scholarly journals Water vapor estimation based on one-year data of E-band millimeter-wave link in the northeast of China

2021 ◽  
Author(s):  
Siming Zheng ◽  
Juan Huo ◽  
Wenbing Cai ◽  
Yinhui Zhang ◽  
Peng Li ◽  
...  
Keyword(s):  
Water Vapor ◽  
Millimeter Wave ◽  
Lower Layer ◽  
Estimation Error ◽  
Weather Forecast ◽  
Previous Method ◽  
Vapor Density ◽  
Precision Data ◽  
One Year ◽  
Microwave Link

Abstract. The amount of water vapor in the atmosphere is very small, but its content varies greatly in different humidity areas. The change of water vapor will affect the transmission of microwave link signals, and most of the water vapor is concentrated in the lower layer, so the water vapor density can be measured by the change of the near-ground microwave link transmission signal. This study collected one-year data of the E-band millimeter-wave link in Hebei, China, and used a model based on the ITU-R to estimate the water vapor density. An improved method of extracting the water vapor induced attenuation value is also introduced. It has a higher time resolution and the estimation error is lower than the previous method. In addition, this paper conducts the seasonal analysis of water vapor inversion for the first time. The monthly and seasonal evaluation index results show a high correlation between the retrieved water vapor density the actual water vapor density value measured by the local weather station. The correlation value for the whole year is up to 0.95, the root mean square error is as low as 0.35, and the average relative error is as low as 0.05. This research shows that millimeter-wave backhaul link provides high-precision data for the measurement of water vapor density and has a positive effect on future weather forecast research.

scholarly journals Estimating Water Vapor Using Signals from Microwave Links below 25 GHz

2021 ◽  
Vol 13 (8) ◽  
pp. 1409
Author(s):  
Kun Song ◽  
Xichuan Liu ◽  
Taichang Gao ◽  
Peng Zhang
Keyword(s):  
Water Vapor ◽  
Weather Forecasting ◽  
Water Cycle ◽  
Correlation Coefficients ◽  
Support Vector ◽  
Vapor Density ◽  
Measurement Resolution ◽  
Sensing Model ◽  
Numerical Weather Forecasting ◽  
Mean Square Errors

Water vapor is a key element in both the greenhouse effect and the water cycle. However, water vapor has not been well studied due to the limitations of conventional monitoring instruments. Recently, estimating rain rate by the rain-induced attenuation of commercial microwave links (MLs) has been proven to be a feasible method. Similar to rainfall, water vapor also attenuates the energy of MLs. Thus, MLs also have the potential of estimating water vapor. This study proposes a method to estimate water vapor density by using the received signal level (RSL) of MLs at 15, 18, and 23 GHz, which is the first attempt to estimate water vapor by MLs below 20 GHz. This method trains a sensing model with prior RSL data and water vapor density by the support vector machine, and the model can directly estimate the water vapor density from the RSLs without preprocessing. The results show that the measurement resolution of the proposed method is less than 1 g/m3. The correlation coefficients between automatic weather stations and MLs range from 0.72 to 0.81, and the root mean square errors range from 1.57 to 2.31 g/m3. With the large availability of signal measurements from communications operators, this method has the potential of providing refined data on water vapor density, which can contribute to research on the atmospheric boundary layer and numerical weather forecasting.

Scanning 10-W Water Vapor DIAL for the Investigation of Atmospheric Turbulence and Land-Atmosphere Feedback

2021 ◽  
Author(s):  
Andreas Behrendt ◽  
Florian Spaeth ◽  
Volker Wulfmeyer
Keyword(s):  
Heat Flux ◽  
Water Vapor ◽  
Latent Heat ◽  
Atmospheric Turbulence ◽  
Latent Heat Flux ◽  
Climate Models ◽  
Weather Forecast ◽  
Surface Characteristics ◽  
Scanning System ◽  
Forecast Models

