COPAS Coastal Center studies the effects of extreme events in the ocean.

The oceanographic campaign was carried out during the month of July in Coliumo Bay, where changes in the coastal ocean during episodes of atmospheric rivers were measured. The results of this study are expected in November of this year.

Currently, little has been studied in Chile on the effects of extreme atmospheric events on the ocean. Changes in precipitation or air temperature, for example, exert a great influence on the population and knowing the impact they can also have on the ocean becomes essential to understand the changes that can arise in it.

Given this, one of the different lines of research that make up the COPAS Coastal Oceanographic Research Center carried out an oceanographic campaign during the month of July to study the effects that atmospheric rivers (ARs) have on the ocean.

To carry out this study, a team of researchers led by Dr. Diego Narváez installed current sensors, temperature, salinity, oxygen and fluorescence in Coliumo Bay. At the same time, a group of researchers led by Dr. Martín Jacques-Coper, was trained in launching weather balloons under the guidance of the Climate and Resilience Research Center – CR2, which serve as a means of transporting a radiosonde, artifact that integrates sensors to monitor meteorological variables, particularly during the occurrence of atmospheric rivers.

atmospheric rivers

But what are atmospheric rivers and what is the importance of studying them? RAs are a weather phenomenon; designate the structure in the atmosphere that transports a considerable amount of water vapor.

They are named in analogy to terrestrial water flows. On an annual average, these happen from 5 to 15 times and are the cause of 50% of the rainfall throughout the Chilean territory. In South America they have a great impact on rainfall and the hydrological cycle; a topic that has emerging research; however, there is currently little information on the effects of this phenomenon in the sea.

“We want to generate information on the influence of atmospheric rivers on the atmosphere, but mainly to know the changes in the physics of the ocean, that is, how the currents, temperature, salinity change and also to know the biological processes that are affected as the oxygen or the marine communities that exist in the coastal zones”, points out Dr. Diego Narváez.

As Dr. Narváez mentions, the campaign also included monitoring of the atmosphere. And it is that something similar, regarding the lack of information, occurs with atmospheric rivers, since several aspects of their structure and dynamics that reach Chile have been studied on a large scale, using data from atmospheric reanalysis and satellite images.

However, these works and data sources do not account for the details at the regional scale and its impacts. This is why the Atmospheric Rivers Observatory, ORA, was implemented some time ago in the Department of Geophysics of the Faculty of Physical and Mathematical Sciences of the University of Concepción.

Regarding this issue, the COPAS Coastal Center researcher, Dr. Martín Jacques, who is also part of CR2, points out that “the interest in monitoring extreme events arises from different groups of researchers; In the case of the COPAS Center, it responds to the need to develop a joint view of the atmosphere and the ocean focused on extreme events.

In particular, we focus on marine and atmospheric heat waves and their interaction, in addition to the influence of atmospheric rivers on oceanographic variables, an aspect that has not been exhaustively addressed and for which we do not have much data. We have the Atmospheric Rivers Observatory, ORA, a joint initiative with several colleagues from atmospheric sciences and led by René Garreaud from CR2, with the aim of complementing our observations and our scientific instruments”, explains Dr. Jacques, also an academic geophysics UdeC.

The study

The group of researchers carried out periods of intense observation of the atmospheric rivers during July. Specifically, they launched radiosondes together with assistants and thesis students to be able to outline the atmosphere, that is, achieve a characterization of the atmospheric conditions during different moments of the evolution of the events. “We did observation of variables not only on the surface, where we typically have weather stations, but also at different levels of the atmosphere and the ocean. In our region, this is an unprecedented campaign to study atmospheric rivers. It will allow us to better understand how these meteorological events operate and develop”, explains Dr. Jacques.

“Approximately 20 atmospheric balloons were launched and we carried out hourly measurements in the ocean at various depths for four weeks; we are now in the stage of analysis of the collected data, the preliminary results of which will be presented in the Congress of Physical Oceanography, Meteorology and Climate of the Southeast Pacific in the month of November”, points out Dr. Narváez.

Valentina Valdés, one of the researchers of this campaign and who is doing a post doctorate at the COPAS Center, points out that “these atmospheric events, both heat waves and atmospheric rivers, have been increasingly recurrent in our country, but they are unknown. the impacts they may have on the water column, so we collect high-frequency data, both physical and biological characteristics of AR events.

In particular, I was in charge of biogeochemical parameters, such as obtaining nutrient samples, primary productivity analysis and the study of microorganisms, which are the ones that mediate biogeochemical cycles in the ocean. To date, we already have some results, however, the analysis of the remaining samples requires time and by the end of the year we could have a large percentage of the data analyzed”, explains the marine biologist.

This campaign continues the challenge assumed by COPAS Coastal in the study of extreme events in the ocean. Let us remember that, at the beginning of this year, the team of researchers carried out measurements on the coasts of the Region, studies that seek to contribute to the understanding of how ecosystems function during extreme events, some of which are expected to be more frequent and more intense due to climate change.