@misc{BendixFriesZarateetal., author = {Bendix, J{\"o}rg and Fries, Andreas and Z{\´a}rate, Jorge and Trachte, Katja and Rollenbeck, R{\"u}tger and Pucha-Cofrep, Franz and Paladines, Renzo and Palacios, Ivan and Orellana-Alvear, Johanna and O{\~n}ate-Valdivieso, Fernando and Naranjo, Carlos and Mendoza, Leonardo and Mejia, Diego and Guallpa, Mario and Gordillo, Francisco and Gonzalez-Jaramillo, Victor and Dobbermann, Maik and C{\´e}lleri, Rolando and Carrillo, Carlos and Araque, Augusto and Achilles, Sebastian}, title = {RadarNet-Sur First Weather Radar Network in Tropical High Mountains}, series = {Bulletin of the American Meteorological Society}, volume = {98}, journal = {Bulletin of the American Meteorological Society}, number = {6}, doi = {10.1175/BAMS-D-15-00178.1}, pages = {1235 -- 1254}, abstract = {Weather radar networks are indispensable tools for forecasting and disaster prevention in industrialized countries. However, they are far less common in the countries of South America, which frequently suffer from an underdeveloped network of meteorological stations. To address this problem in southern Ecuador, this article presents a novel radar network using cost-effective, single-polarization, X-band technology: the RadarNet-Sur. The RadarNet-Sur network is based on three scanning X-band weather radar units that cover approximately 87,000 km2 of southern Ecuador. Several instruments, including five optical disdrometers and two vertically aligned K-band Doppler radar profilers, are used to properly (inter) calibrate the radars. Radar signal processing is a major issue in the high mountains of Ecuador because cost-effective radar technologies typically lack Doppler capabilities. Thus, special procedures were developed for clutter detection and beam blockage correction by integrating ground-based and satelliteborne measurements. To demonstrate practical applications, a map of areas frequently affected by intense rainfall is presented, based on a time series of one radar that has been in operation since 2002. Such information is of vital importance to, for example, infrastructure management because rain-driven landslides are a major issue for road maintenance and safety throughout Ecuador. The presented case study of exceptionally strong rain events during the recent El Ni{\~n}o in March 2015 highlights the system's practicality in weather forecasting related to disaster management. For the first time, RadarNet-Sur warrants a spatial-explicit observation of El Ni{\~n}o-related heavy precipitation in a transect from the coast to the highlands in a spatial resolution of 500 m.}, language = {en} } @misc{MakowskiGiannoniTrachteRollenbecketal., author = {Makowski Giannoni, Sandro and Trachte, Katja and Rollenbeck, R{\"u}tger and Lehnert, Lukas W. and Fuchs, Julia and Bendix, J{\"o}rg}, title = {Atmospheric salt deposition in a tropical mountain rainforest at the eastern Andean slopes of south Ecuador - Pacific or Atlantic origin?}, series = {Atmospheric Chemistry and Physics}, volume = {16}, journal = {Atmospheric Chemistry and Physics}, number = {15}, doi = {10.5194/acp-16-10241-2016}, pages = {10241 -- 10261}, abstract = {Sea salt (NaCl) has recently been proven to be of the utmost importance for ecosystem functioning in Amazon lowland forests because of its impact on herbivory, litter decomposition and, thus, carbon cycling. Sea salt deposition should generally decline as distance from its marine source increases. For the Amazon, a negative east-west gradient of sea salt availability is assumed as a consequence of the barrier effect of the Andes Mountains for Pacific air masses. However, this generalized pattern may not hold for the tropical mountain rainforest in the Andes of southern Ecuador. To analyse sea salt availability, we investigated the deposition of sodium (Na+) and chloride (Cl-), which are good proxies of sea spray aerosol. Because of the complexity of the terrain and related cloud and rain formation processes, sea salt deposition was analysed from both, rain and occult precipitation (OP) along an altitudinal gradient over a period between 2004 and 2009. To assess the influence of easterly and westerly air masses on the deposition of sodium and chloride over southern Ecuador, sea salt aerosol concentration data from the Monitoring Atmospheric Composition and Climate (MACC) reanalysis data set and back-trajectory statistical methods were combined. Our results, based on deposition time series, show a clear difference in the temporal variation of sodium and chloride concentration and Na+ ∕ Cl- ratio in relation to height and exposure to winds. At higher elevations, sodium and chloride present a higher seasonality and the Na+ ∕ Cl- ratio is closer to that of sea salt. Medium- to long-range sea salt transport exhibited a similar seasonality, which shows the link between our measurements at high elevations and the sea salt synoptic transport. Although the influence of the easterlies was predominant regarding the atmospheric circulation, the statistical analysis of trajectories and hybrid receptor models revealed a stronger impact of the north equatorial Atlantic, Caribbean, and Pacific sea salt sources on the atmospheric sea salt concentration in southern Ecuador. The highest concentration in rain and cloud water was found between September and February when air masses originated from the north equatorial Atlantic, the Caribbean Sea and the equatorial Pacific. Together, these sources accounted for around 82.4 \% of the sea salt budget over southern Ecuador.