1. Processes and Methodologies
BUENOS AIRES VAAC
Processes and Methodologies
VAAC Best Practices Seminar
Montréal, 13 to 14 February 2012
Ximena F. Calle
Assistant Remote Sensing Meteorological Division
National Weather Service - Argentina

2. Buenos Aires VAAC Area of Responsibility

3. Q1: Buenos Aires VAAC Organisation Organisational Structure
National Weather Service (NWS), Argentina
Community Services Management Area
Buenos Aires VAAC -Remote Sensing Meteorological Watch Division (RSMWD)
Forecasting Department

4. Q1: Buenos Aires VAAC Organisation Staff
RSMWD Chief
Weather Forecaster
VAAC Forecaster
Automated Processing Dept. staff
Communications Dept. Operator
Aeronautical Meteorology Dept. staff

5. Q2: Model Data NWP Models
ETA NWS
WRF NWS
GFS

6. Q2: Model Data Dispersion Models
HYSPLIT NWS (ETA & GFS)
HYSPLIT READY (on-line)
FALL/3D NWS (ETA)
PUFF (on-line)

7. Q2: Model Data Dispersion Models
VAAC forecaster routinely runs all available dispersion models and uses the one that fits best to the observed VA CLD.
Residual VA CLDs are forecasted by looking at the wind fields outputs of the NWP models.
In case of long eruptions (Chaitén and Cordón-Caulle volcanos) dispersion models are setup considering a release start time prior to the time of the observed VA CLD (e.g. 6, 12 or even 24 hours in advance).

8. Q3: Observational Data Satellite Data
GOES-SA (G-12)
Main source of information.
Processed by VAAC forecaster with TeraScan system.
One image every 15 min.
Day : VA detected mainly using CH1
Night : VA detected using CH2, CH4 and CH2-CH4.
Day & Night: also using CH2 – (1.5 CH4) + (1.5 CH6)

9. Q3: Observational Data Satellite Data
Alternatives to GOES-SA are:
GOES E (G-13, on-line)
METEOSAT – 9 (on-line)
NOAA 15/16/17 (processed by HRPT Division of NWS)
AQUA and TERRA (processed by HRPT Division and by CONAE agency of Argentina)

11. SMN DVMSR GOES – 12 CH1 16-OCT-11

12. Q3: Observational Data Satellite Data
VULNERABILITY TO MONITOR VOLCANIC ASH
GOES-SA Cancellation: There is a great concern about cancellation of GOES-SA. Currently the image reception is very erratic in response to the satellite present situation which will end up in its total cancellation in the near future.
Alternative is GOES-E which covers the whole area of responsibility only every 3 hours and up to 45° South (approx.) every 30 min. Nevertheless, this smaller sector is canceled every time GOES-E is requested to monitor severe weather events over the US.

13. Q3: Observational Data Satellite Data
VULNERABILITY TO MONITOR VOLCANIC ASH
GOES data deficiency in the detection of VA:
The lack of an appropriate channel to detect volcanic ash is the main source of vulnerability in the ability of Buenos Aires VAAC to monitor VA in its area of responsibility …(CH5 instead of CH6 is needed!).

14. Q3: Observational Data Other sources of information
Vulcanological Observatory OVDAS - SERNAGEOMIN of Chile (contacted via AFTN, , telephone)
OVDAS WebCam images
National/International surface meteorological stations network
Pilot reports (received at the Communications Dept. of NWS; if necessary, ARS are requested to ATM staff)

15. OVDAS – SERNAGEOMIN WebCam Futangue

16. APROX. FL100
MOV. HACIA EL SE
OVDAS WEBCAM IMAGE OF REFERENCE TO ESTIMATE THE LEVEL AND DIRECTION OF THE VA PLUME
GOES 12 CH1 16/01/2012

17. Q4: Determination of a volcanic eruption Notification
through…
Satellite images (generated by sectors which are continuously monitored)
OVDAS WebCam images (continuously monitored)
ARP/ARS and SIGMET provided by the WMOs
Automatic satellite detection of hot spots (reception of s from CONAE agency based on AQUA and TERRA scans)
Vulcanological Observatory information
METAR, SPECI, SYNOP

18. Additionally…
Buenos Aires VAAC monitor the status of active or potentially active volcanoes of Chile by daily reception of reports from OVDAS vulcanological observatory.

