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Lecture 12

Lecture 12 - Improving Access.pdf

Earth Sciences
Course Code
Luc Bernier

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Improving Access
Part 1 - Improving Monitoring
Improving Monitoring
Monitoring lies at the heart of water management
It helps in predicting water-related disasters such as floods
It helps assessing the available water
Historically monitoring has relied on a network of stations worldwide for instance
stations measuring water discharge can be used to predict floods
The numbers of these stations have been decreasing over the last 40 years
The same has happened with station measuring evaporative losses
There are many reasons for this decline for instance budget cuts also the privatization of
water services in some countries in some countries has led to layoffs
Automated Monitoring
Will play an increasingly important role
Partly due to the lack of man power the use of more advanced techniques such as
automated monitoring is called to play an increasingly important role in water
Automated stations allow 24 hour monitoring and can operate for weeks or even months
without human assistance
The data can either be recorded or transmitted via radio signals
Weather Radars
Over the past 50 years: have become a vital tool in storm monitoring
There are now extensive radar networks in Europe and North America
These radars can track the speed at which storms are moving, they can immediately track
changes in rainfall intensity even better than weather stations
Information collected can be linked to forecasting of river flow and help predict the
likelihood of a flood as well as help make decisions in terms of public safety
For instance this approach was taken in the US after the 1993 Mississippi flood
Water and Satellites
Can generate profiles, images and: help delineate cloud cover and state of the clouds
The use of satellites has revolutionized observations of weather systems and patterns and
They can be connected to ground radars for instance
They can also collect data from ground sensors and they themselves can incorporate a
number of sensors that for instance can measure the vertical profiles in air temperature or
NASA’s Landsat program
NASA’s Landsat program is an example of the impact of observations made by satellites

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Improving Access
Landsat provides the longest coverage of earth’s conditions at its surface
Landsat has been observing the earth since 1972 and has measured changes in land cover
and vegetation
For example, the growth of Shangai in China over a 20 year interval and the
accompanying changes to the landscape
The key feature of the program is that the data collected is available for download for free
Part 2 - Tracking Climate
A New Map of Earth’s Climates
Climate classification is improved by: adding river discharge monitored by satellites to
help define distinctions between different climate zones and types at the earth’s surface
This system is based on the well known Koppen Classification and has led to a
redefinition to the original climate types which are essentially based on differences in
vegetation between tropical, arid, temperate, cold, and polar climates
Large difference between climate types can be observed in terms of river discharge
For instance low flows persists in dry climates such as deserts with little precipitation
Higher flows are observed in tropical rainforests which have year round precipitation
The temperate polar climate reveals important pulses of melt water in the spring
This new system incorporates now and temperature as well as river discharge in the
redefinition of old climate types
Snow Cover in the Northern Hemisphere
Mean number of days per year with snow on the ground: 1972-1988

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Improving Access
It is possible now with satellite observations to examine patterns of vegetation, soil
moisture, water or snow cover or any other component of the climate system
The full potential of satellite observations is still being realised
For instance here we can see a detailed map of the mean number of days per year with
snow on the ground in the Northern Hemisphere based on data collected between 1972
and 1988
Not surprisingly we can observe in dark green that the location with the highest mean
number of days with snow on the ground is Greeenland
As we move to lower and lower latitudes the number of days with snow on the ground
are decreasing
Northern Hemisphere Snowpack
This map tracks the water equivalent in the snowpack at: the end of the accumulation
period in the Northern Hemisphere based on detailed satellite observations
This map shows the distribution of the water content of the snowpack at the end of winter
The highest values observed tend to be closest to the Arctic circle particularly in Siberia
and tend to decrease with lower latitudes
This information used to be collected using snow gauges involving a network of stations
requiring researchers throughout the world to go into the field and collect the snow
providing less detailed information
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