Upper-level turbulence in the North American and Asian summer monsoon regions sampled in recent aircraft campaigns

Le résumé fourni par la source

We investigate turbulence encountered above 10 km during two recent field campaigns, the Asian Summer Monsoon Chemical & CLimate Impact Project (ACCLIP) and Dynamics and Chemistry of the Summer Stratosphere (DCOTSS). We find that turbulence in cloud-free air is 1.5-3 times more likely to occur within 100 km of active deep convection, above topography, and above atmospheric jets; strong turbulence occurs 4.5-6 times more often in the same conditions. DCOTSS, sampling outflow from overshooting deep convection over the continental US, encountered turbulence most often near the tropopause. ACCLIP, sampling over the northwestern Pacific, encountered turbulence most often in the upper troposphere. We evaluate turbulence indices from ERA5 and find that total horizontal wind deformation divided by Richardson number is a better diagnostic of non-orographic turbulence than commonly used indices TI1, TI2, and TI3. It diagnoses turbulence that is in-cloud, in cloud-free air near deep convection, and/or strong, particularly well.

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