Consequences of change and variability in sea ice on marine ecosystem and biogeochemical processes during the 2007–2008 Canadian International Polar Year program

Change and variability in the timing and magnitude of sea ice geophysical and thermodynamic state have consequences on many aspects of the arctic marine system. The changes in both the geophysical and thermodynamic state, and in particular the timing of the development of these states, have consequences throughout the marine system. In this paper we review the ??consequences?? of change in sea ice state on primary productivity, marine mammal habitats, and sea ice as a medium for storage and transport of contaminants and carbon exchange across the ocean-sea-ice-atmosphere interface based upon results from the International Polar Year. Pertinent results include: 1) conditions along ice edges can bring deep nutrient-rich ??pacific?? waters into nutrient-poor surface waters along the arctic coast, affecting local food webs; 2) both sea ice thermodynamic and dynamic processes ultimately affect ringed seal/polar bear habitats by controlling the timing, location and amount of surface deformation required for ringed seal and polar bear preferred habitat 3) the ice edges bordering open waters of flaw leads are areas of high biological production and are observed to be important beluga habitat. 4) exchange of climate-active gases, including CO₂, is extremely active in sea ice environments, and the overall question of whether the Arctic Ocean is (or will be) a source or sink for CO₂ will be dependent on the balance of competing climate-change feedbacks.     

The policy relevance of global environmental change research

Many scientists are striving to identify and promote the policy implications of their global change research. Much basic research on global environmental change cannot advance policy directly, but new projects can determine the relevance of their research to decision makers and build policy-relevant products into the work. Similarly, many ongoing projects can alter or add to the present science design to make the research policy relevant. Thus, this paper shows scientists working on global change how to make their research policy relevant. It demonstrates how research on physical global change relates to human dimensions studies and integrated assessments. It also presents an example of how policy relevance can be fit retroactively into a global change project (in this case, SRBEX—the Susquehanna River Basin Experiment) and how that addition can enhance the project's status and science. The paper concludes that policy relevance is desirable from social and scientific perspectives.     

URBAN CHANGE,CIRCUITS OF CAPITAL,AND UNEVEN DEVELOPMENT*

The circuits of capital/uneven development model is widely used in geography, urban planning, and the social sciences. Its principal weakness is its marginalizing of local influences in explaining the intensity and patterning of metropolitan investment. A deeper consideration of local culture, politics, and biographies is needed to sensitize the model to the particularities of place. Local creative actors set in motion place-specific forms of change whose logic is tied to structured circumstances.     

The reversal of the solar polar magnetic fields

Observations of the first major active regions and large-scale magnetic field patterns of Cycle 22 are presented. These show that, following the emergence of a trans-equatorial pattern, or cell, of positive flux related to old cycle activity, the first new cycle active regions of the longitude range emerged across the neutral lines of this cell, which continued to grow and expand across the equator for several rotations. The development of a parallel trans-equatorial band of flux of opposite (negative) polarity and the emergence of both new and old cycle active regions across a neutral line of this cell are also described.Simulations using the flux transport equation, and based on synoptic magnetic data provided by the Mount Wilson Observatory, show that, while the growth of the positive region could, in part, be explained by the decay of flux from these new regions, there were significant differences between synoptic contour charts based on the simulations and those constructed from the observed fields. They also show that the development of the negative region cannot reasonably be explained by the decay of the observed active regions.A further example of the counter rotation of decaying active region fields is reported. Here the initial tilt of the negative-positive magnetic axes of two adjacent regions is normal, and simulations based on these data show their combined follower flux moving preferentially polewards. However, the observations show that, after three rotations, the decaying leader flux is entirely poleward of the follower flux.On leave from the School of Mathematics, University of Sydney.     

Moment method for multiple scattering of solar Lα radiation in the nearby interstellar medium

The problem of solar L (1216 Å) photons scattered coherently by interplanetary medium is solved for a realistic density distribution using a simple three-stream division of the radiation field.     

