EC Regional Air Quality Deterministic Prediction System (RAQDPS)

Mike Moran

Air Quality Research DivisionEnvironment Canada, Toronto, Ontario

Mtg on AQ Data Assimilation and Fusion R&D, 16-17 Jan. 2012, Downsview, ON

• Short overview of current EC RAQDPS

• What are the AQ outputs?

• How are they generated?

• How good are they?

• Future plans

Talk Outline

• Follows example of Canadian national UV index

• Year-round, health-based, additive, no-threshold, hourly AQ index

• Developed from daily time-series analysis of air pollutant concentrations and mortality data (Stieb et al., 2008)

• Weighted sum of NO2, O3, & PM2.5 concentrations

• 0 to 10+ range

AQHI: Canada’s National Air Quality Health Index

• Primary messaging tool is the AQHI

• Main target is urban areas > 100,000 population

• Current RAQDPS is GEM-MACH15, a coupled AQ / Wx forecast model that provides twice-daily 48-hour forecasts of hourly AQHI component (NO2, O3, PM2.5) fields, other AQ

fields, and meteorological fields

• UMOS-AQ/MIST statistical post-processing package combines GEM-MACH15 predicted AQ and met fields with previous day’s NO2, O3, and PM2.5 measurements to

forecast hourly AQHI component values at AQ station locations (data fusion step: large reduction in bias)

Canadian AQ Forecasting System

• GEM-MACH is a multi-scale, first-principles, chemical weather forecast model composed of dynamics, physics, and in-line chemistry modules

• GEM-MACH15 is a particular configuration of GEM-MACH chosen to meet EC’s operational AQ forecast needs; its key characteristics include:

– limited-area-model (LAM) grid configuration for North America

– 15-km horizontal grid spacing, 58 vertical levels to 0.1 hPa

– 2-bin sectional representation of PM size distribution (i.e., 0-2.5 and 2.5-10 μm) with 9 chemical components (SO4, NO3, NH4, EC, POA, SOA, CM, S-S, H2O)

– forecast species include O3, NO2, and PM2.5 needed for AQHI plus other gas- and particle-phase concentration and flux fields

GEM-MACH and GEM-MACH15

• GEM-LAM15 is EC’s limited-area regional weather forecast model

• GEM-MACH15’s grid points are co-located with GEM-LAM15 grid points

• GEM-LAM15 supplies meteorological initial conditions and lateral boundary conditions to GEM-MACH15

GEM-LAM15 and GEM-MACH15 Grids

GEM-LAM15 core grid (blue); GEM-MACH15 grid (red)

• AQ forecasting is a mixed IV/BV problem

• GEM-MACH15 is a source-oriented prognostic deterministic Eulerian model

• Pollutant and precursor emissions from all sources are a key input to GEM-MACH, including natural sources such as biogenic emissions, sea salt, wildfires, wind-blown dust, and lightning NOx (only biogenic emissions and sea salt are included now)

Key GEM-MACH15 Inputs: Emissions (1)

• Accuracy of input emissions fields is limited by (a) accuracy of emissions inventories and (b) accuracy of emissions processing (spatial, temporal, and size disaggregation, chemical speciation)

• Only emissions from large U.S. power plants are directly measured (but are not known in future); all other emissions are estimated

Key GEM-MACH15 Inputs: Emissions (2)

Estimated 2011 Annual NO Emissions on GEM-MACH15 Domain

Estimated 2011 Annual NH3 Emissions

on GEM-MACH15 Domain

Sample Spatial Surrogates – Saskatchewan Primary Highways (red) and Secondary Highways (blue)

Temporal Surrogate – LDGV Diurnal Profiles for Weekdays vs. Weekends (FEVER data)

010002000

3000400050006000

70008000

1 3 5 7 9 11 13 15 17 19 21 23

Local Time

Car

s/h

ou

r

Weekday_Car Weekend_Car

• Currently use static climatological seasonal vertical profiles for all species (limiting!)

• Only CO varies in space

• Reasonably good approximation for reactive short-lived species, less so for medium- to long-lived species such as PM, O3, and CO

• Advantageous to locate lateral boundaries over “clean” regions such as oceans

Key GEM-MACH15 Inputs: Chemical Lateral Boundary Conditions

• Considered 2-year period from 1 Aug. 2009 to 31 July 2011

• Looked at Year 1 (2009-10) vs. Year 2 (2010-11)

• Used archived near-real-time hourly O3, PM2.5, and NO2 Canadian data from National Air Pollutant Surveillance (NAPS) network stations and hourly O3 and PM2.5 U.S. data from AIRNow

• Performed some limited screening for outliers

2-Year Performance Evaluation Results for GEM-MACH15

Minimum number of available Canadian and U.S. stations in 2009-2011 for O3, PM2.5, and NO2 in the

Oct.–Mar. and Apr.–Sept. periods

Country/Species O3 PM2.5 NO2

Canada summer 184 170 134

Canada winter 182 171 133

U.S. summer 1,128 597 N/A

U.S. winter 626 599 N/A

Year 1 Annual Correlation (R) Values

O3 PM2.5 NO2

Year 1 & Year 2 Annual Time Series Of National-Average Daily

Maximum 1-h O3 Concentrations At Canadian & U.S. Stations

Cda Year 1

U.S. Year 2

U.S. Year 1

Cda Year 2

Year 1 & Year 2 Annual Time Series Of National-Average Daily

Max’m 1-h PM2.5 Concentrations At Canadian & U.S. Stations

Year 1 & Year 2 Annual Time Series Of National-Average Daily Maximum 1-h NO2 Concentrations At Canadian Stations

Cda Year 1

Cda Year 2

Regions for Model Evaluation

EUSA

ECANWCAN

WUSA

Monthly Variation Of Regional Mean NMB For Daily Maximum PM2.5 For 4 Regions For Full 2 Years

S Migration to IBM p7 computer

S Reduced grid spacing (15 10? km)

S Further improvements to emissions files

S/M Improved process representations

M Migration to GEMv4 (new staggered vertical discretization, updated chemistry bus,

piloting at top of limited-area grid)

M Improved initialization using objectively- analyzed model-measurement fields

M/L Longer forecasts (48 72+ h)

Future Plans (Short- / Medium- / Long-term)

• Current EC RAQDPS produces twice-daily 48-hour forecasts of hourly AQ concentration fields on North American domain with 15-km grid spacing

• GEM-MACH15 performance is limited by accuracy of – meteorological forecasts– input emissions fields– chemical lateral boundary conditions– process representations– horizontal and vertical resolution

• Preliminary GEM-MACH15 performance evaluation is available for 2009-2011 period

• Further performance improvements are expected in next 18 months from implementation of new versions

Summary