Trend analysis of reference evapotranspiration in Northwest China: The roles of changing wind speed and surface air temperature

2012 ◽  
Vol 27 (26) ◽  
pp. 3941-3948 ◽  
Author(s):  
Xiaomang Liu ◽  
Dan Zhang
Keyword(s):  
Wind Speed ◽  
Trend Analysis ◽  
Air Temperature ◽  
Reference Evapotranspiration ◽  
Surface Air Temperature ◽  
Northwest China

scholarly journals Trend Analysis of Reference Evapotranspiration in the São Francisco River Basin, Brazil

2022 ◽  
Author(s):  
Neilon Silva ◽  
Aureo Silva de Oliveira
Keyword(s):  
Wind Speed ◽  
Vapor Pressure ◽  
Trend Analysis ◽  
River Basin ◽  
Air Temperature ◽  
Reference Evapotranspiration ◽  
Net Radiation ◽  
Sao Francisco River ◽  
São Francisco River ◽  
Basin Area

Abstract An important requisite in any water resources management program is the knowledge of the natural processes that regulate the hydrological cycle, especially for spatial and temporal analyses of these processes. This work aimed to explore spatial and temporal trends of reference evapotranspiration (ETo), evaluate ETo variation dynamics and quantify the contribution of each one of the meteorological variables in ETo calculation in the São Francisco River basin. Daily data of maximum and minimum air temperature, mean relative air humidity, wind speed and net radiation from 101 weather stations, for the period from 1961 to 2015, were used and are part of the network of the National Institute of Meteorology (INMET). Climate trend analysis was performed using the non-parametric Mann-Kendall statistical test and the sensitivity analysis for the Penman-Monteith equation was carried out based on partial derivatives as a function of the key meteorological variables of ETo (air temperature, net radiation, wind speed and actual water vapor pressure). A significant increase (p<0.01) in vapor pressure deficit (VPD) associated with the increase in mean air temperature contributed to increments in ETo along the studied period. The scenario in the entire São Francisco River basin is of increase in the values of the climatic variables, particularly evapotranspiration (85% of basin area with increments) and rainfall (52% of basin area with decrements). Results indicate an increase in ETo variation rates of approximately 2.424 mm year-2, on average, in the entire basin. The energy term represents higher weight in ETo calculation in 81% of the basin territory.

Empirical Equations to Estimate Evapotranspiration in Mosul City

2020 ◽  
Vol 27 (4) ◽  
pp. 98-102
Author(s):  
Haqqi Yasin ◽  
Luma Abdullah
Keyword(s):  
Wind Speed ◽  
Relative Humidity ◽  
Air Temperature ◽  
Reference Evapotranspiration ◽  
Sunshine Duration ◽  
Food And Agriculture ◽  
Food And Agriculture Organization ◽  
Daily Data ◽  
Daily Sunshine ◽  
Measured Wind Speed

Average daily data of solar radiation, relative humidity, wind speed and air temperature from 1980 to 2008 are used to estimate the daily reference evapotranspiration in the Mosul City, North of Iraq. ETo calculator software with the Penman Monteith method standardized by the Food and Agriculture Organization is used for calculations. Further, a nonlinear regression approach using SPSS Statistics is utilized to drive the daily reference evapotranspiration relationships in which ETo is function to one or more of the average daily air temperature, actual daily sunshine duration, measured wind speed at 2m height and relative humidity

scholarly journals Estimating the Surface Air Temperature by Remote Sensing in Northwest China Using an Improved Advection-Energy Balance for Air Temperature Model

2016 ◽  
Vol 2016 ◽  
pp. 1-11 ◽  
Author(s):  
Suhua Liu ◽  
Hongbo Su ◽  
Renhua Zhang ◽  
Jing Tian ◽  
Weizhen Wang
Keyword(s):  
Remote Sensing ◽  
Energy Balance ◽  
Air Temperature ◽  
Driving Force ◽  
Regional Scale ◽  
Surface Air Temperature ◽  
Absolute Error ◽  
Northwest China ◽  
Absolute Deviation ◽  
Distance Weighting

To estimate the surface air temperature by remote sensing, the advection-energy balance for the surface air temperature (ADEBAT) model is developed which assumes the surface air temperature is driven by the local driving force and the advective driving force. The local driving force produces a local surface air temperature whereas the advective driving force changes it by adding an exotic air temperature. An advection factorfis defined to measure the quantity of the exotic air brought by the advection. Since thefis determined by the advection, this paper improves it to a regional scale by using the Inverse Distance Weighting (IDW) method whereas the original ADEBAT model uses a constant offfor a block of area. Results retrieved by the improved ADEBAT (IADEBAT) model are evaluated and comparison was made with the in situ measurements, with anR2(correlation coefficient) of 0.77, an RMSE (Root Mean Square Error) of 0.31 K, and a MAE (Mean Absolute Error) of 0.24 K. The evaluation shows that the IADEBAT model has higher accuracy than the original ADEBAT model. Evaluations together with at-test of the MAD (Mean Absolute Deviation) reveal that the IADEBAT model has a significant improvement.

