Arctic Springtime Chemistry-Climate Investigations (ASCCI)

B.-M. Sinnhuber

The Arctic Springtime Chemistry-Climate Investigations (ASCCI) mission will employ the German high altitude and long-range research aircraft HALO to study atmospheric chemistry and transport processes in the Arctic upper troposphere and lower stratosphere (UTLS) and their relevance for climate forcing. Atmospheric composition changes in the UTLS have a large efficiency for surface climate forcing. ASCCI will investigate how composition in the Arctic UTLS is influenced by stratospheric ozone depletion, transport across the tropopause and by pollution in the upper troposphere. During ASCCI HALO will be operated from Kiruna in Northern Sweden during March 2025. The major objectives of the campain are:

Inter-annual variability of Arctic lower stratospheric ozone depletion

  • How much does ozone and ozone depletion processes differ in the Arctic lowermost stratosphere relative to the cold POLSTRACC winter of 2015/16?
  • What is the impact of Arctic ozone depletion on mid-latitude airmasses later in spring?

High latitude stratosphere-troposphere exchange and the structure of the high latitude tropopause

  • By how much is ozone (and other trace gases) in the high Arctic troposphere influenced by transport from the stratosphere?
  • What is the relative contribution of tropopause folding events relative to large scale radiative subsidence?

Short-lived climate pollutants (ozone, aerosols) and their precursors in the Arctic upper troposphere

  • How well do models reproduce pollutants in the Arctic mid and upper troposphere? Observations from POLSTRACC and other campaigns indicate large discrepancies.
  • Is this due to unknown sources, transport pathways or missing chemical processes? 

Timeline:

16 December 2024 Start of ASCCI integrations
Week 10, March 2025 First scientific survey flight from Oberpfaffenhofen
8 March 2025 HALO transfer flight to Kiruna, Sweden
March 2025 Local flights with HALO from Kiruna into the Arctic
3 April 2025 Transfer from Kiruna to Oberpfaffenhofen, end of campaign

 

Instrumentation on HALO:

Instrument Target Parameter Technique Institution
GLORIA H2O, O3, HNO3, ClONO2, PAN, C2H6, …, temperature Imaging IR Limb Sounder KIT / FZ Jülich
WALES Aerosol, H2O, O3 Lidar, downward looking DLR-IPA
DOAS BrO, OClO, O3, NO2 UV/vis spectrometer University Heidelberg
AIMS HCl, HNO3, ClONO2, SO2 Mass Spectrometer DLR-IPA
BAHAMAS meteorologic and avionic data BAsic Measurement And Sensor System DLR-FX
FAIRO O3 UV Photometer/ Chemiluminescence KIT
FISH total/gas-phase H2O Lyman-Alpha Hygrometer FZ Jülich
GhOST-MS CH3Br, CHBr3, CHCl3, CH2Cl2, CH3I, CFCs, SF6 GC-MS University of Frankfurt
HAGAR-V CO2, SF6, CH4, H2, N2O, CFCs, NMHCs GC-MS University of Wuppertal
IPA-NOy NO, NOy Chemiluminescence DLR-IPA
KIT Sonde p, T, humidity, wind Drop Sonde System KIT
UMAQS CO, N2O, CH4 Laser Spectrometer University of Mainz