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Modelling and Observation of Mineral Dust Optical Properties over Central Europe

Chilinski M. T., Markowicz K. M., Zawadzka O., Stachlewska I. S., Kumala W., Petelski T., Makuch P., Westphal D. L., Zagajewski B.

Acta Geophysica

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2016

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Vol. 64, no. 6

2550--2590

EN

This paper is focused on Saharan dust transport to Central Europe/ Poland; we compare properties of atmospheric Saharan dust using data from NAAPS, MACC, AERONET as well as observations obtained during HyMountEcos campaign in June 2012. Ten years of dust climatology shows that long-range transport of Saharan dust to Central Europe is mostly during spring and summer. HYSPLIT back-trajectories indicate airmass transport mainly in November, but it does not agree with modeled maxima of dust optical depth. NAAPS model shows maximum of dust optical depth (~0.04-0.05, 550 nm) in April-May, but the MACC modeled peak is broader (~0.04). During occurrence of mineral dust over Central-Europe for 14% (NAAPS) / 12% (MACC) of days dust optical depths are above 0.05 and during 4% (NAAPS) / 2.5% (MACC) of days dust optical depths exceed 0.1. The HyMountEcos campaign took place in June-July 2012 in the mountainous region of Karkonosze. The analysis includes remote sensing data from lidars, sunphotometers, and numerical simulations from NAAPS, MACC, DREAM8b models. Comparison of simulations with observations demonstrates the ability of models to reasonably reproduce aerosol vertical distributions and their temporal variability. However, significant differences between simulated and measured AODs were found. The best agreement was achieved for MACC model.

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Optical properties of long-range transported volcanic ash over Romania and Poland during Eyjafjallajökull eruption in 2010

Nemuc A., Stachlewska I.S., Vasilescu J., Górska A, Nicolae D, Talianu C

Acta Geophysica

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2014

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Vol. 62, no. 2

350--366

EN

After Eyjafjallajökull volcano eruption on 14 April 2010, due to a complex air mass circulation, Romania was exposed to volcanic ash and its mixture with continental aerosols. Ash particles with an average Ångström (UV-VIS) exponent of 1.4 ± 0.2 and (VIS-IR) of 1.2 ± 0.3, a color ratio (VIS-UV) of 0.54 and (IR-VIS) of 0.49, an average particle depolarization value ~9.4%, and a lidar ratio of 50 sr were retrieved on 18 April from multiwavelength Raman lidar measurements in Bucharest. Mixed volcanic ash with mineral dust particles advected from Sahara, depolarization ~12%, Ångström (UV-VIS) exponent of 1.25 ± 0.25 and (VIS-IR) of 1.45 ± 0.25, an increased color ratio (VIS-UV) of 0.61, (IRVIS) of 0.39 and lidar ratio of 53 sr were identified on 28 April. From observations in Poland conducted by an elastic lidar at 532 nm and a ceilometer at 1064 nm we retrieved an average backscatter related Ångström (VIS-IR) exponent of 1.25 ± 0.35, and a color ratio (IR-VIS) of 0.53 in the layer at about 5.5 km during the night of 16/17 April, indicating fresh ash over Warsaw.

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Evaluation of the boundary layer morning transition using the CL-31 ceilometer signals

Sokół P, Stachlewska I.S, Ungureanu I., Stefan S.

Acta Geophysica

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2014

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Vol. 62, no. 2

367--380

EN

The morning transition of the atmospheric boundary layer from nighttime to daytime conditions was investigated using the Vaisala’s CL-31 ceilometer, located at Magurele, Romania (44.35°N, 26.03°E). Based on the 5-days backward trajectories, we rejected those measurements which were related to the intrusions of long-range transported particles. In the several discussed cases, which are representative for the morning transition in spring and summer seasons over Magurele, the increasing depth of the boundary layer related to the local aerosol load was well discernible. The dynamic change of its depth was estimated with errors using a simple method based on finding the minimum of the first derivative of the ceilometer signal. In the summer, the increase of the boundary layer depth due to the morning transition from the nighttime to daytime conditions starts on average of about 80 min earlier and the growth rate of this depth is 143 ± 6 m/h and about 37% slower than in the spring case.

