Regional Environmental Prediction Over the Pacific Northwest

Mass, Clifford F.; Albright, Mark D.; Ovens, David; Steed, Richard; Maciver, Mark; Grimit, Eric P.; Eckel, Tony; Lamb, Brian; Vaughan, J. K.; Westrick, Kenneth J.; Storck, Pascal; Colman, Brad; Hill, Chris; Maykut, Naydene N.; Gilroy, Mike; Ferguson, Sue A.; Yetter, Joseph A; Sierchio, John M.; Bowman, Clint; Stender, Richard; Wilson, Rob; Brown, W. Norman

doi:10.1175/bams-84-10-1353

Cited by 100 publications

(63 citation statements)

References 10 publications

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“…It also tends to produce higher errors at coastal locations, like YVR, because the marine influence is highly variable and difficult to reproduce with 4 km × 4 km area-averaged temperatures. The poorer statistical scores at both coastal and mountainous stations are consistent with results from similar studies Mass et al, 2003 ) and the less variable wind directions observed in the strait. Wind speeds do not seem to be systematically over-or underestimated by the WRF model at this location which suggests that the flow field within the Strait of Georgia is generally well captured.…”

Section: Meteorological Model Evaluationsupporting

confidence: 90%

A Retrospective Analysis of Ozone Formation in the Lower Fraser Valley, British Columbia, Canada. Part I: Dynamical Model Evaluation

et al. 2013

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We conduct a retrospective study of ozone formation in the Lower Fraser Valley (LFV), using numerical models, observations, and emission inventories in order to understand relationships between reductions in local precursor emissions and episodic ozone concentrations. Because there appears to be little or no impact from precursor emissions upwind of the LFV during ozone episodes and because background concentrations of ozone and its precursors are generally from the North Pacific Ocean and quite low, summertime ozone formation in the LFV is mostly caused by local emissions. The observed change in behaviour of ozone formation must, therefore, arise from reductions in local precursor emissions. We exploit the observed changing precursor emissionozone concentration relationship to perform a dynamical model evaluation. Complicating the analyses are an observed shift in the population patterns within the valley over the last 25 years and a small but documented change in the tropospheric background concentration of ozone. Ozone formation for four episodes, which capture the observed changes in ozone reduction and the different meteorological types that occur during LFV ozone events, are investigated using the Weather Research and Forecasting (WRF)-Sparse Matrix Operator Kernel Emissions (SMOKE)-Community Multiscale Air Quality (CMAQ) modelling system. In order to provide realistic simulations of past events, the SMOKE emission inventory is adjusted to account for temporal changes in the amount of emissions and locations of emission sources. Model output is compared with continuous observations, data collected from field campaigns, and previous modelling efforts. The WRF-SMOKE-CMAQ modelling framework is able to capture the changes in both the magnitude of the ozone concentrations and its spatial behaviour over the period of study. Many of the simulations show that the highest ozone concentrations occur outside the area sampled by the fixed monitoring network and within the LFV's numerous tributary valleys. Not all modelled episodes achieved the same agreement with observations and some of these discrepancies are likely related to shortcomings in the meteorological modelling. The model consistently overpredicts ozone at a number of stations within the City of Vancouver and underpredicts daytime NO x concentrations there. Both results are consistent with a deficiency in NO x emissions. The model shows a changing bias over time which also suggests uncertainties in the emission backcasting.

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Section: Meteorological Model Evaluationsupporting

confidence: 90%

A Retrospective Analysis of Ozone Formation in the Lower Fraser Valley, British Columbia, Canada. Part I: Dynamical Model Evaluation

et al. 2013

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“…These findings are useful to the management of landslide hazards in Seattle in that they identify the most hazardous periods when widespread landsliding can be expected. We speculate that combined with meso-scale, quantitative-precipitation forecasts currently produced on an operational scale for the Pacific Northwest of the United States (Mass et al, 2003), landslide forecasts and warnings may be possible with acceptable accuracy using the approach we outline here.…”

