Bio/Research

It is with great regret and sorrow that we inform you that Prof. Sultan Hameed has passed.

Sultan Hameed was one of the founding members of atmospheric sciences at Stony Brook University (SBU). He began at SBU as a faculty member (Research Associate Professor) in Mechanical Engineering in 1976 with initial research areas in air quality, transport, and the boundary layer. Through collaborations with the late Prof. Robert Cess (also in Mechanical Engineering at the time) and others his research expanded to global climate change, coupled atmosphere-ocean interactions, and atmospheric "centers of action" (i.e., large-scale semi-permanent high- and low-pressure systems, and their impact on atmospheric and oceanic circulations). His appointment was converted to Associate Professor in 1981 and he was promoted to Professor in 1986. His appointment (and others such as Bob Cess) was transitioned to the Institute of Terrestrial and Planetary Atmospheres and what is now the Atmospheric Sciences Division in SoMAS. He also served as Director for ITPA from 2010 to 2014.  Sultan obtained his B. Sc. (Honors) in 1961 and his M. Sc. in 1964 from the University of Karachi and an M.S. in Physics in 1964 from the University of Toronto.  He then completed his Ph.D. in Physics from the University of Manchester in 1968.  He was a Research Associate in Physics at the University of Pisa from 1964 to 1965, at Yeshiva University from 1968 to 1970, at Columbia University from 1970 to 1972 and at NASA GISS, from 1972 to 1976.

Professor Hameed has 135 publications in peer reviewed journals on atmospheric physics and chemistry and climate change.

His graduate student advisees at SBU include: Faez Bakalian, Jane Dignon, Jae Nyung Lee, I. Pittalwala, Wei Shi, Michael Flanagan, Yilin Yi, H. Lagrone, Nicholas Leonardo, Xianzhi Liu, Aichen Niu, Melissa Ou, Hongming Qi, K. Sperber, Xuefeng Wen, P. Wyant, W. Shi, and Yingyi Zhang

In recent years he taught ATM 237/Phys 237 (World Atmosphere and Climate), MAR538 (Univariate Data Analysis), MAR 570 (Multivariate Data Analysis in Marine and Atmospheric Sciences.), ATM 345 (Atmospheric Dynamics and Thermodynamics), and ATM 348 (Atmospheric Physics).

In the late 1990s and early 2000s Sultan Hameed was instrumental in designing the foundation of the current Atmospheric and Oceanic Science (ATM) degree. He also served as an advisor for the ATM program for many years. In an effort to help graduate students with the PhD qualifying exam, he led efforts to start a first-year graduate reading and discussion course in the early 2000s (now part of MAR 543). Among his recent service was as a member of the SoMAS Graduate Curriculum Committee that drafted the new Graduate Program for SoMAS, and the committee that developed the new B.S. degree in Climate Science.

Professor Hameed was a good colleague and a gentle soul who will be sorely missed.

My recent work has focused on the study of the large-scale semi-permanent high- and low-pressure systems known as the Atmospheric Centers of Action. The major centers are the Icelandic Low, the Azores High, the Aleutian Low, the Hawaiian High and the Siberian High in the Northern Hemisphere and the Subtropical Highs in the southern Atlantic, Pacific and the Indian Oceans. Variations in the global circulation cause variations in the intensities and the morphologies of the atmospheric centers of action (COA). In turn, these systems influence atmospheric and oceanic circulations over their respective domains. The centers of action therefore provide links between variations on the global and regional scales. Indices for monthly values of intensity, latitude and longitude of the major centers of action are at the link at the top of this page.

Re-interpretation of the North Atlantic Oscillation

The NAO is usually represented by an index based either on the pressure anomaly difference between two stations chosen to represent the Icelandic Low (Reykjavik, Iceland) and the Azores High (Azores or Lisbon), or an empirical orthogonal function of surface pressure or geopotential over the north Atlantic.  These representations of the NAO overlook the fact that the Icelandic Low and the Azores High change positions continuously. An improved estimate of the influence of  pressure fluctuations on regional climate can be attained through a  quantitative assessment of the fluctuations in the pressures and the locations of the Icelandic Low and the Azores High .We have illustrated the usefulness of this approach in several investigations. (Hameed and Piontovski , 2004; Sanchez-Franks et al., 2016; Riaz et al., 2017; Berdahl et al., 2018).

West Coast Drought and Subtropical Highs

Subtropical high pressure centers of action exist to the west of continents and modulate the influx of moisture into coastal regions. Leonardo and Hameed (2015) showed that rainfall across California is dominated by variations in the pressure of the Hawaiian high;  when the high’s pressure increases, the rainfall in California decreases, and vice versa. Also, east–west shifts in the position of this subtropical high significantly influence winter rainfall. When the Hawaiian high shifts to the west, rainfall increases, and vice versa. The South Pacific High modulates interannual variation of winter precipitation over Chile in a similar manner (Barrett and Hameed, 2017).

Atmosphere’s impact on Gulf Stream Position

The path of the Gulf Stream as it leaves the coast near Cape Hatteras is marked by a sharp gradient in ocean temperature known as the North Wall.  Previous work in the literature has considered processes related to the North Atlantic Oscillation (NAO) in triggering latitudinal displacements of North Wall position.  Hameed et al. (2018)  presented evidence that the Atlantic Meridional Mode (AMM) also impacts interannual variations of   the North Wall position.  The AMM signal from the tropics propagates to the Gulf Stream near 200 m depth and there are two different processes  for this interaction.

It has generally been assumed in oceanography literature that the variations of the North Wall and the Gulf Stream are similar. By utilizing satellite data on sea surface height to identify the Gulf Stream and the 15ºC isotherm at 200 m depth to represent the North Wall, we found that the North Wall and Gulf Stream diverge rapidly east of 71^oW, and their separation is caused by  the presence of mesoscale eddies between them (Chi et al., 2019).

Sea Level Rise

Determining the rate of global sea level rise is important to understanding the impact of climate change. However, this is complicated by local sea-level variability that is one to two orders of magnitude greater than the trend.  Kolker and Hameed (2007) showed that the position and intensity of the Azores High and the Icelandic Low explain major fraction of the variability and trend at key Atlantic Ocean tide gauges over the past century. The COA changes influence winds, pressure and sea-surface temperatures, thereby influencing sea level. Since the role of the COA as meteorological drivers of sea level change was not previously recognized, it is likely that estimates of GSLR by IPCC (2007) are over-estimates.

Links

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