<p>We will present recent measurements made with the water vapor differential absorption lidar (DIAL) of University of Hohenheim (UHOH). This scanning system has been developed in recent years for the investigation of atmospheric turbulence and land-atmosphere feedback processes.</p><p>The lidar is housed in a mobile trailer and participated in recent years in a number of national and international field campaigns. We will present examples of vertical pointing and scanning measurements, especially close to the canopy. The water vapor gradients in the surface layer are related to the latent heat flux. Thus, with such low-elevation scans, the latent heat flux distribution over different surface characteristics can be monitored, which is important to verify and improve both numerical weather forecast models and climate models.</p><p>The transmitter of the UHOH DIAL consists of a diode-pumped Nd:YAG laser which pumps a Ti:sapphire laser. The output power of this laser is up to 10 W. Two injection seeders are used to switch pulse-to-pulse between the online and offline signals. These signals are then either directly sent into the atmosphere or coupled into a fiber and guided to a transmitting telescope which is attached to the scanner unit. The receiving telescope has a primary mirror with a dimeter of 80 cm. The backscatter signals are recorded shot to shot and are typically averaged over 0.1 to 1 s.</p>

scholarly journals Atmospheric observations with E-band microwave links – challenges and opportunities

2020 ◽  
Author(s):  
Martin Fencl ◽  
Michal Dohnal ◽  
Pavel Valtr ◽  
Martin Grabner ◽  
Vojtěch Bareš
Keyword(s):  
Water Vapor ◽  
Size Distribution ◽  
Drop Size ◽  
Drop Size Distribution ◽  
Distribution Data ◽  
Vapor Sensing ◽  
Challenges And Opportunities ◽  
Atmospheric Observations ◽  
Order Of Magnitude ◽  
Microwave Link

Abstract. Opportunistic sensing of rainfall and water vapor using commercial microwave links operated within cellular networks was conceived more than a decade ago. It has since been further investigated in numerous studies predominantly concentrating on the frequency region of 15–40 GHz. This manuscript provides the first evaluation of rainfall and water vapor sensing with microwave links operating at an E band (specifically, 71–76 GHz and 81–86 GHz), which are increasingly updating, and frequently replacing, older communication infrastructure. Attenuation-rainfall relations are investigated theoretically on drop size distribution data. Furthermore, quantitative rainfall estimates from six microwave links, operated within cellular backhaul, are compared with observed rainfall intensities. Finally, the capability to detect water vapor is demonstrated on the longest microwave link measuring 4.86 km in path length. The results show that E-band microwave links are by one order of magnitude more sensitive to rainfall than devices operating in the 15–40 GHz range and are thus able to observe even light rainfalls, a feat practically impossible to achieve previously. The E-band links are, however, substantially more affected by errors related to variable drop size distribution. Water vapor retrieval might be possible from long E band microwave links, nevertheless, the efficient separation of gaseous attenuation from other signal losses will be challenging in practice.

scholarly journals The Effect of Clouds on Water Vapor Profiling from the Millimeter-Wave Radiometric Measurements

1997 ◽  
Vol 36 (9) ◽  
pp. 1232-1244 ◽  
Author(s):  
J. R. Wang ◽  
J. D. Spinhirne ◽  
P. Racette ◽  
L. A. Chang ◽  
W. Hart
Keyword(s):  
Water Vapor ◽  
Millimeter Wave ◽  
Radiometric Measurements

Twilight observations of upper atmospheric sodium, potassium, and lithium

1969 ◽  
Vol 47 (1) ◽  
pp. 85-98 ◽  
Author(s):  
W. A. Gault ◽  
H. N. Rundle
Keyword(s):  
Density Distribution ◽  
Seasonal Variations ◽  
Resonance Line ◽  
Lower Layer ◽  
Atmospheric Transmission ◽  
Sodium Potassium ◽  
Sodium Layer ◽  
Lower Height ◽  
One Year

