APPENDIX C
Past, Current, and Planned Major International Process Studies
PAST PROCESS STUDIES
GATE (GARP1Atlantic Tropical Experiment)—GATE was the first major international field experiment in the tropics with the purpose to understand the tropical atmosphere and its role in the global circulation of the atmosphere and the predictability of the atmosphere in the time range of daily weather forecasts to over 2 weeks. It took place in the summer of 1974 over the tropical Atlantic Ocean from Africa to South America. Twenty countries participated in GATE with 40 research ships, 12 research aircraft, and numerous buoys. These data are still being used today in research. More than 1,000 papers have been published based on the GATE data. A major breakthrough of GATE is the recognition of organized mesoscale convective systems as the main sources of precipitation and convective energy in the tropics. Among others, the GATE soundings have been used as a golden standard in the development of cumulus parameterization in weather and climate models.
TOGA COARE (Tropical Ocean Global Atmosphere Coupled Ocean-Atmosphere Response Experiment)—TOGA COARE was the second major international field campaign in the tropics. Its goal was to describe and understand the principal processes responsible for the coupling and multiscale variability of the ocean and atmosphere in the western Pacific and their interaction with other regions. The field experiment took place over the western Pacific from November 1992 through February 1993. Eighteen countries participated in TOGA COARE with 12 ships, 7 airplanes, and more than 40 moorings. Close to 1,000 papers have been published that are related to TOGA COARE. Among many of its outcomes, the one that contribute most significantly to model improvement is the COARE flux algorithm, which is recognized as the best flux scheme that can be used in models and observational diagnostics.
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1 Global Atmosphere Research Program.
VOCAL-REx (The VAMOS2 Ocean-Cloud-Atmosphere-Land Study Regional Experiment)—VOCAL-REx is another example of multi-nation collaboration to address interactive processes of different components of the Earth system. Its objectives are to understand links between aerosols, clouds, and precipitation and their impacts on marine stratocumulus radiative properties, and physical and chemical couplings between the upper ocean and the lower atmosphere, including the role of mesoscale ocean eddies. It took place during October and November 2008 on and off shore of Chile. Eight countries participated in the field experiment with five research aircraft, two ships, and two surface sites in northern Chile. A major breakthrough of VOCAL-REx is the understanding of the strong role that aerosol-cloud-precipitation coupling plays in marine low clouds, which had previously been thought as controlled mainly by dynamics. Data collected by VOCAL-REx have played crucial roles in developing and refining new parameterization schemes that are used in regional and global models.
SHEBA (The Surface Heat Budget of the Arctic Ocean)—SHEBA is an international research program designed to document, understand, and predict the physical processes that determine the surface energy budget and the sea-ice mass balance in the Arctic. Its overall goal is to acquire the measurements needed to improve the parameterizations of key processes and to integrate new and improved parameterizations into general circulation and climate models. Scientists from seven countries participated in SHEBA. The SHEBA field experiment was a yearlong (October 2, 1997-Oc-tober 12, 1998) measurement on a drifting station in the pack ice of the Arctic Ocean. The drift station made measurement of the vertical column of the ocean, sea ice, and the atmosphere. It was augmented by a buoy array, research aircraft, helicopter surveys, and submarine transects on a larger scale. SHEBA data provide up to date the first and only annual cycle of the surface energy budget for multi-year Arctic ice. They helped improve understanding of many processes critical to the surface energy balance and variability, including supercooled liquid water and advective events from lower latitudes. Knowledge gained from SHEBA data have led to new and improved parameterization of melt ponds, cloud microphysics, and turbulence.
AMMA (The African Monsoon Multidisciplinary Analysis)—AMMA is an international project with an objective of improving knowledge and understanding of the West African monsoon, as well as the environmental and socioeconomic impacts of its variability. It is the biggest program of research on environment and climate issues in Africa. AMMA involved a comprehensive field experiment including ocean, land, and atmospheric measurements in many West African nations and their adjacent seas, on hourly, daily, and up to seasonal timescales over a number of years. The field campaign
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2 Variability of the American Monsoon Systems.
consisted of a long-term monitoring program (2001-2009) based on the existing infrastructure, an Enhanced Observing Period (2005-2007) with specific land-based and sea-based instruments, and four Special Observing Periods in 2006 with intensive measurements from the surface (continent-based and ocean-based) and from the air (research aircraft and balloons) that monitored the pre-monsoon dry season, as well as the onset, peak, and decay of the monsoon. Data collected by the AMMA field campaign have greatly advanced our knowledge on coupling between the atmosphere, land and ocean, and between dynamics, physics, chemistry, biology, and hydrology. These data have also been used in validation and development of global and regional climate and weather models and specific process models (Lebel et al., 2010).
AMY (Asian Monsoon Year)—AMY was a cross-cutting coordinated observation and modeling initiative participated by more than 20 countries. The objectives of AMY are to enhance understanding of ocean-land-atmosphere-biosphere interactions, multiple timescale (from diurnal to intra-seasonal) interaction, and the aerosol-water cycle interaction in the Asian monsoon system, in order to improve their physical representations in coupled climate models, and to develop data assimilation for the ocean-atmosphere-land system in the Asian monsoon region. Its majority of field observations took place during 2008-2010, with 23 field campaigns throughout the Asian monsoon region in four targeted periods: the pre-monsoon period in March-May, the monsoon onset phase in May-June, the monsoon mature phase in July-August, and the winter monsoon from December to February. Among many results, AMY data have revealed how the diurnal cycle, intraseasonal oscillation, and monsoon flow interact to general extreme rainfall that led to flood events with tremendous socioeconomic impacts.
