Geoscience Reference
In-Depth Information
• How can new observations lead to improvements in water management? Over the last
few decades, in situ observations of land surface hydrological variables, such as
streamflow, rainfall and snow have generally been in decline. Regional estimation of
evapotranspiration remains a significant challenge. At the same time, new observation
methods, such as weather radars, flux towers and satellite sensors have led to different
types of measurements, and challenges for their incorporation in the hydrological
models used for hydrological prediction and water management. One example is soil
moisture, which in most models essentially acts as a buffer between the land forcings
(mostly precipitation and evapotranspiration) and runoff, and whose characteristics are
defined by the internal model parameterizations that control runoff production.
Sustained measurements of soil moisture are critically important to understanding,
modeling and prediction of the water cycle.
• How can better climate models contribute to improvements in water management?
Regional precipitation predictions remain a challenge at all timescales from seasonal
forecasting out to centennial climate change. However, there are limited regions with
forecast skill on seasonal timescales, associated mainly with ENSO, and broad scale,
zonally averaged precipitation changes associated with climate change appear to be
detectable. The challenge now is to maximize the skill and reliability of predictions of
regional rainfall changes on all timescales, for all regions around the world. This
requires better understanding and model simulation of the tele-connections and drivers
of regional climate such as changes in the oceans and cryosphere that are relevant to
regional precipitation. Subsequent improved climate prediction systems and better
dissemination of climate prediction information must be developed to deliver the
envisioned information and their ultimate benefit to society.
Prospects for advancements are excellent on this Grand Challenge because of new
observations already underway and those planned for the ensuing decades and the growing
interest in climate predictions on all timescales. Key areas of development include
1.
A new Global Precipitation Mission as detailed at
http://pmm.nasa.gov/GPM
.
''Through improved measurements of precipitation globally, the GPM mission will
help to advance our understanding of Earth's water and energy cycle, improve
forecasting of extreme events that cause natural hazards and disasters, and extend
current capabilities in using accurate and timely information of precipitation to
directly benefit society.'' The joint US National Aeronautics and Space Adminis-
tration (NASA)/Japan Aerospace Exploration Agency (JAXA) mission's Core
Observatory is scheduled for launch in 2014. Most of the world's major space
agencies will participate in this mission through the contribution of constellation
satellites to obtain the desired revisit times to roughly 3 h, over the entire Earth.
2.
Closely related missions such CloudSat (a NASA mission with components from the
Canadian Space Agency to measure clouds and light precipitation) and EarthCARE,
a European Space Agency (ESA) mission (
http://www.esa.int/esaLP/SEM75
KTWLUG_LPearthcare_0.html
) to advance our understanding of the role that
clouds and aerosols play in the climate system), due for launch late 2015, that will
make important contributions to the global precipitation estimates.
3.
New satellite sensors such as soil moisture and ocean salinity (SMOS) (an ESA
mission to map soil moisture and sea surface salinity), Aquarius (a NASA/Space
Agency of Argentina mission to improve sea surface salinity) and future soil
moisture active passive (SMAP) data (a NASA mission dedicated to measuring soil
