On the Sensitivity of the Daily Mean Air Temperature of Egypt to Boundary Layer Schemes Using a High-Resolution Regional Climate Model (RegCM4)

Samy A Anwar*; Sally Mahmoud Mostafa

**Samy A Anwar* and Sally Mahmoud Mostafa**

Volume4-Issue3
Dates: Received: 2023-03-15 | Accepted: 2023-03-20 | Published: 2023-03-22
Pages: 474-484

Abstract

Introduction: Boundary layer processes play an important role in controlling the daily mean air temperature through exchange of turbulent fluxes of water and energy between the ground surface and the atmosphere. Therefore, it is important to explore the role of boundary layer parameterization in simulating the daily mean air temperature particularly on a regional scale.

Methods: To accomplish this task, two simulations were conducted to assess the sensitivity of the mean air Temperature (TMP) of Egypt to boundary layer schemes (Holtslag; HOLT and University of Washington; UW) within the framework of the Regional Climate Model (RegCM4). The RegCM4 was downscaled by the ERA-Interim reanalysis of 1.5 degrees with 25 km horizontal grid spacing over the period 1997-2017. Additionally, ERA5 reanalysis product was used as the observational dataset for the variables: the Total Cloud Cover (CLT), surface short and long wave radiation fluxes (RSDS and RLDS), Skin Temperature (TS), surface Wind Speed (WS), Sensible Heat Flux (HFSS) and TMP.

Results: There is no difference between HOLT and UW regarding the CLT and RSDS; while the UW reduces the bias of the RLDS and WS relative to HOLT particularly in the summer and autumn seasons in comparison with ERA5. Furthermore, HOLT and UW schemes showed a considerable impact on the simulated TS. For instance, UW reduces the TS bias relative to HOLT in all seasons but in the spring and winter seasons; UW induces a negative bias more than HOLT. Concerning the HFSS, UW shows a higher bias than HOLT mainly in the summer and autumn seasons. Because of the noted changes of the simulated HFSS and TS, the UW succeeds in reducing the warm bias of the TMP (noted in the HOLT) in all seasons in comparison with the ERA5. With respect to in-situ observations, the HOLT/UW performance varies with the location as well as the month.

Conclusion: The UW scheme can be recommended for future studies concerning the future climate change of Egypt concerning the regional scale. However for a point scale, caution is needed in interpreting the results with respect to the in-situ observations except for Asswan where HOLT can be recommended.

FullText HTML FullText PDF DOI: 10.37871/jbres1700

Certificate of Publication

Copyright

How to cite this article

Anwar SA, Mostafa SM. On the Sensitivity of the Daily Mean Air Temperature of Egypt to Boundary Layer Schemes Using a High-Resolution Regional Climate Model (RegCM4). 2023 Mar 22; 4(3): 474-484. doi: 10.37871/jbres1700, Article ID: JBRES1700, Available at: https://www.jelsciences.com/articles/jbres1700.pdf

Subject area(s)

