doi:10.1007/s00376-015-5190-8

Caniaux G., H. Giordani, J.-L. Redelsperger, F. Guichard, E. Key, and M. Wade, 2011: Coupling between the Atlantic cold tongue and the West African monsoon in boreal spring and summer. J. Geophys. Res., 116,C04003, doi: 10.1029/2010 JC006570.10.1029/2010JC006570

a0498cda644f9ab3aafb4316d1397f85

http%3A%2F%2Fonlinelibrary.wiley.com%2Fdoi%2F10.1029%2F2010JC006570%2Fcitedby

http://onlinelibrary.wiley.com/doi/10.1029/2010JC006570/citedby[1] The formation of the Atlantic cold tongue (ACT) is the dominant seasonal sea surface temperature signal in the eastern equatorial Atlantic (EEA). A comprehensive analysis of variability in its spatial extent, temperature, and onset is presented. Then, the physical mechanisms which initiate ACT onset, as well as the feedbacks from the ACT to the maritime boundary layer, and how the ACT influences the onset of the West African monsoon (WAM) are discussed. We argue that in the EEA, the air-sea coupling between the ACT and WAM occurs in two phases. From March to mid-June, the ACT results from the intensification of the southeastern trades associated with the St. Helena anticyclone. Steering of surface winds by the basin shape of the EEA imparts optimal wind stress for generating the maximum upwelling south of the equator. During the second phase (mid-June–August), wind speeds north of the equator increase as a result of the northward progression of the intensifying trades and as a result of significant surface heat flux gradients produced by the differential cooling between the ACT and the tropical waters circulating in the Gulf of Guinea (GG). It is anticipated that the atmospheric divergence induced at low levels north of the equator reduces convection over the GG and that increased northward winds shift convection over land. Correlations between the ACT and the WAM onset dates over the last 26 years (1982–2007) measure as much as 0.8. This suggests that the ACT plays a key role in the WAM onset.

Cook K. H., E. K. Vizy, 2006: Coupled model simulations of the West African monsoon system: Twentieth-and twenty-first-century simulations. J.Climate, 19, 3681- 3703.10.1175/JCLI3814.1

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e4f22b101d8a17e25b05fca7095927dd

http%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F2006JCli...19.3681C

refpaperuri:(ef6077c912600934681b37240806f105)

http://adsabs.harvard.edu/abs/2006JCli...19.3681CThe ability of coupled GCMs to correctly simulate the climatology and a prominent mode of variability of the West African monsoon is evaluated, and the results are used to make informed decisions about which models may be producing more reliable projections of future climate in this region. The integrations were made available by the Program for Climate Model Diagnosis and Intercomparison for the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. The evaluation emphasizes the circulation characteristics that support the precipitation climatology, and the physical processes of a 070705rainfall dipole070705 variability mode that is often associated with dry conditions in the Sahel when SSTs in the Gulf of Guinea are anomalously warm. Based on the quality of their twentieth-century simulations over West Africa in summer, three GCMs are chosen for analysis of the twenty-first century integrations under various assumptions about future greenhouse gas increases. Each of these models behaves differently in the twenty-first-century simulations. One model simulates severe drying across the Sahel in the later part of the twenty-first century, while another projects quite wet conditions throughout the twenty-first century. In the third model, warming in the Gulf of Guinea leads to more modest drying in the Sahel due to a doubling of the number of anomalously dry years by the end of the century. An evaluation of the physical processes that cause these climate changes, in the context of the understanding about how the system works in the twentieth century, suggests that the third model provides the most reasonable projection of the twenty-first-century climate.

Cook K. H., E. K. Vizy, 2015: The Congo Basin walker circulation: Dynamics and connections to precipitation. Climate Dyn.,1-21, doi: 10.1007/s00382-015-2864-y.10.1007/s00382-015-2864-y

136b36f36572e2417efe63753f314d76

http%3A%2F%2Flink.springer.com%2F10.1007%2Fs00382-015-2864-y

http://link.springer.com/10.1007/s00382-015-2864-yThe existence, seasonality, and variability of a Congo Basin Walker circulation are investigated in reanalyses, and connections with rainfall are explored. A zonal overturning circulation along the equator connects rising motion in the Congo Basin and sinking in the eastern Atlantic during June through October. This timing is out of phase with precipitation over equatorial Africa, which greatest during spring and fall, and does not correlate with the seasonality of land temperatures. Rather, the zonally-overturning circulation only occurs when the Atlantic cold tongue has formed. Although the cold tongue formation is essential for setting up the Congo Basin Walker circulation, variations in equatorial eastern Atlantic sea surface temperatures are not associated with interannual variability in the strength of the circulation. When cold tongue SSTs are anomalously cool (warm), evaporation from the ocean surface is reduced (enhanced) and the westerly flow advects less (more) moisture into the base of the Congo Basin Walker circulation. This reduces (increases) the release of latent heat in the upbranch and weakens (strengthens) the Walker circulation. This process dominates the pure dry dynamical response to enhanced land/sea temperature differences, which has an opposite sign. A positive correlation connects low-level vertical velocity in the Congo basin with low-level vertical velocity and precipitation over West Africa. A wave response to anomalous vertical velocity in the Congo Basin in several reanalyses suggests a teleconnection into West Africa such that an anomalously strong (weak) upbranch is associated with anomalously strong (weak) rainfall over the Guinean coast and southern Sahel.

Dee D. P., S. Uppala, 2009: Variational bias correction of satellite radiance data in the ERA-Interim reanalysis. Quart. J. Roy. Meteor. Soc. , 135, 1830- 1841.10.1002/qj.493

01d9673d42e38a24b88d2e41f307fdc8

http%3A%2F%2Fonlinelibrary.wiley.com%2Fdoi%2F10.1002%2Fqj.493%2Ffull

http://onlinelibrary.wiley.com/doi/10.1002/qj.493/fullNot Available

Dee D.P., Coruthors, 2011: The ERA-Interim reanalysis: Configuration and performance of the data assimilation system. Quart. J. Roy. Meteor. Soc., 137, 553- 597.10.1002/qj.828

b8698c40-b145-4364-9b39-4e603f942b9f

5e49541e9e977f77d4b4487298c60f84

http%3A%2F%2Fonlinelibrary.wiley.com%2Fdoi%2F10.1002%2Fqj.828%2Fpdf

refpaperuri:(d4649bb38c91f047e85ec096d8587b99)

http://onlinelibrary.wiley.com/doi/10.1002/qj.828/pdfABSTRACT ERA-Interim is the latest global atmospheric reanalysis produced by the European Centre for Medium-Range Weather Forecasts (ECMWF). The ERA-Interim project was conducted in part to prepare for a new atmospheric reanalysis to replace ERA-40, which will extend back to the early part of the twentieth century. This article describes the forecast model, data assimilation method, and input datasets used to produce ERA-Interim, and discusses the performance of the system. Special emphasis is placed on various difficulties encountered in the production of ERA-40, including the representation of the hydrological cycle, the quality of the stratospheric circulation, and the consistency in time of the reanalysed fields. We provide evidence for substantial improvements in each of these aspects. We also identify areas where further work is needed and describe opportunities and objectives for future reanalysis projects at ECMWF. Copyright 2011 Royal Meteorological Society