Section: Discussionmentioning

confidence: 99%

Rainfall characteristics for shallow landsliding in Seattle, Washington, USA

Godt

Baum

Chleborad

2005

Earth Surf Processes Landf

242

152

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Shallow landsliding in the Seattle, Washington, area, has caused the occasional loss of human life and millions of dollars in damage to property. The effective management of the hazard requires an understanding of the rainfall conditions that result in landslides. We present an empirical approach to quantify the antecedent moisture conditions and rainstorm intensity and duration that have triggered shallow landsliding using 25 years of hourly rainfall data and a complementary record of landslide occurrence. Our approach combines a simple water balance to estimate the antecedent moisture conditions of hillslope materials and a rainfall intensity-duration threshold to identify periods when shallow landsliding can be expected. The water balance is calibrated with field-monitoring data and combined with the rainfall intensity-duration threshold using a decision tree. Results are cast in terms of a hypothetical landslide warning system. Two widespread landslide events are correctly identified by the warning scheme; however, it is less accurate for more isolated landsliding. Copyright

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“…Due to the sea-land contrast, a sharp temperature gradient develops across the shoreline and differences of several degrees can be reported between two stations located near the coast and few kilometres inland (Simpson, 1994). It is well known that, when a cold pool develops, differences of several degrees can be reported by two close stations located in a mountain gap and along an adjacent ridge (Myrick et al, 2005;Mass et al, 2003).…”

mentioning

confidence: 99%

Verification of surface minimum, mean, and maximum temperature forecasts in Calabria for summer 2008

Federico

2011

Nat. Hazards Earth Syst. Sci.

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Abstract. Since 2005, one-hour temperature forecasts for the Calabria region (southern Italy), modelled by the Regional Atmospheric Modeling System (RAMS), have been issued by CRATI/ISAC-CNR (Consortium for Research and Application of Innovative Technologies/Institute for Atmospheric and Climate Sciences of the National Research Council) and are available online at meteo.crati.it/previsioni.html (every six hours). Beginning in June 2008, the horizontal resolution was enhanced to 2.5 km. In the present paper, forecast skill and accuracy are evaluated out to four days for the 2008 summer season (from 6 June to 30 September, 112 runs). For this purpose, gridded high horizontal resolution forecasts of minimum, mean, and maximum temperatures are evaluated against gridded analyses at the same horizontal resolution (2.5 km).Gridded analysis is based on Optimal Interpolation (OI) and uses the RAMS first-day temperature forecast as the background field. Observations from 87 thermometers are used in the analysis system. The analysis error is introduced to quantify the effect of using the RAMS first-day forecast as the background field in the OI analyses and to define the forecast error unambiguously, while spatial interpolation (SI) analysis is considered to quantify the statistics' sensitivity to the verifying analysis and to show the quality of the OI analyses for different background fields.Two case studies, the first one with a low (less than the 10th percentile) root mean square error (RMSE) in the OI analysis, the second with the largest RMSE of the whole period in the OI analysis, are discussed to show the forecast performance under two different conditions. Cumulative statistics are used to quantify forecast errors out to four days. Results show that maximum temperature has the largest RMSE, while minimum and mean temperature errors are similar. ForCorrespondence to: S. Federico (s.federico@isac.cnr.it) the period considered, the OI analysis RMSEs for minimum, mean, and maximum temperatures vary from 1.8, 1.6, and 2.0 • C, respectively, for the first-day forecast, to 2.0, 1.9, and 2.6 • C, respectively, for the fourth-day forecast.Cumulative statistics are computed using both SI and OI analysis as reference. Although SI statistics likely overestimate the forecast error because they ignore the observational error, the study shows that the difference between OI and SI statistics is less than the analysis error.The forecast skill is compared with that of the persistence forecast. The Anomaly Correlation Coefficient (ACC) shows that the model forecast is useful for all days and parameters considered here, and it is able to capture day-to-day weather variability. The model forecast issued for the fourth day is still better than the first-day forecast of a 24-h persistence forecast, at least for mean and maximum temperature. The impact of using the RAMS first-day forecast as the background field in the OI analysis is quantified by comparing statistics computed with OI and SI analyses. Minimum temperature is more sensiti...

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Regional Environmental Prediction Over the Pacific Northwest

Cited by 100 publications

References 10 publications

A Retrospective Analysis of Ozone Formation in the Lower Fraser Valley, British Columbia, Canada. Part I: Dynamical Model Evaluation

A Retrospective Analysis of Ozone Formation in the Lower Fraser Valley, British Columbia, Canada. Part I: Dynamical Model Evaluation

Rainfall characteristics for shallow landsliding in Seattle, Washington, USA

Verification of surface minimum, mean, and maximum temperature forecasts in Calabria for summer 2008

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