INCE

Ice nucleating particles are required to trigger the formation of ice crystals in the mixed-phase (liquid and ice) regions of clouds, thereby impacting the transfer of solar and thermal energy through and precipitation formation processes in many clouds. Varied natural and human-caused sources of ice nucleating particles remain poorly quantified and their impact on clouds and climate therefore remain relatively unconstrained. Soils of all types and plant surfaces are sources for ice nucleating particles that are produced when those surfaces are perturbed, such as by wind or fire. Deserts are known as strong global sources of ice nuclei of mineral origin. Plants are reservoirs of special highly effective biological ice nucleating particles (certain bacteria and fungal spores), and the action of these and other microorganisms within soils work to create a distinct population of dominant organic ice nucleating particles that we have identified in agricultural soils. Further, the combustion of plant matter in fires releases black carbon and other particles that are potential ice nucleating particles.

SGP is an ideal location for exploring the contributions of these ice nucleating particle sources in spring. The site is located within an agricultural region where soils are tilled and can be ablated locally/regionally by windstorms, where plant surfaces are perturbed by harvesting and sometimes burning prior to replanting, and where long range transports of dusts (from Asia and the U.S. Southwest) and smokes (from Mexico and other regions) occur in spring. In coordination with NASA and NSF-funded studies, we brought a suite of instruments to the SGP site to augment existing in-situ and remote sensing aerosol instrumentation in order to quantify the types of ice nucleating particles present under various scenarios. Sampling had a special focus to capture impacts of any local field burning in late April through early May, winter wheat harvesting in early June, and local and long range influences of soil dust and smokes through the period. We sampled ice nucleating particle concentrations and the contribution of black carbon types to these using a special real-time measurement system (with NASA support), we monitored biological particle concentrations, and we collected particles onto filters for post-processing measurements of ice nucleating particle concentrations and categorization of these nuclei as of inorganic versus organic (including microbial) origins.

These are the first ever ice nucleating particle measurements at SGP, and may serve as a trial for long term measurements. Source-specific data were obtained toward application in parameterizing ice nucleation for use in regional and global scale modeling.

Timeline

Campaign Data Sets