Taking the Surprise out of Hurricane Season
 
Prior to the 1960's, the biggest storms on Earth could take people by
surprise. Someone standing on a beach in Florida might not know if a
distant bank of clouds was a routine squall or . the harbinger of a
powerful hurricane.
 
The Space Age changed all that. Satellites orbiting the Earth can image,
probe, and track hurricanes, alerting forecasters and laypeople alike to
storms in the offing. In recent decades, the introduction of supercomputers
and physics-based models of storm dynamics, combined with satellite,
airborne, and surface data, have pushed the accuracy of forecasts issued by
the National Oceanic and Atmospheric Administration (NOAA) to a new level
of precision.
 
https://www.youtube.com/watch?v=uEfntUc90dE
 
As forecasters have improved storm tracks, however, an area of forecasting
has lagged behind: predicting the intensity of storms. In other words, how
strong will the winds be blowing when a hurricane makes landfall?
 
Scott Braun, hurricane expert at NASA's Goddard Space Flight Center in
Greenbelt, MD says, "From 1990 to around 2010, there wasn't much
improvement in the accuracy of hurricane intensity forecasts. In the last
several years, we have started to see drops in intensity forecast errors.
This can be credited to a number of factors, including better measurements
from satellite and airborne platforms, improvements to the physics in
numerical weather prediction models, and improved methods of ingesting NOAA
and NASA data into models that describe the state of the atmosphere."
 
An important part of predicting intensity is seeing what's going on deep
inside a storm. Evaporation of water from the warm ocean surface powers
hurricanes and causes them to intensify. Hotter sea surface temperatures at
the base of a storm, therefore, can load a hurricane with more energy. On
the other hand, wind shear can tear a storm apart, causing it to weaken.
 
So, how do you collect data from inside a giant storm?
 
First, you can fly right into it. In recent years NASA has sent research
aircraft directly into or over storms as part of the Genesis and Rapid
Intensification (GRIP) experiment in 2010 and the Hurricane and Severe
Storm Sentinel (HS3) mission from 2012-2014. These aircraft were flown to
investigate the formation and intensification of storms. Operational
airplanes such as NOAA's P-3s and the Air Force's C-130s are hurricane
hunters, and fly missions into the heart of storms to collect valuable
airborne data sets. Additionally, NOAA's Sensing Hazards with Operational
Unmanned Technology (SHOUT) program utilizes a NASA unmanned Global Hawk
aircraft to observe and predict high impact oceanic weather.
 
You can also get a view from an eye in the sky. The Global Precipitation
Measurement (GPM) Core Observatory, a joint mission between NASA and the
Japan Aerospace Exploration Agency (JAXA), launched in February 2014 and
carries instruments that show precipitation location and intensity at
higher resolutions than were previously available.
 
Microwave imagers such as the one onboard GPM can look through the cloud
tops to observe where and how much precipitation occurs. Additionally,
GPM's Dual-frequency Precipitation Radar provides a 3D view of
precipitation structure.
 
Dalia Kirschbaum, a deputy project scientist for GPM says, "Images
from GPM and similar sensors are posted on the internet in near real-time
so forecasters can immediately see the latest data."
 
An upcoming NASA mission aims to improve storm intensity forecasting even
more. The Cyclone Global Navigation Satellite System (CYGNSS) is scheduled
to launch in 2016. CYGNSS's eight micro-satellites will utilize Global
Positioning System (GPS) signals to make surface wind measurements. Direct
GPS signals will pinpoint CYGNSS observatory positions, while GPS signals
reflected off of the ocean surface will indicate wind speed based on how
much the winds rough up that surface (the stronger the winds, the rougher
the ocean surface).
 
CYGNSS will be able to measure winds in heavy rain regions inside the storm
where current wind-sensing satellites have problems, and will provide much
more frequent observations compared to the once- or twice-a-day
measurements from current sensors.
 
Earth-orbiting satellites: helping take the surprise out of hurricane
season since the 1960s.
 
For more information about hurricane season in ever-improving detail, visit
science.nasa.gov.
 
 
Regards,
 
Roger

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