Linking atmospheric circulation patterns with hydro‐geomorphic disasters in Peru

Abstract

The occurrence of El Niño has been generally considered the main driver of hydro‐geomorphic processes in Peru. However, the climatic characterization of hydro‐geomorphic events (HGE) occurring in the absence of El Niño remains scarce. Information contained in the DesInventar disaster database suggests a widespread occurrence of HGE associated to cold‐neutral sea surface temperature (SST) in the central Pacific and south tropical Atlantic. Here, we aim at characterizing synoptic patterns associated with HGE that have occurred over last 35 years related to the different El Niño types and focusing as well on the non‐Niño phases. We use the ERA‐Interim reanalysis climate data and implement self‐organizing maps to assess the link between HGE in Peru and specific synoptic patterns. Results suggest that synoptic patterns associated with La Niña and neutral conditions play an important role in the occurrence of hydro‐geomorphic disasters in Peru during the austral summer. A total of 21% of the events are associated only with the 1972–1973, 1982–1983 and 1997–1998 El Niño events and are mainly focused in the northern Pacific coast of the country (i.e., Tumbes, Piura and Lambayeque) while more than 36% of the recorded events in the database were associated with La Niña and neutral conditions between 1970 and 2013. La Niña‐related events were more relevant in the Andean–Amazonian regions, whereas neutral conditions were related to more frequent HGEs in the southern regions (south of the 13.25°S) along the Peruvian Pacific coast. These outcomes imply an enhanced understanding of the synoptic mechanisms leading to the occurrence of HGE and contribute to a better understanding of the triggers of HGE causing disaster no exclusively related to El Niño‐like years in Peru.

High Impact Weather Events in the Andes

“…Indeed, excessive rainfall over the central and western Amazon have been related to La Niña events, and to warm anomalies in the tropical South Atlantic Ocean (TSA), in association with extreme rainfall and floods, as reported in 2009, 2012 and 2014 (Ronchail et al, 2005;Marengo et al, 2010Marengo et al, , 2011Marengo et al, , 2013Satyamurty et al, 2013). Rodriguez-Morata et al (2018) documented that more than 36% of the hydro-geomorphic disasters reported in Peru during the 1970-2013 period were associated with La Niña and neutral conditions in the equatorial Pacific. The very unusual wet 2014 austral-summer period originated in the eastern slope of the Peruvian and Bolivian Andes and flooded the southern Amazon (Espinoza et al, 2014;Ovando et al, 2016; Figure 13).…”

Large‐Scale Atmospheric Circulation Patterns Associated With U.S. Great Plains Warm Season Droughts Revealed by Self‐Organizing Maps

“…Incorporating more variables into the SOM analysis could also be helpful in providing a more complete picture of drought related fields. For example, 250 hPa wind speed and sea level pressure, as representations for circulation patterns of the upper troposphere and surface, respectively (Loikith et al, ); soil moisture, as an important variable for depicting drought and its long term memory; precipitable water vapor, similar to IVT, can provide information on moisture source, as well as convective instability (Schiro et al, ); outgoing longwave radiation, as proxy for deep convective activities (Rodriguez‐Morata et al, ). However, adding more variables would require a larger sample number for the SOM clustering to converge properly, which can be limited by the availability of the data samples.…”

“…Swales et al () performed SOM analysis on the vertically integrated vapor transport (IVT) field and identified two synoptic settings related to extreme precipitation in the U.S. West. Rodriguez‐Morata et al () characterized synoptic patterns related to hydrogeomorphic processes in Peru with different El Niño types as well as neutral El Niño–Southern Oscillation conditions using a SOM constructed from 200 hPa geopotential and 850 hPa specific humidity fields. Huang et al () constructed a SOM from sea level pressure, sea surface temperature, and surface temperature to investigate the combined effect of Arctic Oscillation and El Niño–Southern Oscillation on the wintertime surface temperature anomalies over East Asia.…”

Two Centuries of Hydroclimatic Variability Reconstructed From Tree‐Ring Records Over the Amazonian Andes of Peru

“…The upper basin of the Peruvian Amazon is highly dependent on the precipitation concentrated during the spring-summer season. Intense precipitation events can cause flooding and landslides, but drought events can result in major loss of economic (i.e., agriculture) activities (Rodríguez-Morata et al, 2018;Young & León, 2009). The precipitation dynamics in the tropical Andes are changing due to rapid global warming and increasing human pressure on the environment.…”