There is a compelling need for an intensive study of convective impacts on the summer stratosphere over North America. Each summer the North American Monsoon Anticyclone (NAMA) dominates the circulation of the North-Western Hemisphere and acts to partially confine and isolate air from the surrounding atmosphere. Strong convective storms in the NAMA regularly penetrate deep into the lower stratosphere (LS), with some ascending above 20 km (~450 K potential temperature). The uniqueness of the NAMA region is most easily seen in satellite measurements of water vapor, which show a large enhancement in the LS over North America not seen either in magnitude or at such high latitudes elsewhere around the globe. But the coupling of tropopause-penetrating convection with large-scale monsoonal motion is poorly understood, as is the impact of convection on the chemical composition of the LS, both in monsoon regions and in the global stratosphere, which receives inputs of moist and polluted monsoon air from the NAMA. The Dynamics and Chemistry of the Summer Stratosphere (DCOTSS) project directly addresses this knowledge gap.
The investigation overview is graphically depicted in Figure 1. The NASA ER-2 aircraft (B) was based out of Salina, Kansas (white star in Figure 1.1A) for two 7-week deployments. Flights targeted several different regions important to understanding the NAMA (A) including inflow regions (1), outflow regions (2) and several different types of convection including recent convection (3) and aged convection (4). During each flight that sampled convection, the ER-2 executed several vertical profiles and flew level transects through convective outflow (C) in order to fully characterize the plume as well as the surrounding background air.
Figure 1
The DCOTSS instrument payload brought together twelve proven instruments for in situ measurements of important trace gases (AWAS, CAFÉ, HUPCRS, HOZ, HWV, UCATS, WI- ICOS), aerosols (PALMS, POPS), reactive species (HAL, CANOE), and meteorological parameters (MMS) necessary to answer the threshold and baseline questions. DCOTSS in situ measurements were complemented by the NEXRAD radar network, satellite data products (e.g. Aura-MLS, ACE- FTS, GOES) and operational modeling (e.g. TRAJ3D, NASA GMAO, NOAA GFS).
Schedule Summary: DCOTSS consisted of a 5-week test flight series and two, 7-week science deployments out of Salina, KS to cover the period from early to late summer. Science data were collected on all 31 DCOTSS flights, including test flights from Palmdale, CA and transit flights between Palmdale and Salina. All data from DCOTSS are now publicly available in the NASA Atmospheric Science Data Center archive. Ongoing data analysis and model efforts are underway to address the DCOTSS science questions, and a list of DCOTSS-related science publications is available.
