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[1] The retreat of the seasonal polar cap at the Phoenix landing site is analyzed through observations of high resolution images and thermal modeling of the CO2 frost mass. Numerical simulations indicate that the onset of CO2 frost formation occurs around Ls = 220° at 68°N; however, the polar hood prevented imaging of the surface during this time. In the late winter/early spring a continuous layer of frost coated the surface obscuring the underlying polygonal patterns; however, rocks are clearly evident indicating that the frost depth was relatively shallow. Rare dark fans originating from rocks are also observed in an image from early spring. Frost dissipated from the polygon centers first and lingered longer in polygon troughs. Polygon centers were first exposed on Ls = 13.9°, and the polygon troughs were frost free by Ls ∼57°. Frost distributions varied slightly between geologic units; however, in general, global observations at similar latitudes are consistent with what is seen in the Phoenix region. A series of hypotheses is also explored to explain the preference for the CO2 frost to linger in the troughs: lower thermal inertia material in the troughs, aeolian redistribution of frost, burial of the ice table via aeolian redistribution of dust, and shadowing. Each of these hypotheses has drawbacks to explaining this phenomenon as stand-alone components. Shadows do play a role in keeping the CO2 frost on the surface; however, this effect is small and cannot alone account for the observations.

[1] Volcanic rootless constructs (VRCs) are the products of explosive lava-water interactions. VRCs are significant because they imply the presence of active lava and an underlying aqueous phase (e.g., groundwater or ice) at the time of their formation. Combined mapping of VRC locations, age-dating of their host lava surfaces, and thermodynamic modeling of lava-substrate interactions can therefore constrain where and when water has been present in volcanic regions. This information is valuable for identifying fossil hydrothermal systems and determining relationships between climate, near-surface water abundance, and the potential development of habitable niches on Mars. We examined the western Tartarus Colles region (25–27°N, 170–171°E) in northeastern Elysium Planitia, Mars, and identified 167 VRC groups with a total area of ∼2000 km2. These VRCs preferentially occur where lava is ∼60 m thick. Crater size-frequency relationships suggest the VRCs formed during the late to middle Amazonian. Modeling results suggest that at the time of VRC formation, near-surface substrate was partially desiccated, but that the depth to the midlatitude ice table was ≲42 m. This ground ice stability zone is consistent with climate models that predict intermediate obliquity (∼35°) between 75 and 250 Ma, with obliquity excursions descending to ∼25–32°. For lava thicknesses ranging from 30 to 60 m and ground ice fractions ranging from 0.1 to 0.3, an ice volume of ∼4–23 km3 could have been melted and/or vaporized by the time the lava solidified, and the associated hydrothermal systems could have retained temperatures >273 K for up to ∼1300 years.

[1] Ground-based measurements of active layer thickness provide useful data for validating/calibrating remote sensing and modeling results. However, these in situ measurements are usually site-specific with limited spatial coverage. Here we apply interferometric synthetic aperture radar (InSAR) to measure surface deformation over permafrost on the North Slope of Alaska during the 1992–2000 thawing seasons. We find significantly systematic differences in surface deformation between floodplain areas and the tundra-covered areas away from the rivers. Using floodplain areas as the reference for InSAR's relative deformation measurements, we find seasonally varying vertical displacements of 1–4 cm with subsidence occurring during the thawing season and a secular subsidence of 1–4 cm/decade. We hypothesize that the seasonal subsidence is caused by thaw settlement of the active layer and that the secular subsidence is probably due to thawing of ice-rich permafrost near the permafrost table. These mechanisms could explain why in situ measurements on Alaskan North Slope reveal negligible trends in active layer thickness during the 1990s, despite the fact that atmospheric and permafrost temperatures in this region increased during that time. This study demonstrates that surface deformation measurements from InSAR are complementary to more traditional in situ measurements of active layer thickness, and can provide new insights into the dynamics of permafrost systems and changes in permafrost conditions.

