Evaluation of near-surface air temperature reanalysis datasets and downscaling with machine learning based Random Forest method for complex terrain of Turkey

2023-01-01
Hasan Karaman, Çağrı
Akyürek, Sevda Zuhal
Near-surface air temperature is a key variable used in a wide range of applications showing the environmental conditions of the Earth. Standard meteorological observations generally provide the best estimation with high accuracy over time for a small area of influence. However, considerable uncertainty arises when point measurements are extrapolated or interpolated over much larger areas. Satellite and reanalysis products have emerged as a viable alternative or supplement to in situ observations due to their availability over vast ungauged regions. Thus, spatial patterns of air temperature can be derived from these products. In this study, we evaluate the performance of several reanalysis products of near-surface air temperature to determine the best product in estimating daily and monthly air temperatures across the complex terrain of Turkey. European Center for Medium-Range Weather Forecasts Reanalysis version 5 (ERA5), (AgERA5), (ERA5-Land), the Modern-Era Retrospective Analysis for Research and Applications version 2 (MERRA2), and the Japanese 55-year Reanalysis (JRA-55) products are assessed with 1120 ground-based gauge stations for the period 2015–2019 over complex terrain having different climate classes according to Köppen-Geiger classification scheme and land surface types. Moreover, several traditional and more sophisticated machine learning downscaling algorithms are applied to increase the products’ spatial resolution. The agreement between ground observations and the different products and the downscaled temperature product is investigated by using a set of commonly employed statistical estimators of mean absolute error (MAE), correlation coefficient (CC), root-mean-square error (RMSE), and bias. Performance analysis of reanalysis air temperature products with ground-based observations on daily and monthly time series has shown that among the five datasets, the AgERA5 product is superior in estimating air temperature over Turkey, both seasonally and annually. Compared to the other datasets, ERA5 and ERA5-Land show similar performance and reach the second highest performance score at both daily and monthly time steps. In terms of improving product performance with spatial downscaling, among the distance-based methods, the best overall performance is obtained by bicubic interpolation with a slight increase in the product performance in monthly and daily time series. However, depending on the season, the Random Forest algorithm's performance is far superior to all other methods used in this study.
Advances in Space Research

Suggestions

Comparison of MODIS-derived land surface temperature with air temperature measurements
Georgiou, Andreas; Akcit, Nuhcan (2017-03-23)
Air surface temperature is an important parameter for a wide range of applications such as agriculture, hydrology and climate change studies. Air temperature data is usually obtained from measurements made in meteorological stations, providing only limited information about spatial patterns over wide areas. The use of remote sensing data can help overcome this problem, particularly in areas with low station density, having the potential to improve the estimation of air surface temperature at both regional a...
Investigation of Turkey's carbon dioxide problem by numerical modeling
Can, Ali; Tokdemir, Turgut; Department of Engineering Sciences (2006)
CO2 emission is very important, because it is responsible for about 60% of the "Greenhouse Effect". The major objectives of this study were to prepare a CO2 emission inventory of Turkey based on districts and provinces by using the fuel consumption data with respect to its sources, to find the CO2 uptake rate of forests in Turkey based on provinces and districts, and to estimate the ground level concentration of CO2 across Turkey using U.S. EPA's ISCLT3 model for the preparation of ground level concentratio...
Enhancing model-based land surface temperature estimates using multiplatform microwave observations
Holmes, Thomas R. H.; Crow, Wade T.; Yılmaz, Mustafa Tuğrul; Jackson, Thomas J.; Basara, Jeffrey B. (2013-01-01)
Land surface temperature plays an important role in surface processes and is a key input for physically based retrieval algorithms of soil moisture and evaporation. This study presents a framework for using independent estimates of land surface temperature from five microwave satellite sensors to improve the accuracy of land surface temperature output from a numerical weather prediction system in an off-line (postprocessing) analysis. First, structural differences in timing and amplitude of the temperature ...
Numerical and analytical investigation of aerosol acoustics through ducts
Arslan, Ersen; Çalışkan, Mehmet; Department of Mechanical Engineering (2017)
The aim of this thesis is to develop a numerical approach which can solve the sound propagation problem in air-filled circular duct containing water droplets (regarded as an aerosol) in order to obtain acoustic absorption and dispersion characteristics of the system. There exist several analytical approaches in literature for treatment of basic aerosol problems with certain limitations; however; in order to solve rather complex cases, these limitations must be handled and worked out. In this study, a couple...
Appropriate passive cooling strategies for hot and humid climates : a case study in cyprus
Hançerli, Mustafa Yılmaz; Elias Özkan, Soofia Tahira; Department of Building Science in Architecture (2008)
In this study, energy conservation potential of appropriate passive cooling and basic heat avoidance strategies were investigated for hot and humid climates. Within this framework, thermal behavior of a case study building that is situated in Cyprus was assessed by collecting temperature and relative humidity data from various rooms of the building during certain days in August. Then, by using feasible simulation strategies of the software tool Summer-Building, the effectiveness of passive cooling measures ...
Citation Formats
Ç. Hasan Karaman and S. Z. Akyürek, “Evaluation of near-surface air temperature reanalysis datasets and downscaling with machine learning based Random Forest method for complex terrain of Turkey,” Advances in Space Research, pp. 0–0, 2023, Accessed: 00, 2023. [Online]. Available: https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85149905254&origin=inward.