Investigation of the diurnal pattern of the vertical distribution of pollen in the lower troposphere using LIDAR

Y M Noh,D Shin,K R Kim,D Mueller,T J Choi,S Shin,H Lee,Y J Choi,K Lee

doi:10.5194/acp-13-7619-2013

Abstract

Abstract. The diurnal pattern of the vertical distribution of biogenic pollen in the lower troposphere was investigated by LIDAR. Meteorological data were taken at the ground. Pollen concentrations were measured at the surface using a Burkard 7-day-recording volumetric spore sampler. Aerosol extinction coefficients and depolarization ratios at 532 nm were obtained from LIDAR measurements in spring (4 May–2 June) 2009 in Gwangju, South Korea. Linear volume depolarization ratios varied between 0.08 and 0.14 and were observed only during daytime (09:00–17:00 local time (LT)) during days of high pollen concentration (4 to 9 May). Daily average pollen concentrations ranged 1000–2500 cm−3 in the same period. The temporal evolution of the vertical distribution of the linear volume depolarization ratio showed a specific diurnal pattern. Linear volume depolarization ratios of more than 0.06, were measured near the surface in the morning. High depolarization ratios were detected up to 2 km aboveground between 12:00 and 14:00 LT, whereas high depolarization ratios were observed only close to the surface after 17:00 LT. Low values of depolarization ratios (≤0.05) were detected after 18:00 LT until the next morning. During the measurement period, the daily variations of the high depolarization ratios close to the surface showed correlation to number concentration measurements of pollen. This finding suggests that high depolarization ratios could be attributed to enhanced pollen concentrations. The diurnal characteristics of the high values of depolarization ratios are thought to be closely associated with turbulent transport. Diurnal and vertical characteristics of pollen, if measured continuously, could be used to improve the accuracy of pollen-forecasting models via data assimilation studies.

Highlights

GeoscientificPollen, which aMre aotmdoespl hDereicvpearltoiclpesmofebniotgenic origin, isM during days of high pollen concentration (4 to 9 May)
The difference of the aerosol optical depth derived from our AERONET sun/sky radiometer and our LIDAR data is less than 10 %
Resolved temperature reduction and potential temperature measured with radiosonde, see Fig. 9, corroborate our assumption that the diurnal pattern of the vertical distribution of pollen was caused by turbulent transport

Summary

Introduction

M during days of high pollen concentration (4 to 9 May). Daily a common cause of allergy-related diseases such as asthma, average pollen concentrations ranged 1000–2500 cm−3 in the rhinitis, and atopic eczema There is convincing evidence that long-range transported pollen can significantly enhance pollen concentrations at both the surface and at elevated altitudes above the receptor sites In these cases, temporally and vertically resolved data of pollen (concentration measurements) are expected to improve the forecasting capability of these models. Experimental data from sampling of pollen aboard aircraft indicates the presence of substantial pollen concentrations at greater heights These results corroborate the hypothesis that recurring meteorological conditions favor vertical exchange and long-range transport of pollen (Mandrioli et al, 1984). The main goal of this study is to understand the vertical characteristics and diurnal patterns of pollen on the basis of the prevailing meteorological conditions via 24 h LIDAR measurements at an urban site during a one-month period when pollen release was most active.

Measurements

Relation of pollen concentration to pollen depolarization ratio

Findings

Conclusions