Dezfuli A. K., S. E. Nicholson, 2013: The relationship of rainfall variability in western equatorial Africa to the tropical Oceans and atmospheric circulation. Part II: The boreal autumn. J. Climate ,26(1), 66-84, doi:10.1175/JCLI-D-11-00686.1.10.1175/JCLI-D-11-00686.1

9a77d767-3332-44f9-98de-d4a4847734fb

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http%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F2013JCli...26...66D

refpaperuri:(dacc155bef59ae7047ba829f3f3ab689)

http://adsabs.harvard.edu/abs/2013JCli...26...66DNot Available

Dezfuli A. K., B. F. Zaitchik, and A. Gnanadesikan, 2015: Regional Atmospheric circulation and rainfall variability in south equatorial Africa. J. Climate,28(2), 809-818, doi: 10.1175/JCLI-D-14-00333.1.10.1175/JCLI-D-14-00333.1

5ec3c773970b31819bf1705a0f738207

http%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F2015JCli...28..809D

http://adsabs.harvard.edu/abs/2015JCli...28..809DNot Available

Fontaine B., P. Roucou, and S. Trzaska, 2003: Atmospheric water cycle and moisture fluxes in the West African monsoon: mean annual cycles and relationship using NCEP/NCAR reanalysis. Geophys. Res. Lett., 30,1117, doi: 10.1029/2002GL 015834.

Grist J. P., S. E. Nicholson, 2001: A study of the dynamic factors influencing the rainfall variability in the west African Sahel. J.Climate, 14, 1337- 1359.567aff7b54b054028090ee7eef0265f4

http%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F2001JCli...14.1337G

/s?wd=paperuri%3A%281288e3bb26ad4ace20cd418d86ca9826%29&filter=sc_long_sign&tn=SE_xueshusource_2kduw22v&sc_vurl=http%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F2001JCli...14.1337G&ie=utf-8

Hagos S. M., K. H. Cook, 2007: Dynamics of the West African monsoon jump. J.Climate, 20, 5264- 5284.29655b2e57a0494216e626a758ee1aa0

http%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F2007JCli...20.5264H

/s?wd=paperuri%3A%28f22b3f331b667173ada996a5e444a1bd%29&filter=sc_long_sign&tn=SE_xueshusource_2kduw22v&sc_vurl=http%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F2007JCli...20.5264H&ie=utf-8

Hagos S. M., C. D. Zhang, 2010: Diabatic heating, divergent circulation and moisture transport in the African monsoon system. Quart. J. Roy. Meteor. Soc., 136, 411- 425.10.1002/qj.538

1b91d740f88de1e94170ba7bb4ee3bf2

http%3A%2F%2Fonlinelibrary.wiley.com%2Fdoi%2F10.1002%2Fqj.538%2Fcitedby

http://onlinelibrary.wiley.com/doi/10.1002/qj.538/citedbyThe dynamics of the West African monsoon system is studied through the diagnosis of the roles of diabatic heating in the divergent circulation and moisture transport. The divergent circulation is partitioned into latent-heating and non-latent-heating (the sum of surface sensible heat flux and radiative heating) driven components based on its field properties and its relationship with diabatic heating profiles. Roles of latent and non-latent diabatic heating in the moisture transport of the monsoon system are thus distinguished. The gradient in surface sensible heat flux between the Saharan heat-low and the Gulf of Guinea drives a shallow meridional circulation, which transports moisture far into the continent on the northern side of the monsoon rain band and thereby promotes the seasonal northward migration of monsoon precipitation. In contrast, the circulation directly associated with latent heating is deep and the corresponding moisture convergence maximum is within the region of precipitation and thus enhances local monsoon precipitation. Meanwhile, latent heating also induces dry air advection from the north. The seasonal northward migration of precipitation is encouraged by neither of the two effects. On the other hand, the divergent circulation forced by remote latent heating influences local moisture distribution through advection. Specifically by bringing Saharan more» air from the north, and driving moisture to the adjacent oceans, global latent heating has an overall drying effect over the Sahel. 芦less

Hastenrath S., 2001: In search of zonal circulations in the equatorial Atlantic sector from the NCEP-NCAR reanalysis. Int. J. Climatol., 21, 37- 47.10.1002/joc.597

5b9adda1-42ca-43ea-a2a5-361ffffcdb6c

16027d67cd7f9d52e52ca45cf5d64bbb

http%3A%2F%2Fonlinelibrary.wiley.com%2Fdoi%2F10.1002%2Fjoc.597%2Fpdf

refpaperuri:(004fa09df041ca92686c82e4cd5f1e27)

http://onlinelibrary.wiley.com/doi/10.1002/joc.597/pdfAbstract The National Center for Environmental Prediction–National Center for Atmospheric Research (NCEP–NCAR) 1958–1997 upper-air dataset has been evaluated for evidence of equatorial zonal circulation cells over the Atlantic and adjacent continents. For January, April, July and October, maps are presented of mid-tropospheric vertical motion, upper-tropospheric divergent flow, and zonal–vertical cross-sections of vertical and divergent zonal motion and total zonal flow. In the boreal winter half-year, a centre of intense ascending motion and upper-tropospheric, mainly northward-directed outflow is located off the mouth of the Amazon. From this centre there is also some outflow into centres of upper-tropospheric convergence and subsidence over the equatorial eastern Pacific and eastern Atlantic, respectively. From January to April, the near-equatorial band of ascending motion shifts southward, and the upper-tropospheric convergence centre is displaced from the Equator into the South Atlantic. In the boreal summer half-year, the band of strongest ascending motion is displaced northward, and two separate centres of upper-tropospheric divergent outflow are found over northern hemispheric Africa and the Central American Seas. From these centres, the outflow is directed approximately southward into the southern hemisphere. The analysis points to the existence of an equatorial zonal circulation cell in the Atlantic sector confined to around January. Copyright 08 2001 Royal Meteorological Society

Hastenrath S., 2006: Circulation and teleconnection mechanisms of northeast Brazil droughts. Prog. Oceanogr., 70, 407- 415.10.1016/j.pocean.2005.07.004

40a792ee34823d232df8f3e5ec2fb481

http%3A%2F%2Fwww.sciencedirect.com%2Fscience%2Farticle%2Fpii%2FS0079661106000565

http://www.sciencedirect.com/science/article/pii/S0079661106000565The Northern Nordeste of Brazil has its short rainy season narrowly concentrated around March-April, when the interhemispheric southward gradient of sea surface temperature (SST) is weakest and the Intertropical Convergence Zone (ITCZ), which is the main rainbearing system for the Nordeste, reaches its southernmost position in the course of the year. The recurrent Secas (droughts) have a severe socio-economic impact in this semi-arid region. In drought years, the pre-season (October-January) rainfall is scarce, the interhemispheric SST gradient weakened and the basin-wide southerly (northerly) wind component enhanced (reduced), all manifestations of an anomalously far northward ITCZ position. Apart from this ensemble of Atlantic indicators, the Secas also tend to be preceded by anomalously warm equatorial Pacific waters in January. During El Nino years, an upper-tropospheric wave train extends from the equatorial eastern Pacific to the northern tropical Atlantic, affecting the patterns of upper-tropospheric topography and divergence, and hence of vertical motion over the Atlantic. The altered vertical motion leads to a weaker meridional pressure gradient on the equatorward flank of the North Atlantic subtropical high, and thus weaker North Atlantic tradewinds. The concomitant reduction of evaporation and wind stirring allows for warmer surface waters in the tropical North Atlantic and thus steeper interhemispheric meridional thermal gradient. Consequently, the ITCZ stays anomalously far North and the Nordeste rainy season becomes deficient.

