全部 标题 作者
关键词 摘要

OALib Journal期刊
ISSN: 2333-9721
费用:99美元

查看量下载量

相关文章

更多...

Northeastern Tropical Atlantic SST and Sahel Rainfall Variability

DOI: 10.4236/acs.2023.134024, PP. 431-454

Keywords: SST-Rain, Sahel Rainfall, Senegal Rainfall, Ocean-Atmosphere Interaction

Full-Text   Cite this paper   Add to My Lib

Abstract:

The SST variability during the summer period in the northeastern tropical Atlantic region (NTA) is characterized by an alternation of warming/cooling which represents 87% of the total variability. The aim of this paper is to study the atmospheric responses as well as the precipitation associated with these oceanic conditions. Based on Reynolds’s SST from 1982 to 2019, a normalized Northern Tropical Atlantic index (NTAI) is computed into the region between 15° - 25°W; 12° - 16°N and a composite analysis is then performed. It is shown that the NTAI is significantly correlated with the SST’s first principal component mode (PC1) in this region. Moreover, the composite of SST anomalies and atmospheric parameters exhibits a strong local ocean-atmosphere interaction which highly impacts the large-scale atmospheric circulation in West Africa, particularly in the western Sahel. An in-depth analysis shows that the atmospheric response to the warm (cold) SST is a cyclonic (anticyclonic) circulation in the lower layers near the West Africa Coast. This cyclonic (anticyclonic) circulation strengthens/reduces the moisture transport towards the continent in the low levels. In the middle layers of the atmosphere (500 hPa), the warm (cold) composite is associated with a decrease (increase) in the intensity of the African Easterly Jet (AEJ) whereas, in the upper atmosphere (200 hPa), the strengthening (weakening) of the Tropical Easterly Jet (TEJ) is observed. With regard to the composite precipitation field, a positive/negative SST anomaly is associated with significantly enhanced/reduced rainfall in the western Sahelian region. It is found that this relationship (correlation) increases as we are closer to the coasts.

