Hakim Gregory J.

No Thumbnail Available
Last Name
Hakim
First Name
Gregory J.
ORCID
0000-0001-8486-9739

Filters

2005 - 2009 1 2020 - 2024 1
2
2
Reset filters

Settings

Search Results

Now showing 1 - 2 of 2
  • Article
    Predictability
    ( 2005-12) Hacker, Joshua ; Hansen, James ; Berner, Judith ; Chen, YangQuan ; Eshel, Gidon ; Hakim, Gregory ; Lazarus, Steven ; Majumdar, Sharanya ; Morss, Rebecca ; Poje, Andrew ; Sheremet, Vitalii A. ; Tang, Youmin ; Webb, Colleen
    A group of junior faculty members and UCAR junior scientists convened in Boulder, CO on June 16-18, 2003 for discussion on future scientific directions. This report summarizes the goals and products of one of the three foci selected for special consideration: predictability. About 15 people, representing physical, mathematical, and biological sciences, were present for round-table discussions. The discussion sought common interpretation of the predictability problem, points of generalization, identification of major hurdles, and potential approaches to their solution. The diverse background of the participants generated a wide-ranging discussion. The participants addressed predictability generally, while supplying specific examples from their own areas of expertise. Recurring themes included the relationship between models and initial conditions, the importance of definitions and the choice of a norm for evaluation, and generalization across systems and disciplines. The group explored potential avenues for generalization through interdisciplinary networking. Short- and long-range challenges were identified related to probabilistic state estimation, verifying predictions and understanding error, and dealing with nonlinearity. In this essay we expand on these themes and challenges, and describe possible future research objectives.
  • Article
    Last millennium hurricane activity linked to endogenous climate variability
    (Nature Research, 2024-01-27) Yang, Wenchang ; Wallace, Elizabeth J. ; Vecchi, Gabriel A. ; Donnelly, Jeffrey P. ; Emile-Geay, Julien ; Hakim, Gregory J. ; Horowitz, Larry W. ; Sullivan, Richard M. ; Tardif, Robert ; van Hengstum, Peter J. ; Winkler, Tyler S.
    Despite increased Atlantic hurricane risk, projected trends in hurricane frequency in the warming climate are still highly uncertain, mainly due to short instrumental record that limits our understanding of hurricane activity and its relationship to climate. Here we extend the record to the last millennium using two independent estimates: a reconstruction from sedimentary paleohurricane records and a statistical model of hurricane activity using sea surface temperatures (SSTs). We find statistically significant agreement between the two estimates and the late 20th century hurricane frequency is within the range seen over the past millennium. Numerical simulations using a hurricane-permitting climate model suggest that hurricane activity was likely driven by endogenous climate variability and linked to anomalous SSTs of warm Atlantic and cold Pacific. Volcanic eruptions can induce peaks in hurricane activity, but such peaks would likely be too weak to be detected in the proxy record due to large endogenous variability.