Showing papers on "Longitude published in 2003"

CO 2 flux history 1982–2001 inferred from atmospheric data using a global inversion of atmospheric transport

Abstract: . Based on about 20 years of NOAA/CMDL's atmospheric CO2 concentration data and a global atmospheric tracer transport model, we estimate interannual variations and spatial patterns of surface CO2 fluxes in the period 01/1982-12/2000, by using a time-dependent Bayesian inversion technique. To increase the reliability of the estimated temporal features, particular care is exerted towards the selection of data records that are homogeneous in time. Fluxes are estimated on a grid-scale resolution (~8o latitude x 10o longitude), constrained by a-priori spatial correlations, and then integrated over different sets of regions. The transport model is driven by interannually varying re-analyzed meteorological fields. We make consistent use of unsmoothed measurements. In agreement with previous studies, land fluxes are estimated to be the main driver of interannual variations in the global CO2 fluxes, with the pace predominantly being set by the El Nino/La Nina contrast. An exception is a 2-3 year period of increased sink of atmospheric carbon after Mt. Pinatubo's volcanic eruption in 1991. The largest differences in fluxes between El Nino and La Nina are found in the tropical land regions, the main share being due to the Amazon basin. The flux variations for the Post-Pinatubo period, the 1997/1998 El Nino, and the 1999 La Nina events are exploited to investigate relations between CO2 fluxes and climate forcing. A rough comparison points to anomalies in precipitation as a prominent climate factor for short-term variability of tropical land fluxes, both through their role on NPP and through promoting fire in case of droughts. Some large flux anomalies seem to be directly related to large biomass burning events recorded by satellite observation. Global ocean carbon uptake shows a trend similar to the one expected if ocean uptake scales proportional to the anthropogenic atmospheric CO2 perturbation. In contrast to temporal variations, the longterm spatial flux distribution can be inferred with lesser robustness only. The tentative pattern estimated by the present inversion exhibits a northern hemisphere land sink on the order of 0.4 PgC/yr (for 01/1996-12/1999, non-fossil fuel carbon only) that is mainly confined to North America. Southern hemisphere land regions are carbon neutral, while the tropical land regions are taking up carbon (e.g., at a rate of 0.8 PgC/yr during 01/1996-12/1999). Ocean fluxes show larger uptake in the Northern mid to high latitudes than in the Southern mid latitude regions, in contrast to the estimates by Takahashi et al. (1999) based on in-situ measurements. On a regional basis, results that differ the most from previous estimates are large carbon uptake of 1 to 1.5 PgC/yr by the Southern temperate Pacific ocean region, weak outgassing from the Southern ocean, and a carbon source from eastern Europe.

Active longitudes in sunspot activity: Century scale persistence

Abstract: A novel analysis of sunspot group data for the past 120 years reveals that sunspots in both northern and southern hemispheres are formed preferably in two persistent active longitudes separated by 180 ◦ . In the Carrington reference frame, the active longitudes continuously migrate in phase with respect to the Carrington meridian with a variable rate. They remain however a quasi-rigid structure. We find that the migration of the active longitudes is determined by changes of the mean latitude of sunspots and the differential rotation. The differential rotation rate calculated from the migration is in agreement with SOHO/MDI measurements. The two active longitude periodically alternate being the dominant region, similar to the "flip-flop" phenomenon known in starspot activity. The period of the oscillations is 3.8 and 3.65 years in the north and south, respectively. The difference between the periods is significant and can be related to the known north-south asymmetry in the solar magnetic activity. Our results provide new observational constraints for current solar dynamo models and strengthen the solar paradigm for magnetic activity on cool stars.

Jupiter's main auroral oval observed with HST-STIS

Abstract: [1] An extended series of FUV images obtained on 7 days during winter 2000–2001, with fixed pointing, yielded highly accurate tracking of emisson features as Jupiter rotated. They provided newly detailed measurements of the degree of corotation of auroral emissions and their variations with changing central meridian longitude. This 2-month data set provides a statistical average location of the auroral emission and leads to the definition of new “reference ovals.” The overall auroral morphology pattern is shown to be fixed in System-III longitude and unchanged over a 5-year period. When arranged in central meridian longitude ranges, the images show a significant contraction of the northern main oval as the central meridian longitude increases from 115 to 255°. The main auroral oval brightness is globally very stable in comparison with its terrestrial counterpart. It is shown to vary with magnetic local time, increasing from noon to dusk and then decreasing again in the magnetic evening. Hectometric emissions observed simultaneously with Galileo and Cassini reveal interplanetary shocks propagating outward from the Sun which may be related to the contraction of the main auroral oval observed in the HST images taken on 14 December 2000. In addition, we find that a brightening and a significant contraction of the main oval observed on 13 January 2001 corresponded to a time of increased solar wind dynamic pressure.