[1] Prior to the Phoenix mission, ice stability simulations predicted that surface rocks at the landing site would produce depressions in the ice table (the boundary between dry and ice-cemented soil) if ground ice at the site were in diffusive equilibrium with atmospheric water vapor. We use stereo images and digital elevation models to investigate variations in the depth of the ice table near two decimeter-scale rocks at the Phoenix landing site and compare the observed depth variations to ice stability simulations. We find that ice table depth variations observed near rocks at the landing site are consistent with our theoretical predictions. Based on our results we conclude that: 1) Water transport in the near-surface regolith occurs primarily via vapor diffusion; 2) Environmental conditions in which water transport is dominated by diffusion have been persistent at the landing site for 100s to 1000s of years or longer; that is, ground ice is in diffusive equilibrium with atmospheric water vapor; and 3) In diffusive equilibrium, thermal stability dictates the depth of the ice table on horizontal length scales as small as centimeters.

[1] The size-frequency distributions of rocks >1.5 m diameter fully resolvable in High Resolution Imaging Science Experiment (HiRISE) images of the northern plains follow exponential models developed from lander measurements of smaller rocks and are continuous with rock distributions measured at the landing sites. Dark pixels at the resolution limit of Mars Orbiter Camera thought to be boulders are shown to be mostly dark shadows of clustered smaller rocks in HiRISE images. An automated rock detector algorithm that fits ellipses to shadows and cylinders to the rocks, accurately measured (within 1–2 pixels) rock diameter and height (by comparison to spacecraft of known size) of ∼10 million rocks over >1500 km2 of the northern plains. Rock distributions in these counts parallel models for cumulative fractional area covered by 30–90% rocks in dense rock fields around craters, 10–30% rock coverage in less dense rock fields, and 0–10% rock coverage in background terrain away from craters. Above ∼1.5 m diameter, HiRISE resolves the same population of rocks seen in lander images, and thus size-frequency distributions can be extrapolated along model curves to estimate the number of rocks at smaller diameters. Extrapolating sparse rock distributions in the Phoenix landing ellipse indicate

[1] In the paper ‘‘Vertical and horizontal structure of winter precipitation systems over the western Pacific around Japan using TRMM data’’ by M. K. Yamamoto et al. (Journal of Geophysical Research, 111, D13108, doi:10.1029/ 2005JD006412, 2006), there are several errors. Table 1 is incorrect. The corrected table appears below. [2] Also, the corresponding author’s e-mail address is incorrect. The correct address is mkyamamoto@nagoya-u.jp.

[1] In the paper ‘‘The rocks of Gusev Crater as viewed by the Mini-TES instrument’’ by S. W. Ruff, P. R. Christensen, D. L. Blaney, W. H. Farrand, J. R. Johnson, J. R. Michalski, J. E. Moersch, S. P. Wright, and S. W. Squyres (Journal of Geophysical Research, 111, E12S18, doi:10.1029/2006JE002747, 2006), owing to a publisher error, a value range in Table 2 is incorrect. Under the ‘‘Watchtower Class’’ subheading, the ‘‘Basaltic Glass’’ value range should read ‘‘35–50’’ instead of ‘‘0–15.’’ The corrected Table 2 is given here.

Results are reported on 26 high-resolution (16-51 steps) Ar-40/Ar-39 age spectra obtained on 12 Apollo-15 melt rocks of different composition using a continuous laser system on submg fragments of recrystallized melt and single-crystal plagioclase clasts from impact melt rocks collected at the Apennine Front where the Imbrium and Serenitatis basins intersect. A table is presented with the summary of the Ar-40/Ar-39 spectrum data, which represent 891 individual temperature step analyses. Also presented are 20 of the 26 age spectra along with their respective K/Ca plots. Melt rock fragments and plagioclase clasts from seven of the 12 samples analyzed yielded reproducible, intermediate-T Ar-40/Ar-39 age spectrum plateaus, which were interpreted as crystallization ages that represent the times of impact of bolides onto the lunar surface.