}, language = {en} } @misc{LehnertWescheTrachteetal., author = {Lehnert, Lukas W. and Wesche, Karsten and Trachte, Katja and Reudenbach, Christoph and Bendix, J{\"o}rg}, title = {Climate variability rather than overstocking causes recent large scale cover changes of Tibetan pastures}, series = {Scientific Reports}, volume = {6}, journal = {Scientific Reports}, number = {1}, doi = {10.1038/srep24367}, abstract = {The Tibetan Plateau (TP) is a globally important "water tower" that provides water for nearly 40\% of the world's population. This supply function is claimed to be threatened by pasture degradation on the TP and the associated loss of water regulation functions. However, neither potential large scale degradation changes nor their drivers are known. Here, we analyse trends in a high-resolution dataset of grassland cover to determine the interactions among vegetation dynamics, climate change and human impacts on the TP. The results reveal that vegetation changes have regionally different triggers: While the vegetation cover has increased since the year 2000 in the north-eastern part of the TP due to an increase in precipitation, it has declined in the central and western parts of the TP due to rising air temperature and declining precipitation. Increasing livestock numbers as a result of land use changes exacerbated the negative trends but were not their exclusive driver. Thus, we conclude that climate variability instead of overgrazing has been the primary cause for large scale vegetation cover changes on the TP since the new millennium. Since areas of positive and negative changes are almost equal in extent, pasture degradation is not generally proceeding.}, language = {en} } @misc{CampozanoCelleriTrachteetal., author = {Campozano, Lenin and C{\´e}lleri, Rolando and Trachte, Katja and Bendix, J{\"o}rg and Samaniego, Esteban}, title = {Rainfall and Cloud Dynamics in the Andes: A Southern Ecuador Case Study}, series = {Advances in Meteorology}, volume = {2016}, journal = {Advances in Meteorology}, doi = {10.1155/2016/3192765}, pages = {15}, abstract = {Mountain regions worldwide present a pronounced spatiotemporal precipitation variability, which added to scarce monitoring networks limits our understanding of the generation processes involved. To improve our understanding of clouds and precipitation dynamics and cross-scale generation processes in mountain regions, we analyzed spatiotemporal rainfall patterns using satellite cloud products (SCP) in the Paute basin (900-4200 m a.s.l. and 6481 km2) in the Andes of Ecuador. Precipitation models, using SCP and GIS data, reveal the spatial extension of three regimes: a three-modal (TM) regime present across the basin, a bimodal (BM) regime, along sheltered valleys, and a unimodal (UM) regime at windward slopes of the eastern cordillera. Subsequently, the spatiotemporal analysis using synoptic information shows that the dry season of the BM regime during boreal summer is caused by strong subsidence inhibiting convective clouds formation. Meanwhile, in UM regions, low advective shallow cap clouds mainly cause precipitation, influenced by water vapor from the Amazon and enhanced easterlies during boreal summer. TM regions are transition zones from UM to BM and zones on the windward slopes of the western cordillera. These results highlight the suitability of satellite and GIS data-driven statistical models to study spatiotemporal rainfall seasonality and generation processes in complex terrain, as the Andes.}, language = {en} } @misc{TrachteBissolliNitscheetal., author = {Trachte, Katja and Bissolli, Peter and Nitsche, H. and Parker, David and Kennedy, John and Kendon, Mike}, title = {Regional climates. Europe and the Middle East}, series = {State of the Climate in 2014, Special Supplement to the Bulletin of the American Meteorological Society, Vol. 96, No. 7, July 2015}, volume = {96}, journal = {State of the Climate in 2014, Special Supplement to the Bulletin of the American Meteorological Society, Vol. 96, No. 7, July 2015}, number = {7}, doi = {10.1175/2015BAMSStateoftheClimate.1}, pages = {191 -- 200}, abstract = {Most of the dozens of essential climate variables monitored each year in this report continued to follow their long-term trends in 2014, with several setting new records. Carbon dioxide, methane, and