Bowen oranı enerji dengesi yöntemiyle belirlenen yüzey enerji akılarının arıma modeli ile tahmini
Estimation of surface energy fluxes determined by the Bowen ratio energy balance method with arima model
Yazar: İREM AYDIN
Danışman: PROF. DR. LEVENT ŞAYLAN
İstanbul Teknik Üniversitesi / Lisansüstü Eğitim Enstitüsü / Meteoroloji Mühendisliği Ana Bilim Dalı / Atmosfer Bilimleri Bilim Dalı
Derece: Yüksek Lisans, 2022
Konu: Meteoroloji = Meteorology
Dizin: ARIMA modelleri = ARIMA models ; Enerji dengesi = Energy balance ; Yüzey enerjisi = Surface energy

Özet:
Dünyadaki en eski bilim dallarından biri olan atmosfer bilimlerinin iki ana konu başlığı birbiri ile direkt ilişkili olan enerji ve su dengesidir. Sanayi devrimi ile hız kazanan tarımsal ve endüstriyel aktiviteler, nüfus artışı gibi nedenler sebebiyle suya olan ihtiyacın artması göz önüne alındığında su kayıplarının belirlenmesi ve kontrolü büyük bir önem taşımaktadır. Yerküre üzerinde yaşanan su kayıplarının başlıca bileşeni kara ve su yüzeylerinden oluşan buharlaşma ve bitkilerden meydana gelen terleme ile atmosfere gönderilen toplam su miktarı olarak tanımlanan evapotranspirasyondur. Enerji ve su dengesinin en önemli ve ortak bileşeni olan evapotranspirasyonun belirlenmesi amacıyla kullanılan birçok teknik bulunmaktadır.
Bowen Oranı Enerji Dengesi (BREB) yöntemi enerji akısı bileşenlerini dolaylı yoldan ölçülmesini sağlayan düşük maliyetli mikrometeorolojik bir yöntemdir. Yöntem net radyasyon, toprak ısı akısı ile iki farklı seviyede sıcaklık ve nem ölçümlerine dayanır.
Bu çalışmada ise BREB sistemi ile enerji akısı bileşenleri hesaplanmış, sonrasında ARIMA modelinin hesaplanan değerlerin tahminindeki başarısı değerlendirilmiştir. 22 Mart 2018 tarihinde BREB sistemine ait aletlerin ilk kurulumu ve testi Meteoroloji Aletleri ve Gözlem Usulleri Laboratuvarında yapılmış, kalibrasyon amacıyla belirli bir süre veri alınmıştır. 24 Mart 2018 tarihinde ise, BREB sisteminin ölçüm kulesi Meteoroloji Gözlem Parkına yerleştirilmiş ve 25 Mart 2018 tarihinde düzenlemeleri yapılan aletler bahsedilen ölçüm kulesine eş yüksekliklere (Yerden 1 m yüksekliğe) yerleştirilmiş ve bir hafta boyunca ölçüm yapılmıştır. Elde edilen ölçüm verileri aracılığıyla bulunan kalibrasyon denklemleri ile farklı seviyelere yerleştirilecek aynı aletlerin birbirleriyle tutarlı sonuçlar vermesini sağlanmıştır. 4 Mayıs 2018 tarihinde ise, aletler önceden planlandığı yerlerine yerleştirilmiş ve veri alınmaya başlanmıştır. Elde edilen veri seti 10 ve 30 dakikalık, saatlik ve günlük değerleri içermektedir.
Çalışma kapsamında elde edilen verilerin 5 Mayıs 2018 – 22 Ağustos 2019 tarihleri arasına ait olanları analiz amacıyla kullanılmıştır. Analiz kısmında öncelikle ham verilerin 10 dakikalık, saatlik ve günlük değerleri kullanılarak ortalama, maksimum ve minimum değerleri bulunmuş; bileşenlere ait grafiklerle bu bileşenlerin zamansal değişimleri ortaya konmaya çalışılmıştır. Sonrasında BREB metodu kullanılarak 10 dakikalık, saatlik ve günlük verilere ait enerji akısı değerleri hesaplanmış, bulunan değerlerin zamanla değişimi grafiklerle gösterilmiştir. Son aşamada ise elde edilen değerler ARIMA modeli aracılığı ile tahmin edilmeye çalışılmıştır.
Çalışma sonucunda ARIMA modelinin özellikle açık hava şartlarında enerji akısı bileşenlerinden olan Net Radyasyon, Hissedilir Isı Akısı ve Buharlaşma Gizli Isı Akısı için 4 – 12 günlük süre zarfında önemli başarı oranları elde ettiğini göstermiştir.

Abstract:
The two main topics of atmospheric sciences, one of the oldest branches of science in the world, are energy and water balance, which are directly related to each other. Considering the increase in the need for water due to reasons such as agricultural and industrial activities and population growth that accelerated with the industrial revolution, the determination and control of water losses is of great importance. The main component of water losses over the earth is evapotranspiration, which is defined as the total amount of water sent to the atmosphere by evaporation from land and water surfaces and transpiration from plants. There are many techniques used to determine evapotranspiration, which is the most important and common component of energy and water balance.