Hastenrath S., P. J. Lamb, 2004: Climate dynamics of atmosphere and ocean in the equatorial zone: A synthesis. Int. J Climatol., 24, 1601- 1612.10.1002/joc.1086

771a684794a5987e5efc14c606d3cce4

http%3A%2F%2Fonlinelibrary.wiley.com%2Fdoi%2F10.1002%2Fjoc.1086%2Ffull

http://onlinelibrary.wiley.com/doi/10.1002/joc.1086/fullAbstract A synopsis is offered of circulation mechanisms in the oceanic regions of the equatorial zone. Over the eastern Atlantic and Pacific, and especially in boreal summer, cross-equatorial flow from the Southern Hemisphere is strong and induces a tongue of cold surface waters, centred to the south of the equator. Upon crossing the equator in these sectors, owing to the Coriolis effect and a kinetic energy imbalance, the airstream speeds up and divergence develops, producing the Intertropical Divergence Zone (ITDZ). Once these processes result in the wind recurving from southeasterly to southwesterly, the flow slows down and becomes convergent, manifest in the Intertropical Convergence Zone, with a maximum to the south of the wind confluence. By contrast, over the western Atlantic and central Pacific and especially in boreal winter, winds in the equatorial band are predominantly from the east, upper-ocean Ekman transport is directed away from the equator, and the upwelling and cold tongue are centred on the equator. Cross-equatorial flow is insufficient to produce recurvature, the ITDZ is narrower and weaker, the divergence maximum is at the equator rather than in low northern latitudes, and the convergence maximum straddles the wind confluence. Over the Indian Ocean, the wind field is dominated by the alternation between the predominantly meridional flow of the winter and summer monsoons. Equatorial westerlies are limited to the short monsoon transition seasons. Essential for their origin is an eastward pressure gradient along the equator and weak southern trade winds, allowing recurvature somewhat south of the equator. Because the zonal pressure gradient is strongest in boreal summer and the southern trade winds are weakest in austral summer, the equatorial westerlies peak in spring and autumn. The boreal autumn equatorial westerlies are the surface manifestation of a powerful zonal-搗ertical circulation cell along the Indian Ocean equator. Equatorial zonal-搗ertical circulation cells require well-developed zonal flow in the lower troposphere along the equator and, therefore, appear confined to the oceanic longitudes and certain seasons. Thus, they are found over the Atlantic only in boreal winter and over the Indian Ocean only in boreal autumn, whereas over the Pacific they prevail all year round. Copyright 2004 Royal Meteorological Society

Hastenrath S., D. Polzin, 2011: Long-term variations of circulation in the tropical Atlantic sector and Sahel rainfall. Int. J.Climatol, 31, 649- 655.10.1002/joc.2116

771f776158fb7be9fa5cb4295d11c095

http%3A%2F%2Fonlinelibrary.wiley.com%2Fdoi%2F10.1002%2Fjoc.2116%2Ffull

http://onlinelibrary.wiley.com/doi/10.1002/joc.2116/fullNot Available

Kanamitsu M., W. Ebisuzaki, J. Woollen, S. K. Yang, J. J. Hnilo, M. Fiorino, G. L. Potter, 2002: NCEP-DOE AMIP-II Reanalysis (R-2). Bull. Amer. Meteor. Soc., 83, 1631- 1643.10.1175/BAMS-83-11-1631

5c7a839e-57c1-4179-b341-b2c9ae942077

78d2ebdd4f6e4bb53b655ae6ada98518

http://www.researchgate.net/publication/234022105_Ncep-Doe_Amip-Ii_Reanalysis_(R-2)

http://www.researchgate.net/publication/234022105_Ncep-Doe_Amip-Ii_Reanalysis_(R-2)Abstract The NCEP–DOE Atmospheric Model Intercomparison Project (AMIP-II) reanalysis is a follow-on project to the “50-year” (1948-present) NCEP-NCAR Reanalysis Project. NCEP–DOE AMIP-II reanalysis covers the “20-year” satellite period of 1979 to the present and uses an updated forecast model, updated data assimilation system, improved diagnostic outputs, and fixes for the known processing problems of the NCEP-NCAR reanalysis. Only minor differences are found in the primary analysis variables such as free atmospheric geopotential height and winds in the Northern Hemisphere extratropics, while significant improvements upon NCEP-NCAR reanalysis are made in land surface parameters and land-ocean fluxes. This analysis can be used as a supplement to the NCEP-NCAR reanalysis especially where the original analysis has problems. The differences between the two analyses also provide a measure of uncertainty in current analyses.

Kobayashi S., M. Matricardi, D. Dee, and S. Uppala, 2009: Toward a consistent reanalysis of the upper stratosphere based on radiance measurements from SSU and AMSU-A. Quart. J. Roy. Meteor. Soc., 135, 2086- 2099.10.1002/mus.24302

f3312e55-739c-4129-93b8-ba51686ce2aa

d600ee51b7a586f5976f9e62afa2ea3f

http%3A%2F%2Fonlinelibrary.wiley.com%2Fdoi%2F10.1002%2Fqj.514%2Fabstract

refpaperuri:(6a8717575217f5473b1fcfa149121df4)

http://onlinelibrary.wiley.com/doi/10.1002/qj.514/abstractRecessive mutations in the anoctamin-5 gene (ANO5) cause a spectrum of clinical phenotypes, including limb-girdle muscular dystrophy (LGMD 2L), distal myopathy, and asymptomatic hyperCKemia.In this report we describe our clinical, electrophysiological, pathological, and molecular findings in a subject with anoctaminopathy-5.A 49-year-old Arabic man from a consanguineous family presented with a 5-year history of myalgias, hyperCKemia and an episode of unprovoked rhabdomyolysis. Muscle biopsy showed mild myopathic changes and interstitial amyloid deposition. ANO5 analysis detected a novel homozygous deletion of approximately 11.9 kb encompassing exons 13-17, predicted to be pathogenic.Anoctaminopathy-5 can manifest with a phenotype reminiscent of metabolic myopathy and should be considered as a potential cause of myalgia and myoglobinuria. Amyloid deposition in the muscle biopsy is helpful for the diagnosis. A novel homozygous ANO5 deletion was identified, suggesting that screening for common mutations may have low yield in non-European subjects.

