CMOS EDMONTON AND OTTAWA

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UNSTABLE, DRI and Water Cycling
Ronald Stewart McGill University
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Specific Objectives of Presentation

• To briefly review DRI and some of its science
• Comment on interactions with UNSTABLE

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Prairie Drought
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CONCERNS

• There are many concerns associated with drought
  but many of these can be summarized under two
  broad categories
• Will there be a drought?
• decadel
• seasonal
• now
• How do we best prepare for and cope with drought?
• many perspectives

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The frequency and severity of droughts are likely
to increase in southern Canada
Gregory et al., 1997
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• Lets first of all understand how drought
  develops, is sustained, and ends and how it is
  structured

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WATER AND ENERGY CYCLING
Drought is an aberration in the Water and energy
cycle
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Extreme Drought
Extreme Wet
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DRI Objective

• To better understand and contribute to the better
  prediction of drought
• Focus mainly but not exclusively on the
• recent 1999-2005 Prairiedrought

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New developments in using satellite measurements
of stable isotopes of water

• Source Worden, J. et al. Importance of rain
  evaporation and continental convection in the
  tropical water cycle. Nature 445, 528-532

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Uncertainties in the hydrological cycle

• Moisture transport and circulation within the
  atmosphere is an integral part of the
  hydrological cycle, but is not well quantified
• Atmospheric moisture can come from both oceanic
  and local evaporative sources, but the relative
  contribution of each to the overall moisture for
  a given region is not easily determined
• Measuring stable isotope ratios in water vapour
  may help to reveal and better indicate the
  relative sources of moisture

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Measuring stable isotopes of tropospheric water
vapour from space

• Simultaneous profiles of HDO and H2O vapour are
  obtained using the Tropospheric Emission
  Spectrometer (TES) aboard the NASA Aura satellite
• From this, the first comprehensive map of the
  global distribution of deuterium (shown as the
  ratio dD) in water vapour is obtained

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• Next plot
• Unit parts per thousand by volume
• Oct 04 March 05
• IR emissions
• 5 km by 8 km footprint

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DEUTERIUM IN WATER VAPOUR 550-800 hPa layer
Tropospheric Emission Spectrometer Aqua satellite
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CLOUD AMOUNT
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Characterizing precipitation at Calgary, AB

• Seasonal total precipitation

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Days with precipitationCalgary

• The fraction of days receiving any amount of
  precipitation
• Climatology (1895-2004) 40
• Drought (1999-2004) 46
• Sub-Drought (2001-2002) 43

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Climatology 1895-2004
Daily Total Precipitation Amount Distribution
Low precipitation events ( 10 mm) account for
52 of total precipitation
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Climatology Low precipitation events 52 of total
Drought 1999-2004 Low precipitation events 58
of total
Sub-drought 2001-2002 Low precipitation events
60 of total
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Daily Precipitation Amounts Calgary
Low precipitation event lt 10 mm
Climatology Low precipitation events 52 of total
Sub-drought 2001-2002 Low precipitation events
60 of total
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What factors led to the 10 mm events?

• Possibilities include
• Loss due to evaporation/sublimation
• Short-lived weather systems
• Change in character of clouds
• Fast moving weather systems

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RADAR PROFILES1 June 2002 Calgary

• Scattered stratiform rain early
• Late in the day there is evidence of water aloft
  (5 km)
• This appears to be high-level moisture as a
  precursor to the rainy pattern on the following
  day

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VIRGA
Courtesy of Barrie Bonsal
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VEGETATION
NDVI
July 11-20, 2002
NDVI Normalized Difference Vegetation Index
Healthy vegetation
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SOME ATMOSPHERIC WATER CYCLING ISSUES

• Water Cycle Issues include
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• Is precipitation being formed aloft?
• Will precipitation reach the ground?
• What is the water vapour source for the
  precipitation?
• How is the water vapour (re-)distributed in the
  vertical and horizontal?
• What is the diurnal cycle of the precipitation?
• Where does the precipitation occur?
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• Contributing factors include
• Type and organization of precipitating system
• Cloud base height
• Drop sizes
• Surface
• ...

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UNSTABLE

• Sub-objectives include
• to better understand, resolve, and quantify
• spatial extent, depth and temporal evolution of
  water vapour in the atmospheric boundary layer
• Mesoscale effects on thunderstorms
• effects of variable surface

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DRI and UNSTABLE

• DRI
• diverse research expertise ( 30)
• datasets (atmosphere, surface )
• analysis tools (DAI )
• UNSTABLE
• aspects linked with water cycling
• focused activity
• observational and model products

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CONCLUDING REMARKS

• DRI is concerned with
• the science of water cycling
• UNSTABLE is concerned with
• overturning of the atmosphere
• DRI and UNSTABLE can
• benefit from collaboration

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And thank you for your attention