Nonmigrating diurnal tides in the thermosphere

Abstract: [1] Horizontal wind measurements from the HRDI and WINDII instruments on the Upper Atmosphere Research Satellite are analyzed to reveal the most prominent nonmigrating diurnal tidal components at 95 km: the eastward propagating diurnal tide with zonal wave number s = 3 (DE3), the standing (s = 0) diurnal oscillation (D0), and the westward propagating diurnal tide with s = 2 (DW2). The strongest DE3 occurs primarily during Northern Hemisphere summer/fall with maximum eastward winds near the equator of order 15 ms−1 and is a vertical extension of the s = 3 Kelvin wave. The first antisymmetric mode of DE3 dominates during October–April, with maximum meridional winds near the equator of order 8 ms−1. D0 exists during nearly all months and is nonsymmetric about the equator with maximum northward wind amplitudes in the Southern Hemisphere of order 7–10 ms−1. DW2 closely resembles the first symmetric propagating mode from classical tidal theory, with maximum northward wind amplitudes of order 10–12 ms−1 during September through February. The combination of DE3, D0, and DW2 with DW1 gives rise to significant longitude variations in the diurnal tide between ±40° latitude. Forcing in the Global Scale Wave Model (GSWM) is calibrated according to the above observations, thus enabling global estimates of nonmigrating tidal temperatures and other fields. For instance, it is estimated that the temperature and eastward wind perturbations associated with DE3 may be as large as 20K and 35 ms−1 at 145 km and 115 km, respectively, over the equatorial region during July.

Latitudinal, vertical, and seasonal variations of C1‐C4 alkyl nitrates in the troposphere over the Pacific Ocean during PEM‐Tropics A and B: Oceanic and continental sources

Abstract: [1] We present concentration distributions of C1-C4 alkyl nitrates observed during the NASA airborne campaigns Pacific Exploratory Mission (PEM) -Tropics A (September–October 1996) and PEM-Tropics B (March–April 1999). The total geographic range for PEM-Tropics A was 45°N–72°S latitude and 153°E–75°W longitude, and for PEM-Tropics B was 40°N–36°S latitude and 149°E–75°W longitude. The maximum altitude for these missions was 12 km. These experiments provide the most extensive set of tropospheric measurements collected to date over the tropical Pacific Ocean. We observed high methyl nitrate (MeONO2, CH3ONO2) mixing ratios (approximately 50 pptv) at low altitudes in a latitude band between 8°N to 13°S stretching across the equatorial Pacific, illustrating the oceanic source of MeONO2. This source may be associated with the high-nutrient, low-chlorophyll character of equatorial Pacific waters. We discuss MeONO2 and ethyl nitrate (EtONO2, C2H5ONO2), whose abundance is dominated by equatorial oceanic sources, 2-Propyl nitrate (2-PrONO2, 2-C3H7ONO2), which has significant oceanic and northern hemispheric (NH) sources associated with urban/industrial hydrocarbon emissions, and 2-butyl nitrate (2-BuONO2 2-C4H8ONO2), which has mostly NH sources. PEM-Tropics A and B resulted in remarkably similar equatorial mixing ratios. The excellent correlations between MeONO2 and the other alkyl nitrates in this region produced comparable correlation slopes between the two expeditions. By contrast, NH air masses influenced by urban/industrial emissions typically exhibited much lower MeONO2:EtONO2, MeONO2:2-PrONO2, and MeONO2:2-BuONO2 ratios. These relationships can be useful as a diagnostic of air mass origin. North of 10°N, the springtime PEM-Tropics B mixing ratios of C2-C4 alkyl nitrates were many-fold higher at low-mid altitudes than for late summer PEM-Tropics A, consistent with strong continental outflow of NMHC precursors during spring.