Kummerow C., W. Barnes, T. Kozu, J. Shiue, and J. Simpson, 1998: The Tropical Rainfall Measuring Mission (TRMM) sensor package. J. Atmos. Oceanic Technol., 15, 809- 817.10.1175/1520-0426(1998)0152.0.CO;2

02df23a3fe3170d74ba8b7f7319d789c

http%3A%2F%2Flink.springer.com%2Farticle%2F10.1007%2FBF01029783

http://onlinelibrary.wiley.com/doi/10.1002/9780471743989.vse10190/pdfAbstract This note is intended to serve primarily as a reference guide to users wishing to make use of the Tropical Rainfall Measuring Mission data. It covers each of the three primary rainfall instruments: the passive microwave radiometer, the precipitation radar, and the Visible and Infrared Radiometer System on board the spacecraft. Radiometric characteristics, scanning geometry, calibration procedures, and data products are described for each of these three sensors.

Lau K.-M., S. Yang, 2003: Walker circulation. Encyclopedia of Atmospheric Sciences, J. R. Holton et al., Eds., Academic Press, 2505- 2510.10.1016/B0-12-227090-8/00206-2

f48afdea164b98c3221bafb5a5783ed7

http%3A%2F%2Fwww.sciencedirect.com%2Fscience%2Farticle%2Fpii%2FB0122270908004504

http://www.sciencedirect.com/science/article/pii/B0122270908004504The term Walker Circulation was first introduced in 1969 by Professor Jacob Bjerknes, referring to the large-scale atmospheric circulation along the longitude–height plane over the equatorial Pacific Ocean. The Walker Circulation features low-level winds blowing

Leduc-Leballeur M., G. de Coëtlogon, and L. Eymard, 2013: Air-Sea interaction in the Gulf of Guinea at intraseasonal time-scales: Wind bursts and coastal precipitation in boreal spring. Quart. J. Roy. Meteor. Soc.,139, 387-400, doi: 10.1002/qj. 1981.10.1002/qj.1981

a528d354-6df6-4dca-b25d-7417a261cd5e

9c8cd99b82e6380de65e7ee3520d2a18

http%3A%2F%2Fonlinelibrary.wiley.com%2Fdoi%2F10.1002%2Fqj.1981%2Fcitedby

refpaperuri:(24b7d4f9460dec71cb85abbfb0677be8)

http://onlinelibrary.wiley.com/doi/10.1002/qj.1981/citedbyThe differences in substrate specificity between Moloney murine leukemia virus protease (MuLV PR) and human immunodeficiency virus (HIV) PR were investigated by site-directed mutagenesis. Various amino acids, which are predicted to form the substrate binding site of MuLV PR, were replaced by the equivalent ones in HIV-1 and HIV-2 PRs. The expressed mutants were assayed with the substrate Val-Ser-Gln-Asn-Tyr decreases Pro-Ile-Val-Gln-NH2 (decreases indicates the cleavage site) and a series of analogs containing single amino acid substitutions in positions P4(Ser) to P3'(Val). Mutations at the predicted S2/S2' subsites of MuLV PR have a strong influence on the substrate specificity of this enzyme, as observed with mutants H37D, V39I, V54I, A57I, and L92I. On the other hand, substitutions at the flap region of MuLV PR often rendered enzymes with low activity (e.g. W53I/Q55G). Three amino acids (His-37, Val-39, and Ala-57) were identified as the major determinants of the differences in substrate specificity between MuLV and HIV PRs.

Lèlè, M. I., L. M. Leslie, P. J. Lamb, 2015: Analysis of low-level atmospheric moisture transport associated with the West African monsoon. J. Climate,28, 4414-4430, doi: 10.1175/ JCLI-D-14-00746.1.10.1175/JCLI-D-14-00746.1

df83cab38a308d25543db63c38d4a2bf

http%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F2015JCli...28.4414L

http://adsabs.harvard.edu/abs/2015JCli...28.4414LNot Available

Liebmann B., C. A. Smith, 1996: Description of a complete (interpolated) outgoing longwave radiation dataset. Bull. Amer. Meteor. Soc., 77, 1725- 1277.10.1175/1520-0477(1996)077<1255:EA>2.0.CO;2

46195721fc13ece74e8aabcae421f366

http%3A%2F%2Fci.nii.ac.jp%2Fnaid%2F10010122825%2F

http://ci.nii.ac.jp/naid/10010122825/Description of a complete (interpolated) outgoing longwave radiation dataset LIEBMANN B. Bull. Amer. Meteor. Soc. 77, 1275-1277, 1996

Mitchell T. D., P. D. Jones, 2005: An improved method of constructing a database of monthly climate observations and associated high-resolution grids. Int. J. Climatol.,25, 693-712, doi: 10.1002/joc.1181.10.1002/joc.1181

fde1a91db2d30a9d77329dd7148d4007

http%3A%2F%2Fonlinelibrary.wiley.com%2Fdoi%2F10.1002%2Fjoc.1181%2Ffull

http://onlinelibrary.wiley.com/doi/10.1002/joc.1181/fullThe station anomalies are interpolated onto a 0.5° grid covering the global land surface (excluding Antarctica) and combined with a published normal from 1961–90. Thus, climate grids are constructed for nine climate variables (temperature, diurnal temperature range, daily minimum and maximum temperatures, precipitation, wet-day frequency, frost-day frequency, vapour pressure, and cloud cover) for the period 1901–2002. This dataset is known as CRU TS 2.1 and is publicly available ( TODO: clickthrough URL http://www.cru.uea.ac.uk/ ). Copyright 08 2005 Royal Meteorological Society

Neupane N., K. H. Cook, 2013: A nonlinear response of Sahel rainfall to Atlantic warming. J. Climate,26, 7080-7096, doi: 10.1175/JCLI-D-12-00475.1.10.1175/JCLI-D-12-00475.1

810f8c1463067ee3713c65dcc74bb237

http%3A%2F%2Fwww.researchgate.net%2Fpublication%2F260183542_A_Nonlinear_Response_of_Sahel_Rainfall_to_Atlantic_Warming

http://www.researchgate.net/publication/260183542_A_Nonlinear_Response_of_Sahel_Rainfall_to_Atlantic_WarmingAbstract The response over West Africa to uniform warming of the Atlantic Ocean is analyzed using idealized simulations with a regional climate model. With warming of 1 and 1.5 K, rainfall rates increase by 30%-50% over most of West Africa. With Atlantic warming of 2 K and higher, coastal precipitation increases but Sahel rainfall decreases substantially. This nonlinear response in Sahel rainfall is the focus of this analysis. Atlantic warming is accompanied by decreases in low-level geopotential heights in the Gulf of Guinea and in the large-scale meridional geopotential height gradient. This leads to easterly wind anomalies in the central Sahel. With Atlantic warming below 2 K, these easterly anomalies support moisture transport from the Gulf of Guinea and precipitation increases. With Atlantic warming over 2 K, the easterly anomalies reverse the westerly flow over the Sahel. The resulting dry air advection into the Sahel reduces precipitation. Increased low-level moisture provides moist static energy to initiate convection with Atlantic warming at 1.5 K and below, while decreased moisture and stable thermal profiles suppress convection with additional warming. In all simulations, the southerly monsoon flow onto the Guinean coast is maintained and precipitation in that region increases. The relevance of these results to the global warming problem is limited by the focus on Atlantic warming alone. However, confident prediction of climate change requires an understanding of the physical processes of change, and this paper contributes to that goal.