References

[1]  Oettli, P., Morioka, Y. and Yamagata, T. (2016) A Regional Climate Mode Discovered in the North Atlantic: Dakar Niño/Niña. Scientific Reports, 6, Article No. 18782.
https://doi.org/10.1038/srep18782
[2]  Feng, M., McPhaden, M., Xie, S.-P. and Hafner, J. (2013) La Niña Forces Unprecedented Leeuwin Current Warming in 2011. Scientific Reports, 3, Article No. 1277.
https://doi.org/10.1038/srep01277
[3]  Kataoka, T., Tozuka, T., Behera, S. and Yamagata, T. (2014) On the Ningaloo Niño/Niña. Climate Dynamics, 43, 1463-1482.
https://doi.org/10.1007/s00382-013-1961-z
[4]  Zhang, L., Han, W., Li, Y. and Shinoda, T. (2018) Mechanisms for Generation and Development of the Ningaloo Niño. Journal of Climate, 31, 9239-9259.
https://doi.org/10.1175/JCLI-D-18-0175.1
[5]  Doi, T., Tozuka, T. and Yamagata, T. (2010) The Atlantic Meridional Mode and Its Coupled Variability with the Guinea Dome. Journal of Climate, 23, 455-475.
https://doi.org/10.1175/2009JCLI3198.1
[6]  Amaya, D.J., DeFlorio, M.J., Miller, A.J. and Xie, S.-P. (2017) WES Feedback and the Atlantic Meridional Mode: Observations and CMIP5 Comparisons. Climate Dynamics, 49, 1665-1679.
https://doi.org/10.1007/s00382-016-3411-1
[7]  de Coëtlogon, G., Janicot, S. and Lazar, A. (2010) Intraseasonal Variability of the Ocean—Atmosphere Coupling in the Gulf of Guinea during Boreal Spring and Summer. Quarterly Journal of the Royal Meteorological Society, 136, 426-441.
https://doi.org/10.1002/qj.554
[8]  Tian, B. and Ren, H.-L. (2022) Diagnosing SST Error Growth during ENSO Developing Phase in the BCC_CSM1.1(m) Prediction System. Advances in Atmospheric Sciences, 39, 427-442.
https://doi.org/10.1007/s00376-021-1189-5
[9]  Li, T. and Philander, S.G.H. (1997) On the Seasonal Cycle of the Equatorial Atlantic Ocean. Journal of Climate, 10, 813-817.
https://doi.org/10.1175/1520-0442(1997)010<0813:OTSCOT>2.0.CO;2
[10]  Xie, S.-P. and Philander, S.G.H. (1994) A Coupled Ocean-Atmosphere Model of Relevance to the ITCZ in the Eastern Pacific. Tellus A: Dynamic Meteorology and Oceanography, 46, 340-350.
https://doi.org/10.1034/j.1600-0870.1994.t01-1-00001.x
[11]  Kusunoki, H., Kido, S. and Tozuka, T. (2020) Contribution of Oceanic Wave Propagation from the Tropical Pacific to Asymmetry of the Ningaloo Niño/Niña. Climate Dynamics, 54, 4865-4875.
https://doi.org/10.1007/s00382-020-05268-5
[12]  Tanuma, N. and Tozuka, T. (2020) Influences of the Interdecadal Pacific Oscillation on the Locally Amplified Ningaloo Niño. Geophysical Research Letters, 47, e2020GL088712.
https://doi.org/10.1029/2020GL088712
[13]  Xue, J., Luo, J.-J., Yuan, C. and Yamagata, T. (2020) Discovery of Chile Niño/Niña. Geophysical Research Letters, 47, e2019GL086468.
https://doi.org/10.1029/2019GL086468
[14]  Zheng, T., Feng, T., Xu, K. and Cheng, X. (2020) Precipitation and the Associated Moist Static Energy Budget off Western Australia in Conjunction with Ningaloo Niño. Frontiers in Earth Science, 8, Article 597915.
https://doi.org/10.3389/feart.2020.597915
[15]  Sultan, B. and Janicot, S. (2003) The West African Monsoon Dynamics. Part II: The “Preonset” and “Onset” of the Summer Monsoon. Journal of Climate, 16, 3407-3427.
https://doi.org/10.1175/1520-0442(2003)016<3407:TWAMDP>2.0.CO;2
[16]  Okumura, Y. and Xie, S.-P. (2004) Interaction of the Atlantic Equatorial Cold Tongue and the African Monsoon. Journal of Climate, 17, 3589-3602.
https://doi.org/10.1175/1520-0442(2004)017<3589:IOTAEC>2.0.CO;2