19. Q4: Determination of a volcanic eruption Confirmation
through…
satellite imagery analysis (direct and using algorithms)
OVDAS WebCam images
contact with the vulcanological observatory
contact with Air Traffic Management
contact with meteorological surface stations in the area

20. Q5: Estimating the boundaries of VA Altitude of top
If possible, visual estimation from web cam images
From estimation of VA CLD top temperature using thermal IR channel (CH4 G12/13) and its correlation with temperature data provided by soundings (observational data or from numerical model).
From correlation between the observed VA CLD movement and the wind information provided by soundings.
If possible, using product ‘Ash Cloud Height’ from MET-9.
From ARP/ARS, SIGMET.

21. Q5: Estimating the boundaries of VA Altitude of base
If possible, visual estimation from web cam images.
From ARP/ARS, SIGMET.
Horizontal extent
From satellite images.
Considering affected meteorological surface stations.

22. Q5: Estimating the boundaries of VA Facing uncertainties
Buenos Aires VAAC indicates presence of ash in a VAA when there is clear evidence in satellite imagery and web cameras. Such evidence is complemented by METAR, SIGMET, Pilot Reports, Volcanic Institutions observations.
VAAC forecasters give sources of information different priorities: - first to satellite and web cam images, and to Vulcanological Observatory information
- second to ARP/ARS (the accuracy of the data provided by these reports is analysed in relation to the relative horizontal and vertical position of the plane).

23. Q5: Estimating the boundaries of VA Facing uncertainties
When ash is obscured by clouds, dust, smoke, etc., the ash boundary is estimated in accordance to the extent and trajectory of ash that could be previously detected in satellite imagery, and also by considering model data.
Model data and direct observation data must keep a high correlation, especially in the case of continuous eruptions. In this case, model outputs will have to adjust to what has been directly observed.

24. Q6: Forecasting VA CLD
VAAC forecasters estimate future ash positions using the dispersion model and/or according with the trajectory detected through the observation and numerical model wind field.
When there are differences between the observed ash boundaries and model initial ash boundaries, model outputs are adjusted in accordance to the observed data.
The operational model in use is the HYSPLIT/GFS, although its output is usually compared with outputs from other models; in case of discrepancies, more weight is given to the one that better reflects the direct observation.

25. Q7: VAAC Output
To issue the VAA and VAG, ash boundary estimates are translated into coordinates by means of GrADS (Grid Analysis and Display System).
There is no policy to restrict the number of layers, areas or coordinates per area.
There is no rule for writing the lat/lon groups in the VAA.

26. Q7: VAAC Output
Buenos Aires VAAC routinely doesn’t provide any supplementary data in addition to the VAA and VAG; the exception occurs when details on these information are provided to users via telephone when required (airlines ask for accurate data!) .
VAAC forecasters follow an internal user guide in the production of VAAC outputs, however a Quality Management System has not been implemented yet.
Quality of VAAC outputs is not being monitored at the moment.

27. Q7: VAAC Output Transmission of VAA and VAG
- VAA : via AFTN and public Internet (txt format)
VAG : only published on the public Internet (png format)
Buenos Aires VAAC does have an Internet web site ( of free access and available in Spanish and English languages. It provides…
current and archive VAA and VAG (in color)
links to all the other VAACs
SIGMETs for volcanic ash clouds (AIREPs are published at the NWS’s web site)
link to Vulcanological Observatory of Chile

28. Thanks to all!!