Abstract
Many cities around the world are located in mountainous areas. Understanding local circulations in mountainous urban areas is important for improving local weather and air quality prediction as well as understanding thermally forced mesoscale flow dynamics. In this study, we examine local circulations in and around the Ulaanbaatar, Mongolia, metropolitan area using the Weather Research and Forecasting model coupled with the Seoul National University Urban Canopy Model. Ulaanbaatar lies in an east–west-oriented valley between the northern base of Mt. Bogd Khan and the southern base of branches of the Khentiin Nuruu mountain range. Idealized summertime fair-weather conditions with no synoptic winds are considered. In the daytime, mountain upslope winds, up-valley winds, and urban breeze circulation form and interact with each other. Mountain upslope winds precede up-valley winds. It is found that the transition of upslope winds to downslope winds on the urban-side slope of Mt. Bogd Khan occurs and the downslope winds in the afternoon strengthen due to urban breezes. In the nighttime, mountain downslope winds and down-valley winds are prominent and strong channeling flows form over the city. The sensitivities of local circulations to urban fraction, atmospheric stability, and soil water content are examined. As urban fraction increases, daytime up-valley winds over the city and daytime downslope winds on the urban-side slope of Mt. Bogd Khan strengthen. Daytime near-surface up-valley winds in the city strengthen with increasing atmospheric stability. As soil water content decreases, daytime near-surface up-valley winds in the city weaken. The daytime urban atmospheric boundary-layer height is found to be sensitive to atmospheric stability and soil water content. This study is a first attempt to examine local circulations in and around the Ulaanbaatar metropolitan area and demonstrates that the city alters mountain slope winds and up-/down-valley winds.
Similar content being viewed by others
References
Arino O, Ramos J, Kalogirou V, Defourny P, Achard F (2010) GlobCover 2009. In: Proceedings of ESA Living Planet Symposium, Bergen, Norway, ESA, SP-686
Baik JJ, Kim YH, Kim JJ, Han JY (2007) Effects of boundary-layer stability on urban heat island-induced circulation. Theor Appl Climatol 89:73–81
Chen F, Dudhia J (2001) Coupling an advanced land surface–hydrology model with the Penn State–NCAR MM5 modeling system. Part I: model implementation and sensitivity. Mon Weather Rev 129:569–585
Chen X, Anel JA, Su A, de la Torre L, Kelder H, van Peet J, Ma Y (2013) The deep atmospheric boundary layer and its significance to the stratosphere and troposphere exchange over the Tibetan Plateau. PLoS One 8(2):e56909. doi:10.1371/journal.pone.0056909
Dudhia J (1989) Numerical study of convection observed during the winter monsoon experiment using a mesoscale two-dimensional model. J Atmos Sci 46:3077–3107
Friedl MA, McIver DK, Hodges JCF, Zhang XY, Muchoney D, Strahler AH, Woodcock CE, Gopal S, Schnieder A, Cooper A, Bacinni A, Gao F, Schaaf C (2002) Global land cover mapping from MODIS: algorithms and early results. Remote Sens Environ 83:287–302
Ganbat G, Han JY, Ryu YH, Baik JJ (2013) Characteristics of the urban heat island in a high-altitude metropolitan city, Ulaanbaatar, Mongolia. Asia Pac J Atmos Sci 49:535–541
Ganbat G, Baik JJ, Ryu YH (2015) A numerical study of the interactions of urban breeze circulation with mountain slope winds. Theor Appl Climatol 120:123–135
Giovannini L, Zardi D, de Franceschi M, Chen F (2014) Numerical simulations of boundary-layer processes and urban-induced alterations in an Alpine valley. Int J Climatol 34:1111–1131
Google Inc (2013) Google Earth. http://maps.google.com. Accessed 10 April 2013
