  The monitoring of the impact of aerosols in Latin America on a local scale is
usually limited due to the infrastructure and instrumentation available. In
Colombia, there are two international ground surface monitoring networks, the
AErosol RObotic NETwork (AERONET) and the Latin American LIDAR NETwork
(LALINET). However, the AERONET performance relies on only one sun photometer
which makes measurements distributed among five ground-based stations in
different cities such as Bogot\'a and Medell\'in. On the other hand, LALINET
has only one ground-based station formed by an elastic LiDAR system located at
Medell\'in. Although Cali is the largest city of Colombian southwestern, with
an accelerated grown rate of both urban and vehicular fleet, and counts with
the third largest population of this country, is not reached by these networks.
Here, we report on the implementation of a monostatic-coaxial multispectral
LiDAR system using a pulsed Nd:YAG laser with 450 mJ of average energy at 1064
nm. To perform the atmospheric measurements, this system is capable of
spatially resolving elastic backscatter down to 3.75 m with a Pulse Repetition
Frequency (PRF) of 10 Hz. We have developed a hybrid algorithm for data
analysis by combining the Fitting and Gradient method and the Klett-Fernald
algorithm to estimate the Planetary Boundary Layer (PBL) Top and the optical
properties of aerosols. This work constitutes the first quantitative
atmospheric exploration to study the aerosols dynamics and the PBL in the
northwest of South America.
