ALBERT

Description: Deviations of radiosonde reports' geopotential heights from the zonal mean are examined. In the summer Northern Hemisphere stratosphere, systematic differences are found between radiosonde instrument types. Persistent meridional wind anomalies, approximately constant in magnitude and fixed in location, have previously been reported in the summer stratosphere, and one such anomaly over Europe is found to be co-located with boundaries between regions in which differing types of radiosonde instruments are used. The magnitude and orientation of the radiosonde geopotential height biases are consistent with the wind anomalies. Because the overall winds tend to be light in this region and season, these wind anomalies can represent significant perturbations of the flow and must be considered when interpreting the results of trajectory and diagnostic studies.

Description: A network of 10 southern hemisphere tropical and Subtropical stations, designated the Southern Hemisphere ADditional OZonesondes, (SHADOZ) project and established from operational sites, provided over 1000 ozone profiles during the period 1998-2000. Balloon-borne electrochemical concentration cell (ECC) ozonesondes, combined with standard radiosondes for pressure, temperature and relative humidity measurements, collected profiles in the troposphere and lower- to mid-stratosphere at: Ascension Island; Nairobi, Kenya; Irene, South Africa: Reunion Island, Watukosek Java; Fiji; Tahiti; American Samoa; San Cristobal, Galapagos; Natal, Brazil.

Description: The Transfer Function Model (TFM) is a semi-analytical, linear model that is designed especially to describe thermospheric perturbations associated with magnetic storms and substorm. activity. It is a multi-constituent model (N2, O, He H, Ar) that accounts for wind induced diffusion, which significantly affects not only the composition and mass density but also the temperature and wind fields. Because the TFM adopts a semianalytic approach in which the geometry and temporal dependencies of the driving sources are removed through the use of height-integrated Green's functions, it provides physical insight into the essential properties of processes being considered, which are uncluttered by the accidental complexities that arise from particular source geometrie and time dependences. Extending from the ground to 700 km, the TFM eliminates spurious effects due to arbitrarily chosen boundary conditions. A database of transfer functions, computed only once, can be used to synthesize a wide range of spatial and temporal sources dependencies. The response synthesis can be performed quickly in real-time using only limited computing capabilities. These features make the TFM unique among global dynamical models. Given these desirable properties, a version of the TFM has been developed for personal computers (PC) using advanced platform-independent 3D visualization capabilities. We demonstrate the model capabilities with simulations for different auroral sources, including the response of ducted gravity waves modes that propagate around the globe. The thermospheric response is found to depend strongly on the spatial and temporal frequency spectra of the storm. Such varied behavior is difficult to describe in statistical empirical models. To improve the capability of space weather prediction, the TFM thus could be grafted naturally onto existing statistical models using data assimilation.

Description: The numerical simulation of CO2 transport (and other tracers such as CO, CH4, and biomass burning tracers) in the atmosphere is required to determine the fate of anthropogenic source gases. Estimation of the CO2 exchange between the ocean surface, the terrestrial biosphere, and the atmosphere is of first-order importance to understanding the global carbon cycle and the processes that are most crucial in determining the atmospheric CO2 concentration. Forward transport simulations have been conducted using two-dimensional, time-dependent grids of average surface fluxes (from TRANSCOM) and three-dimensional wind data from a prototype data assimilation system (FV-DAS) run by the Goddard Data Assimilation Office. The objective is to better understand the contribution of meteorological variability to changes in CO2 and other constituents, By accurately accounting for meteorological variability, through use of assimilated winds, we hope to better characterize the distribution of surface sources and sinks (and chemistry where applicable). With assimilated meteorology such chemistry/transport runs provide the basic framework to analyze existing (and proposed) measurement data on a point-by-point, real-time basis. We compare with measured CO2 concentration gradients on a daily, seasonal, regional, and interhemispheric basis to examine the consistency of sources, sinks, and transport formulation. We will also examine the inter-annual variability of atmospheric CO2 due to atmospheric circulation changes using longer runs with assimilated winds.