The impact of climate change on the global coastal low-level wind jets: EC-EARTH simulations

• The impact of a warmer climate in the coastal jets future climate is investigated.
• An ensemble of EC-Earth CMIP5 simulations is used.
• Future projections show an increase of jet heights (wind speed maxima).
• An increase in the frequency of occurrence of some jets is also to be expected.

Coastal low-level jets (CLLJ) are low tropospheric coast-parallel wind features, confined to the marine atmospheric boundary layer, which lay on the east flank of the semi-permanent sub-tropical high-pressure systems, in the mid-latitudes, along equator-ward eastern boundary currents. Coastal jets are of utmost relevance to the regional climate, through their impact on the along coast sea surface temperature, driving the upwelling of cold deep nutrient-rich waters, and by having a decisive impact on the aridity of the mid-latitude western coastal areas. Here the impact of a warmer climate in the CLLJ climate is investigated, through a 2-member ensemble of EC-Earth CMIP5 simulations of future climate, following the RCP8.5 greenhouse gases emissions scenario. Besides the projected changes of the CLLJ, towards the end of the 21st century, the future characteristics of the coastal jets are also presented. No common feature of projected changes in the seven identified CLLJ areas was identified. The Iberian Peninsula and the Oman coastal jets are the ones that presented the highest differences, compared to present climate: highest projected increases in frequency of occurrence, as well as highest projected increases in jet strength (wind speed at the jet height) and jet height. This study presents a step forward towards a larger ensemble of CLLJ projections, required to better assess robustness and uncertainty of potential future climate change.