Nicholson S. E., P. J. Webster, 2007: A physical basis for the interannual variability of rainfall in the Sahel. Quart. J. Roy. Meteor. Soc., 133, 2065- 2084.10.1002/qj.104

6752bfa5b6222a75f092b1f67394abda

http%3A%2F%2Fonlinelibrary.wiley.com%2Fdoi%2F10.1002%2Fqj.104%2Fcitedby

http://onlinelibrary.wiley.com/doi/10.1002/qj.104/citedbyAbstract A major factor in rainfall variability over Sahelian West Africa is the latitudinal location of the tropical rainbelt. When it is displaced abnormally far northward, the Sahel experiences a wet year. An anomalous southward displacement results in drought. In this paper we examine the question of what controls the location during the boreal summer, hypothesizing that inertial instability plays a role. An analysis of surface pressure and temperature fields, wind fields, divergence and vertical motion show that the criteria for inertial instability are satisfied in wet Augusts but not in dry ones. The key determinant appears to be the surface pressure gradient between the continent and the equatorial Atlantic. When this is large, inertial instability results in the development of a low-level westerly jet. The presence of this jet enhances the horizontal and vertical shear, and displaces the African Easterly Jet northwestward. Associated with this situation is strong vertical motion over the Sahel and subsidence over the Guinea Coast, producing dry conditions over the latter. The result is a rainfall dipole, one of two major modes of variability over West Africa. Important factors include sea surface temperatures (SSTs) in the equatorial Atlantic and pressure in the South Atlantic. The first of these factors suggests a link with the Atlantic Niño mode of tropical Atlantic variability; while the second suggests a possible link with the Pacific and the extratropical South Atlantic. Overall, our study relates the well-known SST influence on Sahel rainfall to atmospheric dynamics over the continent. Copyright 2007 Royal Meteorological Society

Nicholson S. E., A. K. Dezfuli, 2013: The relationship of rainfall variability in western equatorial Africa to the tropical Oceans and atmospheric circulation. Part I: The boreal spring. J. Climate,26(1), 45-65, doi: 10.1175/JCLI-D-11-00653.1.10.1175/JCLI-D-11-00653.1

cbd8edfdf20768905b20bd52de7e28ed

http%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F2013JCli...26...45N

http://adsabs.harvard.edu/abs/2013JCli...26...45NNot Available

Nolan D. S., C. D. Zhang, and S. H. Chen, 2007: Dynamics of the shallow meridional circulation around intertropical convergence zones. J. Atmos. Sci., 64, 2262- 2285.10.1175/JAS3964.1

09761fd3571d321282570e38c4281e8d

http%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F2007JAtS...64.2262N

http://adsabs.harvard.edu/abs/2007JAtS...64.2262NThe generally accepted view of the meridional circulation in the tropical east Pacific is that of a single deep overturning cell driven by deep convective heating in the intertropical convergence zone (ITCZ), similar to the zonal mean Hadley circulation. However, recent observations of the atmosphere from the tropical eastern Pacific have called this view into question. In several independent datasets, significant meridional return flows out of the ITCZ region were observed, not only at high altitudes, but also at low altitudes, just above the atmospheric boundary layer. This paper presents a theory and idealized simulations to understand the causes and dynamics of this shallow meridional circulation (SMC). Fundamentally, the SMC can be seen as a large-scale sea-breeze circulation driven by sea surface temperature gradients when deep convection is absent in the ITCZ region. A simple model of this circulation is presented. Using observed values, the sea-breeze model shows that the pressure gradient above the boundary can indeed reverse, leading to the pressure force that drives the shallow return flow out of the ITCZ. The Weather Research and Forecast Model (WRF) is used to simulate an idealized Hadley circulation driven by moist convection in a tropical channel. The SMC is reproduced, with reasonable similarity to the circulation observed in the east Pacific. The simulations confirm that the SMC is driven by a reversal of the pressure gradient above the boundary layer, and that the return flow is strongest when deep convection is absent in the ITCZ, and weakest when deep convection is active. The model also shows that moisture transport out of the ITCZ region is far greater in the low-level shallow return flow than in the high-altitude return flow associated with the deep overturning, and that a budget for water transport in and out of the ITCZ region is grossly incomplete without it. Much of the moisture carried in the shallow return flow is recycled into the boundary layer, but does not appear to contribute to enhanced cloudiness in the subtropical stratocumulus poleward of the ITCZ.

Pokam W. M., L. A. T. Djiotang, and F. K. Mkankam, 2012: Atmospheric water vapor transport and recycling in equatorial central Africa through NCEP/NCAR reanalysis data. Climate Dyn.,38(9-10), 1715-1729, doi: 10.1007/s00382-011-1242-7.10.1007/s00382-011-1242-7

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refpaperuri:(3f1ae46e0077538bb0367c242924468d)

http://www.springerlink.com/content/2586020245791t5w/Erratum to: Clim Dyn (2012) 38:1715–1729 DOI 10.1007/s00382-011-1242-7 In the original publication of this article, the research centre was incorrectly published as National Center for Environmental Prediction-National Center search (NCEP-), and it should read as National Center for Environmental Prediction- National Center for Atmospheric Research (NCEP-NCAR). In the methodology section, there are errors in the expressions of the net zonal water vapor flux, and the net meridional water vapor flux in Eq.023. The correct expressions are used for the calculations as follows: ...Erratum to: Clim Dyn (2012) 38:1715–1729 DOI 10.1007/s00382-011-1242-7In the original publication of this article, the research centre was incorrectly published as National Center for Environmental Prediction-National Center search (NCEP-), and it should read as National Center for Environmental Prediction- National Center for Atmospheric Research (NCEP-NCAR). In the methodology section, there are errors in the expressions of the net zonal water vapor flux, and the net meridional water vapor flux in Eq.023. The correct expressions are used for the calculations as follows: ...National Center for Atmospheric Research

Pokam W. M., C. L. Bain, R. S. Chadwick, R. Graham, D. J. Sonwa, and F. M. Kamga, 2014: Identification of processes driving low-level westerlies in west equatorial Africa. J. Climate,27(11), 4245-4262, doi: 10.1175/JCLI-D-13-00490.1.10.1175/JCLI-D-13-00490.1

46ebf285f97b805adc7bc62c50b1d5fb

http%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F2014JCli...27.4245W

http://adsabs.harvard.edu/abs/2014JCli...27.4245WNot Available

Pu B., K. H. Cook, 2010: Dynamics of the West African westerly jet. J.Climate, 23( 23), 6263- 6276.10.1175/2010JCLI3648.1