nitrous oxide—the major greenhouse gases released into Earth's atmosphere—once again all reached record high average atmospheric concentrations for the year. Carbon dioxide increased by 1.9 ppm to reach a globally averaged value of 397.2 ppm for 2014. Altogether, 5 major and 15 minor greenhouse gases contributed 2.94 W m-2 of direct radiative forcing, which is 36\% greater than their contributions just a quarter century ago. Accompanying the record-high greenhouse gas concentrations was nominally the highest annual global surface temperature in at least 135 years of modern record keeping, according to four independent observational analyses. The warmth was distributed widely around the globe's land areas, Europe observed its warmest year on record by a large margin, with close to two dozen countries breaking their previous national temperature records; many countries in Asia had annual temperatures among their 10 warmest on record; Africa reported above-average temperatures across most of the continent throughout 2014; Australia saw its third warmest year on record, following record heat there in 2013; Mexico had its warmest year on record; and Argentina and Uruguay each had their second warmest year on record. Eastern North America was the only major region to observe a below-average annual temperature. But it was the oceans that drove the record global surface temperature in 2014. Although 2014 was largely ENSO-neutral, the globally averaged sea surface temperature (SST) was the highest on record. The warmth was particularly notable in the North Pacific Ocean where SST anomalies signaled a transition from a negative to positive phase of the Pacific decadal oscillation. In the winter of 2013/14, unusually warm water in the northeast Pacific was associated with elevated ocean heat content anomalies and elevated sea level in the region. Globally, upper ocean heat content was record high for the year, reflecting the continued increase of thermal energy in the oceans, which absorb over 90\% of Earth's excess heat from greenhouse gas forcing. Owing to both ocean warming and land ice melt contributions, global mean sea level in 2014 was also record high and 67 mm greater than the 1993 annual mean, when satellite altimetry measurements began. Sea surface salinity trends over the past decade indicate that salty regions grew saltier while fresh regions became fresher, suggestive of an increased hydrological cycle over the ocean expected with global warming. As in previous years, these patterns are reflected in 2014 subsurface salinity anomalies as well. With a now decade-long trans-basin instrument array along 26°N, the Atlantic meridional overturning circulation shows a decrease in transport of -4.2 ± 2.5 Sv decade-1. Precipitation was quite variable across the globe. On balance, precipitation over the world's oceans was above average, while below average across land surfaces. Drought continued in southeastern Brazil and the western United States. Heavy rain during April-June led to devastating floods in Canada's Eastern Prairies. Above-normal summer monsoon rainfall was observed over the southern coast of West Africa, while drier conditions prevailed over the eastern Sahel. Generally, summer monsoon rainfall over eastern Africa was above normal, except in parts of western South Sudan and Ethiopia. The south Asian summer monsoon in India was below normal, with June record dry. Across the major tropical cyclone basins, 91 named storms were observed during 2014, above the 1981-2010 global average of 82. The Eastern/Central Pacific and South Indian Ocean basins experienced significantly above-normal activity in 2014; all other basins were either at or below normal. The 22 named storms in the Eastern/Central Pacific was the basin's most since 1992. Similar to 2013, the North Atlantic season was quieter than most years of the last two decades with respect to the number of storms, despite the absence of El Ni{\~n}o conditions during both years. In higher latitudes and at higher elevations, increased warming to be visible in the decline of glacier mass balance, increasing permafrost temperatures, and a deeper thawing layer in seasonally frozen soil. In the Arctic, the 2014 temperature over land areas was the fourth highest in the 115-year period of record and snow melt occurred 20-30 days earlier than the 1998-2010 average. The Greenland Ice Sheet experienced extensive melting in summer 2014. The extent of melting was above the 1981-2010 average for 90\% of the melt season, contributing to the second lowest average summer albedo over Greenland since observations began in 2000 and a record-low albedo across the ice sheet for August. On the North Slope of Alaska, new record high temperatures at 20-m depth were measured at four of five permafrost observatories. In September, Arctic minimum sea ice extent was the sixth lowest since satellite records began in 1979. The eight lowest sea ice extents during this period have occurred in the last eight years. Conversely, in the Antarctic, sea ice extent countered its declining trend and set several new records in 2014, including record high monthly mean sea ice extent each month from April to November. On 20 September, a record large daily Antarctic sea ice extent of 20.14 × 106 km2 occurred. The 2014 Antarctic stratospheric ozone hole was 20.9 million km2 when averaged from 7 September to 13 October, the sixth smallest on record and continuing a decrease, albeit statistically insignificant, in area since 1998.