9,267 research outputs found
Dynamics of Earth's Hadley Circulation
No full textThis thesis advances our understanding of the mechanisms controlling the Hadley circulation, and its interaction with eddies on planetary scales in particular. On Earth, and more generally in a rapidly rotating and differentially heated planet, planetary scale eddies in the extratropics interact with the mean flow in the tropics, contributing to the driving of the Hadley circulation. A hierarchy of numerical models is used to simulate and understand the relative importance of eddies in the driving of the Hadley circulation. In a global warming experiment, the Hadley circulation is found to strengthen in colder climates and weaken in warmer climates, with a maximum strength in a climate close to present-day Earth’s. This nonmonotonicity is shown to be consistent with variations in the eddy activity in the midlatitudes. The cells are also found to widen over the entire range of this climate change. A criterion quantifying the importance of baroclinic waves in setting the depth of the troposphere, which is modified to account for the effect of convective adjustment on planetary Rossby waves activity, is used to explain the shifts in the terminus of the Hadley circulation for a wide range of climate scenarios. Additionally, by comparing simulations with and without ocean heat transport, it is shown that accounting for low-latitude ocean heat transport and its coupling to wind stress is essential to obtain Hadley circulations in a dynamical regime resembling Earth’s. These changes in the strength and extent are found to be captured in a simple one-dimensional model that relies on standard assumptions about the thermodynamic properties of the atmosphere in the low-latitude regions and with a simple representation of eddy fluxes. Further work with this model, which may be amenable to analytical progress, could provide a quantitative understanding for the sensitivity of the Hadley circulation in comprehensive GCM simulations of 21st century global warming scenarios.</p
Letter Written by Mildred M. Hadley to the Bryant College Service Club Dated November 22, 1943
No full text[Transcription begins]
Bryant CollegeService Men’s Dept.Providence, R.I.
This is to notify you of change of address + rating
Harold M. Hadley A.R.T. 3/cN.A.T.T.C., Barracks #3Ward IslandCorpus Christie, Texas
He certainly has appreciated the things you have sent him, and whether or not he has written, I thank you sincerely.
Mildred M. Hadley
540 Weetamoe St.Fall River, Mass.November 22, 1943
[Transcription ends
Letter Written by Mildred M. Hadley to the Bryant College Service Club Dated July 9, 1942
No full text[Transcription begins]
July 9, 1942
Bryant Service Club Bryant College
Dear Students:
You are doing a wonderful work with your Service Club, and I’m sure that the boys appreciate it.
I wish to notify you of the change of address of Harold M. Hadley to: 1102 So. Monroe St., Arlington, Va.
Would it be possible to change his address with the Bryant Alumni Bulletin so that it could be sent there, too. I am forwarding the latest copy to him.
Sincerely,
Mildred M. Hadley (Mrs. Robert C. (Mother)) [Transcription ends
Postcard Written by Harold M. Hadley to the Bryant College Service Club Dated January 3, 1943
No full text[Transcription begins]
Harold M. Hadley, Y3c Navy Department Washington, D. C. Arlington Annex
Bryant Service Club Cr. of Hope St., and Young Orchard Ave., Providence, R. I.
1 – 3 – 43
Dear Friends,
Your cigarettes came through in good condition, and on time.
It sure is swell to hear from the old school. The Alumni Bulletin came just a few days before the Christmas package. I couldn’t help but think of all the good times I had in the happiest two years of my life.
Many things to all the gang that has taken our place.
Sincerely,
Harold M. Hadley [Transcription ends
Letter Written by Harold M. Hadley to the Bryant College Service Club Dated August 22, 1942
No full text[Transcription begins] NAVY DEPARTMENT BUREAU OF NAVIGATION WASHINGTON, D. C.
August 22, 1942
Dear Alums:
Thanks so much for the flat fifties. I am now on duty in Washington, D.C., and my address is as follows:
Harold Miner Hadley, Y3c., USNR Room 3410 Navy Department, Arlington Annex Washington, D. C.
Harold Miner Hadley [Transcription ends
Stephen M. Hadley, 1917-1918
No full textStephen M. Hadley served as acting president for the academic year 1917-1918. Stephen M. Hadley graduated from Penn College in 1884. He returned to Penn College and served in numerous capacities from 1887 to 1930. During that period he took two years off for graduate study
Letter Written by Harold M. Hadley to the Bryant College Service Club Dated June 8, 1942
No full text[Transcription begins]
June 8, 1942 Algiers
Bryant Service Club c/o Bryant College 1 Benevolent Street Providence, R. I.
Gentlemen:
It sure was a great lift to receive a package from the old “alma-mammy.” The happy thoughts that came to my mind of the good times I had and the close friendships made.
