This paper treats the problem of how to transform from global datum, for example, from the International Terrestrial Reference System (ITRS), to a local datum, for example, regional or national, for the practical case of the Lambert projection of the sphere or the ellipsoid-of-revolution to the cone. We design the two projection constants n(ϕ1, ϕ2) and m(ϕ1) for the Universal Lambert Conic projection of the ellipsoid-of-revolution. The task to transform from a global datum with respect to the ellipsoid-of-revolution EA,B2 to local datum with respect to the alternative ellipsoid-of-revolution Ea,b2, without local ellipsoidal height, is solved by an extended numerical example. Ideas in this paper could be of interest to those working with maps and coordinates transformation from global geodetic datum to local geodetic datum and vice versa, under the Universal Lambert Conic projection, and applicable to precise positioning and navigation, boundary demarcation and determination in the marine environment. 相似文献
A repeat hydrographic section has been maintained over two decades along the 180° meridian across the subarctic-subtropical
transition region. The section is naturally divided into at least three distinct zones. In the Subarctic Zone north of 46°N,
the permanent halocline dominates the density stratification, supporting a subsurface temperature minimum (STM). The Subarctic
Frontal Zone (SFZ) between 42°–46°N is the region where the subarctic halocline outcrops. To the south is the Subtropical
Zone, where the permanent thermocline dominates the density stratification, containing a pycnostad of North Pacific Central
Mode Water (CMW). The STM water colder than 4°C in the Subarctic Zone is originated in the winter mixed layer of the Bering
Sea. The temporal variation of its core temperature lags 12–16 months behind the variations of both the winter sea surface
temperature (SST) and the summer STM temperature in the Bering Sea, suggesting that the thermal anomalies imposed on the STM
water by wintertime air-sea interaction in the Bering Sea spread over the western subarctic gyre, reaching the 180° meridian
within a year or so. The CMW in this section originates in the winter mixed layer near the northern edge of the Subtropical
Zone between 160°E and 180°. The CMW properties changed abruptly from 1988 to 1989; its temperature and salinity increased
and its potential density decreased. It is argued that these changes were caused by the climate regime shift in 1988/1989
characterized by weakening of the Aleutian Low and the westerlies and increase in the SST in the subarctic-subtropical transition
region.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
Identification of the distinctive circulation patterns of storminess on the Atlantic margin of Europe forms the main objective of this study; dealing with storm frequency, intensity and tracking. The climatology of the extratropical cyclones that affect this region has been examined for the period 1940–1998. Coastal meteorological data from Ireland to Spain have been linked to the cyclone history for the North Atlantic in the analysis of storm records for European coasts. The study examines the evolution in the occurrence of storms since the 1940s and also their relationship with the North Atlantic Oscillation (NAO). Results indicate a seasonal shift in the wind climate, with regionally more severe winters and calmer summers established. This pattern appears to be linked to a northward displacement in the main North Atlantic cyclone track.
An experiment with the ECHAM4 A-GCM at high resolution (T106) has also been used to model the effect of a greenhouse gases induced warming climate on the climatology of coastal storms in the region. The experiment consists of (1), a 30-year control time-slice representing present-day equivalent CO2 concentrations and (2), a 30-year perturbed period corresponding to a time when the radiative forcing has doubled in terms of equivalent CO2 concentrations. The boundary conditions have been obtained from an atmosphere-ocean coupled OA-GCM simulation at low horizontal resolution. An algorithm was developed to allow the identification of individual cyclone movements in selected coastal zones. For most of the northern part of the study region, covering Ireland and Scotland, results describe the establishment by ca. 2060 of a tendency for fewer but more intense storms.
The impacts of these changes in storminess for the vulnerability of European Atlantic coasts are considered. For low-lying, exposed and ‘soft’ sedimentary coasts, as in Ireland, these changes in storminess are likely to result in significant localised increases in coastal erosion. 相似文献