}, language = {en} } @misc{TrachteObregonBissollietal., author = {Trachte, Katja and Obregon, Andre and Bissolli, Peter and Kennedy, John and Parker, David E. and Trigo, Ricardo M. and Barriopedro, D. E.}, title = {Regional climates. Europe and the Middle East}, series = {State of the Climate in 2011, Bulletin of the American Meteorological Society}, volume = {93}, journal = {State of the Climate in 2011, Bulletin of the American Meteorological Society}, number = {7}, doi = {10.1175/2012BAMSStateoftheClimate.1}, pages = {186 -- 199}, abstract = {Large-scale climate patterns influenced temperature and weather patterns around the globe in 2011. In particu-lar, a moderate-to-strong La Ni{\~n}a at the beginning of the year dissipated during boreal spring but reemerged during fall. The phenomenon contributed to historical droughts in East Africa, the southern United States, and northern Mexico, as well the wettest two-year period (2010 -11) on record for Australia, particularly remarkable as this follows a decade-long dry period. Precipitation patterns in South America were also influenced by La Ni{\~n}a. Heavy rain in Rio de Janeiro in January triggered the country's worst floods and landslides in Brazil's history. The 2011 combined average temperature across global land and ocean surfaces was the coolest since 2008, but was also among the 15 warmest years on record and above the 1981-2010 average. The global sea surface temperature cooled by 0.1°C from 2010 to 2011, associ-ated with cooling influences of La Ni{\~n}a. Global integrals of upper ocean heat content for 2011 were higher than for all prior years, demonstrating the Earth's dominant role of the oceans in the Earth's energy budget. In the upper atmosphere, tropical stratospheric temperatures were anomalously warm, while polar temper atures were anomalously cold. This led to large spring time stratospheric ozone reductions in polar latitudes in both hemispheres. Ozone concentrations in the Arctic strato-sphere during March were the lowest for that period since satellite records began in 1979. An extensive, deep, and persistent ozone hole over the Antarctic in September indicates that the recovery to pre-1980 conditions is proceeding very slowly.Atmospheric carbon dioxide concentrations increased by 2.10 ppm in 2011, and exceeded 390 ppm for the first time since instrumental records began. Other greenhouse gases also continued to rise in concentration and the combined effect now represents a 30\% increase in radia-tive forcing over a 1990 baseline. Most ozone depleting substances continued to fall. The global net ocean carbon dioxide uptake for the 2010 transition period from El Ni{\~n}o to La Ni{\~n}a, the most recent period for which analyzed data are available, was estimated to be 1.30 Pg C yr-1, almost 12\% below the 29-year long-term average. Relative to the long-term trend, global sea level dropped noticeably in mid-2010 and reached a local minimum in 2011. The drop has been linked to the La Nina conditions that prevailed throughout much of 2010-11. Global sea level increased sharply during the second half of 2011. Global tropical cyclone activity during 2011 was well-below average, with a total of 74 storms compared with the 1981-2010 average of 89. Similar to 2010, the North Atlantic was the only basin that experienced above-normal activity.For the first year since the widespread introduction of the Dvorak intensity-estimation method in the 1980s, only three tropical cyclones reached Category 5 intensity level—all in the Northwest Pacific basin.The Arctic continued to warm at about twice the rate compared with lower latitudes. Below-normal summer snowfall, a decreasing trend in surface albedo, and above-average surface and upper air temperatures resulted in a continued pattern of extreme surface melting, and net snow and ice loss on the Greenland ice sheet. Warmer-than-normal temperatures over the Eurasian Arctic in spring resulted in a new record-low June snow cover extent and spring snow cover duration in this region. In the Canadian Arctic, the mass loss from glaciers and ice caps was the greatest since GRACE measurements began in 2002, continuing a negative trend that began in 1987. New record high temperatures occurred at 20 m below the land surface at all permafrost observatories on the North Slope of Alaska, where measurements