Hot Spots for Solar Flares Persisting for Decades: Longitude Distributions of Flares of Cycles 19-23

Abstract: A new analysis method is introduced for investigating whether major flares are clustered in certain fixed regions of the Sun in rigidly rotating coordinate systems. This method is applied to the analysis of major flares of solar cycles 19-23. The northern and southern hemispheres are separately analyzed, and it is found that longitude distributions of flares in the two hemispheres are different. Therefore, the term "hot spot" is used instead of "active longitude." Seven hot-spot systems are found to be significant, with their rotation periods ranging from 25 to 29 days. Four of them are single-hot-spot systems, and the remaining three are double-hot-spot systems. A double-hot-spot system is made of two hot spots that rotate with the same period but are separated by about 180° in longitude. The most significant hot-spot system is the double-hot-spot system with a period of 26.73 days that operated in the northern hemisphere during cycles 20 and 21. It was previously detected by the analysis of flare data of cycles 20 and 21. Now it is found that the prominent hot spot of this system was active during cycle 22. Another double-hot-spot system (with a period of 27.41 days) is found to be in operation in the northern hemisphere during solar cycles 19-21. Another interesting hot-spot system is a single hot spot with a rotation period of 27.0 days, which operated in the northern hemisphere during cycle 21. This hot spot may have the same cause as the 27.03 day periodicity observed in the solar wind speed and interplanetary magnetic field. During cycle 23, a double-hot-spot system with a rotation period of 28.2 days is detected in the southern hemisphere, but none are detected in the northern hemisphere.

Altitude‐extended equatorial spread F observed near sunrise terminator over Indonesia

Abstract: [1] Spatial structure of a post-sunrise backscatter plume associated with a plasma bubble has been observed for the first time with the 47–MHz Equatorial Atmosphere Radar (EAR) in West Sumatra, Indonesia (0.20°S, 100.32°E; dip latitude 10.36°N). This plume is likely associated with a geomagnetic storm. It extended from what appears to be the base of the F layer into the topside ionosphere and differed from all plumes previously observed. It was also extended in longitude (i.e., in the east-west direction), and appeared to involve two spatially separated regions. The plume was first observed around sunrise, close to 200–250 km altitude, but at a time when the E region was not yet sunlit. Spatial maps of the line-of-sight Doppler velocity show that there was upward development and westward drift of backscatter regions, indicative of daytime drift conditions. The observations remain puzzling because the plume continued for approximately two hours after E region sunrise.

Compact text encoding of latitude/longitude coordinates

Abstract: Methods are disclosed for encoding latitude/longitude coordinates within a URL in a relatively compact form. The method includes converting latitude and longitude coordinates from floating-point numbers to non-negative integers. A set of base-N string representations are generated for the integers (N represents the number of characters in an implementation-defined character set being utilized). The latitude string and longitude string are then concatenated to yield a single output string. The output string is utilized as a geographic indicator with a URL.

Freezing height distribution in the tropics

Abstract: The calculation of fade margins required to meet the user-specified availability criteria needs to take into consideration a number of meteorological factors specific to the earth-station location One such factor is the annual average of the freezing level height Information on this height is available in ITU-R Recommendation P 839-3, which provides contours that are generated on a 15° by 15° latitude by longitude resolution grid This paper compares these heights with the bright-band heights (BBH) obtained from the precipitation radar on-board the TRMM (Tropical Rainfall Measuring Mission) satellite Four years of TRMM radar data have been analysed, and their averages are compared within the latitude range covered by the satellite orbit (35°N to 35°S) Comparisons show that the radar bright-band heights typically occur 300 m below the 0°C isotherm heights However, results also indicate that this difference may be latitude dependent Also examined are the year-to-year variability and the seasonal variation In the former case, only 1998 showed BBH values which are somewhat higher in tropical regions, this year having had one of the strongest El Nino events recorded In the latter case, results show significant seasonal variation, becoming more pronounced at higher latitudes Copyright © 2003 John Wiley & Sons, Ltd

Geographic gradients in seed size among and within perennial Australian Glycine species

