Four decades ago, scientists noticed that tropical cyclones form in clusters followed by several weeks of inactivity. This finding was long overlooked until the recent growing interest in subseasonal-to-seasonal prediction of high-impact weather. Research in this area has uncovered that convectively coupled equatorial waves (CCEWs) can partly explain week-to-week tropical cyclone activity through modulations of environmental conditions. However, the physical processes behind that relationship remain unexplored because previous studies have relied on reanalysis datasets, which cannot capture the mesoscale and convective-scale processes that are ultimately necessary for tropical cyclogenesis. That limitation motivates this study, which aims at developing a modeling framework that can capture both planetary-scale waves and tropical cyclones, while using that framework to explore if and how CCEWs modulate tropical cyclogenesis. In the first part of this talk, I will describe the modeling framework—aquaplanet experiments using the Model for Prediction Across Scales-Atmosphere (MPAS-A). I will demonstrate that the MPAS-A aquaplanet experiments produce a climate and weather systems that are consistent with other models and with the real world. In the second part, I will demonstrate that a relationship exists between CCEWs and TC activity in the aquaplanet experiments, but the relationship is different from that identified using reanalysis datasets and it depends on the horizontal grid spacing of the simulations.
A linear two-layer model is used to elucidate the role of prognostic moisture on quasi-geostrophic (QG) motions in the presence of a mean thermal wind. Solutions to the basic equations reveal two instabilities. The well-documented baroclinic instability is characterized by growth at the synoptic scale (horizontal scale of∼1000 km) and systems that grow from this instability tilt against the shear. Moisture-vortex instability— an instability that occurs when moisture and lower-tropospheric vorticity exhibit an in-phase component— exists only when moisture is prognostic. The instability is also strongest at the synoptic scale, but systems that grow from it exhibit a vertically-stacked structure. When moisture is prognostic, baroclinic instability exhibits a pronounced weakening when the thermal wind is easterly. On the other hand, moisture-vortex instability is strongest in this mean state. Based on these results, it is hypothesized that moisture-vortex instability is the dominant instability in humid regions of easterly thermal wind such as the South Asian and African monsoons.
Diverse and inclusive universities and workplaces lead to improvements in science through increased innovation and complex problem solving. The discipline of atmospheric science in the United States has faced challenges in attracting and retaining scientists who are women, people of color, Black, Indigenous, from the LBGTQ community, and people with disabilities. Many of these scientists leave because of exclusive cultures. As concerned members of the atmospheric science community, this may lead one to ask: how can I be an agent of change? Years of research on diversity training have found that simply having the desire to be inclusive does not result in inclusivity. Instead, change needs to happen at the organizational and system level. As individuals, we are part of social systems (e.g., departments, professional societies, institutions) that can be challenging to navigate and change. This seminar will explore how individuals in a community can conceptualize an organization and their potential for enacting change by analyzing their social connections, knowledge and skills, and formal responsibilities. This discussion will be guided by specific examples of creating change in the geosciences from research on a professional development program – Hearts of GOLD (Geo Opportunities for Leadership in Diversity).
Colin Stokes Ramage, an AMS Fellow, passed away on December 17, 2017 at age 96. A pioneer in tropical meteorology, his career spanned World War II to the turn of the 21st century. He was the founding chair of the Department of Meteorology (now the Department of Atmospheric Science) at the University of Hawaii (UH) at Manoa.
Colin was born in New Zealand on March 3, 1921. He earned a B.S. from Victoria University College, Wellington, in 1940. That same year he entered the New Zealand Meteorological Service. He served in the Royal New Zealand Air Force from 1942 to 1946. His specialty was “synoptic meteorology and forecasting; research into meteorology of high Southern Hemisphere latitudes.” Colin joined the Royal Observatory at Hong Kong (now The Observatory) in 1946 as a scientific officer, eventually becoming acting director. His research in tropical meteorology began while at Hong Kong, as evidenced by a series of publications in AMS journals, and he received an Sc.D. from New Zealand in 1961.
In 1956, Colin arrived as an initial hire at the nascent program in meteorology at the University of Hawaii. Initial support for the program was provided by the U.S. Air Force. The program grew to an academic department with Colin as department chair, a post he held until his retirement in 1987.
Colin’s tenure in Hawaii coincided with a number of significant developments in tropical meteorology, oceanography and climate. Some highlights were:
1. Meteorological satellites. On April 1, 1960, Colin and James Sadler were present at Kaena Point, Oahu, awaiting the first images from TIROS-1. They were among the first to use satellite imagery in tropical analysis and research, notably Eastern Pacific tropical cyclones and subtropical cyclones. UH scientists later participated in the Line Islands Experiment (1967), which coincided with the launch of the Applied Technology Satellite (ATS)-1.
2. International Indian Ocean Expedition. Colin was a principal contributor to the planning and execution of the U.S. effort in the International Indian Ocean Expedition (IIOE, 1962-65), which was primarily an oceanographic venture. Colin participated in the development of the meteorology element and spent a year in Mumbai.
In 1971, he published Monsoon Meteorology, incorporating his years of experience in Hong Kong as well as the findings of the IIOE. His course, “Monsoon Meteorology,” remains a standard offering at UH. One of his contributions to the literature was the term “maritime continent.”Colin Stokes Ramage, an AMS Fellow, passed away on December 17, 2017 at age 96. A pioneer in tropical meteorology, his career spanned World War II to the turn of the 21st century. He was the founding chair of the Department of Meteorology (now the Department of Atmospheric Science) at the University of Hawaii (UH) at Manoa.
3. Monsoon Experiment. Colin and UH colleagues were participants in the planning and execution of the Monsoon Experiment (MONEX), a component of the first Global Atmospheric Research Program (GARP) Global Experiment. Colin, colleagues, and students were in Kuala Lumpur for the winter MONEX field phase.
4. El Nino/Southern Oscillation and its consequences. The 1972-73 El Nino drew scientific attention to equatorial ocean-atmosphere interactions. Oceanographers and atmospheric scientists at UH have been prominent in the science of the El Nino/Southern Oscillation. Colin assembled a meteorological atlas of the 1972-73 El Nino. Colin continued to study seasonal-to-interannual climate variability throughout his career.
Colin retired from UH in December 1987. He moved to Boulder, Colorado, where he remained active with the Cooperative Institute for Research in the Environmental Sciences at the University of Colorado. In addition he remained active with UH. In summer 1990, he participated in the field phase of the Tropical Cyclone Motion Experiment in Guam. He also initiated a project to revise the Air Force Forecasters Guide to Tropical Meteorology.
A widower, Colin married again and started a new family and moved to North Carolina in 1990. He served as an adjunct professor at North Carolina State University. In 1995, the revised Air Weather Service Forecasters Guide to Tropical Meteorology was published. In 1999, he published his last scientific paper with Thomas Schroeder on rainfall on Mount Waiʻaleʻale, Kauai, a subject that long fascinated him.
Colin was noted for his keen intellect, his breadth of knowledge (well beyond his science), and his healthy skepticism. He loved to debate, and department seminars were lively events, especially when the physical oceanographers attended, and the subject was El Nino. The larger community became aware of his skepticism of early general circulation and weather prediction models. The skepticism was demonstrated in comments about journal articles as well as a pair of papers in BAMS on outlook for numerical weather prediction.
Colin loved his science and enjoyed the classroom. He read his rain gauge every day up to the day when his health prevented him leaving the house. While an adjunct at North Carolina State, Colin taught a seminar series on tropical meteorology. One attendee, a young faculty member named Steven Businger (now the department chair at Hawaii), commented that Colin “had a twinkle in his eye when he lectured.”