scholarly journals Outdoor thermal performance simulation in campus area during the dry season, Yogyakarta

2019 ◽  
Vol 2 (1) ◽  
pp. 15
Author(s):  
Hasti Widyasamratri ◽  
Arif Kusumawanto ◽  
Fadhilla Tri Nugrahaini
Keyword(s):  
Wind Speed ◽  
Air Temperature ◽  
Thermal Performance ◽  
Meteorological Parameters ◽  
Anthropogenic Activities ◽  
Surface Air Temperature ◽  
Dry Season ◽  
Performance Simulation ◽  
Near Surface ◽  
Significant Area

The outdoor thermal performance reflects the microclimate condition in any significant area. This study simulated the thermal performance with measured and modeled three meteorological parameters, air temperature (Ta), relative humidity (RH), and wind speed in the dry season tropical city. The research focused on thermal performance simulation and distribution, here, we were neglecting anthropogenic activities as the heat source. The result showed that there were different ranges between a measured and simulated value of Ta, RH, and wind speed. The highest Ta difference between measure and simulation occurred at 11 AM, which was 1.97⸰C. The highest difference of RH occurred at 13 PM (26.75%), and the highest different of wind speed was at 11 AM (0.37 m/s) respectively. The heat distribution in the focus area was influenced by the solar direction which impacted the ground and near-surface air temperature.  

scholarly journals A second generation of homogenized Canadian monthly surface air temperature for climate trend analysis

2012 ◽  
Vol 117 (D18) ◽  
pp. n/a-n/a ◽  
Author(s):  
Lucie A. Vincent ◽  
Xiaolan L. Wang ◽  
Ewa J. Milewska ◽  
Hui Wan ◽  
Feng Yang ◽  
...  
Keyword(s):  
Trend Analysis ◽  
Air Temperature ◽  
Second Generation ◽  
Surface Air Temperature ◽  
Climate Trend

scholarly journals Relationships between Vertical Temperature Gradients and PM10 Concentrations during Selected Weather Conditions in Upper Silesia (Southern Poland)

Atmosphere ◽  
2022 ◽  
Vol 13 (1) ◽  
pp. 125
Author(s):  
Ewa Bożena Łupikasza ◽  
Tadeusz Niedźwiedź
Keyword(s):  
Air Pollution ◽  
Air Quality ◽  
Wind Speed ◽  
Air Temperature ◽  
Surface Air Temperature ◽  
Weather Conditions ◽  
Temperature Inversion ◽  
Temperature Gradients ◽  
Upper Silesia ◽  
Southern Poland

This paper studies surface air temperature inversions and their impact on air pollution under the background of meteorological conditions in southern Poland. The relationship of temperature gradients and air quality classes with weather conditions in the most urbanized and polluted part of Poland as represented by the Upper Silesia region (USR) within the administrative boundaries of the Górnośląsko-Zagłębiowska Metropolis (GZM) is presented. Based on probability analysis this study hierarchized the role of the selected weather elements in the development of surface-based temperature inversion (SBI) and air quality (AQ). The thresholds of weather elements for a rapid increase in the probability of oppressive air pollution episodes were distinguished. Although most SBI occurred in summer winter SBIs were of great importance. In that season a bad air quality occurred during >70% of strong inversions and >50% of moderate inversions. Air temperature more strongly triggered AQ than SBI development. Wind speed was critical for SBI and significant for AQ development. A low cloudiness favored SBI occurrence altered air quality in winter and spring during SBI and favored very bad AQ5 (>180 µg/m3) occurrence. The probability of high air pollution enhanced by SBI rapidly increased in winter when the air temperature dropped below −6 °C the wind speed decreased below 1.5 m/s and the sky was cloudless. Changes in the relative humidity did not induce rapid changes in the occurrence of bad AQ events during SBI

scholarly journals Dynamical Downscaling of Surface Air Temperature and Wind Field Variabilities over the Southeastern Levantine Basin, Mediterranean Sea

Climate ◽  
2021 ◽  
Vol 9 (10) ◽  
pp. 150
Author(s):  
Mohamed ElBessa ◽  
Saad Mesbah Abdelrahman ◽  
Kareem Tonbol ◽  
Mohamed Shaltout
Keyword(s):  
Wind Speed ◽  
Air Temperature ◽  
Wind Field ◽  
Climate Model ◽  
Dynamical Downscaling ◽  
Surface Wind ◽  
Surface Air Temperature ◽  
Warming Trend ◽  
Climate Data ◽  
Near Surface

