Convection plays a dominant role in the vertical redistribution of chemicals in the troposphere with implications for radiation, long-range transport, and chemical aging [Pickering et al., 1996; Apel et al., 2012; Bertram et al., 2007]. Transformation of gases and aerosols during convective transport from the boundary layer is critical in understanding the free troposphere and global atmospheric composition [Pickering et al., 2001; Tost et al., 2010]. The research community needs a combination of remote sensing, ground-based lidar, sondes and in situ (aircraft) observations integrating cloud dynamics, microphysics, and chemical properties. Priority research questions include: 2.1.3.1 How are water-soluble species transported and transformed in different types of deep convective systems (Critical)? 2.1.3.2 How do different precipitation forms transform and redistribute water-soluble species (Important)? 2.1.3.3 How does convection produce chemically distinct layers in the troposphere, why do layers persist, and what are the implications of these layers (Critical) ? 2.1.3.4 How do pollution and deep convection interact to deliver pollutants to the upper troposphere (Very Important)? Question Observation Resolution time and space Accuracy Precision 2.1.3.1 Multi-aircraft campaigns focused on sampling deep convective events and including extensive payloads for gases, aerosol, cloud microphysics. scale See specifications for SEAC4RS campaign; add NH3 to payload (accuracy and precision 100 pptv) 2.1.3.2 Ibid. but for different kinds of precipitation systems including shallow convection and frontal lifting Cloud scale Ibid ibid 2.1.3.3 Satellite and aircraft observations of persistent layers – geostationary and LEO lidar aerosol observations, aircraft campaigns Hourly on synoptic to global scale, 1 km 0.05 AOD for lidar, other specs as above 0.05 AOD for lidar, other specs as above 2.1.3.4 Same as 2.1.3.1 Same as 2.1.3.1 Same as 2.1.3.1 Same as 2.1.3.1
Table 2.2.1 Satellite measurements needed for answering Stratospheric Composition Questions. C = Critical; VI = Very Important; I = Important Rank Q 2.2.x.x Measurement Rationale Sampling Resolution Precision Spatial Temporal Horizontal (lat. x long.) Vertical C C VI VI 1.1 1.2 2.3 2.4 Total Column Ozone a) A crucial factor for determining the amount of UV reaching the ground. b) Document spatial coverage of polar ozone losses. Global Weekly for surface UV, daily for process studies 1° x 2° N/A 3 DU C C VI C VI VI I I 1.1 1.2 2.1 2.2 2.3 2.4 3.2 3.3 Ozone profiles a) Separate photochemical changes due to chlorine change from photochemical and transport changes due to climate change b) Separate stratospheric and tropospheric ozone changes Global Weekly for surface UV, daily for process studies 5° x 10° for UV, 1° x 2° for process studies km for UV, 0.5 km for process studies 0.1 ppmv (should be valid in cases of high aerosol loading) C C C VI VI I I 1.1 1.2 2.2 2.3 2.4 3.2 3.3 Temperature Profiles a) Determine kinetic rates for ozone removal b) Temperature trends (see below). Global Weekly for trends, for process studies 5° x 10° for trends, 1° x 2° for process studies 2 km for trends, 0.5 km for process studies 2K/decade (Long-term precision critical; should be valid in cases of high aerosol loading) C C I C VI VI C I I 1.1 1.2 1.4 2.2 2.3 2.4 3.1 3.2 3.3 H2O Quantify processes affecting water vapor and its impact on climate and ozone chemistry Global Weekly for radiative forcing, daily for process studies 5° x 10° for climate impact, 1° x 2° for process studies 2 km 0.5 ppmv (should be valid in cases of high aerosol loading)
C VI I C C I I 1.1 1.3 1.4 2.2 3.1 3.2 3.3 Sulfate aerosols Radiation, separation of natural variability from chlorine-caused changes Global Weekly 5° x 10° 2 km 10%/decade VI C C I 1.3 2.2 3.1 3.3 SO2 Major sulfur uncertainty Global Monthly 5° x 10° 1 km 10 ppt I I I 1.4 3.2 3.3 Polar stratospheric clouds, HNO3 Attribute ozone change to Montreal Protocol Polar (>50°) Daily 1° x 2° 1 km 10%/decade C C VI I C VI I I 1.1 1.2 1.3 1.4 2.2 2.4 3.2 3.3 N2O, CH4, CFCs O3 chemistry, GHGs, dynamics Global Monthly, daily for polar vortex 10° x 10°, 1° x 2° for polar vortex 4 km, 1 km for polar vortex 20%/decade C VI I I I 1.1 1.3 1.4 3.2 3.3 NO, NO2, ClONO2, HNO3, ClO, HCl, BrO Separate ozone loss due to catalytic processes Document temporal change in relative balance of loss processes Global Monthly to seasonal, daily for polar vortex 10° x 10°, 1° x 2° for polar vortex 2 km, 1 km for polar vortex 20%/decade C 1.1 1.2 CO2 GHG Global Seasonal 10° x 10° 4 km 10%/decade C VI VI C 1.3 2.3 3.1 HDO, HCN Convection tracers Global Weekly 1° x 2° 0.5 km < 20 parts per thousand C VI VI C C 1.1 1.3 2.1 2.2 3.1 CO Tropospheric and mesospheric air tracer Global Weekly 1° x 2° 4 km, 0.5 km for UTLS 10 ppb VI 2.3 Precipitation Target species Global Weekly 10° x 10° N/A 10%/decade
breaks down, are an area of active research (Ortland and Alexander, 2014). Intraseasonal and interannual variations in the BDC (e.g., sudden stratospheric warmings, ENSO, and QBO variability) have a clear impact on tropical tropopause temperatures and hence the input of water vapor into the stratosphere. The BDC has also been shown to impact tropical convection (Eguchi and Kodera, 2007) and tropospheric ozone (Neu et al., 2014). Question Observation Resolution time and space Accuracy Precision 4.1.1.1 H2O N2O H2O: Vertical and temporal to resolve tape recorder N2O: day and night 2% H2O < 0.2 ppm N2O < 5 ppb 4.1.1.2 O3, temperature Space: 1 degree, 1 km vertical resolution, Time: 3-hourly for T, 6-12 hourly for u and v. u and v direct measurements should be focused on low latitudes. T < 1K O3 < 2% T < 2K O3 < 5% 4.1.1.3 CH4, SF6, CO2 Space: tropics, midlats, polar, degrees resolution; Tropopause to 30 km; 1-2 km Vertical Resolution. Time: 2 decadal SF6 (2%) CO2 (.1 ppm) CH4 (10 ppb) 4.1.2 How is the mid-to-upper stratosphere temperature responding to GHG increases? 4.1.2.1 How do N2O, CH4, CFCs, HCFCs, and HFCs contribute to this change?