Automatic observation of cloudiness: Analysis of all-sky images

TECO - 2012 |

Brussels (Belgium) |

16-18 October 2012

Automatic observation of cloudiness: Analysis of all-sky images

Yézer González 1

César López 1

Emilio Cuevas 2

1. Sieltec Canarias S.L.

3. Izaña Atmospheric Research Center (AEMET) Spain

TECO - 2012 | Brussels (Belgium) | 16-18 October 2012

Cloud cover estimation

- The influence of clouds on Earth´s radiation balance is a key component of the atmospheric system.

- Cloud monitoring is important for aeronautical purposes and weather forecast.

- Cloud cover estimation is an activity traditionally performed by human observations. These observations are subject to subjective errors.

- Poor espacial and temporal resolution.


Yézer González, César López and Emilio Cuevas TECO-2012 | Brussels | 16-18 October 2012

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SONA

Automatic System of Cloud Observation

SONA features

- CCD sensor. 640x480 pixels, 8 bit, color response from 400 to 700nm and monochrome response from 400 to 1000nm.

- Very durable aluminium housing.

- Borosilitate dome.

- Rotating shadow band.

- Cooling/heating system (-10º to +50ºC).

- Fast frame rates (up to 70 fps).

- Adjustable JPEG compressed still-images or live MJPEG streaming video.

- Transfer of images via FTP, RTP or HTTP.

- Camera control via HTTP, XML-RPC, Telnet



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SONA

Automatic System of Cloud Observation

SONAs in Spain



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The site

- SONA has been developed and tested at the Izaña

Atmospheric Observatory (IZO; 28.5ºN 16ºW;

2,400 m a.s.l.)

- IZO is a Global Atmospheric Watch (GAW) observatory (www.aemet.izana.org) of global importance with a complete atmospheric components measurement program.



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Cloud Detection Procedure

Accurate cloud detection and monitoring is a challenge



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Accurate cloud detection and monitoring is a complex problem

(A) Biological neuron. (B) Computer neuron model or perceptron. (C) Multilayer neural network with and input layer, two hidden neuron layers and a neuron output layer.



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Calibration and training



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Detection



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Image cloud detection in progress…



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Aerosols and Haze

Single photo analysis Multiphoto analysis

Saharan dust

More uncorrelated inputs



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Aerosols and Haze

Original photo Single analysis Multiphoto analysis



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Results

SONA vs. human observations



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Ongoing and Future Activities

Cloud Nowcasting

SONA + photovoltaic system



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Cloud flow determination

Implement last developments of High Resolution Winds Products (Atmospheric motion vectors -AMVs- from MSG/HRVIS) achieved by NWC SAF.

Goal: perform cloud nowcasting using all sky camera images.

J. García-Pereda

AEMET



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Cloud Nowcasting.

NWC SAF products

Cloud Mask Cloud Type

Cloud Top Height Cloud Top Pressure



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Cloud base height estimation

Goal: Estimate type of clouds and corresponding solar radiation attenuation coefficients

Two SONA cameras



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Acknowledgements

-SONA project has received a grant from Consejería de

Hacienda, Canary Islands Government, FEDER funds.

-CIAI´s Basic System Unit (Ramón Ramos, Rubén del

Campo, Cándida Hernández, Virgilio Carreño, Fernando de Ory, Enrique Reyes, Antonio Cruz, Rocío López y

Néstor Castro)

-NWC SAF information for cloud Nowcasting

-Engineers and technicians from SIELTEC



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Thank You



Automatic observation of cloudiness: Analysis of all-sky images

Automatic observation of cloudiness: Analysis of all-sky images

Automatic System of Cloud Observation

Automatic System of Cloud Observation

SONA + photovoltaic system

Thank You

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Automatic observation of cloudiness: Analysis of all-sky images