Global Change Abstracts The Swiss Contribution - SCNAT

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50 period 3 (MAP IOP3) and involves convection of intermediate intensity. To assess the underlying mechanisms and the degree of linearity upon the predictability of the flow, vastly different initial perturbation methodologies are compared, while all simulations use identical lateral boundary conditions to mimic a perfectly predictable synoptic-scale flow. Comparison of the perturbation methodologies indicates that the ensuing patterns of ensemble spread converge within 11 h, irrespective of the initial perturbations employed. All methodologies pinpoint the same meso-betascale regions of the flow as suffering from predictability limitations. This result reveals the important role of nonlinearities. Analysis also shows that hot spots of error growth can quickly (1-2 h after initialization) develop far away from the initial perturbations. This rapid radiation of the initial uncertainties throughout the computational domain is due to both sound and gravity waves, followed by the triggering and/or growth of perturbations over regions of convective instability. The growth of the uncertainties is then limited by saturation effects, which in turn are controlled by the larger-scale atmospheric environment. From a practical point of view, it is suggested that the combined effects of rapid propagation, sizeable amplification, and inherent nonlinearities may pose severe difficulties for the design of EPS or data assimilation techniques related to high-resolution quantitative precipitation forecasting. Journal of the Atmospheric Sciences, 2007, V64, N12, DEC, pp 4467-4478. 08.1-37 Upper-tropospheric flow features and the Alps: An overview Hoinka K P, Davies H C Germany, Switzerland Meteorology & Atmospheric Sciences One focus of the Mesoscale Alpine Programme (MAP) was the study of upper-tropospheric potential vorticity (PV) anomalies that take the form of narrow meridionally elongated troughs termed ‘PV streamers’. A systematic effort was undertaken within the MAP framework to: establish a streamer climatology, develop appropriate instrumentation and undertake a measurement programme to better ascertain their structure, study both their intrinsic dynamics and their modification by the Alps, and perform model experiments to examine their significance for numerical weather prediction. Here an overview is given of the progress made toward achieving these objectives. In particular it is shown that PV streamers translating toward the Alpine region are dynamically Global Change Abstracts – The Swiss Contribution | Atmosphere distinctive and constitute an identifiable precursor of and contribute seminally to heavy precipitation events on the south side of the Alps and possess rich mesoscale sub-structures that can be examined with novel water vapour absorption lidar instrumentation. It is also shown that the accurate representation of a streamer might well be a critical prerequisite for accurate quantitative prediction of mesoscale precipitation. Quarterly Journal of the Royal Meteorological Society, 2007, V133, N625, B, APR, pp 847-865. 08.1-38 GEM/POPs: a global 3-D dynamic model for semi-volatile persistent organic pollutants - Part 2: Global transports and budgets of PCBs Huang P, Gong S L, Zhao T L, Neary L, Barrie L A Canada, Switzerland Modelling , Meteorology & Atmospheric Sciences Global transports and budgets of three PCBs were investigated with a 3-D dynamic model for semivolatile persistent organic pollutants - GEM/POPs. Dominant pathways were identified for PCB transports in the atmosphere with a transport flux peaking below 8 km for gaseous and 14 km for particulate PCB28, and peaking below 4 km for gaseous and 6 km for particulate PCB180. The inter-continental transports of PCBs in the Northern Hemisphere (NH) are dominated in the zonal direction with their route changes regulated seasonally by the variation of westerly jet. The transport pathways from Europe and North Atlantic contributed the most PCBs to the Arctic. Inter-hemispheric transports of PCBs originated from the regions of Europe, Asia and North America in three different flow-paths, accompanying with easterly jet, Asian monsoon winds and trade winds. PCBs from the Southern Hemisphere (SH) could also be exported into the NH. According to the PCB emissions of year 2000, Europe, North America and Asia are the three largest sources of the three PCBs, contributing to the global background concentrations in the atmosphere, soil and water. Globally, PCB28 in soil and water has become a comparable source to the anthropogenic emissions while heavier PCBs such as PCB153 and 180 are still transporting into soil and water. For all three congeners, particulate PCBs are concentrated in the higher levels than gaseous PCBs. More than half of the particulate PCB28 could reach up to the stratosphere, while most of the heavier counter-parts (PCB153 and PCB180) are stored in the troposphere including boundary layer with more than 99% gaseous PCB180 below 6 km. Atmospheric Chemistry and Physics, 2007, V7, N15, pp 4015-4025.
