[1] A single-particle soot photometer (SP2) was flown on a NASA WB-57F high-altitude research aircraft in November 2004 from Houston, Texas. The SP2 uses laser-induced incandescence to detect individual black carbon (BC) particles in an air sample in the mass range of $3-300 fg ($0.15-0.7 mm volume equivalent diameter). Scattered light is used to size the remaining non-BC aerosols in the range of $0.17-0.7 mm diameter. We present profiles of both aerosol types from the boundary layer to the lower stratosphere from two midlatitude flights. Results for total aerosol amounts in the size range detected by the SP2 are in good agreement with typical particle spectrometer measurements in the same region. All ambient incandescing particles were identified as BC because their incandescence properties matched those of laboratory-generated BC aerosol. Approximately 40% of these BC particles showed evidence of internal mixing (e.g., coating). Throughout profiles between 5 and 18.7 km, BC particles were less than a few percent of total aerosol number, and black carbon aerosol (BCA) mass mixing ratio showed a constant gradient with altitude above 5 km. SP2 data was compared to results from the ECHAM4/MADE and LmDzT-INCA global aerosol models. The comparison will help resolve the important systematic differences in model aerosol processes that determine BCA loadings. Further intercomparisons of models and measurements as presented here will improve the accuracy of the radiative forcing contribution from BCA.Citation: Schwarz, J. P., et al. (2006), Single-particle measurements of midlatitude black carbon and light-scattering aerosols from the boundary layer to the lower stratosphere,

Abstract.We describe observations of tropical stratospheric water vapor q that show clear evidence of large-scale

The annual cycle of the net mass transport across the extratropical tropopause is examined. Contributions from both the global‐scale meridional circulation and the mass variation of the lowermost stratosphere are included. For the northern hemisphere the mass of the lowermost stratosphere has a distinct annual cycle, whereas for the southern hemisphere, the corresponding variation is weak. The net mass transport across the tropopause in the northern hemisphere has a maximum in late spring and a distinct minimum in autumn. This variation and its magnitude compare well with older estimates based on representative 90Sr mixing ratios. For the southern hemisphere the seasonal cycle of the net mass transport is weaker and follows roughly the annual variation of the net mass flux across a nearby isentropic surface.

The transformed Eulerian-mean (TEM) residual circulation is used to study the zonally averaged transport of mass in the stratosphere. The residual circulation is estimated from heating rates computed with a radiative transfer model using data from the Upper Atmosphere Research Satellite (UARS) as inputs. An annual cycle exists in the resulting circulation in the lower stratosphere, with a larger net upward mass flux across a pressure surface in the tropics during northern hemisphere winter than during northern hemisphere summer. The annual cycle in upward tropical mass flux follows the annual cycle in downward mass flux across a pressure surface in the northern hemisphere extratropics. It is argued that the annual cycle in zonal momenttim forcing in the northern hemisphere stratosphere is controlling mass flux across a pressure surface in the lower stratosphere both in the tropics and in the northern hemisphere extratropics.averages out, so that the net zonal mean Lagrangian motions are determined by departures from radiative equilibrium. Therefore the residual circulation appears to be a meaningful description of the net Lagrangian motion, even when the conditions cited in Dunkerton's proof are violated. That the TEM residual circulation is a reasonable proxy for net Lagrangian motion has to some extent been shown to be the case by the success in estimating the distribution of stratospheric trace species of a number of two-dimensional chemical/dynamical models that use residual velocities. Most estimates of the strength of the mean meridional circulation in the lower stratosphere have been cast in terms of the annually averaged cross-tropopause mass flux [see Follows, 1992, and references therein]. However, there is also evidence of a seasonal cycle in the strength of the lowerstratospheric mean meridional circulation. By vertically integrating the forcing in the TEM zonal mo'nentum equation estimated from climatological data (using the solution presented by Haynes et al. [1991]), Holton [1990] and Rosenlof and Holton [1993] found an annual cycle in the net tropical upward mass flux across the 100-hPa surface. An annual cycle in net tropical upward mass flux was similarly present in the analysis of National Center for Atmospheric Research 5173 5174 ROSENLOF: RESIDUAL MEAN MERIDIONAL CIRCULATION ANNUAL CYCLE Community Climate Model 2 (NCAR CCM2) output shown by Rosenlof and Holton [1993]. In these cases the maximum upward mass flux occurs in northern hemisphere winter and is approximately twice the minimum that occurs during northern hemisphere summer. Tropical total 0 3 measurements [Shiotani, 1992; Shiotani and Hasebe, 1994] also show an annual cycle with minimum during northern hemisphere winter. Stronger upwelling from the troposphere would advect lower 0 3 air into the stratosphere, resulting in minimum total 0 3 when the tropical upward mass flux is at a maximum. Coincident with a larger tropical upward mass flux during northern hemisphere winter would be greater adiabatic cooling compared with northern hem...

[1] The validation of version 2.2 (v2.2) H 2 O measurements from the Earth Observing System (EOS) Microwave Limb Sounder (Aura MLS) on the Aura satellite are presented.Results from comparisons made with Aqua Atmospheric Infrared Sounder (AIRS), Vaisala radiosondes, frost point hygrometer, and WB57 aircraft hygrometers are presented. Comparisons with the Aura MLS v1.5 H 2 O, Goddard global modeling and assimilation office Earth Observing System analyses (GEOS-5) are also discussed. For H 2 O mixing ratios less than 500 ppmv, the MLS v2.2 has an accuracy better than 25% between 316 and 147 hPa. The precision is 65% at 316 hPa that reduces to 25% at 147 hPa. This performance is better than expected from MLS measurement systematic error analyses. MLS overestimates H 2 O for mixing ratios greater than 500 ppmv which is consistent with a scaling error in either the calibrated or calculated MLS radiances. The validation of the accuracy of MLS v2.2 H 2 O from 121 to 83 hPa which is expected to be better than 15% cannot be confirmed at this time because of large disagreements among the hygrometers used in the AVE campaigns. The precision of the v2.2 H 2 O from 121 to 83 hPa is 10-20%. The vertical resolution is 1.5-3.5 km depending on height. The horizontal resolution is 210 Â 7 km 2 along and perpendicular to the Aura orbit track, respectively. Relative humidity is calculated from H 2 O and temperature. The precision, accuracy, and spatial resolution are worse than for H 2 O.Citation: Read, W. G., et al. (2007), Aura Microwave Limb Sounder upper tropospheric and lower stratospheric H 2 O and relative humidity with respect to ice validation,