Motivation - Introduction to the Atmosphere Research

The atmosphere and thus the climate of the earth is influenced by internal processes and external effects, like solar radiation. This influence spreads through all 5 atmosphere layers (Exosphere, Thermosphere, Mesosphere, Stratosphere, Troposphere) on it's way to the surface of the earth.

The middle atmosphere (Mesosphere and lower Thermosphere) from 50 to 100 km altitude is of special interest.

The involved physical processes are still not fully understood. To their identification there is the need for very precise measurements, for example of temperature-, density- and wind-profiles in these altitude levels.

From indirect measurements in middle latitudes it's known that the temperature decreased drastically, about 16 degrees during the last 40 years. The presumption is obvious that this situation is connected closely to the increase of greenhouse gas like carbon dioxid and methan.

While ground based measurement methodes have a dominating roll in the troposphere, the stratosphere is mostly researched with radio probes. The latter ones are carried by weather balloons up to about 35 km altitude, doing their measurements (for example temperature, density and humidity) and transmit the data back to a ground station or are recovered after the touchdown.

Measurements in the mesophere and thermosphere are done with sounding rockets. For direct measurements normally the instrument is implemented into the rocket and the rockets telemetry is used to transmit the data to a ground station during the flight or the payload will be recovered later.

Indirect measurements in higher altitudes are done for example with LIDAR (Light Detection and Ranging) or satellites. At measurements with LIDAR the backscattered photons of  the laser pulse is registered via a telescope. Then the distance is calculated from the run-time, the density from the number of photons and the temperature from the spectral broadening of the pulse. But just a small part of the meso- and thermosphere can be measured with this methode and the required resolution.

The creation of a density profil is currently already possible by direct measurements. The special air flow during the rocket climb, make it essential to locate the sensor element central inside the payload nose. Unfortunately this position is the most coveted every time, because nearly all sensors generate unadulterated measurement results only there. Additionally the vertical resolution of the realizable density profil is imprecise because of the high speed of the rocket.

Sebastian Finke


S. Finke