One of the most important achievements during the first two years of the Ocean Drilling Program (ODP) was the concerted effort to conduct major programs of logging and downhole measurements upon revisiting three of the deepest holes drilled into the oceanic crust by the Deep Sea Drilling Project (DSDP). This effort established holes 395A, 418A, and 504B (Table 1) as our best reference sites to “ground truth” the structure and physical properties of the upper oceanic crust. The results of logging and downhole measurements at these and other ODP holes and their relationship to regional geophysical studies were the subject of a poster symposium at the AGU 1988 Fall Meeting, from which this special section developed. Although it was not the intent to restrict this special section to results from holes 395A, 418A, and 504B, all of the papers here deal with at least one of these holes. This emphasizes their importance as reference sites, which arises not only because of the extensive downhole measurements but simply because they are among the four deepest DSDP/ODP penetrations into genuine upper oceanic crust (i.e., crust formed at a mid-ocean ridge; Figure 1). Holes 395A and 418A were drilled in North Atlantic crust formed at a slow spreading rate, and 504B was drilled in eastern Pacific crust formed at a moderate spreading rate. Thus the set of reference sites lacks deep holes in crust formed at fast spreading rates, which is a serious shortcoming that will hopefully be addressed by upcoming ODP drilling in the Pacific Ocean. (The set of deep reference holes has already been complemented by the drilling and logging success in 500 m of tectonically exposed gabbros in hole 735B during leg 118 to the southwest Indian Ocean in 1987 [Robinson et al., 1989]; however, interpretation of the logging results from hole 735B had not progressed enough to be included here and will appear first in the work by Robinson et al. [1990].)

The seismicity of the Indian Ocean is primarily confined to the mid-ocean ridge system and its associated rift valley; however, a broad NW-SE band of 29 epicenters is confirmed in the northeastern Indian Ocean—11 of the 29 earthquakes of magnitude 6 or higher. The location of seismic activity on fractures that cut the ridge is shown by the epicenters along the Owen, Prince Edward, and Amsterdam fracture zones and by the epicenters on the fracture at 41°S, 81°E. The seismic activity of the mid-ocean ridge, as shown by the rate of energy release, has been relatively constant since 1922, except for the years 1942 and 1951 when large earthquakes occurred. A solution of the equation Log N = a + b(8 − M), based on data from 76 earthquakes over a period of thirty years, resulted in the values a = −1.78 and b = 0.91 for the mid-ocean ridge system. A table of frequency of occurrence based on this solution shows the frequency of earthquakes to range from fifty years for a magnitude of 8 to one year for a magnitude of 6–6¼.

A three-year research program at Boston University is described. A field survey was made in Texas, Georgia, Martha's Vineyard, and southern states along the Jackson formation. Sandstone taken from the tektite fields was fused into a glass by means of a solar furnace with an energy expenditure of 1.6×1011 ergs g−1. Although solar furnace glass resembled tektite material in its gross characteristics, there were notable differences in the magnetic domains and in the bubble content. Ablation experiments were carried out using tektite material in a plasma jet. It was found that with a Mach number of 0.47 the flange, so characteristic of flight forms, did not form as a stable structure. The new evidence has been combined with existing data in a logic table to assess the various theories of the origin of tektites. Arguments and interpretations are given on the basis of this table to show that tektites are produced as splashes of fused material from terrestrial craters formed by impact with a meteorite or asteroid.

In a recent paper, Robinson [1963] cites some seismic soundings made on the floating ice of McMurdo Sound by the first (IGY) airlifted United States geophysical team in 1958. A full account of this seismic work is scheduled to appear elsewhere [Cook, 1963]. Minor changes have been made in two of the depths given by me for Robinson's paper (see Table 1). Robinson [1963] enumerates several observations that show the probable absence of an unconsolidated layer such as that indicated by spot reflections at stations 1, 6, 7, and 8 of our profile. It is suggested that long refraction, profiles and the dredging by Tressler in 1960, mentioned by Robinson, may have missed the scattered areas of bottom at which I have postulated sock a layer [Cook, 1963], Tressler has since privately confirmed the presence of local pockets of sediment.