began in the late 1970s. Arctic sea ice extent in September 2011 was the second-lowest on record, while the extent of old ice (four and five years) reached a new record minimum that was just 19\% of normal.On the opposite pole, austral winter and spring tem-peratures were more than 3°C above normal over much of the Antarctic continent.However, winter temperatures were below normal in the northern Antarctic Peninsula, which continued the downward trend there during the last 15 years. In summer, an all-time record high tempera-ture of -12.3°C was set at the South Pole station on 25 December, exceeding the previous record by more than a full degree. Antarctic sea ice extent anomalies increased steadily through much of the year, from briefly setting a record low in April, to well above average in December. The latter trend reflects the dispersive effects of low pres-sure on sea ice and the generally cool conditions around the Antarctic perimeter.Unauthenticated | Downloaded 05/07/21 10:23 AM UTC}, language = {en} } @misc{BendixTrachtePalaciosetal., author = {Bendix, J{\"o}rg and Trachte, Katja and Palacios, Enrique and Rollenbeck, R{\"u}tger and G{\"o}ttlicher, Dietrich and Nauss, Thomas and Bendix, Astrid}, title = {El Ni{\~n}o meets La Ni{\~n}a - anomalous rainfall patterns in the "traditional" El Ni{\~n}o region of Southern Ecuador}, series = {Erdkunde}, volume = {65}, journal = {Erdkunde}, number = {2}, doi = {10.3112/erdkunde.2011.02.04}, pages = {151 -- 167}, abstract = {In this paper, the central Pacific cold event of 2008 and its exceptionally warm conditions in the eastern tropical Pacific are analyzed by using rainfall data of south Ecuadorian meteorological stations, sea surface temperatures in the El Ni{\~n}o3 and 1+2 regions, and simulations with the Weather Research and Forecasting (WRF) model. It can be shown that El Ni{\~n}o-like rainfall conditions with severe inundations occur particularly in the coastal plains of southern Ecuador while a central Pacific cold event prevails. In contrary to previous situations, positive rainfall anomalies as a result of El Ni{\~n}o-like conditions in the El Ni{\~n}o1+2 region during the 2008 La Ni{\~n}a event occurred in both regions, the coastal plains and the highlands, for the first time. A detailed analysis of the ocean-atmosphere system during episodes of heavy rainfall reveals typical El Ni{\~n}o circulation and rainfall patterns as observed during previous El Ni{\~n}o events for the coastal area and La Ni{\~n}a-like conditions for the highlands. The spreading of Pacific instability in the Ni{\~n}o1+2 region to the eastern escarpment of the Andes could be the result of a temporary eastward shift of the Walker circulation. The unusual combination of El Ni{\~n}o-like conditions in the eastern tropical Pacific during a La Ni{\~n}a state in the central Pacific is the newest indicator for an impact mode shift regarding severe rainfall anomalies during El Ni{\~n}o/La Ni{\~n}a events in the traditional El Ni{\~n}o area of southern Ecuador since the end of the last century. Since 2000, El Ni{\~n}o events unexpectedly provide below average rainfall while central Pacific La Ni{\~n}a conditions generate exceptional severe flooding in the normally drier coastal plains. The novel sea surface temperature (SST) anomaly dipole structure between the eastern and central/western tropical Pacific and the weakening of El Ni{\~n}o events since 2000 could be due to natural decadal oscillations in the El Ni{\~n}o background state, the Pacific Decadal Oscillation (PDO). However, the observed atmospheric patterns and the recent increase of the SST anomaly difference between the central and the eastern tropical Pacific resemble structures that also result from climate change simulations.}, language = {en} } @misc{TrachteRollenbeckBendix, author = {Trachte, Katja and Rollenbeck, R{\"u}tger and Bendix, J{\"o}rg}, title = {Nocturnal convective cloud formation under clear-sky conditions at the eastern Andes of south Ecuador}, series = {Journal of Geophysical Research Atmospheres}, volume = {115}, journal = {Journal of Geophysical Research Atmospheres}, number = {D24}, doi = {10.1029/2010JD014146}, pages = {15}, abstract = {[1] The formation of nocturnal convective clouds at the eastern Andes of south Ecuador and the adjacent Peruvian Amazon basin was investigated in a numerical model study. Their formation is expected to be an interactive procedure of nocturnal downslope flows in the Andean terrain, which forms a concave drainage system in the target area. Satellite imagery were used for both the identification of a sample case with a nocturnal cold cloud appearance and for the verification of the simulated results. The cloud patterns were distinguished on the basis of IR temperatures. A comparison of the data demonstrated the occurrence of a cold cloud shield in the target area, although the modeled cluster is significantly smaller. Further analysis of the development of the convective cells confirmed the assumed underlying processes. A strong current in the lower atmosphere, presumably a drainage flow, was recognizable in association with strong moisture convergence using a cross section through the cluster. Their presence was confirmed on the basis of their characteristic features and the surface energy fluxes as the driving force for thermally induced downslope flows.