ec regional air quality deterministic prediction system (raqdps) mike moran air quality research...

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