2189e27427c98b12075c96c1927695d6

http%3A%2F%2Fwww.cabdirect.org%2Fabstracts%2F20113025976.html

http://www.cabdirect.org/abstracts/20113025976.htmlThe West African westerly jet (WAWJ) is a low-level westerly jet located at 800°00°--1100°00°N over the eastern Atlantic and the West African coast. It is clearly distinguished from the monsoon westerly flow by its structure and dynamics, and plays an important role in transporting moisture from the tropical eastern Atlantic to Sahelian West Africa during boreal summer. The WAWJ develops in early June, sustains maximum wind speeds of 5--6 m s0903’0903’1 from late July to early September, and weakens and dissipates by mid-October. In its mature stage, the WAWJ is located within the Atlantic ITCZ. It extends from the surface to 700 hPa, with maximum speed at 925 hPa. The jet has a weak semidiurnal cycle, with maxima at 0500 and 1700 local time. A momentum budget analysis reveals that the WAWJ forms when a region of strong westerly acceleration is generated by the superposition of the Atlantic ITCZ and the westward extension of the continental thermal low. The WAWJ is supergeostrophic at its maximum, with zonal pressure gradient and Coriolis accelerations both pointing eastward. While much of the WAWJ''s seasonal variation can be explained by the geostrophic wind, the ageostrophic wind contributes more than 40%% of the wind speed during the jet''s formation and demise. The westward extension of the thermal low is associated with the formation of an offshore low, which is related to seasonal warming of the ocean between 600°00° and 1800°00°N along the coast. The coastal SSTs vary in response to a net surface heating pattern with warming to the north and cooling to the south, which is mainly controlled by solar radiative and latent heat fluxes.

Rienecker, M. M., Coruthors, 2011: MERRA: NASA's modern-era retrospective analysis for research and applications. J.Climate, 24, 3624- 3648.cf3a4d0c-8914-4e1b-8bb6-9247305836fc

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Segele Z.T., P. J. Lamb, and L. M. Leslie, 2009: Large-scale atmospheric circulation and global sea surface temperature associations with Horn of Africa June-September rainfall. Int. J. Climatol., 29( 8), 1075- 1100.53c6808b98ca26dbd22040ed19ad8f26

http%3A%2F%2Fonlinelibrary.wiley.com%2Fdoi%2F10.1002%2Fjoc.1751%2Fpdf

http://onlinelibrary.wiley.com/doi/10.1002/joc.1751/pdfVirtual worlds have become very popular and there have been some attempts to find the motivations and experiences of using them. The aim of this paper is to analyze the motivations and experiences of young ones to utilize virtual worlds. The paper identifies the activities that children perform in virtual worlds, features they use as well as the reasons for abandoning these virtual worlds. The paper presents results of a qualitative field study. The results indicate that features that are liked in the virtual worlds are similar to games. The most liked features for virtual worlds were developing characters and doing things in groups. The activities that were liked the most in virtual worlds were: chatting or doing different things with friends; playing games; and exploring new places. The main reasons to abandon virtual worlds were increased needs for social networking and better gaming experiences. Students showed interest in using games and virtual worlds at schools, but were generally rather skeptic about this possibility.

Simmons A., S. Uppala, D. Dee, and S. Kobayashi, 2007: ERA-Interim: New ECMWF Reanalysis Products from 1989 Onwards. ECMWF Newsletter, No.110, ECMWF, Reading, United Kingdom, 25- 35.692dbc73384cbfc47f478aef876388c3

http%3A%2F%2Fwww.researchgate.net%2Fpublication%2F255267047_ERA-Interim_New_ECMWF_reanalysis_products_from_1989_onwards

http://www.researchgate.net/publication/255267047_ERA-Interim_New_ECMWF_reanalysis_products_from_1989_onwards

Simmons A.J., K. M. Willett, P. D. Jones, P. W. Thorne, and D. P. Dee, 2010: Low-frequency variations in surface atmospheric humidity, temperature, and precipitation: Inferences from reanalyses and monthly gridded observational data sets. Journal of Geophysical Research: Atmospheres (1984-2012), 115,D01110, doi:10.1029/2009JD012442.10.1029/2009JD012442

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http%3A%2F%2Fonlinelibrary.wiley.com%2Fdoi%2F10.1029%2F2009JD012442%2Ffull

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http://onlinelibrary.wiley.com/doi/10.1029/2009JD012442/fullEvidence is presented of a reduction in relative humidity over low-latitude and midlatitude land areas over a period of about 10 years leading up to 2008, based on monthly anomalies in surface air temperature and humidity from comprehensive European Centre for Medium-Range Weather Forecasts reanalyses (ERA-40 and ERA-Interim) and from Climatic Research Unit and Hadley Centre analyses of monthly station temperature data (CRUTEM3) and synoptic humidity observations (HadCRUH). The data sets agree well for both temperature and humidity variations for periods and places of overlap, although the average warming over land is larger for the fully sampled ERA data than for the spatially and temporally incomplete CRUTEM3 data. Near-surface specific humidity varies similarly over land and sea, suggesting that the recent reduction in relative humidity over land may be due to limited moisture supply from the oceans, where evaporation has been limited by sea surface temperatures that have not risen in concert with temperatures over land. Continental precipitation from the reanalyses is compared with a new gauge-based Global Precipitation Climatology Centre (GPCC) data set, with the combined gauge and satellite products of the Global Precipitation Climatology Project (GPCP) and the Climate Prediction Center (CPC), Merged Analysis of Precipitation (CMAP), and with CPC's independent gauge analysis of precipitation over land (PREC/L). The reanalyses agree best with the new GPCC and latest GPCP data sets, with ERA-Interim significantly better than ERA-40 at capturing monthly variability. Shifts over time in the differences among the precipitation data sets make it difficult to assess their longer-term variations and any link with longer-term variations in humidity.

Sorooshian S., K.-L. Hsu, X. G. Gao, H. V. Gupta, B. Imam, and D. Braithwaite, 2000: Evaluation of PERSIANN system satellite-based estimates of tropical rainfall. Bull. Amer. Meteor. Soc., 81, 2035- 2046.8d9965525054746645fe7c5ca0ca8ce4

http%3A%2F%2Fwww.bioone.org%2Fservlet%2Flinkout%3Fsuffix%3Dbibr10%26dbid%3D16%26doi%3D10.5814%252Fj.issn.1674-764x.2012.04.009%26key%3D10.1175%252F1520-0477%282000%29081%3C2035%253AEOPSSE%3E2.3.CO%253B2

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Thorncroft C. D., M. Blackburn, 1999: Maintenance of the African easterly jet. Quart. J. Roy. Meteor. Soc., 125, 763- 786.10.1017/S0025315400011978

