NASA’s GPM Core Observatory to measure global precipitation
Photo: NASAThe GPM (Global Precipitation Measurement) Core Observatory, a joint mission between the US National Aeronautics and Space Administration (NASA) and the Japan Aerospace Exploration Agency (JAXA), will observe worldwide precipitation from space. The satellite was launched into space on 27 February 2014 at 8.37 pm Finnish time.
Finnish researchers develop measurement of snowfall
A group of Finnish researchers has participated in the development of the algorithms, which will make it possible to utilise the satellite‘s measurements, and in collection of results of comparisons. The University of Helsinki, the Finnish Meteorological Institute and the Finnish Environment Institute have all participated especially in observation of snowfall from space. The higher frequencies of the satellite's measurement devices will now make it possible to also measure snow fall for the first time.
Over the course of the GPM satellite project surface observations, which are important in comparison of results, have also been collected in Finland. Ground observation devices belonging to the University of Helsinki, the Finnish Meteorological Institute, NASA and the US Department of Energy's Climate Research Unit are currently on standby at the University of Helsinki's SMEAR II research station at Hyytiälä in Juupajoki ready for observations. The devices collect measurement data on rain on the Earth's surface. The information produced by precipitation measurements on the size distribution of rain drops has also been applied in the Finnish Meteorological Institute's daily weather service. This has improved the accuracy of radar measurements with regard to precipitation.
Global precipitation observed in three hours
The GPM Core Observatory satellite aims to measure precipitation over the entire globe. In the span of three hours, the GPM Core Observatory, which orbits the Earth at an altitude of 407 km, and other satellites involved in the project observe the Earth from the equator to the 65 degrees north and south latitude, i.e. at about Oulu's level in the north. This way the observations cover the majority of the Earth's population and surface area.
The satellite is equipped with a dual frequency precipitation radar and a multi-frequency microwave radiometer. The radar surveys precipitation areas, and its higher frequency is sensitive enough to also measure snowfall and light rain. The radar can be used to form a three dimensional image of the structure of rain, which will enable observation of things such as the structure within clouds and below them. The radiometer was designed to measure total precipitation in all cloud layers.
Observations to benefit climate research
The measurement data from both measurement devices can be utilised when determining the size distribution of all of rain's different parts, monitoring the development of rain and observing its impact on the climate. Researchers can use the material collected by the satellite to study the significance of rain with regard to climate change, fresh water reserves, prevalence of floods and droughts, as well as the formation and monitoring of hurricanes. It is expected that the collected observations will be extremely significant with regard to the development of precipitation forecasting and climate models.
In a project funded by the Academy of Finland, researchers from the Finnish Meteorological Institute, the University of Helsinki and Aalto University have modelled the radar scattering characteristics of snowflakes at different wave lengths, and the changes that the melting of flakes causes to radar observations. At the same time, researchers have studied the accuracy and application of modelling methods in imaging different shaped snowflakes.
Further information:
Researcher Jussi Leinonen tel. +358 50 380 2423, jussi.leinonen@fmi.fi