A Distribution Law for Free-Tropospheric Relative Humidity

2006 ◽  
Vol 19 (24) ◽  
pp. 6267-6277 ◽  
Author(s):  
Steven C. Sherwood ◽  
E. Robert Kursinski ◽  
William G. Read
Keyword(s):  
Relative Humidity ◽  
Global Positioning System ◽  
Large Scale ◽  
Cloud Microphysics ◽  
Convective System ◽  
Distribution Law ◽  
Vertical Variation ◽  
Global Positioning ◽  
Condensation Model ◽  
The Tropics

Abstract The probability distribution of local relative humidity ℛ in the free troposphere is explored by comparing a simple theoretical calculation with observations from the global positioning system (GPS) and the Microwave Limb Sounder (MLS). The calculation is based on a parcel of air that conserves its composition during diabatic subsidence, until it is resaturated by randomly entering a convective system. This simple “advection–condensation” model of relative humidity predicts a probability density for ℛ proportional to ℛr−1, where r is the ratio of time scales associated with subsidence drying and random moistening. The observations obey this distribution remarkably well from 600 to 200 hPa in the Tropics and midlatitudes; possible reasons for this are discussed. The lowest values of ℛ are predicted, and observed, to be the most probable. The observed vertical variation of ℛ is well explained by that of the subsidence time scale, which is set by large-scale dynamics and radiation. These results imply that cloud microphysics exerts little control on water vapor’s greenhouse effect, but that relatively subtle dynamical changes have the potential to alter the strength of its feedback on climate change.

scholarly journals Response of Upper Clouds in Global Warming Experiments Obtained Using a Global Nonhydrostatic Model with Explicit Cloud Processes

2012 ◽  
Vol 25 (6) ◽  
pp. 2178-2191 ◽  
Author(s):  
Masaki Satoh ◽  
Shin-ichi Iga ◽  
Hirofumi Tomita ◽  
Yoko Tsushima ◽  
Akira T. Noda
Keyword(s):  
Global Warming ◽  
Mass Flux ◽  
Cloud Cover ◽  
Large Scale ◽  
Cloud Microphysics ◽  
Microphysics Scheme ◽  
Nonhydrostatic Model ◽  
The Tropics ◽  
Ice Water ◽  
Convective Mass Flux

Abstract Using a global nonhydrostatic model with explicit cloud processes, upper-cloud changes are investigated by comparing the present climate condition under the perpetual July setting and the global warming condition, in which the sea surface temperature (SST) is raised by 2°. The sensitivity of the upper-cloud cover and the ice water path (IWP) are investigated through a set of experiments. The responses of convective mass flux and convective areas are also examined, together with those of the large-scale subsidence and relative humidity in the subtropics. The responses of the IWP and the upper-cloud cover are found to be opposite; that is, as the SST increases, the IWP averaged over the tropics decreases, whereas the upper-cloud cover in the tropics increases. To clarify the IWP response, a simple conceptual model is constructed. The model consists of three columns of deep convective core, anvil, and environmental subsidence regions. The vertical profiles of hydrometers are predicted with cloud microphysics processes and kinematically prescribed circulation. The reduction in convective mass flux is found to be a primary factor in the decrease of the IWP under the global warming condition. Even when a different and more comprehensive cloud microphysics scheme is used, the reduction in the IWP due to the mass flux change is also confirmed.