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http%3A%2F%2Fonlinelibrary.wiley.com%2Fdoi%2F10.1002%2Fqj.49712555502%2Fpdf

refpaperuri:(108a9c787d09d78ce00164a8cfee8d35)

http://onlinelibrary.wiley.com/doi/10.1002/qj.49712555502/pdfNot Available

Thorncroft C. D., H. Nguyen, C. D. Zhang, and P. Peyrillè, 2011: Annual cycle of the West African monsoon: Regional circulations and associated water vapour transport. Quart. J. Roy. Meteor. Soc., 137, 129- 147.10.1002/qj.728

6f8f9e03866a88c1884ebc7c98287fb1

http%3A%2F%2Fonlinelibrary.wiley.com%2Fdoi%2F10.1002%2Fqj.728%2Fabstract

http://onlinelibrary.wiley.com/doi/10.1002/qj.728/abstractAbstract Analysis of the annually varying regional circulations and their relationship to surface conditions and water vapour transport in the West African region is presented. The progression of the West African monsoon is described in terms of four key phases: (i) an oceanic phase between November and mid-April when the rain band is broad with peak values just north of the Equator (651°N); (ii) a coastal phase between mid-April and the end of June when the rainfall peak is in the coastal region around 4°N (over the ocean); (iii) a transitional phase during the first half of July when the rainfall peak decreases; and (iv) a Sahelian phase between mid-July and September when the rainfall peak is more intense and established in the Sahelian region around 10°N. The annual evolution of the moisture fluxes, associated convergence, and rainfall is strongly impacted by the Atlantic cold tongue (cool water close to the Equator between boreal spring and summer) and the Saharan heat-low. The cold tongue strongly regulates the timing and intensity of the coastal rainfall in spring. The heat-low and its associated shallow meridional circulation strongly affect the profile in moisture flux convergence north of the main rain-band maximum; in particular it is responsible for the establishment of a second peak in column moisture flux convergence there (approximately 8° poleward of the rainfall peak). Particular emphasis is given to the coastal rainfall onset in April. A key aspect of this onset is acceleration of low-level cross-equatorial southerly winds, important for establishing the cold tongue, discouraging convection near the Equator and transporting moisture towards the coast. We argue that the rainfall peak is maintained at the coast, rather than steadily moving inland with the solar insolation, due to persistent warm water in the coastal region together with frictionally induced moisture convergence there. Copyright 08 2011 Royal Meteorological Society

Trenberth K. E., D. P. Stepaniak, and J. M. Caron, 2000: The global monsoon as seen through the divergent atmospheric circulation. J.Climate, 13, 3969- 3993.9338592efa8a3cebbc70ed50717d76f7

http%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F2000JCli...13.3969T

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Uppala, S. M., Coruthors, 2005: The ERA-40 re-analysis. Quart. J. Roy. Meteor. Soc., 131, 2961- 3012.10.1256/qj.04.176

2a7d42687edc6f4dfa18a36c7d3be1c7

http%3A%2F%2Fonlinelibrary.wiley.com%2Fdoi%2F10.1256%2Fqj.04.176%2Ffull

http://onlinelibrary.wiley.com/doi/10.1256/qj.04.176/fullAbstract ERA-40 is a re-analysis of meteorological observations from September 1957 to August 2002 produced by the European Centre for Medium-Range Weather Forecasts (ECMWF) in collaboration with many institutions. The observing system changed considerably over this re-analysis period, with assimilable data provided by a succession of satellite-borne instruments from the 1970s onwards, supplemented by increasing numbers of observations from aircraft, ocean-buoys and other surface platforms, but with a declining number of radiosonde ascents since the late 1980s. The observations used in ERA-40 were accumulated from many sources. The first part of this paper describes the data acquisition and the principal changes in data type and coverage over the period. It also describes the data assimilation system used for ERA-40. This benefited from many of the changes introduced into operational forecasting since the mid-1990s, when the systems used for the 15-year ECMWF re-analysis (ERA-15) and the National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) re-analysis were implemented. Several of the improvements are discussed. General aspects of the production of the analyses are also summarized. A number of results indicative of the overall performance of the data assimilation system, and implicitly of the observing system, are presented and discussed. The comparison of background (short-range) forecasts and analyses with observations, the consistency of the global mass budget, the magnitude of differences between analysis and background fields and the accuracy of medium-range forecasts run from the ERA-40 analyses are illustrated. Several results demonstrate the marked improvement that was made to the observing system for the southern hemisphere in the 1970s, particularly towards the end of the decade. In contrast, the synoptic quality of the analysis for the northern hemisphere is sufficient to provide forecasts that remain skilful well into the medium range for all years. Two particular problems are also examined: excessive precipitation over tropical oceans and a too strong Brewer-Dobson circulation, both of which are pronounced in later years. Several other aspects of the quality of the re-analyses revealed by monitoring and validation studies are summarized. Expectations that the -econd-generation- ERA-40 re-analysis would provide products that are better than those from the firstgeneration ERA-15 and NCEP/NCAR re-analyses are found to have been met in most cases. Royal Meteorological Society, 2005. The contributions of N. A. Rayner and R. W. Saunders are Crown copyright.

Uppala S. M., D. P. Dee, S. Kobayashi, P. Berrisford, and A. J. Simmons, 2008: Towards a climate data assimilation system: status update of ERA-Interim. ECMWF Newsletter, No. 115, ECMWF, Reading, United Kingdom, 12- 18.b049b4451ca6109dc3d45d5791497345

http%3A%2F%2Fwww.researchgate.net%2Fpublication%2F284038917_Towards_a_climate_data_assimilation_system_Status_update_of_ERA-Interim

http://www.researchgate.net/publication/284038917_Towards_a_climate_data_assimilation_system_Status_update_of_ERA-Interim

Vizy E. K., K. H. Cook, 2001: Mechanisms by which Gulf of Guinea and eastern North Atlantic Sea surface temperature anomalies can influence African rainfall. J.Climate, 14, 795- 821.10.1175/1520-0442(2001)0142.0.CO;2

09df06a9cb222f14262fac9270e6f7d6

http%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F2001JCli...14..795V

http://adsabs.harvard.edu/abs/2001JCli...14..795VThe sensitivity of precipitation over West Africa to sea surface temperature anomalies (SSTAs) in the Gulf of Guinea and the eastern North Atlantic is studied using a GCM. Results from nine perpetual July simulations with various imposed SSTAs are presented and analyzed to reveal associations between the precipitation and SST fields via large-scale circulation and atmospheric moisture anomalies. Rainfall increases over the Guinean Coast and decreases over the Congo basin when warm SSTAs are present in the Gulf of Guinea. These precipitation perturbations are related to the forcing of a Kelvin and a Rossby wave. The former is associated with a weakening of the Walker circulation, while the latter strengthens the West African monsoon. Rainfall over West Africa is less sensitive to cold SSTAs than to warm anomalies. Three contributing factors are identified as follows: 1) latitude of the SST forcing, 2) background flow, and 3) non-linearity of the Clausius-Clapeyron equation (no more than a 20% effect). Despite the relative insensitivity to eastern North Atlantic SSTAs alone, a superposition of the individual responses to SSTAs is shown to be a poor predictor of the response to combined SSTAs, especially over central northern Africa. A comparison of the modeled moisture budget anomalies to the difference between the summer seasons of 1988 and 1994 from the satellite observations and the NCEP reanalysis is conducted. While there may be many causes of precipitation differences between two particular years, the moisture budget anomalies are similar in that enhanced precipitation along the Guinean coast is supported mainly by low-level wind convergence from the south. The role of advection is also similar in the model and the reanalysis. However, the precipitation decrease over the Congo Basin that is associated with the Kelvin wave response to Gulf of Guinea SSTs in the model is not evident in the observations for these 2 yr.

