The Ocean-Land-Atmosphere Model (OLAM) and the Helicopter Observation Platform (HOP):

New Technologies for Environmental Research

Dr. Roni Avissar

Professor and Dean of the Rosenstiel School of Marine and Atmospheric Sciences (RSMAS )

University of Miami


A helicopter was modified and equipped to perform various in situ and remotely-sensed observations. As compared to other aircraft, the helicopter has the unequaled capability of flying slowly and close to the Earth surface. Furthermore, it can land and refuel at station, which allows performing long-term observations during field campaigns, including from a ship at sea. This presents significant advantages especially for the observations of aerosols and turbulent fluxes of heat, water and other gases in the atmospheric boundary layer. The HOP was equipped with high-

frequency sensors that can measure the 3D components of the wind, temperature, moisture and CO2 in the undisturbed air outside of the zone of influence of the main rotor wake. It was designed to support many other remote and in-situ sensors. For example, an elastic lidar was recently built and mounted on the HOP and an atmospheric chemistry package is under development, in collaboration with the National Center for Atmospheric Research (NCAR). While the demonstration phase of the HOP was successfully completed at Duke University, an operational version of this platform is being designed at the Rosenstiel School. It will be based on the considerable experience gained at Duke University.

The Ocean-Land-Atmosphere Model (OLAM) has been developed to extend the capabilities of the Regional Atmospheric Modeling System (RAMS) to a global modeling framework. OLAM is a new model with regard to its dynamic core, grid configuration, memory structure, and numerical solution technique. It solves a finite-volume analog of the full compressible Navier- Stokes equations in conservation form, and exactly conserves mass, momentum, and internal energy. It uses an unstructured grid and pentahedral grid cells (with a triangular footprint), which easily conforms to the sphere without a coordinate transformation. OLAM’s grid configuration enables local mesh refinement to any degree without the need for special grid nesting algorithms; all communication between regions of different resolutions is by conservative advective and diffusive transport. Apart from its dynamic core and grid configuration, OLAM adopts many of the well-established methods that were developed in RAMS, and it uses the same physical

parameterizations for microphysics, land/vegetation water and energy balances, radiative transfer, and sub-grid cumulus convection. OLAM’s capability and sensitivity is demonstrated in weather forecasting and climate modes with the simulation of hurricanes and deforestation of Amazonia, respectively.

While very different technologies, HOP and OLAM complement each other quite well to advance knowledge in boundary-layer processes and, in particular, in the studies of air-sea and land-atmosphere interactions. Furthermore, they could be used simultaneously in a real-time emergency system.