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Rainfall characteristics over Togo and their related atomospheric circulation anomalies: In Journal of Environmental & Agricultural Sciences, 5:34-48
This study attempts to reveal features of rainfall over Togo, in relationship to the
prevailing atmospheric circulation. The study employed correlation analysis and composite analysis in
the analysis of rainfall, sea surface temperature, wind, and humidity. Empirical orthogonal functions
(EOF) analysis was employed in this study. The years: 1989, 1991, 1995, 2003 and 2007 were
identified to be anomalously wet years while 1982, 1983, 1990, 1992, 2001 and 2006 fall in the
anomalously dry years’ category. The dominant mode of variability exhibits a dipole patter ...
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Global and European climate response to transient forcings since 1870, as simulated in an atmospheric general circulation model
Bichet Adeline - ETH, 2012Predicting and adapting to climate change is one of the major challenges for the twenty-first century. To better understand the future changes in precipitation associated with climate change on the global and regional scale, this thesis investigates, for the past 140 years, the time-varying impact of the major climate forcings on precipitation. To do so, the global climate is simulated between 1870 and 2005 in a transient mode with the atmospheric general circulation model “ECHAM5- HAM”. The model is forced with observationally based time-varying sea surface temperatures (SSTs) and the major ...
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The recent shift in early summer Arctic atmospheric circulation: in Geophysical Research Letters, vol. 39, L19804
The last six years (2007–2012) show a persistent change in early summer Arctic wind patterns relative to previous decades. The persistent pattern, which has been previously recognized as the Arctic Dipole (AD), is characterized by relatively low sea-level pressure over the Siberian Arctic with high pressure over the Beaufort Sea, extending across northern North America and over Greenland. Pressure differences peak in June. In a search for a proximate cause for the newly persistent AD pattern, we note that the composite 700 hPa geopotential height field during June 2007–2012 exhibits a positive ...
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Synergetic monitoring of Saharan dust plumes and potential impact on surface: a case study of dust transport from Canary Islands to Iberian Peninsula
Atmospheric Chemistry and Physics (ACP), Vol. 11. N° 7. Córdoba-Jabonero C.; Sorribas M.; Guerrero-Rascado J.L.; et al. - Copernicus GmbH, 2011The synergetic use of meteorological information, remote sensing both ground-based active (lidar) and passive (sun-photometry) techniques together with backtrajectory analysis and in-situ measurements is devoted to the characterization of dust intrusions. A case study of air masses advected from the Saharan region to the Canary Islands and the Iberian Peninsula, located relatively close and far away from the dust sources, respectively, was considered for this purpose. The observations were performed over three Spanish geographically strategic stations within the dust-influenced area along a co ...
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African biomass burning plumes over the Atlantic: aircraft based measurements and implications for H2SO4 and HNO3 mediated smoke particle activation
Atmospheric Chemistry and Physics (ACP), Vol. 11. N° 7. Fiedler V.; Arnold F.; Ludmann S.; et al. - Copernicus GmbH, 2011Airborne measurements of trace gases and aerosol particles have been made in two aged biomass burning (BB) plumes over the East Atlantic (Gulf of Guinea). The plumes originated from BB in the Southern-Hemisphere African savanna belt. On the day of our measurements (13 August 2006), the plumes had ages of about 10 days and were respectively located in the middle troposphere (MT) at 3900–5500 m altitude and in the upper troposphere (UT) at 10 800–11 200 m. Probably, the MT plume was lifted by dry convection and the UT plume was lifted by wet convection. In the more polluted MT-plume, numerous me ...
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Saharan and Asian dust: similarities and differences determined by CALIPSO, AERONET, and a coupled climate-aerosol microphysical model
This study compares the properties of atmospheric dust from the Saharan deserts and the Asian deserts using data from CALIPSO and AERONET during 2006 and 2007 along with simulations using a coupled climate-microphysical sectional model. Saharan deserts are largely south of 30° N, while Asian ones are primarily north of 30° N, hence they experience different meteorological regimes. Saharan dust lifting occurs all year long, primarily due to subtropical weather systems. However, Asian dust is lifted mostly in spring when mid-latitude frontal systems lead to high winds. Rainfall is more abundant ...
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Understanding the transport of Patagonian dust and its influence on marine biological activity in the South Atlantic Ocean
Atmospheric Chemistry and Physics (ACP), Vol. 11. N° 3. Johnson M.S.; Meskhidze N.; Kiliyanpilakkil V.P.; et al. - Copernicus GmbH, 2011The supply of bioavailable iron to the high-nitrate low-chlorophyll (HNLC) waters of the Southern Ocean through atmospheric pathways could stimulate phytoplankton blooms and have major implications for the global carbon cycle. In this study, model results and remotely-sensed data are analyzed to examine the horizontal and vertical transport pathways of Patagonian dust and quantify the effect of iron-laden mineral dust deposition on marine biological productivity in the surface waters of the South Atlantic Ocean (SAO). Model simulations for the atmospheric transport and deposition of mineral du ...
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Characteristics, sources, and transport of aerosols measured in spring 2008 during the aerosol, radiation, and cloud processes affecting Arctic Climate (ARCPAC) Project
Atmospheric Chemistry and Physics (ACP), Vol. 11. N° 3. Brock C.A.; Cozic J.; Bahreini R.; et al. - Copernicus GmbH, 2011We present an overview of the background, scientific goals, and execution of the Aerosol, Radiation, and Cloud Processes affecting Arctic Climate (ARCPAC) project of April 2008. We then summarize airborne measurements, made in the troposphere of the Alaskan Arctic, of aerosol particle size distributions, composition, and optical properties and discuss the sources and transport of the aerosols. The aerosol data were grouped into four categories based on gas-phase composition. First, the background troposphere contained a relatively diffuse, sulfate-rich aerosol extending from the top of the sea ...