Abstract: In the Northern Hemisphere, a latitudinal gradient of increasing seed size towards the equator has been well documented. Because of a paucity of studies from the Southern Hemisphere, however, the global generality of this latitudinal gradient in seed size is unknown. This study investigated variation in seed size in relation to latitude among and within perennial Glycine species across Australia. Seed size was estimated from over 1500 provenances covering the latitudinal, longitudinal and altitudinal extents of 37 taxa within the subgenus. In order to ensure that any observed latitudinal gradient in seed size existed independently of two other major geographic variables, longitude and altitude, we controlled for their influence via the use of general linear models. Among species, a significant negative relationship emerged between seed size and latitude when latitude was considered on its own and after accounting for the influence of longitude and altitude in models. For Australian populations of the subgenus Glycine, mean species seed size increased by 4.23% with each shift of one degree of latitude towards the equator and increased significantly along an east–west cline across the continent, by 2.25% with each degree of longitude. This latter relationship was obtained both when longitude was considered on its own and after controlling for the influence of latitude and altitude in models. Patterns of seed size variation with latitude and longitude within species mirrored patterns among species, although there were some notable exceptions. Altitude was significantly related to seed size among species only after removing the linear effects of latitude and longitude, when the trend was for lowland species to have smaller seeds. In contrast to the interspecific pattern, some intraspecific negative trends were found within G. canescens and G. cyrtoloba, which accords with Baker's hypothesis for an inverse relation between seed size and altitude. We discuss the relationships between seed size and the three geographic variables in the subgenus Glycine, with respect to environmental factors that could account for the trends detected.

A study of the equatorial anomaly ionosphere using tomographic images

Abstract: [1] Tomographic techniques are applied to relative total electron content (TEC) data obtained using radio signals transmitted by the polar orbiting Navy Navigation Satellite System (NNSS) and received at a chain of six stations located at approximately 121°E longitude Images reconstructed for each satellite passage provide a picture of electron density over a 25° latitude range and to an altitude of about 1000 km at a longitude of 121°E Over 350 ionospheric images of the northern equatorial anomaly region have been reconstructed for October/November 1994 The daytime equatorial anomaly crest is a prominent feature of the reconstructed images The rms difference between foF2 computed from tomographic images and foF2 measured by two ionosondes is found to be less than 12% Causes for the differences are discussed We show how the crest develops on average days in October and November and discuss the nature of seasonal variations The fully developed anomaly core is aligned approximately along geomagnetic field lines, resulting in the existence of strong and directional gradients in the anomaly region As a consequence, the crest latitude and the maximum vertical TEC (VTEC) latitude are noncoincident The tilt of the anomaly core also causes the slant TEC integrated through the crest to be highly directional In fact, the use of spherical stratification in predicting slant TEC based on the knowledge of the vertical TEC may give an error as large as 30 to 50% in some directions Implications for GPS ranging measurements are discussed

Vertical E × B drift velocity variations and associated low-latitude ionospheric irregularities investigated with the TOPEX and GPS satellite data

Abstract: . With a well-selected data set, the various events of the vertical E × B drift velocity variations at magnetic-equator-latitudes, the resultant ionospheric features at low-and mid-latitudes, and the practical consequences of these E × B events on the equatorial radio signal propagation are demonstrated. On a global scale, the development of a equatorial anomaly is illustrated with a series of 1995 global TOPEX TEC (total electron content) maps. Locally, in the Australian longitude region, some field-aligned TOPEX TEC cross sections are combined with the matching Guam (144.86° E; 13.59° N, geographic) GPS (Global Positioning System) TEC data, covering the northern crest of the equatorial anomaly. Together, the 1998 TOPEX and GPS TEC data are utilized to show the three main events of vertical E × B drift velocity variations: (1) the pre-reversal enhancement, (2) the reversal and (3) the downward maximum. Their effects on the dual-frequency GPS recordings are documented with the raw Guam GPS TEC data and with the filtered Guam GPS dTEC/min or 1-min GPS TEC data after Aarons et al. (1997). During these E × B drift velocity events, the Port Moresby (147.10° E; - 9.40° N, geographic) virtual height or h'F ionosonde data (km), which cover the southern crest of the equatorial anomaly in the Australian longitude region, show the effects of plasma drift on the equatorial ionosphere. With the net ( D ) horizontal (H) magnetic field intensity parameter, introduced and called D H or Hequator-Hnon-equator (nT) by Chandra and Rastogi (1974), the daily E × B drift velocity variations are illustrated at 121° E (geographic) in the Australian longitude region. The results obtained with the various data show very clearly that the development of mid-latitude night-time TEC increases is triggered by the westward electric field as the appearance of such night-time TEC increases coincides with the E × B drift velocity reversal. An explanation is offered with the F-region dynamo theory and electrodynamics, and with the ionospheric-plasmaspheric coupling. A comparison is made with the published model results of SUPIM (Sheffield University Plasmasphere-Ionosphere Model; Balan and Bailey, 1995) and experimental results of Park (1971), and the good agreement found is highlighted. Key words. Ionosphere (electric fields; equatorial ionosphere; mid-latitude ionosphere)

