Precipitation Characteristics at Two Locations in the Tropical Andes by Means of Vertically Pointing Micro-Rain Radar Observations

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.

Clustering of Rainfall Types Using Micro Rain Radar and Laser Disdrometer Observations in the Tropical Andes

“…These results about short rainfall duration support evidence from previous observations [4,14]. Orellana-Alvear et al [4] analyzed the rainfall events duration using the LPM disdrometer and found that the mean event duration is around 3 h. In the same way, Seidel et al [14] confirmed that the short duration events are dominant in this study area by using MRR data. Furthermore, the short duration of the events evidenced the necessity of high temporal resolution to capture their variability.…”

“…Furthermore, the short duration of the events evidenced the necessity of high temporal resolution to capture their variability. However, the instruments' time resolution (e.g., rain gauge) limit capturing the variability in these events [14,68]. Padrón et al [68] already discussed the influence of different instrument time resolution (rain gauge and disdrometer laser) in rainfall data after finding that the rain gauge underestimates rainfall catch.…”

“…Besides, disdrometers are instruments that retrieve characteristics as particle spectrum, the rain rate, the quantity, and the type of rain [10]. These instruments have been used to analyze the rainfall dynamic in mountain areas [4,12,[14][15][16][17]. In the Tropical Andes, the diurnal dynamics of the precipitation were studied by Bendix et al [16] using MRR data.…”

“…The authors found that convective type (rainfall associated with higher rain rate and Dm) was more common in the lower elevation sites while light rain was more frequent in higher sites. Seidel et al [14] using MRR data, found that short events (less than 3 h) were dominant in the Tropical Andes and nocturnal precipitation is more of the stratiform type.…”

Random forest-based rainfall retrieval for Ecuador using GOES-16 and IMERG-V06 data

“…In areas characterized by a coarse network of operational rain gauge stations, highly variable spatiotemporal precipitation patterns cannot fully be captured. This particularly holds for regions with a complex climate and topography (Seidel et al, 2019). Ecuador is one of such areas; the Andes Mountains characterize the country with the highest peaks exceeding elevations of 6268 m above sea level (m.a.s.l.…”