The DROPPS program to study the polar summer mesosphere

Abstract

DROPPS (The Distribution and Role of Particles in the Polar Summer Mesosphere) was a highly coordinated international study conducted in July 1999. It involved two sequences of rockets launched from the Norwegian rocket range in Andøya, Norway. These studies were designed to investigate the properties of the polar summer mesosphere, particularly relating to polar mesospheric summer echoes (PMSE) and their possible relationship to particles (aerosol and dust layers) and to noctilucent clouds (NLC). Each of the two sequences included a DROPPS NASA-Black Brant payload, consisting of an array of instruments to measure the electrodynamic and optical structure of the mesosphere and lower thermosphere. The instruments were provided by participants from several US and European laboratories. The DROPPS payloads were each accompanied by a sequence of several European payloads (MIDAS, Mini-MIDAS, and Mini-DUSTY) designed to study electrodynamic and neutral atmospheric structure of the same region, and by several meteorological rockets to provide wind and temperature data in the critical region of study. ALOMAR Lidars, and MF and MST Radars (all located adjacent to the Andøya launch site) were used to continuously monitor the mesosphere for NLCs and PMSEs, respectively. EISCAT VHF radar (Tromsø, Norway) provided similar information about PMSEs at 130 km NE from Andøya. Sequence 1 was launched during the night of 5–6 July into a strong PMSE display with a weak NLC at the base of the PMSE. Sequence 2 was launched on the early morning of 14 July into a strong NLC, but surprisingly with no PMSE evident. Here we describe the details of the program along with a few preliminary results.