New Statistical downscaling methods and applications for Turkey

Hava ve iklim süreçlerinin yeryüzündeki yaşam üzerinde hayati etkileri vardır. İklim değişkenliği ve değişiminin anlaşılabilmesi, bölgesel ve yerel iklim tanılarının geliştirilmesi, iklim çalışmalarının temel konularından biridir. İklim etkilerini araştıranlar genelde iklim değişiminin ve değişkenliğinin geçmişi, bugünü ve geleceği hakkında detaylı ve doğru bilgilere gereksinim duyarlar. İklim değişimi ve değişkenliği konusunda önemli ve temel araçlar genel dolaşım modelleridir (GDM). Ne yazık ki kaba sayısal çözünürlük üzerinde çalıştırılan GDM’ler yerel iklim değişimi ve değişkenliği hakkında doğru bilgi veremezler. Bu bağlamda, GDM’lerin kısıtlarından dolayı “ölçek küçültme” stratejilerinin geliştirilmesine gerek vardır. İklim araştırma ve etkilerinin arasındaki farklı ölçekler; “ölçek küçültme” ve “ölçek büyültme” yaklaşımları ile birbirine bağlanabilir. Bu çalışma, yeni ölçek küçültme yöntemlerini geliştirme ve Türkiye üzerine uygulanması konusunda ilk ve tek araştırmadır. Anahtar Kelimeler: Bölgesel, genel dolaşım modeli, iklim etki, ölçek küçültme, Türkiye, yinelemeli yapay sinir ağları.Weather and climate have a profound influence on life on earth. Understanding climate variability and climate change reveals the increasing need for improving regional and local-scale climate diagnosis which is one of the main goals of climate research. The climate impact researches usually require accurate and detailed climate information on yesterday, present, and tomorrow with high resolution space scale. The main and important tools of studying climate are general circulation models (GCMs). Unfortunately, GCMs running on coarse resolution may not be able to detect the local scale climate variability. The spatial-scale mismatch between climate research and climate impact studies has to be bridged by ?downscaling? on the side of the climate research and ?upscaling? on the side of the climate impact research. This study is the first research of developing downscaling strategies over Turkey. Two new downscaling strategies for climate diagnosis are developed in this study. The proposed methods are based on artificial recurrent neural networks (RNN) and multivariate statistical techniques that derive transfer functions from the large-scale free troposphere variables of which are assumed to govern the local climate over Turkey. This study presents two new approaches for downscaling monthly near-surface air temperature and total precipitation for Turkey stations by surface large-scale pressure systems and upper air circulations derived from National Centers for Environmental Prediction- National Center of Atmospheric Research (NCEP-NCAR) Reanalysis data sets. Keywords: Regional, general circulation model, climate impact, downscaling, Turkey, artificial recurrent neural networks