There are two people whose address I would like to have: Edmond Avery White ‘40 Roger Pillsbury - U.S.N. Air Corps
The last I knew of “Ed” White’s travels came to me from the Alumni Bulletin. At that time, he was in training in the Army Air Corps.
The barracks we are in now have just been built, consequently the writing tables aren’t in yet. When we get “straightened out” I’ll write another letter about the country.
I can’t tell you how much I appreciate your gift. So I’ll just say, “Thanks.”
Sincerely yours, Harold M. Hadley [Transcription ends
Hadley, L H M, 404704
No full textThis record was harvested from a previous catalogue system and will be withdrawn in 2025. Information in this record may be superseded or incomplete. Visit this record in UMA's new catalogue at: https://archives.library.unimelb.edu.au/nodes/view/389590Surname: HADLEY. Given Name(s) or Initials: L H M. Military Service Number or Last Known Location: 404704. Missing, Wounded and Prisoner of War Enquiry Card Index Number: 49723.213523
Item: [2016.0049.21883] "Hadley, L H M, 404704
Tracking sperm whales using passive acoustics and particle filters
No full textPassive acoustics provides a powerful tool for marine mammal research and mitigation of the risk posed by high energy anthropogenic acoustic activities through monitoring animal positions. Animal vocalisations can be detected and utilised in poor visibility conditions and while animals are dived. Marine mammal research is often conducted on restricted financial budgets by non-government organisations and academic institutions from boats or ships towing hydrophone arrays often comprising only two elements. The arrival time-delay of the acoustic wavefront from the vocalising animals across the array aperture is computed, often using freely available software, and typically regarded as the bearing of the animal to the array. This methodology is limited as it provides no ranging information and, until a boat manoeuvre is performed, whether the animal is to the left or right of the array remains ambiguous. Methods of determining range that have been suggested either negate the fact the animal is moving, rely on robust detection of acoustic reflections, rely on accurate equipment calibration and knowledge of the animal’s orientation or require modification of hydrophone equipment. There is a clear need to develop an improved method of estimating animal position as relative bearing, range and elevation to a hydrophone array or boat based on time-delay measurements. To avoid the costs of upgrading hydrophone arrays, and potentially the size of the vessels required to tow them, a software solution is desirable. This thesis proposes that the source location be modelled as a probability density function and that the source location is estimated as the mean. This is developed into a practical method using particle filters to track sperm whales. Sperm whales are the ideal subject species for this kind of development because the high sound pressure levels of their impulsive vocalisations (up to 236 dB re 1 ?Pa) makes them relatively simple to detect. Simulation tracking results demonstrate particle filters are capable of tracking a manoeuvring target using time-delay measurements. Tracking results for real data are presented and compared to the pseudotrack reconstructed from a tag equipped with accelerometers, magnetometers, a depth sensor and an acoustic recorder placed on the subject animal. For the majority of datasets the animal is tracked to a position relatively close to the surface sighting position. Sperm whales are typically encountered in groups, therefore a viable tracking solution needs to be capable of tracking multiple animals. A multiple hypothesis tracking method is proposed and tested for associating received vocalisations with animals, whereby vocalisations are correctly associated for periods exceeding 15 minute
Role of the seasonally-oscillating Hadley Cell in interhemispheric mixing
No full textDue to the character of the original source materials and the nature of batch digitization, quality control issues may be present in this document. Please report any quality issues you encounter to [email protected], referencing the URI of the item.Includes bibliographical references.Issued also on microfiche from Lange Micrographics.The contribution of the seasonally-oscillating Hadley cell to the interhemispheric mixing of trace chemical species is studied using a zonally-symmetric kinematic model of the Hadley cell flow based upon the first steady-state and first transient modes of a Fouiier fit to the observed tropical wind fields. A two box model is used as a standard of comparison. The chaoticity of the Hadley cell model flow for small perturbations is proven. Numerical experiments are performed for an array of steady state and transient mode amplitudes in order to gain further insight to the chaos/mixing of the flow. Poincar6 sections illustrate the qualitative general mixing behavior. Residence time analysis gives quantitative measures of average parcel behavior for the various cases, while transport experiments give quantitative measures of mixing and transport for the large scale motions. Transfer experiments are performed in all parameter scenarios for cases with and without a northern hemisphere source. Transfer results show remarkable similarity to the two box model solution behavior and a direct fit of box model solutions to Hadley cell transfer results reveals the mixing time-scale. All experiments show that mixing increases when steady-state amplitude decreases and/or transient mode amplitude increases. The case with the observed modal amplitudes is found to be in a region of good mixing in the parameter space. The mixing time-scale for this case is found to be about 4.5 months which is faster than observations. Further research will be necessary to determine the reasons for this seemingly over-efficient mixing. However, results definitely indicate the seasonally-oscillating Hadley cell flow to be a significant contributor to the interhemispheric mixing
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