During the passage of R.V. Chain from Bermuda to Helsinki in July 1960, we made four determinations of the flow of heat through the sea bottom, in the fashion devised by Bullard [1954]. We measured the temperature gradient in the bottom sediments with thermometers in a cylindrical probe and found the thermal conductivity of the sediments near each station from a core sample. The results are given in Table 1. The gradients in this table are based on the temperature differences, extrapolated to long times, between two resistance thermometers in the bottom half of a steel probe of 3.2 cm outer diameter. These resistors were spaced 2.2 meters apart, with the lower resistor half a meter above the end of the probe. The higher one penetrated at least 1.8 meters into the sediments at every station, as was shown by the rise in its temperature over that of a resistor at the top of the probe. The ocean water about 100 meters above the bottom was taken to give a standard of zero temperature difference along the probe; this assumption is unlikely to lead to more than a per cent or two of error in the results.

In September 1967, 14 ocean bottom heat flow measurements were attempted in the Tasman Sea from the ESSA Coast and Geodetic Survey ship Oceanographer. Seven of these are considered successful and are presented in Table 1 and Figure 1.

Nineteen new heat-flow measurements in the Caribbean Sea and the western Atlantic and one in the Gulf of Mexico were made during 1962 and 1963 on Lamont expeditions. Five measurements were taken on Vema cruise 1.8, six on Vema cruise 19, and nine on Conrad cruise 7, and the results are given in Table 1. All gradients were measured with the Ewing thermograd. This instrument uses short time constant thermistor probes mounted on outriggers on a piston corer; it is fully described by Gerard et al. [1962] and Langseth et al. [1964].

The heat flow was determined in four deep boreholes drilled while making the basic geological investigations of the basement of the Carpathian foredeep and Flysch zone in South Moravia. The coordinates and the depth of the boreholes together with the value of the heat flow determined are given in Table 1. For this purpose the results of temperature measurements provided by the Czechoslovak Oil Mines, Hodonin, were elaborated; the course of the temperature gradient in the boreholes and the average temperature gradient for the individual lithostratigraphic units were determined (Figure 1). The measuring element used was a temperature-dependent resistor (a thin copper wire), the resistance of which changes linearly with the temperature.

The present paper is concerned with studies related to the capture of aeolian mineral particles in the Sargasso Sea region in late June 1980. Attention is given to measurement techniques, aerosol sampling, particle trap sampling, investigations utilizing scanning electron microscopy, and the obtained results. Conceivable sources for nonbiogenic particles measured in the water column are related to fallout from the Mount St. Helens eruption and soil materials transported by winds from the North American or African continents. It is found that present aerosol transport models are not adequaely addressing the transport of giant particles from the Sahara to the Sargasso Sea. Data regarding the variation of Sargasso Sea aerosol mass concentrations with time are presented in a table.

The diffusion model of degradation of topographic features is a promising means by which vertical offsets on Holocene faults might be dated. In order to calibrate the method, we have examined present-day profiles of wave-cut shoreline scarps of late Pleistocene lakes Bonneville and Lahontan. It may be assumed that these scarps were initially at least as steep as the angle of repose. Offsets range from 1 to 12 m, and present slope angles range from 9° to 29°. A parameter called apparent diffusion age, defined as half the mean square horizontal extent of the slope function of each profile, is plotted as a function of scarp offset. The points show a clear trend of apparent age increasing nearly linearly with offset. If linear diffusion held and scarps were initially vertical, apparent diffusion age would be the same for all the shoreline profiles. The increasing trend can only partly be explained by nonvertical initial scarp slope, and therefore the rate of transport of material downslope must increase significantly faster than a linear law in the range of slopes spanned by the data. The transport law must become linear at small slope to reduce scatter between profiles with varying ambient slopes. The transport law adopted for the purpose of dating is k0(1 + 5s2), where s is local slope. The transport coefficient k0 is correlated inversely with fan slope, suggesting that there is a dependence on the particle size distribution. A table is included that allows easy application of the model to scarps with simple initial shape.

