The First WISE Case Study: A Water and Energy Balance Investigation of the Severe Drought in the Canadian Prairies

Transcription

1 The First WISE Case Study: A Water and Energy Balance Investigation of the Severe Drought in the Canadian Prairies Kit Szeto Environment Canada Ron Stewart McGill University

2 What do we want to do? Use the WEBS approach to study extreme hydrometeorological events The first study will be a drought case Drought is the most serious hydrometeorological extreme event in many places around the world

3

4 Why the Canadian Prairie Drought Case? Certainly an extreme event - the worst drought in over a hundred years in the Canadian Prairies! The event overlapped the CEOP and MAGS Builds upon datasets and tools developed for MAGS WEBS and CEOP The study also benefits from DRI, a current large Canadian drought research initiative that focuses on the event

5 Objectives of the Study To evaluate the surface and atmospheric water and energy budgets, and their deviations from the mean state, for the Canadian Prairie region during the drought period by using various source datasets To assess how well aspects of the extreme event are represented in the various datasets and to explore implications of the assessment results to the use of current model/assimilation/remote-sensing products in drought monitoring and study applications, and to the improvement of drought predictions

6 The Canadian Prairies NCEP/ERA40 grid boxes 60N 50N MRB Hudson Bay Pacific Ocean SRB 130W 120W 90W 80W BERMS CEOP reference site (star)

7 Despite the vulnerability of the region s agricultural activities to climate variability and change, no comprehensive WEBS have yet been Causing developed economic for loss this of more drought-prone than $3.6B for region Canada in 2002 alone

8 Precipitation Anomalies

9 Water and Energy Budgets Atmospheric Water Q = E P + MC + RESQ t Surface Water W = P E N + RESW t Atmospheric Temperature {T} C p = QR + LP + SH + HC + REST t Surface Temperature Cv {Ts} = QRS LE SH + G t Source: John Roads Q=Atmospheric Precipitable Water, mm W=Surface Water (M+S), mm M=Soil Moisture, mm S=Snow, mm T=Atmospheric Temperature, K Ts=Surface Skin Temperature, K T2=Surface Air Temperature (at 2m), K E=Evaporation, mm/day P=Precipitation, mm/day MC=Moisture Convergence, mm/day N=Runoff, mm/day LP=Latent Heat of Condensation, W/m**2 SH=Sensible Heat (which is positive upward), W/m**2 HC=Dry Static Energy Convergence, W/m**2 LE=Latent Heat of Evaporation (which is positive upward), W/m**2 QR=Atmospheric Radiative Heating (which is negative), W/m**2 QRS=(NSW+NLW)=Surface Radiative Heating, W/m**2 NSW=Net Shortwave Radiation at the Bottom of Atmosphere (BOA), W/m**2 NLW=Net Longwave Radiation at the Bottom of Atmosphere (BOA), W/m**2 NSW (0)=Net Shortwave Radiation at the Top of Atmosphere (TOA), W/m**2 NLW (0)=Net Longwave Radiation at the Top of Atmosphere (TOA), W/m**2 RESQ=Atmospheric Residual Water Forcing, mm/day RESW=Surface Residual Water Forcing, mm/day REST=Atmospheric Residual Dry Static Energy Forcing, W/m**2 G=Surface Residual Temperature Forcing, W/m**2

10 Local (L), regional (R) and global (G) observations Parameter Source Resolution Coverage Period Rawinsondes (L) Sites Various - Current Precipitable Water GVAP/NVAP (G) 1 deg Snow SSMI (R) 25 km 1978 Dec Mar (Dec-Mar) Surface Air Temperature CANGRID (R) 50 km Dec Atmospheric Enthalpy Rawinsondes (L) Sites Various - Current CANGRID (R) 50 km Dec CMAP (G) 2.5 deg Sep Precipitation GPCP (G) 2.5 deg Dec Current (The Discharge WSC (L) sites Pas) ISCCP FD (G) 280 km Radiative Fluxes BERMS (L) Sites Sensible/Latent Heat Flux BERMS (L) Sites Current Cloud Cover Datasets Global (G) and regional (R) analysis and model datasets 1983 Jul Jun Current Surface Obs (L/R) Sites Various - Current Dataset Resolution Coverage period CRCM (R) 51 km 1997 Apr Dec CMC (R) 35/24 km 1997 Mar - Current NCEP-R2 (G) 2.5 deg 1979 Jan - Current ERA-40 (G) 2.5 deg 1957 Sep Aug

11 Other Datasets: NARR NLDAS-E, GLDAS new CRCM (with CLASS-3) high resolution blended precip data? other model data? CEOP satellite data? Others

12 Assessment Period and Focuses: Study period: for the formation and mature phases of the drought, and for the maximum overlap of available datasets Longer-term budget climatologies from ERA-40, NCEP-R2 and precipitation observations Focus on both the regional mean and spatialtemporal variability of the budgets

13 The SRB Climate System in a Nutshell: Ensemble Mean Annual Cycles of Water and Energy Budgets HC LP E SH RES QR Atmospheric Energy MC Atmospheric Water RESQ P QRS RESW P RESG SH Surface Energy LE Surface Water N E

14 Variability among Budgets Assessments - Annual Cycles of Atmospheric Water Budgets MC RES E P

15 Variability among Budgets Estimates.cont. Surface SH and LE near BERMS Site Budg ets ( K/d) Surface latent heat flux Year CMC_LE ERA40_LE NCEP_LE CRCM_LE BERMS_LE Budg ets ( K/d) Surface sensible heat flux CMC_SH ERA40_SH NCEP_SH RCM_SH BERMS_SH Year

16 Variability among Budgets Estimates.cont.NDJFM P anomalies (mm/d) 0.3 ERA40 NDJFM P anomaly NCEP-R2 NDJFM_P_anom ERA40 99 NCEP-R

17 Variability among Budgets Estimates.cont.NDJFM SWE Anomalies (mm) 50 ERA-40 Feb-Mar SWE anomaly ERA NCEP Feb-Mar SWE Anomaly NCEP-R

18 Variability among Budgets Estimates.cont.AMJJ Soil Moisture anomalies (mm) 30 ERA40 AMJJ Soil moisture Anomaly ERA NCEP-R2 AMJJ Soil moisture anomaly NCEP-R

19 Deliverables: Comprehensive datasets for studying water and energy cycling during the extreme drought event WEBS diagnostics for the drought event Assessments of how well aspects of the extreme event are represented in the various datasets and their implications for the use of current model/assimilation/remote-sensing products in drought monitoring and study applications, and for the improvement of drought predictions Joint publications

20 Timeline spring: Data acquisition, preliminary data processing and calculations 2007 summer: WEBS calculations 2007 autumn: Result analysis 2008: Joint publication summarizing results of the study

21 People:

22 Next Steps Need your participation! Data acquisition and processing, WEBS calculations task-sharing and coordination

23 Summary of annual basin-average water and energy budgets for the SRB Data\Para Q M SWE T2m H P E MC N HC SH RESQ REST NCEP CMC CRCM ERA Reg Obs Globl Obs Average ERA Avg Average(MRB) %Error %Error(MRB) Data\ LP QRS QR TOA TOA TOA BOA BOA BOA BOA Cloud RESW RESG Parameter SWD SWU LWU SWD LWU SWU LWD cover NCEP CMC CRCM ERA Reg Obs Globl Obs Average ERA Avg Average(MRB) %Error %Error(MRB) All water storage terms are in mm, T2m in K, enthalpy (H) in 10^9J/km2, moisture fluxes in mm/day energy fluxes in K/day.