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Mesoscale convective systems observed during AMMA and their impact on the NOx and O3 budget over West Africa
Atmospheric Chemistry and Physics (ACP), Vol. 11. N° 3. Huntrieser H.; Schlager H.; Lichtenstern M.; et al. - Copernicus GmbH, 2011During the "African Monsoon Multidisciplinary Analysis" (AMMA) field phase in August 2006, a variety of measurements focusing on deep convection were performed over West Africa. The German research aircraft Falcon based in Ouagadougou (Burkina Faso) investigated the chemical composition in the outflow of large mesoscale convective systems (MCS). Here we analyse two different types of MCS originating north and south of the intertropical convergence zone (ITCZ, ~10° N), respectively. In addition to the airborne trace gas measurements, stroke measurements from the Lightning Location Network (LINE ...
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Evaluating a 3-D transport model of atmospheric CO2 using ground-based, aircraft, and space-borne data
Atmospheric Chemistry and Physics (ACP), Vol. 11. N° 3. Feng L.; Palmer P.I.; Yang Y.; et al. - Copernicus GmbH, 2011We evaluate the GEOS-Chem atmospheric transport model (v8-02-01) of CO2 over 2003–2006, driven by GEOS-4 and GEOS-5 meteorology from the NASA Goddard Global Modeling and Assimilation Office, using surface, aircraft and space-borne concentration measurements of CO2. We use an established ensemble Kalman Filter to estimate a posteriori biospheric+biomass burning (BS + BB) and oceanic (OC) CO2 fluxes from 22 geographical regions, following the TransCom-3 protocol, using boundary layer CO2 data from a subset of GLOBALVIEW surface sites. Global annual net BS + BB + OC CO2 fluxes over 2004–2006 for ...
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Representation of tropical deep convection in atmospheric models – Part 1: Meteorology and comparison with satellite observations
Atmospheric Chemistry and Physics (ACP), Vol. 11. N° 3. Russo M.R.; Marécal V.; Hoyle C.R.; et al. - Copernicus GmbH, 2011Fast convective transport in the tropics can efficiently redistribute water vapour and pollutants up to the upper troposphere. In this study we compare tropical convection characteristics for the year 2005 in a range of atmospheric models, including numerical weather prediction (NWP) models, chemistry transport models (CTMs), and chemistry-climate models (CCMs). The model runs have been performed within the framework of the SCOUT-O3 (Stratospheric-Climate Links with Emphasis on the Upper Troposphere and Lower Stratosphere) project. The characteristics of tropical convection, such as seasonal c ...
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Origin and radiative forcing of black carbon transported to the Himalayas and Tibetan Plateau
Atmospheric Chemistry and Physics (ACP), Vol. 11. N° 3. Kopacz M.; Mauzerall D.L.; Wang J.; et al. - Copernicus GmbH, 2011The remote and high elevation regions of central Asia are influenced by black carbon (BC) emissions from a variety of locations. BC deposition contributes to melting of glaciers and questions exist, of both scientific and policy interest, as to the origin of the BC reaching the glaciers. We use the adjoint of the GEOS-Chem model to identify the location from which BC arriving at a variety of locations in the Himalayas and Tibetan Plateau originates. We then calculate its direct and snow-albedo radiative forcing. We analyze the seasonal variation in the origin of BC using an adjoint sensitivity ...
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Origin and radiative forcing of black carbon transported to the Himalayas and Tibetan Plateau
Atmospheric Chemistry and Physics (ACP), Vol. 11. N° 3. Kopacz M.; Mauzerall D.L.; Wang J.; et al. - Copernicus GmbH, 2011The remote and high elevation regions of central Asia are influenced by black carbon (BC) emissions from a variety of locations. BC deposition contributes to melting of glaciers and questions exist, of both scientific and policy interest, as to the origin of the BC reaching the glaciers. We use the adjoint of the GEOS-Chem model to identify the location from which BC arriving at a variety of locations in the Himalayas and Tibetan Plateau originates. We then calculate its direct and snow-albedo radiative forcing. We analyze the seasonal variation in the origin of BC using an adjoint sensitivity ...
Carbon Dioxide and Climate : perspectives on a Scientific Assessment
Many of the findings of the Charney Report on CO2 induced climate change (1979) are still valid, despite 30 additional years of climate research and observations. This paper considers the reasons why the report was so prescient, and assesses the progress achieved since its publication. We suggest that emphasis on the importance of physical understanding gained through the use of theory and simple models, both in isolation and as an aid in the interpretation of the results of General Circulation Models, provided much of the authors’ insight at the time. Increased emphasis on these aspects of re ...
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Interannual Variability of Snow Depth over the Tibetan Plateau and Its Associated Atmospheric Circulation Anomalies
The interannual variability of wintertime snow depth over the Tibetan Plateau (TP) and related atmospheric circulation anomalies were investigated based on observed snow depth measurements and NCEP/NCAR reanalysis data. Empirical orthogonal function (EOF) analysis was applied to identify the spatio-temporal variability of wintertime TP snow depth. Snow depth anomalies were dominated by a monopole pattern over the TP and a dipole structure with opposite anomalies over the southeastern and northwestern TP. The atmospheric circulation conditions responsible for the interannual variability of TP s ...
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