Table 1 contains the results of sea surface-temperature and meteorological observations made on board the Carnegie during her sub-Antarctic cruise,1 December 6, 1915-April 1, 1916, from Lyttelton (New Zealand) to South Georgia and Lyttelton. Reports that have thus far come from this region are few and incomplete, and as the part of the Great Southern Ocean traversed is the scene of such rapid and extreme changes in meteorological conditions, any additional information on the subject may be of interest. The Carnegie made a complete circum-navigation of the globe; from west to east, mainly between the parallels of latitude 50° and 60° south, in one season, the summer of 1915–1916, during which Sir Ernest Shackelton's expedition was meeting with such serious reverses. The meteorological observations made by the two parties of his expedition, and those obtained on the Carnegie, are especially valuable because they are contemporaneous records of the conditions prevailing in different parts of the southern regions at that time.

Table 1 contains the final sunspot-numbers for 1946 for the whole disk of the Sun, based on observations made at the Zurich Observatory, supplemented by series furnished by other cooperating observatories. Table 2 gives the number of spot-groups on each day for the year 1946. The yearly mean of the group-numbers is 7.8. The yearly mean of the relative-numbers is 92.6, against 33.2 in 1945.

The following table contains the records of seismographs in North America and the Hawaiian Islands for the second half of 1904. The times are Greenwich mean civil time beginning at midnight. The following abbreviations are used: P. T. = preliminary tremors; P. P. = principal part, sometimes called long waves. The location of the stations, the type of instrument installed and the components of the motion registered are as follows

The following investigation is based on the hourly readings of the magnetometers (1887–1905) and on the measurements of the Edelmann magnetographs (1906–1919) at the Irkutsk Meteorological and Magnetical observatory. In Table 1 the number of magnetic storms, or of major disturbances, are tabulated according to months and years. In this connection, I have considered all the cases in which at least one of the following conditions for the range, or magnitude of the disturbance, is satisfied:D≧1°;H≧0.0500 C.G.S.;Z≧0.500 C.G.S.

Table 1 contains the final sunspot-numbers for 1940, for the whole disk of the Sun, based on observations made at the Zurich Observatory, supplemented by series furnished by other cooperating observatories for days (indicated by asterisks) on which no observations were possible at Zurich. Table 2 gives the yearly means of the relative numbers, R, since the last minimum 1933 and the number of days without spots.

During the course of another investigation in which large ions were being measured by means of the large ion-counter of the Department of Terrestrial Magnetism [see 1 under “References” at the end of paper] an abnormally high large-ion count was noted during the night of December 3–4, 1941. The sudden rise in count preceded a widespread fog along the North Atlantic Coast, reported as being the worst in the past five years. Comparison of the ion-count record with the record of visibility observed at Boiling Field (Table 1) showed that the concentration of large ions had risen to an unusually large value about seven hours before the fog set in, decreased during the fog, and increased to a large value again after the disappearance of the fog. Another dense fog formed during the next day but, unfortunately, no ion-measurements were made at this time.

Mrs. Mulders, who for many years has been estimating the solar character-figures from K2 and Hα spectroheliograms, is leaving the Observatory this month. She is moving to San Francisco where her husband has accepted a position with the United States Navy. It seems to me that this is a good time to terminate the publication [in Terr. Mag. since 1930] of these character-figures, which have not proved very useful and whose publication at Zurich was terminated some years ago. Since several magnetic observatories estimate the magnetic character-figure and since other more quantitative measures are superseding it, I question the advisability of continuing its publication also. It is probably worth while to continue the table of magnetic storms and the remarks about the solar activity contemporary with them.

In continuation of data on geomagnetic activity at the Cheltenham Magnetic Observatory [see Terr. Mag., 52, 403–409 and 522 (1947)], the K-indices for October to December, 1947, as determined from the photographic records, are given in Table 1.

