Can we extrapolate climate in an inner basin? The case of the Red Sea

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Highlights

  • The relevance of extrapolating the climate in inner basins is presented.

  • Use of short/long-term regional/global reanalyses to assess future of the Red Sea.

  • Variability of wind and waves in the Red Sea follow Atlantic Multidecadal Oscillation.

  • Reported decreasing trend in the last decades is part of 70-year large-scale cycle.

  • The decreasing trend may overturn in the coming decades.

Abstract

We examine the possibility of making useful climate extrapolations in inner basins. Stressing the role of the local geographic features, for a practical example we focus our attention on the Red Sea. We observe that in spite of being an enclosed and relatively small Sea, its climate conditions are heavily affected by those of the larger neighboring regions, in particular the Mediterranean and the Arabian Seas. Using existing high-resolution information of the recent decades, we use both reasoned extrapolation and knowledge of, past and future, longer term general climatic information to frame what is presently possible to assess for the Red Sea. Specifically, the northern part, influenced by the Mediterranean Sea, shows a clear decreasing trend of both the meteorological and wave conditions in the recent decades. However, within a longer span record of 100 years, this decrease appears to be part of a 70-year cycle, which may be overturning, partly at least, in the coming decades. These trends are consistent with the expectations inferred from regional climatic indices, such as North Atlantic Oscillation and Atlantic Multidecadal Oscillation. No similar long term trend has been found for wave, hence implicitly the wind, conditions in the southern part of the basin. As expected, some correlation exists with the typical patterns of the Indian Ocean, but without any specific indication of a future trend. We suggest that, suitably adapted for the specific local conditions and dominant patterns, similar correlation and physical patterns may exist in several of the enclosed areas of the world, opening the possibility of exploring their possible trends in the future decades.

Section snippets

The basic question

The ever increasing measurement capabilities, particularly from space, coupled with the high quality of the present meteorological models, provide a solid background of the Earth present climate. For instance, global meteorological models, together with various satellite observations, produce a fairly accurate distribution of different weather parameters such as temperature, wind speed, ocean surface waves, etc., in the form of both analyses and short-to-medium range forecasts. For the details

The area of interest

A thorough description of the Red Sea wind and wave characteristics is provided by (Langodan et al., 2014, Langodan et al., 2015, Langodan et al., 2018, henceforth L14, L15 and L18 respectively) out of which we summarize here the information relevant for the present study.

The Red Sea (see Fig. 1) is a slightly more than 2000 km long basin, located between Africa and Asia, extending in a rather straight North-North-West to South-South-East direction (NNW to SSE; henceforth the four cardinal

The available information

Our basic information is the extensive hindcast of the wind and wave conditions described in L18. This hindcast is possibly the best information presently available for the Red Sea. Starting from ERA-I as initial and boundary information, a two-step nested domain, respectively at 30 and 10 km resolution, has been used for daily 36 h runs using an assimilative Weather and Research Forecasting (WRF) model (Skamarock et al., 2008). The first 12 h were considered as spin-up, and the remaining 24 h

What we can say about the future of the Red Sea

The data and trends outlined in the previous section suggest a clear decrease in the number and intensity of the events entering the Red Sea from the Mediterranean since 1979. A milder decrease of the stronger events is present in the S to N systems associated with the NW monsoon in the Arabian Sea, and only minor changes are seen in the Tokar Gap wind. The question is what can we project for the relatively near future, say order of 20–40 years?

The natural thing would be to extrapolate the

General Discussion

The general question we started from is how feasible is to forecast the wind and wave climate in an inner basin for the forthcoming few decades. We purposely focused on the inner seas because their climate is often strongly linked to their geography, and as such, potentially dependent at a critical level on details of the general pattern. This often makes their forecast much more challenging and uncertain than the deriving global fields. As an example, we have investigated the Red Sea, a long

Data availability

The regional reanalysis used in this study could be requested from the corresponding author. All climate indices including Atlantic Multi-decadal Oscillation (AMO) and North Atlantic Oscillation (NAO) are retrieved from National Center for Atmospheric Research (NCAR) climate data guide (https://climatedataguide.ucar.edu/). The global reanalysis ERA-Interim and ERA-20c are retrieved from ECMWF archives.

Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgements

This research was supported by the King Abdulla University of Science and Technology (KAUST) under the virtual Red Sea Initiative (Grant # REP/1/3268-01-01). Sabique Langodan was supported by the General Commission of Survey (GCS), under Project RGC/3/1612-01-01 made by Office of Sponsored research (ORS)/KAUST, Kingdom of Saudi Arabia. Luigi. Cavaleri worked on this subject during a visit to KAUST. He was also supported by the EU contract 730030 (H2020-EO-2016, “CEASELESS”). Jesús Portilla

References (33)

  • D.P. Dee et al.

    The ERA-Interim reanalysis: configuration and performance of the data assimilation system

    Q. J. Roy. Met. Soc.

    (2011)
  • T. Felis et al.

    A coral oxygen isotope record from the northern Red Sea documenting NAO, ENSO, and North Pacific teleconnections on Middle East climate variability since the year 1750

    Paleaoceanography

    (2000)
  • M. Ghil et al.

    Advanced spectral methods for climatic time series

    Rev. Geophys.

    (2002)
  • H. Hersbach

    The ERA5 atmospheric reanalysis

    Am. Geophys. Union Fall Meet.

    (2016)
  • L.H. Holthuijsen

    Waves in Oceanic and Coastal Waters

    (2007)
  • Integrated Forecast System documentation – Cy43r3

    Operational Implementation

  • Cited by (5)

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