Regional downscaled future change of clear‐air turbulence over East Asia under RCP8.5 scenario within the CORDEX‐EA‐II project

Abstract

Driven by four global coupled atmosphere–ocean models (GCMs) from the Coupled Model Intercomparison Project Phase 5 (CMIP5) ensemble (CNRM‐CM5, GFDL‐ESM2M, EC‐EARTH, and MPI‐ESM‐LR), future changes (2040–2059) of clear‐air turbulence (CAT) in winter over East Asia under Representative Concentration Pathway 8.5 (RCP8.5) scenario are projected with the regional climate model (RCM) RegCM4 and 18 CAT diagnostics based on the second phase of Coordinated Regional Downscaling Experiment East Asia (CORDEX‐EA‐II) framework. Evaluation of RegCM4 with ERA‐Interim shows that RegCM4 and diagnostics can well reproduce the spatial distribution of CAT potential. The probability of CAT potential is expected to increase over most East Asia between 35°N and 50°N, Southeast China, western Pacific, and North India in the future. The CAT potential that significantly affects aviation safety shows a remarkable increase over North and Northeast China, part of East China, and Tibet‐Plateau. In the whole domain of East Asia, the multi‐diagnostics ensemble‐average frequency increase is 6.9% for light CAT (with an intra‐ensemble range of 4.1–18%), 9.1% (5.0–24%) for light‐to‐moderate CAT, 12% (5.9–26%) for moderate CAT, 13% (7.2–29%) for moderate‐to‐severe CAT, and 15% (8.5–33%) for severe CAT. Stronger CAT is more likely to happen, which would be a constant threat, although greater scatter exists among these diagnostics, which implies the uncertainties are also significant in the projection.

Clear-air turbulence trends over the North Atlantic in high-resolution climate models

“…Clear-Air Turbulence (CAT) is an upper-level atmospheric phenomenon that has a hazardous and expensive impact on the aviation sector. Atmospheric turbulence is the leading cause (71%) of all in-flight weather-related injuries ( Hu et al 2021) and annually costs the United States of America US$200 million (Williams 2014). CAT usually develops in cloud-free, stably stratified atmospheric environments (Jaeger and Sprenger 2007) and is undetectable using current onboard radar equipment.…”

“…The three latest generations are CMIP3, CMIP5, and CMIP6 (Bock et al 2020). Hu et al (2021), using CMIP5 GCMs for their control state and a regional climate model, found an increase in CAT severities across the South China Sea, with moderate turbulence increasing by 12% over 50 years. Storer et al (2017) also found a significant rise in moderate wintertime CAT across the globe.…”

Influence of airborne LiDAR wavelength on the detection distance of clear air turbulence

“… – 4 With global air traffic and rising concentrations of greenhouse gases (CO2) in the atmosphere, the frequency of CAT will continue to grow, seriously threatening aviation safety 4 – 6 Real-time detection and early warning of CAT have become hot spots in international aviation safety. To ensure enough medium-intensity CAT prewarning time, the detection distance of CAT should be at least 15 km, 7 where no large particles, such as clouds, rain, snow, and hail as carriers, which greatly deteriorates the prediction and detection using traditional approaches (even including the most advanced weather radar) 1 , 8 , 9 .…”