}, language = {en} } @misc{TrachteNaussBendix, author = {Trachte, Katja and Nauss, Thomas and Bendix, J{\"o}rg}, title = {The Impact of Different Terrain Configurations on the Formation and Dynamics of Katabatic Flows: Idealised Case Studies}, series = {Boundary-Layer Meteorology}, volume = {134}, journal = {Boundary-Layer Meteorology}, number = {2}, doi = {10.1007/s10546-009-9445-8}, pages = {307 -- 325}, abstract = {Impacts of different terrain configurations on the general behaviour of idealised katabatic flows are investigated in a numerical model study. Various simplified terrain models are applied to unveil modifications of the dynamics of nocturnal cold drainage of air as a result of predefined topographical structures. The generated idealised terrain models encompass all major topographical elements of an area in the tropical eastern Andes of southern Ecuador and northern Peru, and the adjacent Amazon. The idealised simulations corroborate that (i) katabatic flows develop over topographical elements (slopes and valleys), that (ii) confluence of katabatic flows in a lowland basin with a concave terrainline occur, and (iii) a complex drainage flow system regime directed into such a basin can sustain the confluence despite varying slope angles and slope distances.}, language = {en} } @misc{BendixTrachteCermaketal., author = {Bendix, J{\"o}rg and Trachte, Katja and Cermak, Jan and Rollenbeck, R{\"u}tger and Nauß, Thomas}, title = {Formation of Convective Clouds at the Foothills of the Tropical Eastern Andes (South Ecuador)}, series = {Journal of Applied Meteorology and Climatology}, volume = {48}, journal = {Journal of Applied Meteorology and Climatology}, number = {8}, doi = {10.1175/2009JAMC2078.1}, pages = {1682 -- 1695}, abstract = {This study examines the seasonal and diurnal dynamics of convective cloud entities—small cells and a mesoscale convective complex-like pattern—in the foothills of the tropical eastern Andes. The investigation is based on Geostationary Operational Environmental Satellite-East (GOES-E) satellite imagery (2005-07), images of a scanning X-band rain radar, and data from regular meteorological stations. The work was conducted in the framework of a major ecological research program, the Research Unit 816, in which meteorological instruments are installed in the Rio San Francisco valley, breaching the eastern Andes of south Ecuador. GOES image segmentation to discriminate convective cells and other clouds is performed for a 600 × 600 km2 target area, using the concept of connected component labeling by applying the 8-connectivity scheme as well as thresholds for minimum blackbody temperature, spatial extent, and eccentricity of the extracted components. The results show that the formation of convective clouds in the lowland part of the target area mainly occurs in austral summer during late afternoon. Nocturnal enhancement of cell formation could be observed from October to April (particularly February-April) between 0100 and 0400 LST (LST = UTC - 5 h) in the Andean foothill region of the target area, which is the relatively dry season of the adjacent eastern Andean slopes. Nocturnal cell formation is especially marked southeast of the Rio San Francisco valley in the southeast Andes of Ecuador, where a confluence area of major katabatic outflow systems coincide with a quasi-concave shape of the Andean terrain line. The confluent cold-air drainage flow leads to low-level instability and cellular convection in the warm, moist Amazon air mass. The novel result of the current study is to provide statistical evidence that, under these special topographic situations, katabatic outflow is strong enough to generate mainly mesoscale convective complexes (MCCs) with a great spatial extent. The MCC-like systems often increase in expanse during their mature phase and propagate toward the Andes because of the prevailing upper-air easterlies, causing early morning peaks of rainfall in the valley of the Rio San Francisco. It is striking that MCC formation in the foothill area is clearly reduced during the main rainy season [June-August (JJA)] of the higher eastern Andean slopes. At a first glance, this contradiction can be explained by rainfall persistence in the Rio San Francisco valley, which is clearly lower during the time of convective activity (December-April) in comparison with JJA, during which low-intensity rainfall is released by predominantly advective clouds with greater temporal endurance.}, language = {en} }