Wang C., 2005: ENSO, Atlantic climate variability, and the Walker and Hadley circulations. The Hadley Circulation: Present, Past, and Future, H. F. Diaz and R. S. Bradley, Eds., Kluwer Academic Publishers, 173- 202.10.1007/978-1-4020-2944-8_6

0bdd1e828d77571bc865a0589c526682

http%3A%2F%2Flink.springer.com%2F10.1007%2F978-1-4020-2944-8_7

http://link.springer.com/10.1007/978-1-4020-2944-8_7This chapter describes and discusses the Walker and Hadley circulations associated with the El Ni09o/Southern Oscillation (ENSO), the Atlantic “Ni09o”, the tropical Atlantic meridional gradient variability, the Western Hemisphere warm pool (WHWP), and the North Atlantic Oscillation (NAO). During the warm phase of ENSO, the Pacific Walker circulation, the western Pacific Hadley circulation, and the Atlantic Hadley circulation are observed to be weakened, whereas the eastern Pacific Hadley circulation is strengthened. During the peak phase of the Atlantic Ni09o, the Atlantic Walker circulation weakens and extends eastward and the Atlantic Hadley circulation strengthens. The tropical Atlantic meridional gradient variability corresponds to a meridional circulation in which the air rises over the warm sea surface temperature (SST) anomaly region, flows toward the cold SST anomaly region aloft, sinks in the cold SST anomaly region, then crosses the equator toward the warm SST region in the lower troposphere. During periods when the NAO index is high, the atmospheric Ferrei and Hadley circulations are strengthened, consistent with surface westerly and easterly wind anomalies in the North Atlantic and in the middle to tropical Atlantic, respectively. The chapter also discusses a tropo-spheric bridge by the Walker/Hadley circulation that links the Pacific El Ni09o with warming of the tropical North Atlantic (TNA) and the WHWP.

Wang C. Z., 2002a: Atlantic climate variability and its associated atmospheric circulation cells. J.Climate, 15, 1516- 1536.10.1175/1520-0442(2002)015<1516:ACVAIA>2.0.CO;2

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http%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F2002JCli...15.1516W

refpaperuri:(0cb1e4a5a00f99f267f5213e96324115)

http://adsabs.harvard.edu/abs/2002JCli...15.1516WPhenomena important for Atlantic climate variability include the Atlantic zonal equatorial mode, the tropical Atlantic meridional gradient mode, and the North Atlantic Oscillation (NAO). These climate phenomena and their associated atmospheric circulation cells are described and discussed using the NCEP-NCAR reanalysis field and the NCEP sea surface temperature (SST) from January 1950 to December 1999. Atmospheric divergent wind and vertical motion are used for the identification of atmospheric circulation cells. During the peak phase of the Atlantic equatorial mode, the Atlantic Walker circulation weakens and extends eastward, which results in surface westerly wind anomalies in the equatorial western Atlantic. These westerly wind anomalies are partly responsible for warming in the equatorial eastern Atlantic that occurs in the second half of the year. The Atlantic equatorial mode involves a positive ocean-atmosphere feedback associated with the Atlantic Walker circulation, similar to the Pacific El Nino. The tropical Atlantic meridional gradient mode is characterized by a strong SST gradient between the tropical North Atlantic (TNA) and the tropical South Atlantic. Corresponding to the meridional gradient mode is an atmospheric meridional circulation cell in which the air rises over the warm SST anomaly region, flows toward the cold SST anomaly region aloft, sinks in the cold SST anomaly region, then crosses the equator toward the warm SST region in the lower troposphere. The analysis presented here suggests that the Pacific El Nino can affect the TNA through the Walker and Hadley circulations, favoring the TNA warming in the subsequent spring of the Pacific El Nino year. The NAO, characterized by strong westerly airflow between the Icelandic low and the Azores high, is also related to an atmospheric meridional circulation. During the high NAO index, the atmospheric Ferrel and Hadley cells are strengthened, consistent with surface westerly and easterly wind anomalies in the North Atlantic and in the mid-to-tropical Atlantic, respectively.

Wang C. Z., 2002b: Atmospheric circulation cells associated with the El Niño-southern oscillation. J.Climate, 15, 399- 419.9ac69b31-d2f4-453c-927d-c6589f6871a9

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Wang C. Z., 2004: ENSO, Atlantic climate variability, and the Walker and Hadley circulations. The Hadley Circulation: Present, Past, and Future, H. F. Diaz and R. S. Bradley, Eds., Advances in Global Change Research, Vol. 21, Springer, Netherlands, 85- 120.10.1007/978-1-4020-2944-8_6

0bdd1e828d77571bc865a0589c526682

http%3A%2F%2Flink.springer.com%2F10.1007%2F978-1-4020-2944-8_7

Washington R., R. James, H. Pearce, W. M. Pokam, and W. Moufouma-Okia, 2013: Congo Basin rainfall climatology: can we believe the climate models? Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences, 368(1625),20120296, doi: 10.1098/rstb.2012.0296.10.1098/rstb.2012.0296

23878328

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http%3A%2F%2Fmed.wanfangdata.com.cn%2FPaper%2FDetail%2FPeriodicalPaper_PM23878328

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http://med.wanfangdata.com.cn/Paper/Detail/PeriodicalPaper_PM23878328The Congo Basin is one of three key convective regions on the planet which, during the transition seasons, dominates global tropical rainfall. There is little agreement as to the distribution and quantity of rainfall across the basin with datasets differing by an order of magnitude in some seasons. The location of maximum rainfall is in the far eastern sector of the basin in some datasets but the far western edge of the basin in others during March to May. There is no consistent pattern to this rainfall distribution in satellite or model datasets. Resolving these differences is difficult without ground-based data. Moisture flux nevertheless emerges as a useful variable with which to study these differences. Climate models with weak (strong) or even divergent moisture flux over the basin are dry (wet). The paper suggests an approach, via a targeted field campaign, for generating useful climate information with which to confront rainfall products and climate models.

Zhang C. D., P. Woodworth, and G. J. Gu, 2006: The seasonal cycle in the lower troposphere over West Africa from sounding observations. Quart. J. Roy. Meteor. Soc., 132, 2559- 2582.10.1256/qj.06.23

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http%3A%2F%2Fonlinelibrary.wiley.com%2Fdoi%2F10.1256%2Fqj.06.23%2Fabstract

http://onlinelibrary.wiley.com/doi/10.1256/qj.06.23/abstractNot Available