Vertical scaling of temperature, wind and humidity fluctuations: dropsondes from 13 km to the surface of the Pacific Ocean

Abstract

Observational data were taken in the ‘vertical’ structure at 2 Hz from research dropsondes for temperature, wind speed and relative humidity during the ∼800 s it takes to reach the surface from the ∼13 km altitude of the National Oceanic and Atmospheric Administration (NOAA) Gulfstream 4SP aircraft. The observations were made mainly through the depth of the troposphere above the eastern Pacific Ocean from 15° N to 43° N (dropsondes) and 60° N (aircraft) in 2004. Grand averages of some key figures and of probability distribution functions (PDFs) were formed by compounding the data from the Winter Storms Projects 2004, 2005 and 2006, comprising 246, 324 and 315 (some dropped up to 60° N) useable sondes, respectively. This sizeable data set was used to representatively characterize the statistical fluctuations in the ‘vertical’ structure from 13 km to the surface. The fluctuations are resolved at 5–10 m altitude, so covering up to 3 orders of magnitude of typical tropospheric weighting functions for passive remote sounders. Average ‘vertical’ statistical, multifractal, scaling exponents H, C ₁ and α of temperature, wind speed and humidity fluctuations observed at high resolution were computed and are available as potential generators of representative, scale-invariant summaries of the vertical structure of the marine troposphere, for use in design and retrieval of remotely sounded observations.

Acknowledgements

The efforts of the aircrew and staff of the NOAA Aircraft Operations Center are greatly appreciated. We are grateful to the National Weather Service and M. Shapiro for provision of a significant fraction of the flight hours and dropsondes as part of the Winter Storms 2004 Project. We thank O. Cooper, G. Hübler, D. Parrish, E. Ray, K. Rosenlof and D. Sueper of the then NOAA Aeronomy Laboratory, now the Chemical Sciences Division of the NOAA Earth System Research Laboratory, for help with flight planning and instrument installation.