Global Change Abstracts – The Swiss Contribution | Atmosphere 51 08.1-39 Validation of Aura Microwave Limb Sounder Ozone by ozonesonde and lidar measurements Jiang Y B, Froidevaux L, Lambert A, Livesey N J, Read W G, Waters J W, Bojkov B, Leblanc T, Mcdermid I S, Godin Beekmann S, Filipiak M J, Harwood R S, Fuller R A, Daffer W H, Drouin B J, Cofield R E, Cuddy D T, Jarnot R F, Knosp B W, Perun V S, Schwartz M J, Snyder W V, Stek P C, Thurstans R P, Wagner P A, Allaart M, Andersen S B, Bodeker G E, Calpini B, Claude H, Coetzee G, Davies J, de Backer H, Dier H, Fujiwara M, Johnson B, Kelder H, Leme N P, Koenig Langlo G, Kyro E, Laneve G, Fook L S, Merrill J, Morris G, Newchurch M, Oltmans S J, Parrondos M C, Posny F, Schmidlin F, Skrivankova P, Stubi R, Tarasick D, Thompson A, Thouret V, Viatte P, Vomel H, von der Gathen P, Yela M, Zablocki G USA, France, Scotland, Netherlands, Denmark, New Zealand, Switzerland, Germany, South Africa, Canada, Belgium, Japan, Brazil, Finland, Italy, Malaysia, Spain, Czech Republic, Poland Meteorology & Atmospheric Sciences , Modelling (1) We present validation studies of MLS version 2.2 upper tropospheric and stratospheric ozone profiles using ozonesonde and lidar data as well as climatological data. Ozone measurements from over 60 ozonesonde stations worldwide and three lidar stations are compared with coincident MLS data. The MLS ozone stratospheric data between 150 and 3 hPa agree well with ozonesonde measurements, within 8% for the global average. MLS values at 215 hPa are biased high compared to ozonesondes by similar to 20% at middle to high latitude, although there is a lot of variability in this altitude region. Comparisons between MLS and ground-based lidar measurements from Mauna Loa, Hawaii, from the Table Mountain Facility, California, and from the Observatoire de Haute-Provence, France, give very good agreement, within similar to 5%, for the stratospheric values. The comparisons between MLS and the Table Mountain Facility tropospheric ozone lidar show that MLS data are biased high by similar to 30% at 215 hPa, consistent with that indicated by the ozonesonde data. We obtain better global average agreement between MLS and ozonesonde partial column values down to 215 hPa, although the average MLS values at low to middle latitudes are higher than the ozonesonde values by up to a few percent. MLS v2.2 ozone data agree better than the MLS v1.5 data with ozonesonde and lidar measurements. MLS tropical data show the wave one longitudinal pattern in the upper troposphere, with similarities to the average distribution from ozonesondes. High upper tropospheric ozone values are also observed by MLS in the tropical Pacific from June to November. Journal of Geophysical Research Atmospheres, 2007, V112, ND24, DEC 15 ARTN: D24S34. 08.1-40 The impact of reducing the maximum speed limit on motorways in Switzerland to 80 km h(-1) on emissions and peak ozone Keller J, Andreani Aksoyoglu S, Tinguely M, Flemming J, Heldstab J, Keller M, Zbinden R, Prevot A S H Switzerland, England Urban Studies , Meteorology & Atmospheric Sciences , Modelling Hot and dry conditions in summer 2003 led to ozone levels that substantially exceeded the Swiss ambient air quality standard. We investigated how emissions and ozone levels would have changed in this period if the maximum speed limit on Swiss motorways were decreased from 120 to 80 km h(-1). The air quality model package MM5 / CAMx was applied to two nested domains, both including Switzerland. Anthropogenic emissions were based on various European and Swiss data sources. The simulations for the reference case were based on current driving behaviour. In the reduction case, nitrogen oxides (NOx) emissions from road traffic were lower by about 4% with respect to the current total NOx release. Emissions of volatile organic compounds (VOC) were not significantly affected. The peak ozone levels decreased by less than 1%. Environmental Modelling Software, 2008, V23, N3, MAR, pp 322-332. 08.1-41 The evolution of ERA-40 surface temperatures and total ozone compared to observed Swiss time series Kunz H, Scherrer S C, Liniger M A, Appenzeller C Switzerland, USA Meteorology & Atmospheric Sciences The aim of this paper is to compare long term changes derived from ERA-40 reanalysis with the corresponding changes found in carefully homogenized observational data. Focus is given on two climate key parameter, daily surface temperature (T2) and total ozone in the Alpine region for the period 1961-2000. Overall the two temperature data sets agree well. The reanalysed temperature trend (0.3 degrees C /decade) is similar to the trend in raw data but underestimates the trend derived from homogenized data by 0.1 degrees C/decade. Differences between ERA-40 and the observations decrease with time. The bias is reduced from +/- 2
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