Midday F2-region critical frequencies as obtained at Deal, New Jersey, are given in Table 1. The values are given in mc/sec and are for the O-component. The period covered by these readings is from June 1938 to April 1939. Most of the readings were obtained near noon and all, except those marked with an asterisk, were obtained between 11h 30m and 13h 30m EST.

This report is a continuation of those already published in this Journal1 and gives monthly mean hourly values of the heights and penetration-frequencies of the ionosphere as obtained by means of automatic multifrequency ionospheric recording apparatus located near Watheroo, Western Australia, in latitude 30° 19′.1 south, longitude 115° 52′.6 east of Greenwich, which operates over the frequency-range 0.516 to 16.0 Mc/sec. Table 1 gives the monthly mean hourly values of the height of maximum electron-density (hmax), unconnected for retardation in lower regions2, and the minimum virtual height (hmin) for both the F1- and F2-regions, the penetration-frequencies for the E-, F1-, and F2-regions, and the lowest frequency at which echoes were observed when that frequency was higher than 0.516 Mc/sec.

The annual review of the “Caractere magnetique de chaque jour” for 1933 has been drawn up in the same manner as for preceding years. Forty-nine observatories contributed to the quarterly tables, forty-eight of them sent complete data. Table II (reproduced as Table 1 below) of the annual review, contains the mean character of each day for each month. The lists of calm days and disturbed days, and the days recommended for reproduction are also reprinted here as Table 2.

I enclose the list of K-indices of geomagnetic activity at Abinger for July to September, 1947, in Table 1. In view of the interest which is now attached to “Sudden-Commencement” phenomena, I append in Table 2 a list of the times at which these characteristic movements have appeared on the Abinger traces during the same period. The time is “Universal Time” (UT = GMT). An asterisk (*) indicates that the movement, though abrupt, was not characteristically “sudden.”

Attention was called by Mr. F. S. Johnson1 to the fact that Figure 2 of the article, ‘Physical properties of the atmosphere from 90 to 300 kilometers,’ published in the September 1956 issue (Vol. 61, No. 3, p. 520) of this JOURNAL, did not agree with the density values given in Table 1. Upon checking the illustrative figure, it was found that by mistake of the authors the wrong figure had been included. The correct Figure 2, consistent with Tables 1 and 2 and with the text, is given below.

The Table on page 478 gives mean K-indices from the reports from 26 observatories and character-figures, C, from 31. The quiet and disturbed days were selected in accordance with the method outlined on pages 219–227 in the December, 1943, issue of this Journal except that the daily indices B are no longer available. The method is a preferential selection based upon the C-numbers, the sums of the eight daily mean K-indices, the greatest daily K-index, and the sums of the squares of the eight daily mean K-indices.

Summaries of American URSI broadcasts have appeared regularly in this JOURNAL since the issue for December, 1930. As set forth in this JOURNAL for June, 1937, “The Department of Terrestrial Magnetism and the United States Coast and Geodetic Survey with the cooperation of the United States Army and the United States Navy communication-services and several amateur radio stations have undertaken to supply the American character-figure based upon the reports of the seven American-operated observatories—those of the Department of Terrestrial Magnetism at Huancayo in Peru and at Watheroo in Western Australia, and those of the United States Coast and Geodetic Survey at Cheltenham (Maryland), Honolulu (Hawaii), San Juan (Puerto Rico), Sitka (Alaska), and Tucson (Arizona).” This character-figure is being designated CA, and its values for the first twelve, the second twelve, and all twenty-four hours of each Greenwich day for July to September, 1942, are given in Table 1.

The particulars of these records of earthquakes noted on the magnetograms of the Watheroo Magnetic Observatory, Western Australia, are given in the following tables. Table 1 shows also the times of the phases obtained on the seismograph at Perth according to the data supplied by Government Astronomer Curlewis.