Twilight resonance emissions due to atmospheric sodium, lithium, and potassium have been measured for over one year. The existence of the potassium resonance line was verified by using an absorption cell.Several problems of measuring the emissions and of subsequently calculating a density distribution are discussed. The widths of about 13 km and the topside scale heights of about 4.5 km obtained for the sodium layer are significantly less than obtained at Saskatoon in previous measurements. Atmospheric transmission functions have been recalculated with the results that the sodium and lithium layers are both at about the same height of around 90 km. A lower height of about 85 km was obtained for the potassium layer.The seasonal variations of sodium and lithium twilight abundances are shown to be similar with additional sharp enhancements of lithium abundances thought to be due to natural and man-made injections of lithium. Any seasonal variations of the potassium abundances in the lower layer were masked by large day-to-day fluctuations.

scholarly journals Prospects for Erratic and Intensifying Madden-Julian Oscillations

Climate ◽  
2020 ◽  
Vol 8 (2) ◽  
pp. 24
Author(s):  
Patrick Haertel
Keyword(s):  
Water Vapor ◽  
Tropical Cyclones ◽  
Radiative Forcing ◽  
Coupled Model ◽  
Equatorial Indian Ocean ◽  
Madden Julian Oscillation ◽  
Kelvin Wave ◽  
Late 20Th Century ◽  
Planetary Scale ◽  
One Year

The Madden–Julian Oscillation (MJO) is a planetary-scale convective disturbance that typically forms in the equatorial Indian Ocean, propagates slowly eastward, and dissipates near the date line. This study examines how the MJO changes in response to a changing radiative forcing in a fully-Lagrangian coupled model (LCM) that is shown to simulate robust and realistic MJOs. After the LCM is spun up for 160 years to reproduce the late 20th century climate, non-water-vapor longwave optical depth is increased over 70 years to model the effects of increasing concentrations of greenhouse gases. The model is then run for another 30 years without additional changes to the radiative forcing. After the radiative forcing is modified, the MJO generally becomes more frequent and intense, but it is also more variable from one year to the next. Not only do composite MJO rainfall perturbations increase, but wind, temperature, and moisture perturbations also become stronger. The aspect of the MJO’s structure that changes the most is the largely dry equatorial Kelvin wave circulation that circumnavigates the globe between moist phases of the MJO. Potential impacts of these changes included alterations to the way in which the MJO modulates tropical cyclones, monsoon disturbances, and El Niño.

Ground-Based Microwave Radiometer Profiler Observations before a Heavy Rainfall

2011 ◽  
Vol 137 ◽  
pp. 312-315
Author(s):  
Wen Jing Xu ◽  
Hong Yan Liu
Keyword(s):  
Water Vapor ◽  
Temporal Resolution ◽  
Density Profile ◽  
Heavy Rainfall ◽  
Microwave Radiometer ◽  
Cloud Water ◽  
Vapor Density ◽  
Apparent Change

Ground-based 12-channel microwave radiometer profiler TP/WVP-3000 can provide temperature and vapor density profile per minute up to 10 km height. The observations feature apparent change before heavy rainfall obtained by TP/WVP-3000 is presented in this paper. It demonstrates the detailed thermodynamic features that the atmosphere becomes colder and drier above height 3-4 km about 9 hours before the rain, the integrated water vapor gradually increases from 5 cm to 9 cm, the integrated cloud water change from near zero to 15 mm and the vapor density also increases rapidly about half an hour before the rain, which can be concluded that the radiometer profiler is able to improve the understanding of mesoscale weather in this case due to the profiler significantly improves the temporal resolution of atmospheric thermodynamic observations.

Retrievals of column water vapor using millimeter-wave radiometric measurements

2002 ◽  
Vol 40 (6) ◽  
pp. 1220-1229 ◽  
Author(s):  
J.R. Wang ◽  
P. Racette ◽  
M.E. Tiesky ◽  
W. Manning
Keyword(s):  
Water Vapor ◽  
Millimeter Wave ◽  
Radiometric Measurements
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