The Bowen Ratio Energy Balance (BREB) method is a low-cost micrometeorological method that provides indirect measurement of energy flux components. The method is based on measurements of net radiation, soil heat flux, and temperature and humidity at two different levels.
In this study, the energy flux components were calculated with the BREB system, and then the success of the ARIMA model in estimating the calculated values was evaluated. 
The instruments of the BREB system, which arrived on March 22, 2018, were installed and tested in the Meteorology Instruments and Observation Methods  Laboratory, and data was taken for a certain period of time for calibration purposes. On March 24, 2018, the measurement tower of the BREB system was installed in the Meteorology Observation Park, and the instruments (temperature and relative humidity sensors), whose arrangements were made on March 25, 2018, were placed at equal heights (1 m above the ground) to calibrate them and the measurement was made for a week. With the calibration equations found through the measurement data obtained, it was ensured that the same instruments placed at different levels would give consistent results with each other. On May 4, 2018, the instruments were placed in their pre-planned places and data began to be collected. The resulting data set includes 10 and 30 minutes, hourly and daily values.
The data obtained within the scope of the study between the dates of 5 May 2018 - 22 August 2019 were used for analysis. In the analysis part, firstly, the average, maximum and minimum values of the raw data were found by using the 10-minute, hourly and daily values; With the graphs of the components, the temporal changes of these components were tried to be revealed. Afterwards, energy flux values of 10-minute, hourly and daily data were calculated using the BREB method, and the change of the values over time was shown with graphs. In the last stage, the obtained values were tried to be estimated through the ARIMA model.
When BREB analyzes were examined,the average of the Bowen ratio value obtained as a result of the calculations made using 10-minute data between the measurement intervals is -0.01, the maximum is 9.99, the minimum is -9.99, and the standard deviation is 1.63. The average of the sensible heat flux is 61.06 W/m2, the maximum is 66.17 W/m2, the minimum is -747.82 W/m2, and the standard deviation is 155.38 W/m2. The average latent heat flux is 190.93 W/m2, its maximum is 997.84 W/m2, its minimum is -99.57, and its standard deviation is 124.65 W/m2. Seasonal changes of 10-minute data are included in the study. The results show that the net radiation and soil heat flux values are highest in summer and minimum values in winter, as expected, considering that the surface warming reaches a maximum in summer and a minimum in winter. It has been observed that the average of the soil heat flux has negative values in winter and autumn, while it has positive values in summer and spring. It has been observed that the perceptible heat flux average is higher than the latent heat flux average due to high heating and low precipitation in summer, and lower due to heavy closure and precipitation in autumn and winter months. 
The average of the Bowen ratio value obtained as a result of the calculations made using hourly data between the measurement ranges is -0.03, the maximum is 20.66, and the minimum is -23.68. The average of the sensible heat flux is 46.08 W/m2, the maximum is 714.79 W/m2, and the minimum is -448.93 W/m2.  The average latent heat flux of evaporation is 53.02 W/m2, the maximum is 851.82 W/m2, and the minimum is -99.21 W/m2. The standard deviation values of the variables are 1.63, 152.16 W/m2 and 117.11 W/m2, respectively. 
The average of the Bowen ratio value obtained as a result of the calculations made using daily data between the measurement ranges is -0.10, the maximum is 14.63, and the minimum is -10.20. The average of the sensible heat flux is 50.89 W/m2, the maximum is 257.70 W/m2, and the minimum is -76.59 W/m2. The average latent heat flux of evaporation is 48.88 W/m2, the maximum is 238.45 W/m2, and the minimum is -87.26 W/m2. The standard deviation values of the variables are 0.54, 77.48 W/m2 and 61.36 W/m2, respectively.
When ARIMA analyzes were examined, the most successful predictor was net radiation. The first 10 values on clear atmosphere days, the first 7 values on cloudy days and the first 2 values on rainy days were calculated with a high success rate.  Latent heat flux estimations were the next variable with high success values. Here, forecast consistency is ranked as clear days, rainy days, and closed days.  The estimates belong to the sensible heat flux with the lowest consistency. For the open atmosphere, the province gives good results from 4 days. On the other hand, in closed atmosphere conditions, the error rate is not below 50%. As with the latent heat flux, the results of this variable on rainy days are better than the results on cloudy days. In summary, while the best results were obtained in the estimations made for open atmosphere conditions, the variable with the highest success in estimations was net radiation. 
It was seen that the ARIMA model took AR(p=7.8), I(d=1) and MA(q=7.8) values under open atmosphere conditions. On the other hand, in case of closed atmosphere, these values were AR(p=3,2.7), I(d=2) and MA(q=2.5,6), respectively. Finally, when we look at the rainy days, it is seen that the diversity of these parameters increases. Good results were obtained with AR(p=5,6,8), I(d=1,2) and MA(q=6.7), respectively. But the models for different weather conditions are in a similar pattern. The forecast results offer significant success rates in short-term forecasts of 4 to 12 days.