EGU General Assembly 2020
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the Creative Commons Attribution 4.0 License.

The coastal El Niño-Event of 2017 in Ecuador and Peru - a weather Radar analysis

Rütger Rollenbeck, Andreas Fries, Jörg Bendix, Johanna Orellana-Alvear, Mario Guallpa, Franz Pucha, Rodolfo Rodriguez, and Rolando Celleri
Rütger Rollenbeck et al.
  • Marburg, Laboratory for Climatology and remote sensing, Geography, Marburg, Germany (

The arid coastal region of Ecuador and Peru belong to the regions experiencing the strongest impact of the El-Niño-Phenomenon. In spite of neutral to cold conditions after the decaying 2015/16 El Niño, unexpected by internationl scientists and local authorities alike, in 2017 the region was hit by torrential rain falls causing floodings, erosion and landslides with many fatalities and significant damage to infrastructure.

RadarNetSur (, initiated in 2012 to 2015 forms the first weather radar network in that region and was capable of monitoring the development of the 2017 event up to its culmination, providing insight into rainfall distribution (resolution of 500 m) on a 5-minute time step. The network consists of 3 X-Band-scanning weather Radars with a range of 60 to 100 km, thus covering 80000 km² from 2° S to 4°S. In 2019 the network was extended far into Peru with a new system in Piura.

We present results of the analysis of the event and compare it to the conditions in the years 2014, 2015 and 2016, to point out spatial patterns and process dynamics, which led to this unusual coastal El-Niño during central Pacific La-Niña conditions. Apparently, the isolated warming of the Niño 1+2 regions off the coast was the main driver of these strong rainfalls, but the local expression of weather patterns is shaped by topographic conditions interacting with the synoptical situation (West wind bursts) and small-scale circulation systems like the sea-breeze and mountain-valley breeze. Most intense rainfall is associated with disturbances in the divergence field which are intensified by changes of the synoptical flow direction.   We assume, that either the conventional understanding of the ENSO-impact on the regional scale is insufficient, or, the ENSO-phenomenon is slowly transitioning into a more complex behavior.

How to cite: Rollenbeck, R., Fries, A., Bendix, J., Orellana-Alvear, J., Guallpa, M., Pucha, F., Rodriguez, R., and Celleri, R.: The coastal El Niño-Event of 2017 in Ecuador and Peru - a weather Radar analysis, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19903,, 2020

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Presentation version 1 – uploaded on 05 May 2020
  • CC1: Comment on EGU2020-19903, Lai Bun Lok, 05 May 2020

    Very interesting presentation. Does your new RNP system offer coverage of the Lobitos region (just above Talara) in Peru ? Which month of 2019 do you have first data from that system ? Many thanks in advance.

    • AC1: Reply to CC1, Rütger Rollenbeck, 05 May 2020

      Yes, Talara is covered by the Radar. We have data from August 2019 till April 2020 - afterwards the Radar is switched off due to lack of rainfall. 

      • CC2: Reply to AC1, Lai Bun Lok, 05 May 2020

        Thank you Rütger. May I kindly contact you directly regarding that data ?

        • AC2: Reply to CC2, Rütger Rollenbeck, 05 May 2020

          of course. Please write to

  • CC3: Comment on EGU2020-19903, Manuel Figueroa, 05 May 2020

    great job! I am wondering if it could be possible to use the radar to quantify the presence or absence of precipitation on the eastern side of the Andes. 
    During this period, some clouds on the eastern side could across to the western side? or this is less probable. Thanks in advance.

    • AC3: Reply to CC3, Rütger Rollenbeck, 05 May 2020

      We will study exactly that. Although we have lesse coverage on the eastern Andean slopes, we still are able to see these spill-over processes. As to how much they contribute to heavy rains is a matter of my current research

      • CC4: Reply to AC3, Manuel Figueroa, 05 May 2020

        Great! I'm interested in the radar data over Loja region because is part of my study area. Is this data available? Because it would be interesting to compare TRMM or CHIRPS rainfall in the last years, isn't it?. Thanks for your display, Rütger.

        • AC4: Reply to CC4, Rütger Rollenbeck, 05 May 2020

          yes, for Loja we have the longest time series, actually since 2002 (although with many long interruptions)

          • AC5: Reply to AC4, Rütger Rollenbeck, 05 May 2020

            For data access please consider writing me an email:

            • CC5: Reply to AC5, Manuel Figueroa, 09 May 2020

              I will. Thank you a lot.