Planetary latitudes in Babylonian mathematical astronomy.

Abstract: La theorie de la latitude planetaire babylonienne a ete etudiee pour determiner la longitude des planetes a un temps donne. L'A. presente cette theorie et demontre comment chaque latitude planetaire est fonction de la longitude

Longitude variability of the solar semidiurnal tide in the lower thermosphere through assimilation of ground- and space-based wind measurements

Abstract: [1] Wind measurements from the Upper Atmosphere Research Satellite (UARS) and model output from the Middle Atmosphere General Circulation Model (GCM) at Kyushu University are used to investigate the nature of nonmigrating semidiurnal tides between 50–55°N using combined space-based (SBM) and ground-based (GBM) wind measurements at 95 km. The GCM is used to create a mock database to test the effects of various sampling scenarios, data gaps, and relative weighting between SBM and GBM, on retrieval of the longitude structure of the semidiurnal tide. SB sampling is based upon orbital characteristics of UARS. GB sampling corresponds to hourly radar measurements from Saskatoon (52°N, 107°W), Sheffield (53°N, 4°W), Collm (52°N, 15°E), Obninsk (55°N, 37°E), and Kazan (56°N, 49°E). Results are presented for the month of August when semidiurnal amplitudes are large and sampling by UARS instruments is good. By compositing over a 5–10 day “fit span,” it is found that the combination of temporal coverage by GB radars and spatial sampling by the satellite is sufficient to allow reasonable recovery of the zonal wave number s = 1, 2, 3 components of the semidiurnal tide. Over significantly longer fit spans, the contributions of GBM become less critical. Using actual UARS and GBM during 1–20 August 1993, the semidiurnal amplitude of eastward wind is found to vary from a minimum value (12 ms−1) at 20°E, to a maximum of 45 ms−1 near 160°E, and a secondary maximum (29 ms−1) at 300°E. The zonal wave number components corresponding to this longitude variation in the semidiurnal tide are 7.7 ± 1.9 ms−1, 19.8 ± 1.5 ms−1 and 13.0 ± 1.3 ms−1 for s = 1, 2, 3 (westward), respectively where ±1−σ uncertainties are indicated. These results are in reasonable agreement with those simulated within the Kyushu GCM. However, there is roughly a four- to five-hour phase offset between the phases recovered from the observational data and from the Kyushu GCM, possibly connected with strong model phase gradients in this atmospheric regime.

Algorithm for Autonomous Longitude and Eccentricity Control for Geostationary Spacecraft

Abstract: To lower satellite orbital maintenance cost, spacecraft designers are seeking flight software that provides more autonomy. Longitude and eccentricity are good candidates for autonomous control of geostationary spacecraft.The algorithm presented couples longitude control with eccentricity control. Longitude drift is modeled as onedegree-of-freedom motion and controlled with a quadratic equation predicting the subspacecraft Earth reference longitude after a predetermined amount of time. After formulation of the basic longitude control algorithm, addition of a differential corrections scheme resulted in an improved longitude error of ′0.015° longitude. Finally, implementation of longitude control and two-part maneuvers for eccentricity control successfully met the desired mission constraints. The algorithms developed form the basis for preparation of flight software for a geostationary spacecraft scheduled to launch in the next few years.

