Three years of routine Raman lidar measurements of tropospheric aerosols: Backscattering, extinction, and residual layer height

Abstract

Abstract.We have performed a three-year series of routine lidar measurements at preselected times. The measurements were performed between 1 December 1997, and 30 November 2000, at Kühlungsborn, Germany (54 • 07 N, 11 • 46 E). Using a Rayleigh/Mie/Raman lidar system, we measured the aerosol backscatter coefficients at three wavelengths and the extinction coefficient at one wavelength. The present data analysis focuses on after-sunset Raman measurements obtained on cloud-free days. Aerosol backscatter profiles are available for altitudes above 100 m, while the majority of the extinction measurements has been restricted to heights above the residual layer. The residual layer shows an annual cycle with its maximum height in summer (2000 m) and minimum height in winter (850 m). The backscatter coefficients in the residual layer were found to be about 10 times higher than above. The mean aerosol optical depth above the residual layer and below 5 km is 0.3(±1.0) × 10 −2 in summer, and 1.5(±1.0) × 10 −2 in winter, which almost is negligible compared to values measured in during daytime in the planetary boundary layer. A cluster analysis of the backward trajectories yielded two major directions of air mass origin above the residual layer and 4 major directions inside. A marked difference between the aerosol properties dependent on the air mass origin could be found for air masses originating from the west and travelling at high wind speeds. Comparing the measured spectral dependence of the backscatter coefficients with data from the Global Aerosol Data Set, we found a general agreement, but only a few conclusions with respect to the aerosol type could be drawn due to the high variability of the measured backscatter coefficients.

Technical Note: One year of Raman-lidar measurements in Gual Pahari EUCAARI site close to New Delhi in India – Seasonal characteristics of the aerosol vertical structure

“…The other locations are Thessaloniki in Greece, Kühlungsborn in Germany and Seoul/Gosan in Republic of Korea. Our annual backscatter values (355, 532 and 1064 nm) near New Delhi were about the double compared to values by Schneider et al (2002) measured in Northern Germany. The south European backscatter (355 and 532 nm) and extinction (355 nm) values measured in Thessaloniki (Amaridis et al, 2005;Giannakaki et al, 2010) were at about the same level as our values.…”

On the spectral dependence of backscatter from cirrus clouds: Assessing CALIOP's 1064 nm calibration assumptions using cloud physics lidar measurements

“…This conclusion was later referenced by Althausen et al [2000] to support the use of a cirrus cloud color ratio of 1 to calibrate the 1064 nm channel of their 6‐wavelength, 11‐channel system. Schneider and Eixmann [2002] also report using an assumed color ratio of 1 for cirrus clouds to calibrate their 1064 nm channel. Taking a slightly different tack, Sugimoto et al [2001] calibrated the 1064 nm data by assuming a color ratio of 1 for water clouds for the 2‐channel lidar aboard the Japanese research ship Mirai.…”

Stratospheric impact of the Chisholm pyrocumulonimbus eruption: 2. Vertical profile perspective

“…Most of the soundings in summer 2001 were performed for tropospheric aerosol detection [ Schneider and Eixmann , 2002], the others for the examination of noctilucent clouds in the mesosphere [ Alpers et al , 2000]. A limited number of observations focus on the UTLS.…”