The “U-Tube”: An improved aspirated temperature system for mobile meteorological observations, especially in severe weather

Journal of Atmospheric and Oceanic Technology ◽

10.1175/jtech-d-21-0008.1 ◽

2021 ◽

Author(s):

Sean M. Waugh

Keyword(s):

Solar Radiation ◽

Response Time ◽

Severe Weather ◽

Temperature Measurements ◽

Original Design ◽

High Solar Radiation ◽

Frontal Zones ◽

Meteorological Observations ◽

General Response ◽

Key Aspects

AbstractObtaining quality air temperature measurements in complex mesoscale environments, such as thunderstorms or frontal zones, is problematic, and particularly challenging from a moving platform. For some time mobile weather platforms known as Mobile Mesonets (MMs) have used custom aspirated temperature shields. The original design was known as the “J-Tube”, which addresses some but not all of the unique problems associated with mobile temperature measurements. For VORTEX-2 2009, a second, well documented shield, the R.M. Young (RMY) 43408 was included but was also found to have certain shortcomings in some severe weather environments. Between the end of VORTEX2 2009 and the start of VORTEX2 2010, a third and new shield called the “U-tube” was designed, tested and installed.Reported here are the results of efforts to better characterize the J-Tube, RMY 43408, and the U-Tube. Several tests designed to isolate key aspects of a radiation shield’s performance, such as performance in rain, high solar radiation, varying wind conditions, and general response time were completed. A period of intercomparison between the three shields during the 2010 season of VORTEX 2 is also used to highlight each shield being used in “real world” conditions. Results indicate that the U-Tube has several significant advantages over the J-tube and 43408 in terms of aspiration rate, sampling efficiency, performance during rain, variable winds, and high solar radiation periods, as well as response time. Given these results, the U-tube should be utilized for mobile observations going forward.

Download Full-text

Effect of snow-covered ground albedo on the accuracy of air temperature measurements

Atmospheric Measurement Techniques ◽

10.5194/amt-14-6195-2021 ◽

2021 ◽

Vol 14 (9) ◽

pp. 6195-6212

Author(s):

Chiara Musacchio ◽

Graziano Coppa ◽

Gaber Begeš ◽

Christina Hofstätter-Mohler ◽

Laura Massano ◽

...

Keyword(s):

Solar Radiation ◽

Air Temperature ◽

Incident Radiation ◽

Data Availability ◽

Temperature Measurements ◽

Natural Soil ◽

Quality Of Data ◽

Full Data ◽

Near Surface ◽

Meteorological Observations

Abstract. Solar radiation is one of the main factors which introduce significant deviations between thermometers reading and true air temperature value. Techniques to protect the sensors from direct radiative influence have been adopted almost since the beginning of meteorological observations. Reflected radiation from a snow-covered surface can also cause extra warming to thermometers hosted in solar shields, which are not always optimised to protect the sensors from this further radiative heat transfer. This phenomenon can cause errors in near-surface temperature measurements results, with a relevant impact on the quality of data records and series. This study experimentally evaluates the effect of reflected radiation from a snow-covered surface on the accuracy of air temperature measurements. The investigation is based on the evaluation of temperature differences between pairs of identical instruments, positioned above ground covered by natural vegetation, with one instrument in snow-free conditions and the other above a snow-covered surface, at the same time and at the same site. The work involved a representative number of sensors and shields, in terms of different typologies, technologies and engineering solutions, from different manufacturers. A mountain site with acceptable field conditions, offering long-lasting snow presence to maximise data availability, was selected to perform the experiment. Quantities of influence, such as relative humidity, wind speed and direction and solar radiation (global and reflected), were constantly measured. The main findings of this work show that none of the involved instruments were immune to the extra heating due to the snow-reflected radiation. Excluding nighttimes and days of high wind or low incident radiation, the differences among sensors positioned above natural soil and identical ones exposed to snow albedo ranged up to more than 3 ∘C. Solar screens with forced ventilation showed a partially reduced effect compared to most of the naturally ventilated ones. A full data analysis is reported here, together with complete results and uncertainties.

Download Full-text

Movements of the Quebec Bridge’s Suspended Span Measured by GNSS Technology

GEOMATICA ◽

10.5623/cig2016-405 ◽

2016 ◽

Vol 70 (4) ◽

pp. 298-312

Author(s):

Rock Santerre ◽

Youssef Smadi ◽

Stéphanie Bourgon

Keyword(s):

Solar Radiation ◽

Vertical Movement ◽

Original Design ◽

Load Effect ◽

Loading Effect ◽

Bridge Span ◽

High Solar Radiation ◽

Design Calculations ◽

Suspended Bridge ◽

Train Loading

The Quebec Bridge was completed in 1917 and it is still the longest cantilever bridge in the world. Overall, the actual movements of its suspended span, as detected by GNSS (between 2012 and 2013), are in fair agreement with the original design calculations: for the train loading effect on the vertical movement (17 cm for one freight train); the transversal wind load effect on the transversal movement (32 cm for a wind speed of 170 km/h); and the temperature loading effect on the ver ti cal movement of the suspended span (3.2 cm for a 50°C temperature variation). Further movements have been detected by GNSS technology, namely: the transversal and longitudinal movements of the suspended bridge span due to train passages (11 cm transversally, at the top of the suspended span, and 1 cm longitudinally); the transversal movement of the bridge caused by solar radiation (differential) conditions on both sides of the bridge (5 cm for high solar radiation values); and the longitudinal movement of the suspended span of the Quebec Bridge at temperatures lower than 6°C (7 cm to −25°C).