Mobile information terminal with camera

Abstract: PROBLEM TO BE SOLVED: To provide a camera-equipped mobile information terminal that can automatically suppress occurrence of flickers SOLUTION: A CPU control section 7 acquires the latitude/longitude data of the current position of the terminal from a GPS antenna 10 and a GPS control section 9 A memory 7M stores the latitude/longitude data of an arbitrary number of points on a border line obtained from modeling a border line of actual commercial power frequencies by an approximate line in the form of a table The CPU control section 7 references/compares entered latitude data with latitude data in the table, discriminates between which points on the model border line the current point of the terminal exists, discriminates the commercial power frequency of an area where the terminal is in use, through comparison processing between the longitude information of the two points obtained and the entered longitude data and sets the time which is an integral multiple of the period of the frequency, to the storage time of a CMOS imaging element of a camera 1

Portable apparatus and map display system

Abstract: PROBLEM TO BE SOLVED: To enable a user to recognize at what number of stories the user exists in a building when the user exists in the building. SOLUTION: When the user operates a portable telephone 3, the portable telephone 3 detects the latitude, longitude and height of a present position and transmits the latitude and the longitude to a map information provision server 200. When the map information provision server 200 receives the latitude and the longitude from the portable telephone 3, the server retrieves the above sea level data corresponding to the latitude and the longitude from a sea level data database 26b and generates the image of the map around the latitude and the longitude. The map information provision server 200 transmits the above sea level data and the image of the map to the portable telephone 3. The portable telephone 3 computes the number of stories from the detected height, height of story and above sea level data and displays the number of stories together with the image of the map. COPYRIGHT: (C)2005,JPO&NCIPI

Method and device for displaying map

Abstract: PROBLEM TO BE SOLVED: To provide a method and a device for displaying a present position on a map of a map application of a mobile phone or a portable information terminal by obtaining the present position replacing a GPS receiver SOLUTION: In the map display method and device, the longitude and the latitude of a building and a structure are obtained, and recorded in a recording medium such as a bar-code and a wireless IC tag to be stuck on the building and the structure whose longitude and latitude are obtained A map application capable of displaying the present position from the longitude and the latitude is installed in the mobile phone or the portable information terminal, the longitude and the latitude are read from the recording medium stuck on the building or the structure, and the present position is displayed on the map of the map application c1 of the mobile phone or the portable information terminal Thus, calculation for supplementing with a GPS satellite or obtaining the longitude and the latitude is made unnecessary, and the longitude and the latitude can be instantly obtained even at a place such as underground or inside a building where the GPS satellite cannot be seen, and no errors occur in the longitude and the latitude of the present position COPYRIGHT: (C)2005,JPO&NCIPI

Spatial Fluctuation of Forest Fires and Their Response to Global Change

Abstract: Forest fires have circles and frequency in time. This paper utilizes the historical forest fires data (1980-1999) in Heilongjiang province, and calculates the centroids of annual fire points and annual fire scars, the coordinates of centroids are denoted in geographic coordinates. We study the fluctuation of the centroids using spectrum analysis method. Results show: the centroids of forest fires scars fluctuate along the axis of East Longitude 126.97°and North Latitude 49.63°, and the fluctuation has clear circle. The circles along Longitude and latitude are both 3.3a. The extreme values in East, West, South and North are 128.68°E, 52.82°N, 123.08°E, 46.86°N respectively. The centroids of forest fires points fluctuate along the axis of East Longitude 127.90°and North Latitude 48.69°, and the fluctuation has no clear circle. The extreme values in East, West, South and North are 129.22°E,50.37°N,125.18°E,47.28°N respectively.

The apparent longitude distribution of solar flares

Abstract: The distribution of solar flares in solar disk longitude averaged over many solar rotations must be uniform. However, heliographic longitude distributions constructed from observed flare locations are obviously not uniform. In the wavelength ranges we consider (hard and soft X-rays and Halpha), where the emission is presumed to be nearly isotropic, we find a wavelength-dependent bias such that fewer flares than expected occur near the limb. We can explain this bias in terms of the method of locating the flare (from Halpha) and the flare magnitude and duration. This work has implications that are relevant to measuring directivity in emission processes and also the possibility of identifying limb flares by statistical means in catalogues rather than by the time-consuming inspection of images.

An introduction—Latin America

Abstract: Latin America occupies an extremely large portion of the Western Hemisphere and covers six time zones. From north to south, this region extends from Tijuana, Mexico (33° north latitude) to the city of Ushuaia, Argentina (55° south latitude). From west to east, the region extends from Tijuana (120° west longitude) to Recife, Brazil (37° west longitude).