water vapor monitoring using wireless communication networks measurements

Water Vapor Water Vapor Monitoring using Monitoring using

Wireless Wireless Communication Communication

Networks Networks Measurements Measurements

Noam DavidNoam DavidThe Department of Geophysics & Planetary The Department of Geophysics & Planetary Sciences, TAUSciences, TAU

TheThe ResearchResearch TeamTeam

Prof. Pinhas Alpert –Prof. Pinhas Alpert –meteorologymeteorology

Team members:Team members: Dr. Rana SamuelsDr. Rana Samuels Artem ZinevichArtem Zinevich Ori AuslenderOri Auslender

Prof. Hagit Messer – Prof. Hagit Messer – signal processingsignal processing

Noam DavidNoam David Dani CharkaskyDani Charkasky Ronen RadianRonen Radian Yoni OstromtzkiYoni Ostromtzki

WirelessWireless CommunicationCommunication NetworksNetworks

Base Station 1

Base Station 2

User 1

User 2

• These links are built close to the ground, and operate in a frequency range of tens of GHz

• In many wireless communication systems the Received Signal Level (RSL) is measured and recorded.

• In wireless communication, the RSL depends on atmospheric conditions.

Transmission losses due to atmosphericTransmission losses due to atmospheric conditionsconditions

Absorption and scattering of the radiation, at frequencies of tens of GHz, are directly related to the atmospheric conditions, primarily precipitation,

oxygen, water vapor, mist and fog (Ulaby, 1981).

The idea: Water Vapor The idea: Water Vapor MonitoringMonitoring• In typical conditions of:

• 1013 hPa pressure

• 15ºC temperature

• water vapor density of 7.5 gr/m3

The water vapor density can be measured!

• Part of the wireless systems have a magnitude resolution of 0.1 dB per link.

)/( 2.0 kmdB

The model: microwave The model: microwave propagation in moist airpropagation in moist air

- The attenuation due to water vapor and due to dry air [dB/km]

f - The link's frequency [GHz].

N” - The imaginary part of the complex refractivity measured in N units, a function of the frequency f [GHz], pressure p[hPa], temperature T [°C] and the water vapor density ρ[gr/m3].

*ITU-R Recommendations P. 676-6: Attenuation by atmospheric gases, September 2005

[dB/km] ),,,("1820.0 TpffNwO

ResulResultsts

Water Vapor MonitoringWater Vapor Monitoring

4.53

km

Tzrifin

Ramla

Ben Gurion Airport

Frequency: 22.525 GHzSurface station-link distance: ~6.5 kmLength: 4.53 kmReceiver and transmitter heights: 95, 63 [m] ASL

Water Vapor MonitoringWater Vapor Monitoring

Number of days: 25Correlation: 0.89RMSD: 3.4 [g/m3]

Water Vapor Density- Central Israel 09/2007 (03:00 a.m.)

05

1015202530

26/08/2007 31/08/2007 05/09/2007 10/09/2007 15/09/2007 20/09/2007 25/09/2007 30/09/2007

Date

Wat

er V

apo

r D

ensi

ty (

g/m

^3)

Microwave Humidity Gauge (Lod Airport)

Water Vapor MonitoringWater Vapor Monitoring

3.86

km

Harduf

Kiryat Ata

Frequency: 22.725 GHzSurface station-link distance: ~7.5 kmLength: 3.86 kmReceiver and transmitter heights: 265, 233 [m] ASL

Water Vapor MonitoringWater Vapor Monitoring

Correlation: 0.9RMSD: 1.8 [gr/m3]2 rainy days were excluded (7 and 22 November)

Water Vapor Density- North Israel 11/2005 (03:00 a.m)

0

5

10

15

20

25

30/10/2005 04/11/2005 09/11/2005 14/11/2005 19/11/2005 24/11/2005 29/11/2005 04/12/2005

Date

Wate

r V

ap

or

Den

sit

y

[g/m

^3]

Microwave Humidity Gauge (K. Ata)

SummarySummary Our results show relatively good agreement between the

conventional way to measure water vapor and our proposed, novel method

The technique is restricted to weather conditions which exclude rain, fog or clouds along the propagation path

Since measurements from the microwave link are line integrated data, where in-situ measurements are point measurements in a humidity gauge, some disparities are expected

The method only requires standard data (saved by the communication system anyway), therefore the costs are minimal