The Tercentenary of The Royal Observatory at Greenwich

Sadler, D. H.

doi:10.1017/s0373463300037668

Cited by 3 publications

(9 citation statements)

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“…However, the main feature is the decrease of the southerly flux within 6" of latitude, indicating convergence of moisture flux. The large value of precipitation in box 3 fits well with the climatological position of the line of maximum cloudiness for May (Sadler 1975). In the continental boxes the meridional flux is from the north and decreases as the air moves south towards the zone of convergence.…”

Section: (A) Water Vapour Budgetssupporting

confidence: 68%

Water Vapour Transport Over Africa and the Atlantic Ocean During Summer 1979

Cadet¹,

Nnoli²

1987

Quart J Royal Meteoro Soc

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The water vapour transport over Africa and the eastern Atlantic Ocean during the 1979 summer is studied. The analysis is based on wind fields from the European Centre for Medium Range Weather Forecasts and humidity fields derived from a three-layer precipitable water data set.The evolution of the bi-weekly mean fields of water vapour flux in the surface to 850mb layer shows the progressive penetration of moisture over West Africa during the summer. At low levels during the maximum activity of the African monsoon, the southerly flow penetrates up to 20"N and there is a large belt of westerlies around 10"N. The fluxes between 700 and 500mb suggest the importance of the African easterly jet (AEJ) as a major artery for moisture for West Africa.Vertically integrated fluxes across different sections have been analysed. Across the equator at the longitudes of the Gulf of Guinea the flux shows a decreasing trend due to the northward propagation of the intertropical discontinuity over west Africa. Near 22"N, the flux is mainly from the north at the beginning of the summer and becomes southerly during surges of the monsoon. The flux from West Africa toward the Atlantic Ocean is large, indicating that moisture from the Gulf is transported upward and advected westward by the AEJ. The fluxes oscillate with two main periods, around 3-5 days and 5-7 days.Water vapour budgets have been estimated for boxes located over the Gulf of Guinea and West Africa.The Gulf of Guinea is a source of water vapour transported northward and westward by the trade winds. OverWest Africa at low levels, moisture comes from the Gulf of Guinea. In the mid-troposphere there is a strong easterly moisture flux associated with the AEJ and originating from central Africa. This moisture seems to come initially from the Gulf of Guinea. Because it is mainly divergent, the mid-tropospheric flux may have little influence on rainfall over West Africa. The budget study also emphasizes the importance of evapotranspiration over the belt north of the Gulf of Guinea where water vapour is recycled and transported northward.

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Section: (A) Water Vapour Budgetssupporting

confidence: 68%

Water Vapour Transport Over Africa and the Atlantic Ocean During Summer 1979

Cadet¹,

Nnoli²

1987

Quart J Royal Meteoro Soc

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“…The supernova remnants (SNR) in the Large Magellanic Cloud (LMC), which have recently been discussed by Mathewson and Clarke (1973), Danziger and Dennefeld (1976ö), and Lasker (1976), are obvious candidates for more detailed observations by direct imaging because they lie in relatively uncluttered and unobscured areas at a known and common distance. Accordingly, in 1975 we began a photographic survey for the purpose of comparing the nebular structure in a high-excitation line with that in a low-excitation one.…”

mentioning

confidence: 99%

“…Previous experience with SNRs in the LMC (Lasker 1976) showed that the appearances in Ha + [N n] and in [S n] ÂÀ6716, 6731 are quite similar, and the [S n] was chosen over the Ha because it is less influenced by confusion from nearby (radiatively energized) nebulae and because it is more easily excited. (Also, instrumental limitations precluded our separating Ha and [N ii] ÂÀ6548, 6583.)…”

mentioning

confidence: 99%

Supernova remnants in the Large Magellanic Cloud - A photographic study in /O III/ and /S II/

Lasker

1977

PASP

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For three supernova remnants in the Large Magellanic Cloud, N86, N186D, and N206, monochromatic plates are used to compare the structure in a line of high excitation, [O III] \5007, with that in lines of low excitation, [S n] M6716, 6731. The images in [O ill] as compared to [S n] tend to be concentrated toward the periphery of the remnants (N86, N186D, and N206), to be sharper (N86, N186D), to lie outside the peak of the [S n] emission (N206), and perhaps to have less prominent filamentary structure (N86).Explanations are suggested in terms of the structures of the regions associated with the shock waves.

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“…2 The development a century later of the chronometer by John Harrisonp rovided the first portable gauge for use by the mariner and enabled a complete scientific basis to be established for navigation at. sea.…”

mentioning

confidence: 99%

“…The establishment in 167^ of the Royal Greenwich Observatory was the direct consequence of the need to provide such a laboratory gauge. 2 The development a century later of the chronometer by John Harrisonp rovided the first portable gauge for use by the mariner and enabled a complete scientific basis to be established for navigation at. sea.…”

mentioning

confidence: 99%

The Role of Time in Navigation

Stratton¹

1976

J. Navigation

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Time is so much a part of everyday experience that no thought is normally given to the meaning of the word. The scientific measurement of a quantity such as time, however, requires the definition of a gauge as a standard of measurement that is reasonably invariant to human experience and the creation of a measurement language capable of independent empirical reproduction so that one laboratory can share experience with another using only a written language to do so.Time as a means of scientific measurement for navigation requires a further extension of this experience to independent reproduction on a moving craft.

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The Tercentenary of The Royal Observatory at Greenwich

Cited by 3 publications

References 0 publications

Water Vapour Transport Over Africa and the Atlantic Ocean During Summer 1979

Water Vapour Transport Over Africa and the Atlantic Ocean During Summer 1979

Supernova remnants in the Large Magellanic Cloud - A photographic study in /O III/ and /S II/

The Role of Time in Navigation

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