellite-borne infrared sensors of the sea surface temperature is also investigated. In terms of the overall average for the complete Atlantic Ocean data set, the skin of the sea is about 0-30 deg K cooler than the bulk at about 10cm below the surface. There are only a few cases of the skin being warmer than the bulk temperature, on the other hand there are some occasions when the skin can be of the order of 1 -0 deg K cooler than the bulk. There is a suggestion that the skin effect at night-time is smaller than it is during the day-time, and a possible explanation of this is given in terms of the complication of the diurnal thermocline. The skin effect can be an important source of error in the validation of space-borne sensors of SST, particularly with the requirement for high accuracy of SST measurement for climate studies. In terms of the retrieval of SST from satellite infrared sensors the skin effect is only one of several physical effects that create uncertainty in the value of SST.

ISSN:0143-1161    

DOI:10.1080/01431168908903920

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

The Advanced Very High Resolution Radiometer (AVHRR) instrument, carried by the NOAA-TIROS/N series of operational meteorological satellites can, on a routine basis, provide observational data which allow interpretation in terms of parameters related to water quality. In principle, some, though not all of the algorithms applied to Coastal Zone Colour Scanner data can be transformed for use with AVHRR observations. In combination with the operational character of the NOAA satellites this opens up the way to applications in monitoring of open sea and inland waters. Algorithms and results for some examples of such potential applications are presented.

ISSN:0143-1161    

DOI:10.1080/01431168908903921

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

The aims of this presentation were (i) to simulate the solar zenith angle effect on the Global Vegetation Index (GVI), (ii) to derive an expression for removing such an effect from the GVI data by the above simulation procedure and (iii) to apply this relation to the GVI data obtained from the NOAA-AVHRR imagery.

ISSN:0143-1161    

DOI:10.1080/01431168908903922

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

The phenology of Iberian vegetation is described using twelve full resolution Advanced Very High Resolution Radiometer short wave vegetation index images for the period April to October 1985 and 1986. The characteristics of the most appropriate vegetation classification scheme for use with these data are discussed.

ISSN:0143-1161    

DOI:10.1080/01431168908903923

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Normalized difference vegetation index (NDVI) data obtained from the Advanced Very High Resolution Radiometer (AVHRR) on board NOAA-9 have been analysed to assess their utility for monitoring the vegetation of Tunisian grazing lands. Preliminary analysis shows that the NDVI provides a sensitive indicator of monthly variations in biomass which correlate with spatial and temporal changes in growing conditions. Investigations suggest that the percentage contribution of the soil background to total recorded reflectance, provides an important limiting factor to the sensitivity of the NDVI, creating a threshold beyond which the accuracy of this index becomes less reliable.

ISSN:0143-1161    

DOI:10.1080/01431168908903924

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

NOAA-7 Advanced Very High Resolution Radiometer (AVHRR) Global Vegetation Indices (GVI) were used during the 1986 rainy season (June-September) over Senegal to monitor rainfall. The satellite data were used in conjunction with ground-based measurements so as to derive empirical relationships between rainfall and GVI. The regression obtained was then used to map the total rainfall corresponding to the growing season, yielding good results. Normalized Difference Vegetation Indices (NDVI) derived from High Resolution Picture Transmission (HRJT) data were also compared with actual evapotranspiration (ET) data and proved to be closely correlated with it with a time lapse of 20 days.

ISSN:0143-1161    

DOI:10.1080/01431168908903925

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Advanced Very High Resolution Radiometer (AVHRR) data have been used to assess the dynamics of forest transformations in three parts of the tropical belt. A large portion of the Amazon Basin has been systematically covered by Local Area Coverage (LAC) data in the 1985-1987 period. The analysis of the vegetation index and thermal data led to the identification and measurement of large areas of active deforestation. The Kalimantan/Borneo forest fires were monitored and their impact was evaluated using the Global Area Coverage (GAC) 4 km resolution data. Finally, High Resolution Picture Transmission (HRPT) data have provided preliminary information on current activities taking place at the boundary between the savanna and the forest in the Southern part of West Africa. The AVHRR approach is found to be a highly valuable means for carrying out deforestation assessments in regional and global perspectives.

ISSN:0143-1161    

DOI:10.1080/01431168908903926

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Automatic methods to correct vegetation index images from AVHRR are developed and tested. The corrected images are used to plot the temporal variations of the normalized difference vegetation indices in the HAPEX domain for two kinds of vegetation cover. The curves are interpreted differentiating the signal due to phenology from that probably caused by problems of haze or anisotropy.

ISSN:0143-1161    

DOI:10.1080/01431168908903927

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor