Estimate of the Arctic Convective Boundary Layer Height from Lidar Observations: A Case Study

L Di Liberto,A Viola,M Maturilli,I Pietroni,F Angelini,G Di Donfrancesco,S Argentini,G Gobbi,R Neuber,F Cairo,M Snels,F Fierli

doi:10.1155/2012/851927

Abstract

A new automated small size lidar system (microlidar or MULID) has been developed and employed to perform aerosol measurements since March 2010 at Ny Ålesund (78.9°N,11.9°E), Svalbard. The lidar observations have been used to estimate the PBL height by using the gradient method based on abrupt changes in the vertical aerosol profile and monitor its temporal evolution. The scope of the present study is to compare several approaches to estimate the PBL height, by using lidar observations, meteorological measurements by radio soundings, and a zero-order one-dimensional model based on a parameterization of the turbulent kinetic energy budget within the mixing layer, under the assumptions of horizontal homogeneity, and neglecting radiation and latent heat effects. A case study is presented here for a convective PBL, observed in June 2010 in order to verify whether the Gradient Method can be applied to lidar measurements in the Arctic region to obtain the PBL height. The results obtained are in good agreement with the PBL height estimated by the analysis of thermodynamic measurements obtained from radio sounding and with the model.

Highlights

There is no region on Earth where the climate is changing faster than in the Arctic
A proper characterization of the Arctic planetary boundary layer (PBL) processes, including the exchange of momentum, heat, moisture, and chemical species between the surface and the free troposphere, is needed for a better understanding of the forcings that drive the changes going on in these regions. In this context the PBL height is an important parameter as it allows to define a scale on which several processes in the Arctic PBL occur
The analysis showed that under suitable conditions the gradient method allows the determination of aerosol layers over the Svalbard region

Summary

Introduction

There is no region on Earth where the climate is changing faster than in the Arctic. Recent studies show that processes in the lower atmosphere are critical for a proper understanding and modelling of Arctic climate change [1,2,3]. A proper characterization of the Arctic PBL processes, including the exchange of momentum, heat, moisture, and chemical species between the surface and the free troposphere, is needed for a better understanding of the forcings that drive the changes going on in these regions. In this context the PBL height is an important parameter as it allows to define a scale on which several processes in the Arctic PBL occur. According to [4], the measurement of tracers concentration is the only direct method allowing the estimate of the PBL height under stable conditions as in such conditions the thermodynamic approach is neither reliable nor well defined

Objectives

Methods

Discussion

Conclusion