[17]  Biasutti, M., Battisti, D.S. and Sarachik, E.S. (2004) Mechanisms Controlling the Annual Cycle of Precipitation in the Tropical Atlantic Sector in an Atmospheric GCM. Journal of Climate, 17, 4708-4723.
https://doi.org/10.1175/JCLI-3235.1
[18]  Giannini, A., Saravanan, R. and Chang, P. (2005) Dynamics of the Boreal Summer African Monsoon in the NSIPP1 Atmospheric Model. Climate Dynamics, 25, 517-535.
https://doi.org/10.1007/s00382-005-0056-x
[19]  Meynadier, R., de Coëtlogon, G., Leduc-Leballeur, M., Eymard, L. and Janicot, S. (2016) Seasonal Influence of the Sea Surface Temperature on the Low Atmospheric Circulation and Precipitation in the Eastern Equatorial Atlantic. Climate Dynamics, 47, 1127-1142.
https://doi.org/10.1007/s00382-015-2892-7
[20]  Tomaziello, A.C.N., Carvalho, L.M.V. and Gandu, A.W. (2016) Intraseasonal Variability of the Atlantic Intertropical Convergence Zone during Austral Summer and Winter. Climate Dynamics, 47, 1717-1733.
https://doi.org/10.1007/s00382-015-2929-y
[21]  Crespo, L.R., Keenlyside, N. and Koseki, S. (2019) The Role of Sea Surface Temperature in the Atmospheric Seasonal Cycle of the Equatorial Atlantic. Climate Dynamics, 52, 5927-5946.
https://doi.org/10.1007/s00382-018-4489-4
[22]  Nicholson, S.E. (2013) The West African Sahel: A Review of Recent Studies on the Rainfall Regime and Its Interannual Variability. International Scholarly Research Notices, 2013, Article ID: 453521.
https://doi.org/10.1155/2013/453521
[23]  Diakhaté, M., Lazar, A., de Coëtlogon, G. and Gaye, A.T. (2018) Do SST Gradients Drive the Monthly Climatological Surface Wind Convergence over the Tropical Atlantic? International Journal of Climatology, 38, e955-e965.
https://doi.org/10.1002/joc.5422
[24]  Brandt, P., Caniaux, G., Bourlès, B., Lazar, A., Dengler, M., Funk, A., Hormann, V., Giordani, H. and Marin, F. (2011) Equatorial Upper-Ocean Dynamics and Their Interaction with the West African Monsoon. Atmospheric Science Letters, 12, 24-30.
https://doi.org/10.1002/asl.287
[25]  Liu, W., Cook, K.H. and Vizy, E.K. (2020) Role of the West African Westerly Jet in the Seasonal and Diurnal Cycles of Precipitation over West Africa. Climate Dynamics, 54, 843-861.
https://doi.org/10.1007/s00382-019-05035-1
[26]  Pu, B. and Cook, K.H. (2012) Role of the West African Westerly Jet in Sahel Rainfall Variations. Journal of Climate, 25, 2880-2896.
https://doi.org/10.1175/JCLI-D-11-00394.1
[27]  Lélé, M.I. and Leslie, L.M. (2016) Intraseasonal Variability of Low-Level Moisture Transport over West Africa. Climate Dynamics, 47, 3575-3591.
https://doi.org/10.1007/s00382-016-3334-x
[28]  Pu, B. and Cook, K.H. (2010) Dynamics of the West African Westerly Jet. Journal of Climate, 23, 6263-6276.
https://doi.org/10.1175/2010JCLI3648.1
[29]  Hersbach, H., Bell, B., Berrisford, P., Hirahara, S., Horányi, A., Muñoz-Sabater, J., Nicolas, J., Peubey, C., Radu, R., Schepers, D., et al. (2020) The ERA5 Global Reanalysis. Quarterly Journal of the Royal Meteorological Society, 146, 1999-2049.
[30]  Reynolds, R.W., Smith, T.M., Liu, C., Chelton, D.B., Casey, K.S. and Schlax, M.G. (2007) Daily High-Resolution-Blended Analyses for Sea Surface Temperature. Journal of Climate, 20, 5473-5496.
https://doi.org/10.1175/2007JCLI1824.1
[31]  Harris, I., Osborn, T.J., Jones, P. and Lister, D. (2020) Version 4 of the CRU TS Monthly High-Resolution Gridded Multivariate Climate Dataset. Scientific Data, 7, Article No. 109.
https://doi.org/10.1038/s41597-020-0453-3
