Diurnal Cycle of Precipitation and Winds Over the Huancayo Observatory (Central Peruvian Andes), Using a Ka Band Cloud-profiling Radar (MIRA 35C) and Boundary Layer Tropospheric Radar (BLTR)

The Peruvian Andes has an important population above 3000masl, where the agriculture and livestock are the main economic activity. At these altitudes the adverse weather events such as frost, heavy rains, hail and droughts are quite frequente, which makes them very vulnerable. For this reason, the Atmospheric Microphysics and Radiation Laboratory (LAMAR) was implemented at the Huancayo Observatory (12° 02'18 ''S, 75° 19'22''W, 3300 masl). The main gol of LAMAR is to understund the physical and dynamical processes of the atmosphere to explain climate change, climatic variability and extreme weather events in the Peruvian Andes.

The main objective of this work is to characterize the diurnal cycle of precipitation and winds during the austral summer (JFM) using the Ka-band cloud-profiling radar (MIRA 35C) and a boundary layer tropospheric radar (BLTR), which are operating in LAMAR. Data from January-March 2016 were analyzed, to identify the precipitation events the threshold value of 10dB was used. The preliminary results indicate that during the nights, between 00 and 09 HLT, the precipitations are lighter and stratiform type; while during the afternoon and early evening there are deeper convective clouds with more intense precipitations, with the peak between 17 and 19 LT. These results are consisten with the rain gauges measurements. Winds during the rainy season (austral summer) are predominantly easterly during the morning untill 14-15 LT, being very weak from 23 to 9 LT near the surface untill 1-1.5 km, just during the occurrence of stratiform type rainfall. On the other hand, during the afternoon and early night, during the peak of convective rainfall, there is southeasterly wind up to 2-2.5 km above the surface. In contrast, for dry conditions during the austral winter (JJA) the winds are northwestly, during the afternoon and early night the winds are northern. A similar pattern is observed, evaluating rainy days and dry days during the rainy season. This indicates that rainfall in the valley is associated with southeastly flows, while dry conditions with northeastly flow.