@misc{SeidelTrachteOrellanaAlvearetal., author = {Seidel, Jochen and Trachte, Katja and Orellana-Alvear, Johanna and Figueroa, Rafael and C{\´e}lleri, Rolando and Bendix, J{\"o}rg and Fernandez, Ciro and Huggel, Christian}, title = {Precipitation Characteristics at Two Locations in the Tropical Andes by Means of Vertically Pointing Micro-Rain Radar Observations}, series = {Remote Sensing}, volume = {11}, journal = {Remote Sensing}, number = {24}, doi = {10.3390/rs11242985}, pages = {18}, abstract = {In remote areas with steep topography, such as the Tropical Andes, reliable precipitation data with a high temporal resolution are scarce. Therefore, studies focusing on the diurnal properties of precipitation are hampered. In this paper, we investigated two years of data from Micro-Rain Radars (MRR) in Cuenca, Ecuador, and Huaraz, Peru, from February 2017 to January 2019. This data allowed for a detailed study on the temporal precipitation characteristics, such as event occurrences and durations at these two locations. Our results showed that the majority of precipitation events had durations of less than 3 h. In Huaraz, precipitation has a distinct annual and diurnal cycle where precipitation in the rainy season occurred predominantly in the afternoon. These annual and diurnal cycles were less pronounced at the site in Cuenca, especially due to increased nocturnal precipitation events compared to Huaraz. Furthermore, we used a fuzzy logic classification of fall velocities and rainfall intensities to distinguish different precipitation types. This classification showed that nightly precipitation at both locations was predominantly stratiform, whereas (thermally induced) convection occurred almost exclusively during the daytime hours.}, language = {en} } @misc{TrachteSeidelFigueroaetal., author = {Trachte, Katja and Seidel, Jochen and Figueroa, Rafael and Otto, Marco and Bendix, J{\"o}rg}, title = {Cross-Scale Precipitation Variability in a Semiarid Catchment Area on the Western Slopes of the Central Andes}, series = {Journal of Applied Meteorology and Climatology}, volume = {57}, journal = {Journal of Applied Meteorology and Climatology}, number = {3}, doi = {10.1175/JAMC-D-17-0207.1}, pages = {675 -- 694}, abstract = {Spatiotemporal precipitation patterns were investigated on the western slopes of the central AndesMountains by applying EOF and cluster analysis as well as the Weather Research and Forecasting (WRF)Model. In the semiarid catchment area in the highlands of Lima, Peru, the precipitation is assumed to be across-scale interplay of large-scale dynamics, varying sea surface temperatures (SSTs), and breeze-dominatedslope flows. The EOF analysis was used to encompass and elucidate the upper-level circulation patternsdominating the transport of moisture. To delineate local precipitation regimes, a partitioning cluster analysiswas carried out, which additionally should illustrate local effects such as the altitudinal gradient of the Andes. Theresults demonstrated that especially during the transition to the dry season, synoptic-scale circulation aloft controlsthe precipitation (correlation coefficients between 0.6 and 0.9), whereas in the remaining seasons the slope breezesdue to the altitudinal gradient mainly determine the precipitation behavior. Further analysis with regard to thespatiotemporal precipitation variability revealed an inversion of the precipitation distribution along the elevationalgradient within the study area, mainly during February (29\%) and March (35\%), that showed correlations withcoastal SST patterns ranging between 0.56 and 0.67. WRF simulations of the underlying mechanisms disclosed thatthe large-scale circulation influences the thermally induced upslope flows while the strength of southeastern low-level winds related to the coastal SSTs caused a blocking of easterlies in the middle troposphere through a reducedanticyclonic effect. This interplay enables the generation of precipitation in the usually drier environment at lower elevations, which leads to a decrease in rainfall with increasing elevation.}, language = {en} }