DYNAMO (Dynamics of the Madden-Julian Oscillation)—DYNAMO was the most recent international field campaign aimed at the tropical atmosphere-ocean system. Its overall goal was to improve understanding the processes key to MJO initiation. Based on its three main hypotheses on the roles of convection-environment interaction, evolution of cloud population, and air-sea interaction, DYNAMO’s intensive sounding and radar arrays over the central equatorial Indian Ocean collected data from October 2011 to February 2012, and its broad sounding network continued data collection until March 2012. Sixteen countries participated in DYNAMO with four research vessels, two airplanes, rive special ground stations, and several sites of enhanced radiosondes. Although DYNAMO data are still being analyzed, initial results have revealed new findings in regime change of aerosol and evolution of cloud microphysics through the Madden-Julian Oscillation (MJO) life cycle, interaction between the MJO and ITCZ, and ocean memory of MJO forcing through mixing related to prolonged vertical current shear, among others. DYNAMO data have been used in test-
ing parameterization of cloud microphysics and convective cold pools and in helping validate numerical models of the atmosphere and ocean of different configurations and complexities.
CURRENT AND FUTURE PROCESS STUDIES
YOPP (The Year of Polar Prediction)—YOPP (mid-2017 to mid-2019) is an international program that coordinates a period of intensive observing, modeling, verification, user-engagement and education activities for the purpose of enabling a significant improvement in environmental prediction capabilities for the polar regions and beyond on a wide range of timescales. The observational component of YOPP is built upon several elements. A major one is MOSAiC (Multidisciplinary drifting Observatory for the Study of Arctic Climate), which will deploy a polar research vessel starting in newly formed Arctic sea ice around September 2018, and drifting with the ice over the course of a year, to study a full annual cycle of coupled atmosphere-ice-ocean-biogeochemical system processes. Other observational activities will include intensive observing periods (IOPs) during which aircraft flights and other research vessels will be deployed. In addition, land-based stations as part of the Sustaining Arctic Observing Network (SAON) provide numerous observations of Arctic system through staffed observatories and autonomous instruments. Many model experiments on a hierarchy of scales will be conducted, aimed at understanding and improving model predictability. Many countries will participate in the YOPP field observations.
SOCRATES (Southern Ocean Clouds, Radiation, Aerosol Transport Experimental Study)—SOCRATES is another ongoing international field experiment, which will take place in 2016-2019 in a region where numerical models perform particularly poorly. Its primary objective is to collect a data set suitable to study interactions between microphysics dynamics and radiation in mixed-phase and supercooled clouds. It includes four themes: (1) synoptically varying vertical structure of boundary layers and clouds, (2) seasonal and synoptic variability in cloud condensation and ice nucleus concentration and the role of local biogenic sources, (3) supercooled liquid and mixed-phase clouds, and (4) satellite retrievals related to clouds, precipitation, and aerosols. Five countries will participate in its field observations aboard ships (July-September 2017 and January-March 2018), airplanes and pilotless aircraft (January-March 2018), ground stations (several IOPs during 2016-2019), and moorings (January 2016-December 2019). SOCRATES observations will be used to advance understanding of the variability of Southern Ocean cloud systems on a broad scale and their underpinning processes, such as aerosol physicochemical properties, aerosol-cloud-precipitation interactions, and to reduce model biases in this region.
YMC (Years of the Maritime Continent)—YMC is a 2-year (planned for mid-2017 to mid-2019) international project with its goal of “observing the weather-climate system of the Earth’s largest archipelago to improve understanding and prediction of its local variability and global impact.” There are five YMC science themes: Atmospheric Convection, Upper-Ocean Processes and Air-Sea Interaction, Stratosphere-Troposphere Interaction, Aerosol, and Prediction Improvement. YMC will engage in five main activities: Data Sharing, Field Campaigns, Modeling, Prediction and Applications, and Outreach and Capacity Building. Scientists from 13 countries are participating in the planning of YMC. The platform for the YMC field experiment will include numerous research vessels, airplanes, suites of ground facilities, mobile radars, and oceanic autonomous devices and moorings. These special instruments will be augmented by the regional observing networks of radars, radiosondes, surface meteorological and climatological observations, and marine stations. Cloud-permitting data assimilation products will be made to synthesize data to be collected by the field experiment and the observing networks. YMC data will be used to test and evaluate parameterization schemes in climate models, which have suffered from several severe biases in the Maritime Continent region.
Process Study for the Marginal Ice Zone (MIZ)—The MIZ refers to the region near the sea ice edge where sea ice concentrations are low and floes are small enough to permit the influx of ocean waves. The MIZ is widest in late summer, and the summertime width in the Arctic has broadened significantly in recent decades (Strong and Rigor, 2013). The Office of Naval Research (ONR) is already conducting a 5-year study of the Arctic MIZ that began in 2012, with project website3 and science and experimental plan (Lee et al., 2012). The project has an extensive observational component that extensively utilizes autonomous sampling with sea gliders and acoustically tracked floats, both of which can measure under sea ice. An array of buoys measures wave heights and ice mass balance. A goal of the project is to improve estimates of wave-floe interactions and develop methods of modeling the sea ice floe size distributions. Three models are taking part in the project. All three are Arctic regional models, and only one has an atmosphere component (the other two are ocean-sea ice only). One of the ocean-sea ice only modeling groups is undertaking the development of floe size distribution capability (Zhang et al., 2015). The other two are specializing in fine resolution (up to 1/12 degree).
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3http://www.apl.washington.edu/project/project.php?id=miz, accessed January 27, 2016.
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