“HIAPER Pole-to-Pole Observations” of Carbon Cycle and Greenhouse Gases (HIPPO) Will measure cross sections from the surface to the tropopause, at 5 times of year in a 3-year period, for a comprehensive suite of tracers: CO2, CH4, O2:N2, Ar:N2, CO, N2O, 13/12CO2,C18/16O2, H2, SF6, H2O, PAN, O3, CFCs, HFCs, HCFCs, CH3X (X=Cl, Br, I), H1211, COS, CS2, and black carbon. HIPPO will transect the mid-Pacific ocean and return over E. Pacific. “Pre-HIPPO” , based at Jeffco, is a test mission for the payload, aircraft, and sampling concepts. it will combine with START-08 (April-June 2008) and coordinate with ARCTAS (March-April; July).

Science Questions How can we use atmospheric aircraft data to help determine the global sources and sinks of CO2 and other major greenhouse gases? What is the role of the Southern Ocean in global budgets of CO2 and O2? HIPPO data for CO2, the O2:N2 ratio, and the Ar:N2 ratio, will be assessed and inverted using GEOS-CHEM. How can we establish tracer “clocks”, and determine age spectra, for air in the Tropical Tropopause Layer and global remote troposphere? We will use our seasonally varying tracers for quantitative analysis of this question.

Science Questions What are the rates for vertical exchange, mixing within a hemisphere, and inter-hemispheric transport, and how do these transport processes interact with source distributions to produce concentration gradients for key species (CO2, CH4, CO, O2 and black carbon) in the carbon cycle and for tracers used to diagnose the carbon cycle (SF6, HCFCs, COS)? . How do vertically resolved tracer data provide new constraints on global inverse models for sources and sinks of CO2 and related gases? HIPPO will address these questions by obtaining the first set of high-definition, seasonally resolved, global tracer data, nearly pole-to-pole and surface-to- tropopause, and interpreting the observed tracer distributions and fluxes with the GEOS-CHEM global 3- D chemical transport model. We will estimate global sources and sinks of CO2, CH4, and CO.

Global Models Produce Different Meridional Gradients, with changing relationships as a function of altitude Latitude gradients for CO2 in three TRANSCOM models: GCTM (black), SKYHI (grn), and TM2 (red). Surface fluxes were the same in all runs. TM2, has a small meridional gradient in the PBL (eg. Fig 1i) an also a small vertical gradient, both due to more rapid vertical mixing than in GCTM or SKYHI.

Vertical gradients for CO2 in three TRANSCOM models: GCTM (black), SKYHI (grn), and TM2 (red). Surface fluxes were the same in all runs. TM2, has a small meridional gradient in the PBL and also a small vertical gradient, both due to more rapid vertical mixing than GCTM or SKYHI.

Net annual regional CO2 flux after inversion B. Stephens PBL gradients (ppm) (60N – 0N) with fixed surface flux

Pre-HIPPO/HIPPO/START08 G-V Payloads HAIS/HARVARD Quantum Cascade Laser Spectrometer (QCLS) (CO2, CH4, CO, N2O) NOAA UCATS GC-ECD (CO, CH4, H2, N2O, SF6); uv-O3; TDL-H2O NOAA PANTHER GC (PAN, CFCs, HCFCs, H1211, CH3X, COS, CS2) NCAR in situ O2:N2 NOAA Ozone ("classic") NCAR/Scripps MEDUSA flasks (O2:N2, Ar:N2, CO2, 12/13C16/18O2) NCAR CO § HAIS/Miami whole air (CO, CH4, hydrocarbons, halocarbons, COS,…) § HAIS/NCAR NO/NOy § CU CLH Laser Hygrometer H2O § HARVARD CO (VUV CO sensor)¶ NOAA SP2 (Black Carbon)¶ NOAA flasks (NWAS) (CFCs, 13/12CO2, HCFCs, HFCs, COS, CS2, CH3X)¶ HARVARD CO2 (IRGA-based CO2 sensor)¶ §START: Omitted on HIPPO global ¶HIPPO: Omitted on START08

HIPPO Global: 5 missions over 3-4 years 1st mission January 2009; duration 17—25 days each .

Aug. 3-6 2007 May 2007 The subvisible cirrus were in air that was relatively old. This indicates they formed in situ, and are dehydrating the air mass.. Alternatively, the subvisible cirrus could have blown off convective anvils and been hydrating the air.Hence distinguishing these possibilities is a major advance. S. Wofsy,S. Park

HIPPO Deliverables (1) Publicly available global data sets for CO2, CH4, CO, N2O, 13/12CO2, C16/18O2, O2:N2 and Ar:N2 ratios, CFCs, H1211, HCFCs, CH3X (X=Cl, Br, I), COS, CS2, O3, H2O, SF6, H2, PAN and black carbon: full seasonal cycle, ca. pole-to-pole, surface to tropopause. (2) Inverse studies of CO2 and other HIPPO tracers (3) Analysis of the seasonal exchanges and global budgets of CO2 and O2, with special focus on the Southern Ocean (4) Transport and mixing rates in the TTL (6) Characterize the vertical propagation of the seasonal cycle through the troposphere (7) Global sources and sinks for CH4 (8) Distribution of pollution in remote areas of the atmosphere.

pre-HIPPO/START08 During April-June 2008 the pre-HIPPO campaign will take place combined with NCAR's Stratosphere-Troposphere Analyses of Regional Transport (START08) campaign. Proof of concept and payload. Based in Broomfield, CO. Operational period (2008): 21 April – 16 May (nominal—earlier start expected) 16 June – 28 June Goal: Additional Science Goal: Additional flights (2 pairs, one in each operational period) in the Arctic/sub-Arctic boundary layer will address these specific goals: (1) quantify seasonal sources of CH4 ; (2) characterize pollution transport from Europe and Asia (especially PAN). These flights are intended to complement the ARCTAS mission planned for just before and after pre-HIPPO/START-08.

Proof-of-concept/ payload validation flights North South Pre-HIPPO/START08: Proof-of-concept/ payload validation flights

Pre-HIPPO/START08: Arctic CH4 source flights Overnight, Churchill Pre-HIPPO/START08: Arctic CH4 source flights