[32]  Cadet, D.L. and Nnoli, N.O. (1987) Water Vapour Transport over Africa and the Atlantic Ocean during Summer 1979. Quarterly Journal of the Royal Meteorological Society, 113, 581-602.
https://doi.org/10.1002/qj.49711347609
[33]  Fontaine, B., Roucou, P., and Trzaska, S. (2003) Atmospheric Water Cycle and Moisture Fluxes in the West African Monsoon: Mean Annual Cycles and Relationship Using NCEP/NCAR Reanalysis. Geophysical Research Letters, 30, Article No. 1117.
https://doi.org/10.1029/2002GL015834
[34]  Meynadier, R., de Coëtlogon, G., Bastin, S., Eymard, L. and Janicot, S. (2015) Sensitivity Testing of WRF Parameterizations on Air-Sea Interaction and Its Impact on Water Cycle in the Gulf of Guinea. Quarterly Journal of the Royal Meteorological Society, 141, 1804-1820.
https://doi.org/10.1002/qj.2483
[35]  Bjerknes, J. (1969) Atmospheric Teleconnections from the Equatorial Pacific. Monthly Weather Review, 97, 163-172.
https://doi.org/10.1175/1520-0493(1969)097<0163:ATFTEP>2.3.CO;2
[36]  Chang, P., Yamagata, T., Schopf, P., Behera, S.K., Carton, J., Kessler, W.S., Meyers, G., Qu, T., Schott, F., Shetye, S., et al. (2006) Climate Fluctuations of Tropical Coupled Systems—The Role of Ocean Dynamics. Journal of Climate, 19, 5122-5174.
https://doi.org/10.1175/JCLI3903.1
[37]  Richter, I., Xie, SP., Morioka, Y., Doi, T., Taguchi, B. and Behera, S. (2017) Phase Locking of Equatorial Atlantic Variability through the Seasonal Migration of the ITCZ. Climate Dynamics, 48, 3615-3629.
https://doi.org/10.1007/s00382-016-3289-y
[38]  Stevens, B., Duan, J., McWilliams, J.C., Münnich, M. and Neelin, J.D. (2002) Entrainment, Rayleigh Friction, and Boundary Layer Winds over the Tropical Pacific. Journal of Climate, 15, 30-44.
https://doi.org/10.1175/1520-0442(2002)015<0030:ERFABL>2.0.CO;2
[39]  Lindzen, R.S. and Nigam, S. (1987) On the Role of Sea Surface Temperature Gradients in Forcing Low-Level Winds and Convergence in the Tropics. Journal of Atmospheric Sciences, 44, 2418-2436.
https://doi.org/10.1175/1520-0469(1987)044<2418:OTROSS>2.0.CO;2
[40]  Sweet, W., Fett, R., Kerling, J. and La Violette, P. (1981) Air-Sea Interaction Effects in the Lower Troposphere across the North Wall of the Gulf Stream. Monthly Weather Review, 109, 1042-1052.
https://doi.org/10.1175/1520-0493(1981)109<1042:ASIEIT>2.0.CO;2
[41]  Wallace, J.M., Mitchell, T.P. and Deser, C. (1989) The Influence of Sea-Surface Temperature on Surface Wind in the Eastern Equatorial Pacific: Seasonal and Interannual Variability. Journal of Climate, 2, 1492-1499.
15
https://doi.org/10.1175/1520-0442(1989)002<1492:TIOSST>2.0.CO;2
[42]  Caniaux, G., Giordani, H., Redelsperger, J.-L., Guichard, F., Key, E., and Wade, M. (2011) Coupling between the Atlantic Cold Tongue and the West African Monsoon in Boreal Spring and Summer. Journal of Geophysical Research: Oceans, 116, C04003.
https://doi.org/10.1029/2010JC006570
[43]  Foltz, G.R., Brandt, P., Richter, I., Rodríguez-Fonseca, B., Hernandez, F., Dengler, M., Rodrigues, R.R., Schmidt, J.O., Yu, L., Lefevre, N., Cotrim Da Cunha, L., McPhaden, M.J., Araujo, M., Karstensen, J., Hahn, J., Martín-Rey, M., Patricola, C.M., Poli, P., Zuidema, P., Hummels, R., Perez, R.C., Hatje, V., Lübbecke, J.F., Polo, I., Lumpkin, R., Bourlès, B., Asuquo, F.E., Lehodey, P., Conchon, A., Chang, P., Dandin, P., Schmid, C., Sutton, A., Giordani, H., Xue, Y., Illig, S., Losada, T., Grodsky, S.A., Gasparin, F., Lee, T., Mohino, E., Nobre, P., Wanninkhof, R., Keenlyside, N., Garcon, V., Sánchez-Gómez, E., Nnamchi, H.C., Drévillon, M., Storto, A., Remy, E., Lazar, A., Speich, S., Goes, M., Dorrington, T., Johns, W.E., Moum, J.N., Robinson, C., Perruche, C., de Souza, R.B., Gaye, A.T., López-Parages, J., Monerie, P.-A., Castellanos, P., Benson, N.U., Hounkonnou, M.N., Trotte Duhá, J., Laxenaire, R. and Reul, N. (2019) The Tropical Atlantic Observing System. Frontiers in Marine Science, 6, Article 206.
