Bendix, J. (2000): <b>Precipitation dynamics in Ecuador and Northern Peru during the 1991/92 El Niño - A Remote Sensing perspective</b>. <i>International Journal of Remote Sensing</i> <b>21</b>(3), 533-548.
Resource Description
Title:
Precipitation dynamics in Ecuador and Northern Peru during the 1991/92 El Niño - A Remote Sensing perspective
FOR816dw ID:
186
Publication Date:
2000-01-01
License and Usage Rights:
PAK 823-825 data user agreement. (www.lcrs.de/dataagreementp3.do)
Resource Owner(s):
Individual:
Jörg Bendix
Contact:
email:
bendix <at> staff.uni-marburg.de
Deutschhausstraße 12
Room No. 02 A 48
35032 Marburg
Faculty of Geography
Germany
Abstract:
The formation, dynamics and spatial distribution of heavy precipitation<br/>
during the 1991/92 El Nin˜o in Ecuador and northern Peru were examined<br/>
by means of Meteosat-3 imagery, NOAA-AVHRR-based multichannel sea<br/>
surface temperatures (MCSST) and additional meteorological observations. The<br/>
Convective and Stratiform Technique (CST) was used for rain retrieval by means<br/>
of Meteosat IR data and a cross-correlation approach was applied to Meteosat<br/>
image sequences to derive cloud motion winds (CMW) which are essential for<br/>
the analysis of circulation patterns leading to severe precipitation. From an<br/>
analysis of 45 days with severe precipitation it is proven that three mechanisms<br/>
were responsible for the formation of heavy rains. Each mechanism reveals a<br/>
speci? c localized impact. (1) The most frequent mechanism (frequency of ~61%)<br/>
represents an extended land–sea breeze system. During such weather conditions,<br/>
predominantly locally con? ned precipitation patterns occured. Areas a? ected by<br/>
the sea wind front during the day were the coastal plains up to the 1000m contour<br/>
line on the western Andean slope. Local maxima in the frequency of cloudiness<br/>
leading to precipitation could be found at isolated peaks of a lower coastal<br/>
cordillera. At night the highest frequency of precipitation was found over the<br/>
warm water surface of the Gulf of Guayaquil, mainly due to its coastal shape<br/>
which signi? cantly favours convergence of the nocturnal land breeze. (2)<br/>
Convection, initiated in the coastal plain and on the western Andean slopes<br/>
during the afternoon, was signi? cantly intensi? ed by an entrainment of remainders<br/>
of cirrus shields from the Amazon basin. These cloud fragments spilled over the<br/>
Andes with well-developed trades in the mid/upper troposphere which blew in<br/>
the opposite direction to the daily sea/up-slope breeze. The spill over points were<br/>
characterized by areas of deep convection on the western Andean slopes and were<br/>
frequently valley axes perpendicular to the mountain chain as well as the Andean<br/>
depression in southern Ecuador. (3) During the main El Nin˜o phase (March–<br/>
April ), heavy and persistent precipitation was extended over wide areas of the<br/>
coastal plain showing neither a distinct diurnal cycle nor preferential areas. Deep<br/>
convection was frequently organized in mesoscale convective complexes (MCC)<br/>
and was spatially correlated with MCSST > 27ß . The extensive instability of the<br/>
troposphere during these weather conditions was marked by convective cloud<br/>
streets and an intensi? cation of the meridional Hadley circulation o? the coast<br/>
of southern Ecuador and Peru.
Keywords:
| Ecuador | El Nino | precipitation dynamics | Nothern Peru |
