INTRODUCTION
There is a high spatial and temporal climatic variability in the Andean
regions of Colombia, and it can be analyzed in the short term, when the
information dates only a few years back, or the long term, when
information for a longer period is available. Both types of analysis
allow characterizing and knowing the patterns of climatic variables in
space and time (Martínez & Salas, 2015). Knowing the spatio-temporal
variability of the main climatic variables on its intra-daily and
intra-annual scale in a tropical Andean city is an urban planning tool
that strengthens decision-making. Precipitation is fundamental since it
directly defines the water supply or availability and is considered one
of the most important mechanisms in the global hydrological cycle (Marín
et al., 2005). Therefore, knowing this variability becomes a water
heritage management tool, where its proper management involves
agricultural practices, human and hydroelectric consumption, the
ecosystems, and other industrial or mining uses. Proper management and
planning thus require implementing actions that minimize the impact of
water use, so it is necessary to analyze and detect historical
modifications on the spatial and temporal characteristics and behaviors
of the pluviometric regime (Puertas, Carvajal, & Quintero, 2011).
Understanding the diurnal rain cycle is important in the short
term for many reasons: the main one is
because the amplitude and phase of this cycle are the result of the
interaction between dynamic and radiative processes. The successful
explanation of such processes is a useful measure to make sense of
atmospheric physics at these time scales (Zuluaga, Poveda, & Mejia,
2004), which allows understanding regional patterns of climate behavior.
This knowledge is basic for the physical parameterization of climate
models (Gui-Ying & Slingo, 2001). Some factors that directly affect
local atmospheric dynamics and cause changes in diurnal precipitation
cycles are orography, relative humidity and thermodynamic processes
(Poveda et al., 2002). Due to its importance, the diurnal cycle of
precipitation has been studied for a long time (Albright, Mock, Recker,
& Reed, 1981; Gray & Jacobson, 1977; McGarry & Reed, 1978). In
Colombia, precipitation has been extensively studied on monthly or
longer periods, while the daytime cycle has been little studied due to
the scarce information available from ground stations until relatively
recently. The studies carried out to date (Bedoya-Soto, Aristizábal,
Carmona, & Poveda, 2019; Mapes, Warner, Xu, & Negri, 2003a, 2003b;
Poveda et al., 2005; Snow, 1976; Suárez-Cobián, 1959; Trewartha, 1981;
Trojer, 1959; Zuluaga et al., 2004) have allowed to recognize fixed
patterns as a bimodal behavior in the diurnal cycle of precipitation in
the western zone of the central mountain range of Colombia, with peaks
in the afternoon and towards midnight, driest periods between 9:00 -
11:00 h, and highly variable cycles between contiguous stations.
To make up for the lack of ground stations that allow such research to
be carried out, the latest studies have concentrated on the use of
satellite or radar information on both cloudiness and precipitation.
Thus, studies regarding the frequency, intensity and diurnal cycle of
rain use satellite information from different sources, such as CMORPH
(Climate Prediction Center Morphing technique), PERSIANN (Precipitation
Estimation from Remotely Sensed Information using Artificial Neural
Networks), TRMM3B42 (Tropical Rainfall Measuring Mission daily and
sub-daily (3hr) averages precipitation), which in turn have been
compared to ground records. The results indicate that the spatial
distribution is comparable on monthly scales, yet diurnal scales deviate
in up to 30% (Dai, Lin, & Hsu, 2007). Rozante et al. (2018) reach
similar conclusions, identifying that the satellites Itegrated
Multi-satellite Retrievals for Global Precipitation Measurement (IMERG)
and Global Satellite Mapping of Precipitation (GSMap) overestimate
diurnal rainfall in northern Brazil when compared to TRMM, reason why
they conclude that the GSMaP satellite could replace the TRMM which will
soon go out of orbit (Rozante, Vila, Barboza Chiquetto, Fernandes, &
Souza Alvim, 2018). Most of these studies have concluded that, in the
tropics, maximum convection or precipitation tends to occur late at
night or in the early morning (Gui-Ying & Slingo, 2001).
Finally, the intra-hourly distribution of precipitation is analyzed by
means of a frequency analysis. The temporal distribution of events is
important because it has been established that the hydrological response
and the maximum peak of runoff flow depend directly on the maximum
intensity of precipitation (Adams & Howard, 1986; Ball, 1994; El-Jabi
& Sarraf, 1991; V. P. Singh, 1997; Šraj, Dirnbek, & Brilly, 2010).
Therefore, adequately estimating the design storm allows to obtain
design floods for hydraulic infrastructure. Design storms must be based
on the dimensionless shapes observed in each particular region, which is
why their analysis has been widely carried out in the USA (Chow,
Maidment, & Mays, 1994) and in different parts of the world using the
data from the registers, in order to replicate design storms for
hydraulic infrastructures (Azli & Rao, 2010; Huff, 1967; S. C. Singh et
al., 2017).
This research aims to characterize the rain events and the diurnal cycle
of precipitation in the city of Manizales, a tropical Andean city,
taking into account the hydrometeorological 2010-2018 data of the city
stations of the network of the Risk Management Unit (IDEA UN Manizales
& CORPOCALDAS, 2015), a network that belongs to the Caldas Integrated
Environmental Monitoring System (SIMAC because of its name in Spanish),
where an effort is being made to improve meteorological information that
allows for this type of analysis. The SIMAC is a recent system and,
although it now has 124 installed hydrometeorological stations, only 13
of these stations allow simultaneous analysis of the last 9 years. It is
very important to highlight that the interannual and multiannual
analysis of climate variability and climate change was not performed,
basically because there are not yet long enough series for a complete
and detailed analysis of this type of variability within Manizales. This
analysis is still relevant given its contribution to the knowledge of
short-term temporal-spatial variability in the city.