The Cape Town Magnetic Observatory, which was established for the Polar Year 1932–1933, was unsuitable as a permanent observatory owing to magnetic disturbances caused by the electric railways. The observatory, however, continued in operation until the end of 1940, when a new observatory at Hermanus was ready for work. Table 1 gives the mean yearly values of the magnetic elements at the Magnetic Observatory, Hermanus, for the years 1941 and 1942, and also gives the relation between these and the Cape Town values for the years 1933–1940, which were published in this JOURNAL September 1941, p. 364.

In continuation of data on geomagnetic activity at the Cheltenham Magnetic Observatory [see Terr. Mag., 52, 403–409 and 522 (1947), and 53, 166–167 (1948)] the K-indices for July to September, 1948, as determined from the photographic records, are given in Table 1.

In Nature of June 19, 1926, January 8, and September 3, 1927, I gave some results of the photographic work on the aurora borealis from my stations in southern Norway. The complete results for the period 1911 to 1922 have been published in detail in Geofysiske Publikasjoner. Since 1922 observers at six stations have been making photographic determinations of the height and situation of the aurora. The following table summarizes the collected material from photographs, arranged chronologically, corresponding to the dates when aurora were photographed. Column I gives the number of successful photographs from one station only; column II shows the number of pairs of photographs taken simultaneously from two stations in telephonic communication to determine the height and situation of the aurora; column III shows the number of successful simultaneous photographs taken from three stations, and column IV the number from four stations.

Summaries of American URSI broadcasts have appeared regularly in this Journal since the issue for December, 1930. As set forth in this Journal for June, 1937, “The Department of Terrestrial Magnetism and the United States Coast and Geodetic Survey with the cooperation of the United States Army and the United States Navy communication-services and several amateur radio stations have undertaken to supply the American character-figure based upon the reports of the seven American-operated observatories—those of the Department of Terrestrial Magnetism at Huancayo in Peru and at Watheroo in Western Australia, and those of the United States Coast and Geodetic Survey at Cheltenham (Maryland), Honolulu (Hawaii), San Juan (Puerto Rico), Sitka (Alaska), and Tucson (Arizona).“ This character-figure is being designated CA, and its values for the first twelve, the second twelve, and all twenty-four hours of each Greenwich day for October to December, 1946, are given in Table 1.

Table 1 contains the final sunspot-numbers for 1947 for the whole disk of the Sun, based on observations made at the Zurich Observatory, supplemented by series furnished by other co-operating observatories. Table 2 gives the number of spot-groups on each day for the year 1947. The yearly mean of the group-numbers is 13.4, against 7.8 in 1946. The yearly mean of the relative numbers is 151.6, against 92.6 in 1946.

Herewith (Table 1) are the daily international magnetic character-figures C for 1943, established by Professor J. Bartels and essentially derived from the data of 16 observatories. Professor Bartels also selected as days of magnetic disturbance during 1943 for reproduction the following (hours given are in universal time, that is, GMT)

This report is a continuation of those already published in this JOURNAL and gives monthly mean hourly values of the heights and penetration-frequencies of the ionospheric.regions as obtained from the automatic multifrequency ionospheric recording apparatus located near Huancayo, Peru, South America, in latitude 12° 02′.7 south, longitude 75° 20′.4 west of Greenwich, which operates over a frequency-range 0.516 to 16.0 Mc/sec. A complete discussion of these data will be made in an annual summary. Table 1 gives the monthly mean hourly values of the actual heights of maximum electron-density (hmax), uncorrected for retardation in lower regions2, and the minimum virtual height (hmax) for both the F1- and F2-Vregions, the penetration-frequencies for the E-, F1-, and F2-regions, and the lowest frequency at which echoes were observed when that frequency was greater than 0.516 Mc/sec.

The information contained in this report is similar in character to that supplied for previous months. Table 1, as before, gives the mean hourly values of minimum virtual height and critical frequency of the o wave-component for the ionospheric regions for each hour during October, November, and December 1939, over those periods of the day when these values are scaled. It also includes mean hourly values of the lowest frequency recorded, fmin, when this frequency exceeded the lower limit of the frequency-sweep, namely, 16.0 to 0.516 megacycles per second. Figure 1 gives the data of Table 1 in graphical form.