Hidalgo J, Masson V, Pigeon G (2008a) Urban-breeze circulation during the CAPITOUL experiment: numerical simulations. Meteorol Atmos Phys 102:243–262
Hidalgo J, Pigeon G, Masson V (2008b) Urban-breeze circulation during the CAPITOUL experiment: observational data analysis approach. Meteorol Atmos Phys 102:223–241
Hidalgo J, Masson V, Gimeno L (2010) Scaling the daytime urban heat island and urban breeze circulation. J Appl Meteorol Climatol 49:889–901
Hong SY, Noh Y, Dudhia J (2006) A new vertical diffusion package with an explicit treatment of entrainment processes. Mon Weather Rev 134:2318–2341
Jarvis A, Reuter HI, Nelson A, Guevara E (2008) Hole-filled SRTM for the globe version 4. http://srtm.csi.cgiar.org. Accessed 28 Jan 2011
Lee SH, Baik JJ (2011) Evaluation of the vegetated urban canopy model (VUCM) and its impacts on urban boundary layer simulation. Asia Pac J Atmos Sci 47:151–165
Lee SH, Kim HD (2010) Modification of nocturnal drainage flow due to urban surface heat flux. Asia Pac J Atmos Sci 46:453–465
LeMone MA, Tewari M, Chen F, Dudhia J (2013) Objectively determined fair-weather CBL depths in the ARW-WRF model and their comparison to CASES-97 observations. Mon Weather Rev 141:30–54
Lemonsu A, Masson V (2002) Simulation of a summer urban-breeze over Paris. Bound Layer Meteorol 104:463–490
Lin YL, Farley RD, Orville HD (1983) Bulk parameterization of the snow field in a cloud model. J Clim Appl Meteorol 22:1065–1092
Ma M, Pu Z, Wang S, Zhang Q (2011) Characteristics and numerical simulations of extremely large atmospheric boundary-layer heights over an arid region in north-west China. Bound Layer Meteorol 140:163–176
Martilli A (2003) A two-dimensional numerical study of the impact of a city on atmospheric circulation and pollutant dispersion in a coastal environment. Bound Layer Meteorol 108:91–119
Miao S, Chen F, LeMone MA, Tewari M, Li Q, Wang Y (2009) An observational and modeling study of characteristics of urban heat island and boundary layer structures in Beijing. J Appl Meteorol Climatol 48:484–501
Mlawer EJ, Taubman SJ, Brown PD, Iacono MJ, Clough SA (1997) Radiative transfer for inhomogeneous atmospheres: RRTM, a validated correlated-k model for the longwave. J Geophys Res 102:16663–16682
Richiardone R, Brusasca G (1989) Numerical experiments on urban heat island intensity. Quart J Roy Meteorol Soc 115:983–995
Ryu YH, Baik JJ (2013) Daytime local circulations and their interactions in the Seoul metropolitan area. J Appl Meteorol Climatol 52:784–801
Ryu YH, Baik JJ, Lee SH (2011) A new single-layer urban canopy model for use in mesoscale atmospheric models. J Appl Meteorol Climatol 50:1773–1794
Ryu YH, Baik JJ, Han JY (2013) Daytime urban breeze circulation and its interaction with convective cells. Quart J Roy Meteorol Soc 139:401–413
Skamarock WC, Klemp JB, Dudhia J, Gill DO, Barker DM, Duda MG, Huang XY, Wang W, Powers JG (2008) A description of the advanced research WRF version 3. NCAR, Boulder
Vukovich FM, Dunn JW (1978) A theoretical study of the St. Louis heat island: Some parameter variations. J Appl Meteorol 17:1585–1594
Acknowledgments
The authors are grateful to two anonymous reviewers for providing valuable comments on this work. This work was funded by the National Research Foundation of Korea (NRF) grant funded by the Korea Ministry of Science, ICT and Future Planning (MSIP) (No. 2012-0005674).
Author information
Authors and Affiliations
Corresponding author
Additional information
Responsible Editor: S. Hong.
Rights and permissions
About this article
Cite this article
Ganbat, G., Baik, JJ. Local circulations in and around the Ulaanbaatar, Mongolia, metropolitan area. Meteorol Atmos Phys 127, 393–406 (2015). https://doi.org/10.1007/s00703-015-0374-4
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s00703-015-0374-4