Ground-Based Videometric Method and System for the Real-Time Measurement of Aircraft Landing Track

2014 ◽  
Vol 635-637 ◽  
pp. 824-831 ◽  
Author(s):  
Xiang Zhou ◽  
Zhi Hui Lei ◽  
Dan Fu ◽  
Xiao Hu Zhang
Keyword(s):  
Real Time ◽  
Global Positioning System ◽  
Large Scale ◽  
Time Measurement ◽  
Landing Point ◽  
The Real ◽  
Aircraft Landing ◽  
Real Time Measurement ◽  
Global Positioning ◽  
New Type

This paper proposes a ground-based videometric method and system for measuring the glide track of landing aircraft in real time. The proposed method is applicable for large-scale measurement via regional relays with multiple cameras. Its measurement ranges from kilometers away to the landing point, and it simultaneously fulfills the real-time measurement of the position and trajectory of aircraft. The real-time measurement result of the actual aircraft landing process shows a deviation from DGPS(Difference Global Positioning System) as small as 20 cm in the measuring region of 1 km. The proposed measurement method for aircraft landing track based on videometrics can establish a new type of landing aid system removed from radar and GPS.

scholarly journals UAV ONBOARD GPS IN POSITIONING DETERMINATION

2016 ◽  
Vol XLI-B1 ◽  
pp. 1037-1042
Author(s):  
K. N. Tahar ◽  
S. S. Kamarudin
Keyword(s):  
Coordinate System ◽  
Global Positioning System ◽  
Large Scale ◽  
Control Point ◽  
Critical Issue ◽  
Ground Control ◽  
Positioning System ◽  
Ground Control Points ◽  
Global Positioning ◽  
Point Positioning

The establishment of ground control points is a critical issue in mapping field, especially for large scale mapping. The fast and rapid technique for ground control point’s establishment is very important for small budget projects. UAV onboard GPS has the ability to determine the point positioning. The objective of this research is to assess the accuracy of unmanned aerial vehicle onboard global positioning system in positioning determination. Therefore, this research used UAV onboard GPS as an alternative to determine the point positioning at the selected area. UAV is one of the powerful tools for data acquisition and it is used in many applications all over the world. This research concentrates on the error contributed from the UAV onboard GPS during observation. There are several points that have been used to study the pattern of positioning error. All errors were analyzed in world geodetic system 84- coordinate system, which is the basic coordinate system used by the global positioning system. Based on this research, the result of UAV onboard GPS positioning could be used in ground control point establishment with the specific error. In conclusion, accurate GCP establishment could be achieved using UAV onboard GPS by applying a specific correction based on this research.

Evaluation of a soft-copy photogrammetry system for tree-plot measurements

1993 ◽  
Vol 23 (9) ◽  
pp. 1781-1785 ◽  
Author(s):  
P.A. Gagnon ◽  
J.P. Agnard ◽  
C. Nolette
Keyword(s):  
Global Positioning System ◽  
Large Scale ◽  
Tree Height ◽  
Aerial Photographs ◽  
Positioning System ◽  
Crown Diameter ◽  
Forest Inventories ◽  
Global Positioning ◽  
Soft Copy

This article describes and evaluates the application of a soft-copy photogrammetry system to large-scale forest inventories. A specially designed software, developed by the authors, has been investigated in terms of accuracy and general operability. Tests based on 1:1100 color aerial photographs, taken with a 10-m cross-boom system and digitized at resolutions of 300, 450, and 600 dots per inch, confirmed the expected tree-height accuracies of 48, 32, and 24 cm, respectively. This indicates that a photographic scale of 1:800 and a scanning resolution of 800 dots per inch could produce a tree-height precision of the order of 10 cm. The tests have shown that model orientation takes about 15 min; for a tree plot of 24 trees, measurements (height and crown diameter) and observations (species and condition) also take about 15 min. As the important problem of positioning a helicopter over a tree plot has now been solved using global positioning system receivers, the results and information presented in this paper indicate that the existing technology can provide a rigorous and operational photogrammetric system for large-scale forest inventories and regeneration monitoring.

