Cloud detection in the Tropics--a suitable tool for climate-ecological studies in the high mountains of Ecuador

The detection of clouds and the analysis of cloud frequency play an important role for operational weather prediction as well as for climate-ecological studies. A threshold technique for cloud detection in the tropical mountainous area of Ecuador is presented which is based on National Oceanic and Atmospheric Administration Advanced Very High Resolution Radiometer (NOAA-AVHRR) data. Cloud classification is performed for both day and night overpasses by applying several threshold tests which also include ancillary terrain information. From a set of 155 images, maps of relative cloud frequency are calculated for Ecuador and adjacent areas as well as the central study area of an ecological project in southern Ecuador (Loja). Results show a clear relation between topography, main airflow and cloudiness due to barrage and lee-effects. The spatial extension of high mountain ecosystems such as the Ecuadorian Páramo has been proven to be significantly influenced by the spatial pattern of cloud frequency.

[1]  Eric A. Smith,et al.  ISCCP Cloud Algorithm Intercomparison. , 1985 .

[2]  R. Srinivasan,et al.  An automated cloud detection method for daily NOAA-14 AVHRR data for Texas, USA , 2002 .

[3]  Vincenzo Levizzani,et al.  Cloud classification using METEOSAT VIS-IR imagery , 1992 .

[4]  M. Kästner,et al.  Alpine cloud climatology using long-term NOAA-AVHRR satellite data , 2001 .

[5]  Erwin Beck,et al.  Analysis of undisturbed and disturbed tropical mountain forest ecosystems in Southern Ecuador , 2001 .

[6]  D. Nullet,et al.  Forest climatology near the tree line in Hawai'i , 1993 .

[7]  K. T. Kriebel,et al.  The cloud analysis tool APOLLO: Improvements and validations , 2003 .

[8]  Anna Ghelli.  Data assimilation for numerical weather prediction , 1992 .

[9]  W. Lauer.  ECOCLIMATOLOGICAL CONDITIONS OF THE PARAMO BELT IN THE TROPICAL HIGH MOUNTAINS1 , 1981 .

[10]  L. Alados-Arboledasb,et al.  Estimation of photosynthetically active radiation under cloudy conditions , 1999 .

[11]  Jörg Bendix,et al.  Precipitation dynamics in Ecuador and northern Peru during the 1991/92 El Nino: A remote sensing perspective , 2000 .

[12]  Robert S. Schemenauer,et al.  Advective, orographic and radiation fog in the Tarapacá region, Chile , 2002 .

[13]  W. Rossow,et al.  The International Satellite Cloud Climatology Project (ISCCP): The First Project of the World Climate Research Programme , 1983 .

[14]  W. Menzel,et al.  Discriminating clear sky from clouds with MODIS , 1998 .

[15]  G. Gesell,et al.  An algorithm for snow and ice detection using AVHRR data An extension to the APOLLO software package , 1989 .

[16]  Jörg Bendix,et al.  Experiments with a straightforward model for the spatial forecast of fog/low stratus clearance based on multi-source data , 1998 .

[17]  P. Sklenář,et al.  Rain-Shadow in the High Andes of Ecuador Evidenced by Páramo Vegetation , 2003 .

[18]  W. Silver,et al.  Interception of hori-zontal pre-cipitation by elfin cloud forest in the Luquillo Mountains, Eastern Puerto Rico. , 1998 .

[19]  E. O'connor,et al.  The CloudSat mission and the A-train: a new dimension of space-based observations of clouds and precipitation , 2002 .

[20]  G. Grell,et al.  A description of the fifth-generation Penn State/NCAR Mesoscale Model (MM5) , 1994 .

[21]  Michel Desbois,et al.  Automatic classification of clouds on Meteosat imagery - Application to high-level clouds , 1982 .

[22]  Arthur P. Cracknell,et al.  A simple cloud masking approach using NOAA AVHRR daytime data for tropical areas , 1995 .

[23]  Karl-Göran Karlsson.  Development of an operational cloud classification model , 1989 .

[24]  Brian J. Etherton,et al.  Cloud top phase determination from the fusion of signatures in daytime AVHRR imagery and HIRS data , 1997 .

[25]  W. Paul Menzel,et al.  High-Spatial-Resolution Surface and Cloud-Type Classification from MODIS Multispectral Band Measurements , 2003 .

[26]  Jörg Bendix,et al.  A satellite-based climatology of fog and low-level stratus in Germany and adjacent areas , 2002 .

[27]  Anita M. Seddon,et al.  Segmentation of clouds using cluster analysis , 1985 .

[28]  K. R. Hardy,et al.  Threshold functions for automated cloud analyses of global meteorological satellite imagery , 1995 .

[29]  Martyn M. Caldwell,et al.  Solar Ultraviolet Radiation as an Ecological Factor for Alpine Plants , 1968 .

[30]  R. Barry.  MOUNTAIN CLIMATOLOGY AND PAST AND POTENTIAL FUTURE CLIMATIC CHANGES IN MOUNTAIN REGIONS: A REVIEW , 1992 .

[31]  R. Saunders,et al.  An improved method for detecting clear sky and cloudy radiances from AVHRR data , 1988 .

[32]  F. Bretherton,et al.  Cloud cover from high-resolution scanner data - Detecting and allowing for partially filled fields of view , 1982 .

[33]  R. Saunders,et al.  An automated scheme for the removal of cloud contamination from AVHRR radiances over western Europe , 1986 .

[34]  R. Bradley,et al.  Climate Variability in the Andes of Ecuador and Its Relation to Tropical Pacific and Atlantic Sea Surface Temperature Anomalies , 2000 .

[35]  J. Bendix,et al.  Studies on the thermal conditions of soils at the upper tree line in the Páramo of Papallacta (Eastern Cordillera of Ecuador) , 2001 .

[36]  Josef Kittler,et al.  Clustering algorithms for use with images of clouds , 1986 .

[37]  Hermann Mannstein,et al.  Operational detection of contrails from NOAA-AVHRR-data , 1999 .

[38]  M. Richter.  Using epiphytes and soil temperatures for eco-climatic interpretations in southern Ecuador , 2003 .