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İstanbul Teknik Üniversitesi (2017)

Cosmo-clm (cclm) Climate Simulations Over Turkey : Performance Evaluation And Climate Projections For The 21st Century

Yürük, Cemre

Titre : Cosmo-clm (cclm) Climate Simulations Over Turkey : Performance Evaluation And Climate Projections For The 21st Century

Türkiye İçin Cosmo-clm (cclm) İklim Simülasyonları : Performans Değerlendirmesi Ve 21. Yüzyıl İklim Projeksiyonları

Auteur : Yürük, Cemre

Université de soutenance : İstanbul Teknik Üniversitesi

Grade : Master of Science (MS) 2017

Résumé
In this study, the results of regional climatology based on NCAR/NCEP Reanalysis and MPI-ESM-LR driven COSMO-CLM (CCLM) simulations over Turkey and its vicinity are presented. The main purposes of this thesis are to ascertain the capability of the non-hydrostatic regional climate model CCLM in capturing temperature and precipitation and also, to investigate the effect of climate change on temperature and precipitation distribution through 21st century by employing the current extreme Intergovernmental Panel on Climate Change (IPCC) scenario, Representative Concentration Pathways 8.5 (RCP8.5). The simulations are conducted at two different horizontal grid spacings (0.44° and 0.11°). The outputs of earth system model (ESM) MPI-ESM-LR are downscaled to first coarse resolution over mother domain, which covers Turkey and its vicinity. Then, it is downscaled to high resolution over northwestern Turkey for reference period (RF) of 1971-2005 by using CCLM in order to assess the ability of the model to reproduce the climatological features of the region. Moreover, NCAR/NCEP Reanalysis data is also dynamically downscaled by following the same steps to explore the inherent performance of the CCLM for the same region that has complex topography and shorelines. In addition, the future projections are forced by MPI-ESM-LR covering 2011-2100 with proposed changes under IPCC RCP8.5 scenario. The validation of CCLM is evaluated with respect to various observational data sets. The 0.44° resolution simulations of CCLM for reference period are compared with Climatic Research Unit (CRU) gridded data by interpolating CRU values to CCLM grid. Furthermore, CCLM simulations having 0.11° resolution compared with meteorological observations obtained from TSMS stations after the model results are bilinearly interpolated to stations’ location. A focus is put on near-surface conditions and the analyses of the simulations are carried out on annual and seasonal basis. When the annual and seasonal averages of mean 2-m temperatures are analyzed, it is concluded that both the reanalysis and ESM driven CCLM model results show similar temperature distribution with CRU over the mother domain for 1971-2005. The model evaluation reveals that the coupled CCLM is able to approximately reproduce the observed spatial variation of 2-m temperature over Turkey in winter and autumn seasons that are dominated by cold bias in CCLM_NCEP1. Although the both simulations driven with NCEP1 and ESM have generally larger biases (>2℃) over mountainous regions such as Caucasus Mountains, it underestimates the temperatures (<-2℃) over northeastern part of Turkey.

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