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Obserwacje pyłu wulkanicznego nad Polską w kwietniu 2010 roku

Markowicz K.M., Zawadzka O., Stachlewska I.S.

Przegląd Geofizyczny

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2010

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Z. 3-4

119-143

PL

Celem pracy jest analiza napływu pyłu wulkanicznego nad obszar Polski w połowie kwietnia 2010 r. Wybuch wulkanu Eyjafjoll na Islandii 14 kwietnia spowodował emisję pyłów i gazów do atmosfery, które przesuwały się w kierunku zachodniej i środkowej części Europy. Analiza trajektorii wstecznych pokazała, że pył wulkaniczny pojawił się nad Polską 16 kwietnia. Potwierdziły to obrazy satelitarne wykonane z kompozycji barwnej kanałów w obszarze widzialnym, środkowej oraz dalekiej podczerwieni. Badania własności optycznych pyłów wulkanicznych przeprowadzono w Laboratorium Transferu Radiacyjnego Instytutu Geofizyki UW w Warszawie oraz na Stacji Transferu Radiacyjnego SolarAOT w Strzyżowie na Podkarpaciu. Pomiary prowadzone przy użyciu ceilometru pokazały występowanie aerozolu wulkanicznego w postaci 2-3 warstw do wysokości ok. 5 km nad powierzchnią ziemi. Wyznaczony na podstawie tych pomiarów współczynnik ekstynkcji aerozolu wynosił maksymalnie 0,02-0,03 km-1 (nad ranem 17 kwietnia) dla długości fali 1064 nm. Na ogół jednak przyjmował on znacznie niższe wartości. Obliczona na podstawie profilu ekstynkcji grubość optyczna pyłu wulkanicznego była również niska. Jedynie nad ranem 17 kwietnia osiągała wartości 0,03 w 1064 nm. Niewielkie zawartości pyłu wulkanicznego w pionowej kolumnie atmosfery potwierdzają również pomiary fotometrami słonecznymi w Warszawie i Strzyżowie. W okresie od 17 do 18 kwietnia notowano małe wartość całkowitej grubość optycznej aerozolu, mieszczące się w przedziale 0,11-0,16 (dla 500 nm), podczas gdy średnia klimatyczna wartość grubość optycznej aerozolu w kwietniu wynosi ok. 0,25.

EN

Optical properties of a volcanic aerosol obtained by direct observations from Radiation Transfer Observatory at the Institute of Geophysics University of Warsaw and Aerosol and Radiation Observatory SolarAOT in Strzyżów (south eastern part of Poland) together with Meteosat Second Generation observations are discussed. Aerosol optical properties measured by the Multi-Filter Rotating Shadowband Radiometer (Model MFR-7), Microtops sun photometer, and CHM-15K ceilometer between 14 and 23 April 2010 are investigated . Back-trajectories calculated for 16 and 17 April show advection of air masses from Iceland in the lower and the middle troposphere. Satellite observations performed by the Spinning Enhanced Visible and Infrared Imager (SEVIRI) instrument onboard of the MSG2 confirmed ash over Poland. Unfortunately, cloudy conditions during this day prevented remote observations of the atmosphere's optical properties from the ground. However, surface observations performed on 17 April by the ceilometer indicate volcanic ash layers. At around midnight first ash layer appeared at 5 km. One hour later the second layer between 3 and 4 km was observed. An aerosol layer between 0.5 and 2 km was also measured, however it is difficult to determine the type of remotely sensed particles. After sunset very weak ash clouds were recorded between top of the boundary layer and 4 km. During the day those ash layers were not measured, probably due to a poor signal to noise ratio of the ceilometer's signal. Extinction coefficient for volcanic ash was estimated as 0.02-0.03 km-1 and aero-sol optical thickness was calculated about 0.03 at 1064 nm. Sun photometers' observations at both stations show small total aerosol optical thickness which varies between 0.11 and 0.16 (at 500 nm) during 17 and 18 April 2010. However, the mean aerosol optical thickness for April is about 0.25.