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  • Author or Editor: Ajay Raghavendra x
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Ajay Raghavendra, Paul E. Roundy, and Liming Zhou

Abstract

A frequency–wavenumber power () spectrum was constructed using satellite-derived outgoing longwave radiation (OLR) and brightness temperature for the tropical latitudes. Since the two datasets overlap for over 34 years with nonintersecting sources in error and compare relatively well with each other, it is possible to diagnose trends in the tropical wave activity from the two datasets with confidence. The results suggest a weakening trend in characterized by high interannual variability for wave activity occurring in the low-frequency part of the spectrum and a steady increase in with relatively low interannual variability for wave activity occurring in the high-frequency part of the spectrum. The results show the parts of the spectrum representing the Madden–Julian oscillation and equatorial Rossby wave losing and other parts of the spectrum representing Kelvin waves, mixed Rossby–gravity waves, and tropical disturbance–like wave activity gaining . Similar results were obtained when trends in variance corresponding to the first principal component were produced using spectrally filtered OLR data representative of atmospheric equatorial waves. Spatial trends in the active phase of wave events and the mean duration of events are also shown for the different wave types. Linear trends in for the entire spectrum and regional means in the spectrum corresponding to the abovementioned five wave types with confidence intervals are also presented in the paper. Finally, we demonstrate that El Niño–Southern Oscillation variability does not appear to control the overall spatial patterns and trends observed in the spectrum.

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Dylan R. Card, Heather S. Sussman, and Ajay Raghavendra
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Dylan R. Card, Heather S. Sussman, and Ajay Raghavendra

Abstract

Graduate school provides an opportunity for students to enhance their knowledge and skill sets and to develop the qualifications to seek high-skilled employment. However, many graduate students are plagued with personal and financial stressors that can decrease research productivity and professional growth. With ballooning student loan debt and economic inflation, stakeholders should review the financial well-being of our current and future graduate students with greater frequency to ensure the continued fast-paced advancement of science. This study investigated the annual stipend, university fees, housing costs, cost of living, and the state income tax rate of 39 atmospheric science graduate programs in the United States to determine the effective income for first-year graduate students in the 2020–21 academic year. Results showed a large spread in advertised stipend amounts ranging between $19,139 and $41,520 (USD). After taking into account annual university fees, housing costs, and state income tax and normalizing by the cost of living, effective income had a decreased spread ranging between $12,287 and $25,240. Prospective graduate students should not focus on the advertised stipend when deciding between schools since it does not always accurately represent the affordability of the graduate program. The future of scientific research relies on the next generation of scientists. Therefore, graduate programs across the country should focus on providing fair financial compensation in order to attract students with exceptional research skills who otherwise may leave academia to pursue higher-paying jobs after college.

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Shealynn R. Cloutier-Bisbee, Ajay Raghavendra, and Shawn M. Milrad

Abstract

Heat waves are increasing in frequency, duration, and intensity and are strongly linked to anthropogenic climate change. However, few studies have examined heat waves in Florida, despite an older population and increasingly urbanized land areas that make it particularly susceptible to heat impacts. Heavy precipitation events are also becoming more frequent and intense; recent climate model simulations showed that heavy precipitation in the three days after a Florida heat wave follow these trends, yet the underlying dynamic and thermodynamic mechanisms have not been investigated. In this study, a heat wave climatology and trend analysis are developed from 1950 to 2016 for seven major airports in Florida. Heat waves are defined based on the 95th percentile of daily maximum, minimum, and mean temperatures. Results show that heat waves exhibit statistically significant increases in frequency and duration at most stations, especially for mean and minimum temperature events. Frequency and duration increases are most prominent at Tallahassee, Tampa, Miami, and Key West. Heat waves in northern Florida are characterized by large-scale continental ridging, while heat waves in central and southern Florida are associated with a combination of a continental ridge and a westward extension of the Bermuda–Azores high. Heavy precipitation events that follow a heat wave are characterized by anomalously large ascent and moisture, as well as strong instability. Light precipitation events in northern Florida are characterized by advection of drier air from the continent, while over central and southern Florida, prolonged subsidence is the most important difference between heavy and light events.

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