Download Full-text

Effect of snow-covered ground albedo on the accuracy of air temperature measurements

10.5194/amt-2021-63 ◽

2021 ◽

Author(s):

Chiara Musacchio ◽

Graziano Coppa ◽

Gaber Begeš ◽

Christina Hofstätter-Mohler ◽

Laura Massano ◽

...

Keyword(s):

Solar Radiation ◽

Air Temperature ◽

Temperature Data ◽

Data Availability ◽

Temperature Measurements ◽

Data Series ◽

Quality Of Data ◽

Full Data ◽

Near Surface ◽

Meteorological Observations

Abstract. Solar radiation is one of the main factors introducing significant deviations between thermometers reading and true air temperature value. Techniques to protect the sensors from direct radiative influence have been adopted almost since the beginning of meteorological observations. Reflected radiation from snow-covered surface can also cause extra warming to thermometers hosted in solar shields, not always optimized to protect the sensors from this further backward radiative heat transfer. This phenomenon can cause errors in near-surface temperature data series, with relevant impact on the quality of data records. The study here presented experimentally evaluates the effect of albedo radiation from snow-covered surface, on the accuracy of air temperature measurements. The investigation is based on evaluating temperature differences between couples of identical instruments positioned above ground covered by natural vegetation, being one in snow-free conditions and the other above snow-covered surface, at the same time in the same site in close vicinity. The work involved a representative number of different typologies of sensors and shields from different manufactures. A mountain site with appropriate field conditions, offering long-lasting snow presence to maximize data availability, was selected to host the experiment. Quantities of influence such as relative humidity, wind speed and direction, solar radiation (direct and reflected) were constantly measured. The effect was evaluated to range up to more than 3 °C for some typologies of sensors. Full data analysis is here reported, together with complete results. This main scope of this work is to report on an experimental estimation and method to evaluate and include this effect as a component of uncertainty in temperature data series for near-surface stations above snowy areas.

Download Full-text

Long-term variations of surface solar radiation in China from routine meteorological observations

Atmospheric Research ◽

10.1016/j.atmosres.2021.105715 ◽

2021 ◽

pp. 105715

Author(s):

Xuefang Yang ◽

Wenmin Qin ◽

Lunche Wang ◽

Ming Zhang ◽

Zigeng Niu

Keyword(s):

Solar Radiation ◽

Surface Solar Radiation ◽

Meteorological Observations ◽

Long Term Variations

Download Full-text

Mechanically Aspirated Solar Radiation Shields: A CFD and Neural Network Design Analysis

10.1115/imece2001/htd-24287 ◽

2001 ◽

Author(s):

B. M. Fichera ◽

R. L. Mahajan ◽

T. W. Horst

Keyword(s):

Neural Network ◽

Solar Radiation ◽

Temperature Sensor ◽

Temperature Measurements ◽

Analysis And Design ◽

Computational Fluid Dynamics Analysis ◽

Radiation Shields ◽

Input Variables ◽

The Relationship

Abstract Accurate air temperature measurements made by surface meteorological stations are demanded by climate research programs for various uses. Heating of the temperature sensor due to inadequate coupling with the environment can lead to significant errors. Therefore, accurate in-situ temperature measurements require shielding the sensor from exposure to direct and reflected solar radiation, while also allowing the sensor to be brought into contact with atmospheric air at the ambient temperature. The difficulty in designing a radiation shield for such a temperature sensor lies in satisfying these two conditions simultaneously. In this paper, we perform a computational fluid dynamics analysis of mechanically aspirated radiation shields (MARS) to study the effect of geometry, wind speed, and interplay of multiple heat transfer processes. Finally, an artificial neural network model is developed to learn the relationship between the temperature error and specified input variables. The model is then used to perform a sensitivity analysis and design optimization.

Download Full-text

The Potential of Solar Air Heating in the Turkish Industrial Sector

Periodica Polytechnica Mechanical Engineering ◽

10.3311/ppme.13028 ◽

2018 ◽

Vol 63 (1) ◽

pp. 57-66

Author(s):

Balázs Bokor ◽

Hacer Akhan ◽

Dogan Eryener ◽

László Kajtár

Keyword(s):

Solar Radiation ◽

Energy Savings ◽

Measurement Data ◽

Industrial Sector ◽

Climatic Conditions ◽

Cold Climate ◽

Conventional Heating ◽

Industrial Building ◽

High Solar Radiation ◽

Mathematical Correlation

Transpired solar collector (TSC) systems are simple solutions for the preheating of ventilation air with solar energy. Their performance is a function of several environmental factors, so the climatic conditions of the location play an important role. In this paper, the effect of different climatic zones on the thermal performance of the TSC is investigated. To exclude other sources of influence, the same reference industrial building is examined in four Turkish locations (Antalya, Istanbul, Ankara and Sivas) representing different climatic conditions. RETScreen simulation is carried out for all four regions to obtain the drop of conventional heating requirement in case absorber azimuth of 0°, 45° and 90°. To illustrate the performance, temperature rise, heating energy savings and annual solar fraction are presented. Generally, it can be stated that a location with cold climate and high solar radiation at the same time benefits most from the use of a TSC system. A mathematical correlation has been found showing the solar fraction's dependence on solar radiation and heating degree days. Finally, simulation results have been compared to a set of measurement data from an industrial building's TSC system near Istanbul.

Download Full-text