On the average rate of growth in sunspot number and the size of the sunspot cycle

The average rate of growth during the ascending portion of the sunspot cycle, defined here as the difference in smoothed sunspot number values between elapsed time (in months) t and sunspot minimum divided by t, is shown to correlate (r 0.78) with the size of the sunspot cycle, especially for t 18 months. Also, the maximum value of the average rate of growth is shown to highly correlate (r = 0.98) with the size of the cycle. Based on the first 18 months of the cycle, cycle 22 is projected to have an R(M) = 186.0 ± 27.2 (at the ± 1 level), and based on the first 24 months of the cycle, it is projected to have an R(M) = 201.0 ± 20.1 (at the ± 1 level). Presently, the average rate of growth is continuing to rise, having a value of about 4.5 at 24 months into the cycle, a value second only to that of cycle 19 (4.8 at t = 24 and a maximum value of 5.26 at t = 27). Using 4.5 as the maximum value of the average rate of growth for cycle 22, a lower limit can be estimated for R(M); namely R(M) for cycle 22 is estimated to be 164.0 (at the 97.5% level of confidence). Thus, these findings are consistent with the previous single variate predictions that project R(M) for cycle 22 to be one of the greatest on record, probably larger than cycle 21 (164.5) and near that of cycle 19 (201.3).     

On the level of skill in predicting maximum sunspot number: A comparative study of single variate and bivariate precursor techniques

Precursor prediction techniques have generally performed well in predicting the maximum amplitude of sunspot cycles, based on cycles 10–21. Single variate methods based on minimum sunspot amplitude have reliably predicted the size of the sunspot cycle 9 out of 12 times, where a reliable prediction is defined as one having an observed maximum amplitude within the prediction interval (determined from the average error). On the other hand, single variate methods based on the size of the geomagnetic minimum have reliably predicted the size of the sunspot cycle 8 of 10 times (geomagnetic data are only available since about cycle 12). Bivariate prediction methods have, thus far, performed flawlessly, giving reliable predictions 10 out of 10 times (bivariate methods are based on sunspot and geomagnetic data). For cycle 22, single variate methods (based on geomagnetic data) suggest a maximum amplitude of about 170 ± 25, while bivariate methods suggest a maximum amplitude of about 140 ± 15; thus, both techniques suggest that cycle 22 will be of smaller maximum amplitude than that observed during cycle 19, and possibly even smaller than that observed for cycle 21. Compared to the mean cycle, cycle 22 is presently behaving as if it is a + 2.6 cycle (maximum amplitude about 225). It appears then that either cycle 22 will be the first cycle not to be reliably predicted by the combined precursor techniques (i.e., cycle 22 is an anomaly, a statistical outlier) or the deviation of cycle 22 relative to the mean cycle will substantially decrease over the next 18 months. Because cycle 22 is a large amplitude cycle, maximum smoothed sunspot number is expected to occur early in 1990 (between December 1989 and May 1990).     

On the maximum rate of change in sunspot number growth and the size of the sunspot cycle

Statistically significant correlations exist between the size (maximum amplitude) of the sunspot cycle and, especially, the maximum value of the rate of rise during the ascending portion of the sunspot cycle, where the rate of rise is computed either as the difference in the month-to-month smoothed sunspot number values or as the average rate of growth in smoothed sunspot number from sunspot minimum. Based on the observed values of these quantities (equal to 10.6 and 4.63, respectively) as of early 1989, one infers that cycle 22's maximum amplitude will be about 175 ± 30 or 185 ± 10, respectively, where the error bars represent approximately twice the average error found during cycles 10–21 from the two fits.     

Bimodality and the Hale cycle

Because of the bimodal distribution of sunspot cycle periods, the Hale cycle (or double sunspot cycle) should show evidence of modulation between 20 and 24 yr, with the Hale cycle having an average length of about 22 yr. Indeed, such a modulation is observed. Comparison of consecutive pairs of cycles strongly suggests that even-numbered cycles are preferentially paired with odd-numbered following cycles. Systematic variations are hinted in both the Hale cycle period and R _sum (the sum of monthly mean sunspot numbers over consecutively paired sunspot cycles). The preferred even-odd cycle pairing suggests that cycles 22 and 23 form a new Hale cycle pair (Hale cycle 12), that cycle 23 will be larger than cycle 22 (in terms of R _M, the maximum smoothed sunspot number, and of the individual cycle value of R _sum), and that the length of Hale cycle 12 will be longer than 22 yr. Because of the strong correlation (r = 0.95) between individual sunspot cycle values of R _sum and R _M, having a good estimate of R _Mfor the present sunspot cycle (22) allows one to predict its R _sum, which further allows an estimation of both R _Mand R _sum for cycle 23 and an estimation of R _sum for Hale cycle 12. Based on Wilson's bivariate fit (r = 0.98), sunspot cycle 22 should have an R _Mequal to 144.4 ± 27.3 (at the 3- level), implying that its R _sum should be about 8600 ± 2200; such values imply that sunspot cycle 23 should have an R _sum of about 10500 ± 2000 and an R _Mof about 175 ± 40, and that Hale cycle 12 should have an R _sum of about 19100 ± 3000.