Kendini tanımlayan yer sistem modellerine doğru: Bir iş akışı uygulaması

The application of scientific workflow systems for orchestrating complex tasks is still an open research area. In particular, earth system related modeling applications consists of different tasks that are closely related to each other and scientific workflow systems can be used to simplify these sub processes and their relationships. The motivation for this work is driven by the complexities of running a large modeling system on a high performance computing and network systems and need to reduce those complexities, particularly for the average user.In this study, it is presented and analyzed a new methodology to combine scientific workflow system and modeling framework approach together to create standardized work environment. Then, the proposed methodology is tested using a typical and realistic earth system modeling application. The result of example workflows that are based on the proposed methodology is a part of this study.A Modeling framework is a standardized programming environment for combining model components and couplers of different kinds of earth system models using a common calling interface. Earth System Modeling Framework (ESMF) is one of the most popular examples for this approach. It consists of a superstructure for coupling components of Earth system applications and an infrastructure of robust, high-performance utilities and data structures that ensures consistent component behavior. Extending beyond the modeling framework approach, scientific workflow systems create standardized interfaces to a variety of technologies and automate the execution and monitoring of a heterogeneous workflow. Namely, a scientific workflow system is a problem-solving environment that simplifies tasks by creating meaningful and easy understandable sub-tasks and combining them to form executable data management and analysis pipelines. Kepler was chosen as the workflow environment for this work because it is open source, platform independent, and it supports different models of computation such as Process Network (PN) and Synchronous Data Flow (SDF). Kepler is a scientific workflow system that is based on the Ptolemy II project. The actor-oriented design of Kepler enables users to create hierarchically structured scientific workflows. The overall execution of model is controlled by separate component that is called a director (a special actor). Kepler supports different model of computation types via its directors.In application example, a regional coupled climate modeling system is developed for Mediterranean region and integrated into workflow system to provide better representation of regional climate system. This application has crucial importance in downscaling output of the global circulation models over Turkey and near regions. It also can be used to create better representation of regional climate for the future scenarios. The workflow application also collects provenance information automatically from the coupled earth system modeling system to reproduce, compare and debug results. The coupled atmosphere-ocean modeling system is based on NCAR's Weather Research and Forecasting (WRF) and Regional Ocean Modeling System (ROMS) model. To couple atmosphere and ocean models the ESMF library is used. For the atmospheric component (WRF), the experimental ESMF-IO structure is used to create ESMF fields and states to share data between different model components. The WRF ESMF-IO is also modified to add field level metadata into coupling variables (heat and momentum fluxes) of atmospheric model. In ocean component (ROMS), the coupler code is written to control each model component and also the gridded component code is developed to run each earth system model via ESMF init, run and finalize methods. The gridded component level metadata is added into coupler to create prototype version of self-describing modeling system. The results show that the developed workflow environment is capable of running different earth system models on a different high performance computing resource with a meaningful abstraction. The proposed work environment acts as an abstraction layer and hides the detail of the used infrastructure and earth system model from user and it also collect standardized provenance information about both model and computing resource to represent the work environment as possible as it can. Keywords: Scientific workflow, model coupling, provenance information, Kepler, ESMF.Bilimsel iş akış sistemlerinin karmaşık bileşen ve süreçler içeren çalışmalarda kullanılması, günümüzde oldukça popüler bir araştırma alanıdır. Özellikle yer sistem bilimleri açısından bakıldığında, birbirlerine sıkı bir şekilde bağlı, birçok alt bileşen içeren yer sistem modellerine ait süreçlerin basitleştirilmesi ve modüler bir yapıya kavuşturularak standartlaştırması için, bilimsel iş akış sistemleri kullanılabilir. Bu çalışmanın asıl amaçlarından biri, karmaşık yer sistem modelleme uygulamalarının, yüksek başarımlı hesaplama sistemlerinde çalıştırılmasının gittikçe zorlaşması, kendi kendisini tanımlayan yer sistem modellerine ve varolan karmaşık modelleme sistemlerinin anlamlı bir şekilde soyutlaştırılarak ortalama bir kullanıcı seviyesine indirgenmesine duyulan ihtiyaçtır. Bu amaçla, literatürde sıkça kullanılan bilimsel iş akışı ve çerçeve yaklaşımlarının birleştirilerek standartlaştırılmış bir çalışma ortamının yaratılması için yeni bir metodoloji geliştirilmiştir. Önerilen metodolojinin sınanması amacıyla, gerçekçi bir yer sistem modelleme uygulaması kullanılmış ve sonuçları analiz edilmiştir. Bu amaçla geliştirilen uygulama örneği, çerçeve yaklaşımı kullanılarak birleştirilmiş bir atmosfer-okyanus model sisteminin, bölgesel iklim sistemini daha gerçekçi olarak modellemek amacıyla iş akış sistemine entegre edilmesi ve model bileşenlerinden köken bilgisinin otomatik olarak toplanması süreçlerini içermektedir. Sonuçlar iş akışı ortamına entegre edilen model sistemlerinin daha kolay kullanılabildiğini ve toplanan köken bilgisinin çalışmanın evrimini kayıt altına alması açısından son derece önemli olduğunu göstermektedir. Ayrıca modellerin kuple edilmesi için kullanılan çerçeve uygulaması (ESMF), her bir alt yer sistem modeli için standart bir arayüz tanımlayarak model kuple sürecini ve yönetimini kolaylaştırmaktadır. Anahtar Kelimeler: Bilimsel iş akışı, çerçeve yaklaşımı, köken bilgisi, Kepler, ESMF

Relative Pollen Productivity Estimates for Mediterranean Plant Taxa: A New Study Region in Turkey

This study estimates relative pollen productivity (RPP) for plant taxa from Southern Anatolia, an important region in the Mediterranean with a long history of human settlements. RPP estimates are required for quantitative pollen-based reconstruction of past land cover modelling. The application of the reconstruction by the REVEALS model in the Mediterranean basin is constrained due to the scarcity of the RPP values specific to the region. To better understand the relationship between vegetation cover and land use in the Mediterranean area, the present study aims to provide a set of RPPs for Turkey and the Mediterranean region. The study area centres around Gölhisar Lake in southwestern Turkey. Modern pollen data are collected from moss pollsters from 21 sites together with vegetation surveys. RPP estimates for the main taxa characteristic of the Mediterranean region are obtained (referenced to evergreen Quercus t.) using the extended R-value (ERV) model through the analysis of modern pollen assemblages. The most reliable results are acquired with the ERV sub-model 2 and Prentice’s taxon-specific method (using a Gaussian plume dispersal model) to distance-weighted vegetation data, corresponding to a Relative Source Area of Pollen (RSAP) value of 102 m. RPPs of dominant taxa in the study area are obtained for Quercus coccifera/Fagaceae (1 ± 0), Juniperus/Cupressaceae (0.279 ± 0.001), Fabaceae (0.008 ± 0.000), Pinus/Pinaceae (5.782 ± 0.011), and Poaceae (0.112 ± 0.001) and are comparable with other RPPs obtained in the Mediterranean region