Climate Change Biology

References

Trenberth KE, Fasullo JT, Kiehl J. Earth’s global energy budget. Bull Am Meteor Soc. 2009;90:311-323.
Ali MFA, Salah Z, Asklany SA, Hassan M, Harhash M, Wahab MMA. A Comparison of three boundary layer schemes for numerical weather prediction. Appl Math Inf Sci. 2020;14(6):1093-1101. doi: 10.18576/amis/140616.
Winton M. Surface albedo feedback estimates for the AR4 climate models. J Clim. 2006;19:359-365.
Walter KM, Zimov SA, Chanton JP, Verbyla D, Chapin FS 3rd. Methane bubbling from Siberian thaw lakes as a positive feedback to climate warming. Nature. 2006 Sep 7;443(7107):71-5. doi: 10.1038/nature05040. PMID: 16957728.
Baklanov A, Grisogono B, Bornstein R, Mahrt L, Zilitinkevich S, Taylor P, Larsen S, Rotach M, Fernando HJS. On the nature, theory, and modeling of atmospheric planetary boundary layers. Bull Am Meteor Soc. 2011;92:123-128.
Stensrud D. Parameterization schemes: Keys to understanding numerical weather prediction models. Cambridge: Cambridge University Press; 2007. p.459.
Giorgi F, Coppola E, Solmon F, Mariotti L, Sylla MB, Bi X, Elguindi N, Diro GT, Nair V, Giuliani G, Turuncoglu UU, Cozzini S, Güttler I, O’Brien TA, Tawfik AB, Shalaby A, Zakey AS, Steiner AL, Stordal F, Sloan LC, Branković C. RegCM4: Model description and preliminary tests over multiple CORDEX domains. Clim Res. 2012;52:7-29.
Güttler I, Branković Č, O’Brien TA, Coppola E, Grisogono B, Giorgi F. Sensitivity of the regional climate model RegCM4.2 to planetary boundary layer parameterisation. Clim Dyn. 2014;43:1753-1772. doi: 10.1007/s00382-013-2003-6.
Holtslag AAM, Boville BA. Local versus nonlocal boundary layer diffusion in a global model. J Clim. 1993;6:1825-1842.
Grenier H, Bretherton CS. A moist PBL parameterization for large scale models and its application to subtropical cloud topped marine boundary layers. Mon Weather Rev. 2001;129:357-377.
Mitchell TD, Jones PD. An improved method of constructing a database of monthly climate observations and associated high- resolution grids. Int J Climatol. 2005;25:693-712.
Kalmár T, Pieczka I, Pongrácz R. A sensitivity analysis of the different setups of the RegCM4.5 model for the Carpathian region. Int J Climatol. 2021;41(Suppl 1):E1180-E1201. doi: 10.1002/joc.6761.
Anwar SA, Salah Z, Khaled W, Zakey AS. Projecting the potential evapotranspiration in egypt using a high-resolution Regional Climate Model (RegCM4). Environ Sci Proc. 2022;19:43. doi: 10.3390/ecas2022-12841.
Mostafa SM, Anwar SA, Zakey AS, Wahab MMA. Bias-correcting the maximum and minimum air temperatures of Egypt using a high-resolution Regional Climate Model (RegCM4). Eng Proc. 2023;31:73. doi: 10.3390/ASEC2022-13852.
Anwar SA. Inﬂuence of direct-downscaling and one-way nesting on daily mean air temperature of Egypt using the RegCM4. 2023a Mar 09;4(3): 338-347. doi: 10.37871/jbres1681.
Hersbach H, Bell B, Berrisford P, Hirahara S, Horanyi A, Muñoz-Sabater J, Nicolas J, Peubey C, Radu R, Schepers D, Simmons A, Soci C, Abdalla S, Abellan X, Balsamo G, Bechtold P, Biavati G, Bidlot J, Bonavita M, De Chiara G, Dahlgren P, Dee D, Diamantakis M, Dragani R, Flemming J, Forbes R, Fuentes M, Geer A, Haimberger L, Healy S, Hogan RJ, Holm E, Janiskova M, Keeley S, Laloyaux P, Lopez P, Lupu C, Radnoti G, de Rosnay P, Rozum I, Vamborg F, Villaume S, Thépaut JN. The ERA5 global reanalysis. QJR Meteorol Soc. 2020;146:1999-2049.
Wang X, Chen D, Pang G, Anwar SA, Ou T, Yang M. Effects of cumulus parameterization and land-surface hydrology schemes on Tibetan Plateau climate simulation during the wet season: Insights from the RegCM4 model. Clim Dyn. 2021;57:1853-1879. doi: 10.1007/s00382-021-05781-1.
Anwar SA, Reboita MS, Llopart M. On the sensitivity of the amazon surface climate to two land-surface hydrology schemes using a high-resolution Regional Climate Model (RegCM4). Int J Climatol. 2022;42(4):2311-2327. doi: 10.1002/joc.7367.
Anwar SA, Kim Y. On the role of leaf area index parameterization in simulating the terrestrial carbon fluxes of Africa using a regional coupled climate-vegetation model. Eng Proc. 2023;31:9. doi: 10.3390/ASEC2022-13839.
Anwar SA. Simulating the surface solar irradiance of Africa using a regional climate model: Influence of vegetation-runoff coupled system. Eng Proc. 2023b;31:15. doi: 10.3390/ASEC2022-13814.