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In this study the radiative impact of three separate cirrus anvil systems that occurred during the Maritime Continent Thunderstorm Experiment is investigated. Retrievals of microphysical cloud properties and an independent radar measurement are used to develop an appropriate set of radar reflectivity factor (Z)-ice water content (IWC) parameterizations. This set of parameterizations is then applied to the reflectivity field of a scanning 5.2-cm radar. The three-dimensional ice water structure is used as input to a two-stream radiative transfer model using an independent pixel approximation for several different stages in the life cycle of the cloud system. Peak radiative heating/cooling occurs at many different levels from just below the tropopause down to the freezing level. This behavior is attributed to spatial variability of the anvil cloud-top height. There is a distinct difference between the average radiative heating profile in the presence of island-based convection as compared with oceanic convection. The island-based convection results in a heating profile that concentrates cloud-top solar heating and IR cooling higher in the atmosphere and with a greater magnitude in comparison with studies of oceanic convection. Island-based thunderstorms can play a major role in the large-scale radiative energy balance. The net radiative convergence averaged over a simplified diurnal cycle and over a 120 x 120 [km.sup.2] grid box containing an island-based thunderstorm and its associated anvil cloud is near zero. When considering the energy balance over the tropical western Pacific, it is important to consider the 'Maritime Continent' region with all of its small islands separately from the oceanic regime.

Algorithms to correlate of solar surface radiation data between observation sites estimate that a spacing between sites of about 150 km is optimal. Researchers studied data simoultaneously gathered from eleven broadband solar instruments installed over a 5600 sq.km. area at sites in central Wisconsin. Correlation between sites using the entire record, individual day correlations and pairwise regression statistics established that correlations were best at a radius of 75 km from each site.

The U.S. Department of Energy's Atmospheric Radiation Measurement (ARM) Program is deploying sensitive, millimeter-wave cloud radars at its Cloud and Radiation Test Bed (CART) sites in Oklahoma, Alaska, and the tropical western Pacific Ocean. The radars complement optical devices, including a Belfort or Vaisala laser ceilometer and a micropulse lidar, in providing a comprehensive source of information on the vertical distribution of hydrometeors overhead at the sites. An algorithm is described that combines data from these active remote sensors to produce an objective determination of hydrometeor height distributions and estimates of their radar reflectivities, vertical velocities, and Doppler spectral widths, which are optimized for accuracy. These data provide fundamental information for retrieving cloud microphysical properties and assessing the radiative effects of clouds on climate. The algorithm is applied to nine months of data from the CART site in Oklahoma for initial evaluation. Much of the algorithm's calculations deal with merging and optimizing data from the radar's four sequential operating modes, which have differing advantages and limitations, including problems resulting from range sidelobes, range aliasing, and coherent averaging. Two of the modes use advanced phase-coded pulse compression techniques to yield approximately 10 and 15 dB more sensitivity than is available from the two conventional pulse modes. Comparison of cloud-base heights from the Belfort ceilometer and the micropulse lidar confirms small biases found in earlier studies, but recent information about the ceilometer brings the agreement to within 20-30 m. Merged data of the radar's modes were found to miss approximately 5.9% of the clouds detected by the laser systems. Using data from only the radar's two less-sensitive conventional pulse modes would increase the missed detections to 22%-34%. A significant remaining problem is that the radar's lower-altitude data are often contaminated with echoes from nonhydrometeor targets, such as insects.