The characteristics of near surface air temperature and wind field over the Southeastern Levantine (SEL) sub-basin during the period 1979–2018 were simulated. The simulation was carried out using a dynamical downscaling approach, which requires running a regional climate model system (RegCM-SVN6994) on the study domain, using lower-resolution climate data (i.e., the fifth generation of ECMWF atmospheric reanalysis of the global climate ERA5 datasets) as boundary conditions. The quality of the RegCM-SVN simulation was first verified by comparing its simulations with ERA5 for the studied region from 1979 to 2018, and then with the available five WMO weather stations from 2007 to 2018. The dynamical downscaling results proved that RegCM-SVN in its current configuration successfully simulated the observed surface air temperature and wind field. Moreover, RegCM-SVN was proved to provide similar or even better accuracy (during extreme events) than ERA5 in simulating both surface air temperature and wind speed. The simulated annual mean T2m by RegCM-SVN (from 1979 to 2018) was 20.9 °C, with a positive warming trend of 0.44 °C/decade over the study area. Moreover, the annual mean wind speed by RegCM-SVN was 4.17 m/s, demonstrating an annual negative trend of wind speed over 92% of the study area. Surface air temperatures over SEL mostly occurred within the range of 4–31 °C; however, surface wind speed rarely exceeded 10 m/s. During the study period, the seasonal features of T2m showed a general warming trend along the four seasons and showed a wind speed decreasing trend during spring and summer. The results of the RegCM-SVN simulation constitute useful information that could be utilized to fully describe the study area in terms of other atmospheric parameters.

Using the ERA5 dataset of atmospheric variables to estimate daily reference evapotranspiration in Sicily, Italy.

2021 ◽  
Author(s):  
Giuseppe Provenzano ◽  
Matteo Ippolito
Keyword(s):  
Wind Speed ◽  
Solar Radiation ◽  
Air Temperature ◽  
Management Practices ◽  
Reference Evapotranspiration ◽  
Dew Point ◽  
Climate Data ◽  
Crop Evapotranspiration ◽  
Time Step ◽  
Mediterranean Countries

&lt;p&gt;Crop evapotranspiration (ET) plays a key role in many hydrological processes involving the soil-plant-atmosphere system. The concept of reference crop evapotranspiration (ET&lt;sub&gt;0&lt;/sub&gt;) was introduced to estimate the atmosphere evaporation demand independently of crop type, development stage and management practices. Among the available methods to estimate ET&lt;sub&gt;0&lt;/sub&gt;, the Penman-Monteith equation proposed by the Food and Agriculture Organization of the United Nations (FAO56-PM), is considered one of the most accurate, so that it is assumed as a reference to calibrate other simplified procedures. In several regions of the world, the limited availability of meteorological observations to estimate ET&lt;sub&gt;0&lt;/sub&gt; can be overcome by using gridded reanalysis dataset created by data assimilation of weather observations. Different datasets with relatively high spatial resolution but different in terms of Spatio-temporal resolution have been generated and are freely downloadable at the global scale. The latest ERA5-Land product released in 2019 is characterized by a spatial grid to 0.1&amp;#176; latitude and 0.1&amp;#176; longitude. The database provides several land variables at hourly time-step including, among others, air temperature, dew point temperature and solar radiation at 2.0 m above the soil surface, as well as the wind speed components at 10 m height.&lt;/p&gt;&lt;p&gt;The objective of the research was to assess the suitability of ERA5-Land dataset of climate data to predict daily reference evapotranspiration in Sicily, Italy. For the period 2006-2015, the performance of the reanalysis data to capture the local climate variables was assessed based on the comparison with the corresponding ground data measured by a network of 39 climate stations in Sicily belonging to the Agrometeorological Information Service (SIAS). After evaluating the statistical errors associated with each climatic variables retrieved from the ERA5-Land, the comparison between daily ET&lt;sub&gt;0&lt;/sub&gt; values obtained with the FAO56-PM and considering both the dataset was carried out.&lt;/p&gt;&lt;p&gt;The analysis showed that air temperature, solar radiation and wind speed retrieved by the ERA-5 dataset resulted in quite good agreement with the corresponding measured on the ground, with an average root mean square error (RMSE) equal respectively to 1.8&amp;#176;C, 2.9 MJm&lt;sup&gt;-2&lt;/sup&gt;d&lt;sup&gt;-1&lt;/sup&gt;, and 1.3 ms&lt;sup&gt;-1&lt;/sup&gt; and corresponding mean bias errors (MBE) of -0.4&amp;#176;C, 1.0 MJm&lt;sup&gt;-2&lt;/sup&gt;d&lt;sup&gt;-1&lt;/sup&gt;&amp;#160; and -0.1 ms&lt;sup&gt;-1&lt;/sup&gt;. On the other hand, relative air humidity was characterized by average values of RMSE and MBE respectively equal to 10.3% and 5.6%. When considering all the examined climate stations, the RMSE and MBE values associated with ET&lt;sub&gt;0&lt;/sub&gt; ranged from 0.4 to 1.3 mm d&lt;sup&gt;-1&lt;/sup&gt;, and -1.0 and 0.0 mm d&lt;sup&gt;-1&lt;/sup&gt;, supporting the possibility to consider the ERA-5 data to obtain suitable estimations of crop reference evapotranspiration even for other Mediterranean countries where measured climate data are not available.&lt;/p&gt;

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