Table 1 contains for the Pilar Magnetic Observatory, Argentina, the five-minute means of magnetic declination, D, derived from the magnetometer values for every minute from 9h 58m to 16h 32m, Greenwich civil mean time May 29, 1919, and of the corresponding magnetograph values on May 28 and 30, all referred to the mean base-line 7° 35′.92. The bracketted quantities indicate that occasionally one (or more) of the single-minute values of the five, from which the mean was to be taken, was missed. At 14h 49m, G. M. T., May 30, the base-line was displaced +1′.0 by an earthquake, and the corrected base-line of 7° 36′.92 was used accordingly, to reduce the subsequent readings. The geographic coordinates are: latitude, 31° 40′ S.; longitude, 63° 53′ or 4h 15m.5 W. [Besides the magnetic observations complete meteorological data for May 28–30, as also solar-radiation observations for May 28 and 29, were supplied. — Ed.]

The annual review of the “Caractere magnetique de chaque jour,” for 1910 has been drawn up in the same manner as the preceding years. Forty-three observatories contributed to the quarterly reviews; when the tables were prepared, thirty-four of them had sent complete data. One of the observatories communicated its method of classification; one adopted another method in the course of the year. Table II of the annual review, containing the mean character of each day and of each month, and the list of “calm days” is reprinted here.

Summaries of American URSI broadcasts have appeared regularly in this Journal since the issue for December, 1930. As set forth in this Journal for June, 1937, “The Department of Terrestrial Magnetism and the United States Coast and Geodetic Survey with the cooperation of the United States Army and the United States Navy communication-services and several amateur radio stations have undertaken to supply the American character-figure based upon the reports of the seven American-operated observatories—those of the Department of Terrestrial Magnetism at Huancayo in Peru and at Watheroo in Western Australia, and those of the United States Coast and Geodetic Survey at Cheltenham (Maryland), Honolulu (Hawaii), San Juan (Puerto Rico), Sitka (Alaska), and Tucson (Arizona).” This character-figure is being designated CA, and its values for the first twelve, the second twelve, and all twenty-four hours of each Greenwich day for July to September 1946, are given in Table 1.

Table 1 contains the final sunspot-numbers for 1935, for the whole disc of the Sun, based on observations made at the Zurich Observatory, supplemented by series furnished by other cooperating observatories for days (indicated by asterisks) on which no observations were possible at Zurich. Table 2 gives the yearly means of the relative numbers,R, since the last minimum 1933 and the number of days without spots.

The annual review of the “Caractere magnetique de chaque jour” for 1913 has been drawn up in the same manner as the preceding years. Forty-three observatories contributed to the quarterly reviews; 42 of them sent complete data. Table II of the annual review, containing the mean character of each day and of each month, the list of “calm days” and the days recommended for reproduction are reprinted here.

During April and May 1937, R. O. Sandoval of the Magnetic Section of the National Astronomical Observatory of Mexico made observations of the absolute values of the magnetic elements at Oaxaca and Puebla. The results of these observations are shown in Table 1. Mr. Sandoval's instrument was CIW-type magnetometer-inductor No. 107 manufactured by the Precise Instrument Company, and the values shown in the Table are corrected to International Magnetic Standards. At Oaxaca the station is at the airport 2.5 km from the Cathedral, ISO meters northwest of the north end of the hangar and four meters east of road to farm. It is marked by a wooden peg. True azimuths from south through west are: Cross, Merced Church, 34° 11′.2; cross Santo Domingo Church, 52° 18′3.

Table 1 contains the final sunspot-numbers for 1938, for the whole disk of the Sun, based on observations made at the Zurich Observatory, supplemented by series furnished by other cooperating observatories for days (indicated by asterisks) on which no observations were possible at Zurich. Table 2 gives the yearly means of the relative numbers, R, since the last minimum 1933 and the number of days without spots.