https://doi.org/10.3389/fmars.2019.00206
[44]  Zhang, Y., Xu, J., Yang, N. and Lan, P. (2018) Variability and Trends in Global Precipitable Water Vapor Retrieved from Cosmic Radio Occultation and Radiosonde Observations. Atmosphere, 9, Article No. 174.
https://doi.org/10.3390/atmos9050174
[45]  Thorncroft, C.D. and Rowell, D.P. (1998) Interannual Variability of African Wave Activity in a General Circulation Model. International Journal of Climatology, 18, 1305-1323.
https://doi.org/10.1002/(SICI)1097-0088(1998100)18:12<1305::AID-JOC281>3.0.CO;2-N
[46]  Cornforth, R.J., Hoskins, B.J. and Thorncroft, C.D. (2009) The Impact of Moist Processes on the African Easterly Jet-African Easterly Wave System. Quarterly Journal of the Royal Meteorological Society, 135, 894-913.
https://doi.org/10.1002/qj.414
[47]  Wang, Z. and Elsberry, R.L. (2010) Modulation of the African Easterly Jet by a Mesoscale Convective System. Atmospheric Science Letters, 11, 169-174.
https://doi.org/10.1002/asl.262
[48]  Lafore, J.-P., Flamant, C., Guichard, F., Parker, D.J., Bouniol, D., Fink, A.H., Giraud, V., Gosset, M., Hall, N., Höller, H., Jones, S.C., Protat, A., Roca, R., Roux, F., Saïd, F. and Thorncroft, C. (2011) Progress in Understanding of Weather Systems in West Africa. Atmospheric Science Letters, 12, 7-12.
https://doi.org/10.1002/asl.335
[49]  Parker, D.J., Thorncroft, C.D., Burton, R.R. and Diongue-Niang, A. (2005) Analysis of the African Easterly Jet, Using Aircraft Observations from the JET2000 Experiment. Quarterly Journal of the Royal Meteorological Society, 131, 1461-1482.
https://doi.org/10.1256/qj.03.189
[50]  Houze Jr., R.A. and Betts, A.K. (1981) Convection in Gate. Reviews of Geophysics, 19, 541-576.
https://doi.org/10.1029/RG019i004p00541
[51]  Thorncroft, C.D. and Hoskins, B.J. (1994) An Idealized Study of African Easterly Waves. I: A Linear View. Quarterly Journal of the Royal Meteorological Society, 120, 953-982.
https://doi.org/10.1002/qj.49712051809
[52]  Lafore, J.-P. (2007) La mousson africaine. Atmosphériques, 33, 8-9.
[53]  Diongue, A., Lafore, J.-P., Redelsperger, J.-L. and Roca, R. (2002) Numerical Study of a Sahelian Synoptic Weather System: Initiation and Mature Stages of Convection and Its Interactions with the Large-Scale Dynamics. Quarterly Journal of the Royal Meteorological Society, 128, 1899-1927.
https://doi.org/10.1256/003590002320603467
[54]  Peyrillé, P. and Lafore, J.-P. (2007) An Idealized Two-Dimensional Framework to Study the West African Monsoon. Part II: Large-Scale Advection and the Diurnal Cycle. Journal of the Atmospheric Sciences, 64, 2783-2803.
https://doi.org/10.1175/JAS4052.1
[55]  Mathon, V., Laurent, H. and Lebel, T. (2002) Mesoscale Convective System Rainfall in the Sahel. Journal of Applied Meteorology, 41, 1081-1092.
https://doi.org/10.1175/1520-0450(2002)041<1081:MCSRIT>2.0.CO;2
[56]  Camara, M., Diedhiou, A. and Gaye, A. (2011) African Easterly Waves and Cyclonic Activity over the Eastern Atlantic: Composite and Case Studies. International Journal of Geophysics, 2011, Article ID: 874292.
https://doi.org/10.1155/2011/874292

Full-Text

Contact Us

[email protected]

QQ:3279437679

WhatsApp +8615387084133