An Off-Site Approach to Late Iron Age and Roman Landscapes on the Northern Plateau, Spain

2013 ◽  
Vol 16 (2) ◽  
pp. 289-313 ◽  
Author(s):  
Jesús García-Sánchez ◽  
Miguel Cisneros
Keyword(s):  
Iron Age ◽  
Global Positioning System ◽  
Large Scale ◽  
Survey Methodology ◽  
Field Survey ◽  
Positioning System ◽  
Late Iron Age ◽  
Castilla Y Leon ◽  
Global Positioning ◽  
New Settlements

Since 2009, a large-scale archaeological field survey – the Ager Segisamonensis Survey Project – has been carried out on the Northern Plateau of the Iberian Peninsula, in the Burgos province (Castilla y León), Spain. The aim of this project is to understand the Iron Age/Roman transition in terms of settlement strategies and landscape exploitation. The field survey has been undertaken in the landscape surrounding an Iron Age settlement and the successive Roman city of Segisamo – modern Sasamón. The goal is not the discovery of new settlements, but the recognition of the so-called ‘dwelling landscape’ and its evolution. In this article, we highlight our field survey methodology based on hand-held Global Positioning System (GPS) instruments and the creation of a recording system of ‘aggregation units'.

scholarly journals Shearwaters know the direction and distance home but fail to encode intervening obstacles after free-ranging foraging trips

2019 ◽  
Vol 116 (43) ◽  
pp. 21629-21633 ◽  
Author(s):  
Oliver Padget ◽  
Geoff Stanley ◽  
Jay K. Willis ◽  
Annette L. Fayet ◽  
Sarah Bond ◽  
...  
Keyword(s):  
Global Positioning System ◽  
Large Scale ◽  
Positioning System ◽  
Global Positioning ◽  
Displacement Experiments ◽  
Integration Mechanisms ◽  
Gps Tracks ◽  
Free Ranging ◽  
Manx Shearwater ◽  
Pelagic Seabird

While displacement experiments have been powerful for determining the sensory basis of homing navigation in birds, they have left unresolved important cognitive aspects of navigation such as what birds know about their location relative to home and the anticipated route. Here, we analyze the free-ranging Global Positioning System (GPS) tracks of a large sample (n = 707) of Manx shearwater, Puffinus puffinus, foraging trips to investigate, from a cognitive perspective, what a wild, pelagic seabird knows as it begins to home naturally. By exploiting a kind of natural experimental contrast (journeys with or without intervening obstacles) we first show that, at the start of homing, sometimes hundreds of kilometers from the colony, shearwaters are well oriented in the homeward direction, but often fail to encode intervening barriers over which they will not fly (islands or peninsulas), constrained to flying farther as a result. Second, shearwaters time their homing journeys, leaving earlier in the day when they have farther to go, and this ability to judge distance home also apparently ignores intervening obstacles. Thus, at the start of homing, shearwaters appear to be making navigational decisions using both geographic direction and distance to the goal. Since we find no decrease in orientation accuracy with trip length, duration, or tortuosity, path integration mechanisms cannot account for these findings. Instead, our results imply that a navigational mechanism used to direct natural large-scale movements in wild pelagic seabirds has map-like properties and is probably based on large-scale gradients.

scholarly journals Prospects of GIS-Passportization of Natural Plague Foci in the Territory of the Russian Federation

2012 ◽  
pp. 48-53
Author(s):  
A. A. Kuznetsov ◽  
A. M. Porshakov ◽  
A. N. Matrosov ◽  
E. V. Kuklev ◽  
V. B. Korotkov ◽  
...  
Keyword(s):  
Global Positioning System ◽  
Large Scale ◽  
Spatial Differentiation ◽  
Topographic Maps ◽  
Positioning System ◽  
Gis Technologies ◽  
Global Positioning ◽  
The Russian Federation ◽  
Methodological Approaches ◽  
High Degree

Characterized in brief are the results of natural plague foci passportization carried out in the late XX century. Evaluation of the principle of formalized spatial differentiation between enzootic territories is made. The principle can guarantee high degree of data ordering, obtained in the process of epizootiological surveillance. Therefore, prospects of a new stage of plague foci passportization based on GIS-technologies are viewed, the strategy is determined, and methodological approaches for its realization are put forward. Large-scale implementation of digital topographic maps and global positioning system into the work of plague control organizations is accentuated.

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