Anomalous scaling of mesoscale tropospheric humidity fluctuations

Water vapor fluctuations are measured and analyzed at an unprecedented 10-m resolution throughout the troposphere. Computation of structure functions shows that specific humidity variations observed by research aircraft over the Pacific Ocean exhibit anomalous scaling from about 50 m to 100 km in ho rizontal range. The scaling laws show different characteristics for the mar ine boundary layer, the tropical free troposphere, and the extratropical fr ee troposphere. More specifically, boundary-layer humidity fluctuations are less smooth and more stationary than those in the free troposphere, while the extratropical free tropospheric variations are less intermittent than t hose in the other two regions. The anomalous scaling results argue against passive advection by a spatially smooth flow (chaotic advection) at these s cales.