1 Modelled Meteorology - Applicability to Well-test Flaring Assessments Environment and Energy...
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1 Modelled Meteorology - Modelled Meteorology - Applicability to Well-test Applicability to Well-test Flaring Assessments Flaring Assessments Environment and Energy Division Alex Schutte Science & Community Environmental Knowledge Fund Forum and Workshop May 29 th , 2003
1 Modelled Meteorology - Applicability to Well-test Flaring Assessments Environment and Energy Division Alex Schutte Science & Community Environmental
1 Modelled Meteorology - Applicability to Well-test Flaring
Assessments Environment and Energy Division Alex Schutte Science
& Community Environmental Knowledge Fund Forum and Workshop May
29 th, 2003
Slide 2
2 Assessing Potential Impacts from Flares Objective: To ensure
adequate protection of the environment prior to emitting pollutants
into the atmosphere In mountainous terrain - Wind Speed and Wind
Direction are the main factors affecting potential impacts.
Slide 3
3 Overview Modelled vs Measured Meteorological Data Best data
for estimating impacts are measured data Would need significant
amounts to cover every valley Modelled data can provide a potential
worst case indication prior to the event Current WLAP Accepted
Dispersion Models require meteorological data from one location and
assume a uniform wind field (pollutants disperse in a straight
line).
Slide 4
The best is on-site observation of wind and temperature for a
five year period Typically - one year observations at another
location topography often very different and off- site weather
(wind) not the same as that on the site Meteorology
Slide 5
5 Objective Research compared meteorological model outputs with
independent site measurements to assess the accuracy of
substituting modelled meteorological data for in situ
observations
Slide 6
6 Approach Stage 1 - The Mesoscale Model Version 5 (MM5)
Prognostic meteorological model was compared for use in current
models Stage 2 - The output from MM5 was then coupled with a
Diagnostic meteorological model (CALMET) and the resultant
meteorological fields similarly assessed.
Slide 7
7 Approach Stage 3 - A few case studys using observed
measurements vs the above results were assessed
Slide 8
8 Climate Long term Wind Speed and Direction Data available at
4 stations in Northern BC - PG, FSJ, Beatton River, Fort
Nelson
Slide 9
9 Upper Air Stations Western Canada is limited - Prince George
- Fort Nelson
Slide 10
10 SurfaceStations Environment Canada No wind data Forestry
Historically no data collection in winter WLAP/Industry few long
term records in areas of flaring activities
12 Stage 1 - Conclusions MM5 data at a 20km resolution does not
sufficiently resolve the wind field Finer resolution data may be
able to resolve the winds however would require applying the model
to a smaller area (More resources)
Slide 13
13 Stage 2 Applied CALMET to a 1km Resolution Supplemented with
actual meteorology except for the station of Interest Results were
compared
Slide 14
14 Stage 2 CALMET Extracted (Grid 21, 43) Wind Rose versus
Rotated Top Actual Rotated (33 degrees) Bottom - Tumbler 1993-1994-
CALMET Extraction for Grid Point (21,43)
Slide 15
15 Stage 2 CALMET Extracted Grid Point (20,38) Wind Rose versus
Rotated Tumbler Top Actual Rotated (55 degrees) Bottom - Tumbler
1993-1994- CALMET
Slide 16
16 Illustration of 3-D Wind field
Slide 17
17 Stage 2 - Summary CALMET wind fields are more realistic than
the current assumed uniform wind fields A 1km resolution was
sufficient to provide a reasonable representation Prognostic (MM5)
or UBC (MC2) data should be used as input to the model Avoids the
straight impact limitation in ISC3
Slide 18
18 Stage 3 Case Studies Current Regulatory Requirements: No in
situ meteorological data use surrogate station. Both ISC and RTDM
must be run and combined into one set of model outputs. Protocols
focus on worst-case concentrations
Slide 19
19 Stage 3 Model Results For each case, WLAP methods were
applied and then the CALMET/CALPUFF methods were applied. Results
produced similar maximum worst case concentrations neither model
indicated a propensity to be higher or lower. The spatial
distribution of concentrations were different.
Slide 20
20 Model Illustration Data (Raw) Dir Ws 107.7000 0.5330 86.3000
0.7140 78.0000 1.7170 243.2300 0.4170 73.0000 0.0680 194.1100
1.4140 176.2000 5.4580 345.2000 0.5730 218.7700 1.9120 205.4600
1.4190 226.3000 1.8590 270.8000 2.6700 Calms to (1m/s) in ISC3,
Dir- Wind Towards
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Straight-line Gaussian models assume instantaneous dispersion
for the hour with a uniform wind field. When used to predict
concentrations, if meteorology is not local, results can be
meaningless. Even if local meteorology is used, results may not be
valid - too much reg. focus on max. Model predictions may indicate
unlikely high concentrations in unlikely locations affects how
others may conduct monitoring. Current Shortcomings
Slide 33
33 New Approach - Using CALMET/CALPUFF Among other conclusions
in the report: It is a viable approach that can act as a substitute
for collecting long-term meteorological data in the region. Using a
modelled refined data set eliminates the subjectivity of
applying/rotating other data sets. Large modelling domains can be
created one time for many flaring locations. Limited by the
availability of prognostic data to a fine enough resolution.
Slide 34
34 Future Possibilities Evolve to the point where
CALPUFF/CALMET is viable for all locations in addition to the study
area Future Research (perhaps joint with UBC) to evaluate refined
data sets (eg. 1km), and perhaps even use as real meteorology?
Evaluate how the more meaningful results compare with ambient
sampling, based on actual data Research better ways to site ambient
monitors that do not rely on worst-case ambient predictions (e.g.
wind prob. & direction, etc)