Simultaneous visible and near-infrared time resolved observations of the outer Solar System object (29981) 1999 TD10

The outer Solar System object (29981) 1999 TD₁₀ was observed simultaneously in the R, and J and H bands in September 2001, and in B, V, R, and I in October 2002. We derive B−V=0.80±0.05 mag, V−R=0.48±0.05 mag, R−I=0.44±0.05 mag, R−J=1.24±0.05 mag, and J−H=0.61±0.07 mag. Combining our data with the data from Rousselot et al. (2003, Astron. Astrophys. 407, 1139) we derive a synodic period of 15.382±0.001 hr in agreement with the period from Rousselot et al. Our observations at the same time, with better S/N and seeing, show no evidence of a coma, contrary to the claim by Choi et al. (2003, Icarus 165, 101).     

Size, albedo, and taxonomic type of potential spacecraft target Asteroid (10302) 1989 ML

The Amor-type near-Earth Asteroid (10302) 1989 ML has an “Earth-like” orbit (period 1.44 yr, eccentricity 0.14, inclination 4.4°), therefore the energy required to reach it from the Earth is relatively small making it a very attractive target for rendezvous missions. We have observed 1989 ML in the thermal-infrared using the Spitzer Space Telescope, and compared these data with optical and near-infrared observations. The Spitzer results imply a diameter of 0.28±0.05 km and a geometric albedo of 0.37±0.15; together with the reflectance spectrum they are consistent with the relatively rare E classification.     

Spatial characterization of marine recreational boating: Exploring the use of an on-the-water questionnaire for a case study in the Pacific Northwest

Information about spatial patterns of recreational boating is important for managing environmental, safety, and social impacts. However, traditional spatial mapping techniques such as remote sensing are often unable to project entire vessel routes or to link with other important data such as demographics, activities, or purpose of trip. This study, conducted in a part of Canada’s southern Strait of Georgia, uses an on-the-water-questionnaire to map recreational boating distribution/density in a complex, multiple-use marine setting. Goals of this study were to explore an on-the-water questionnaire as a means of capturing boating distribution and density, explore the potential contributions of such information to marine spatial planning, and assess the strengths and limitations of the method. Boaters (n=519) were intercepted while engaged in boating trips and were asked to plot the route of their trip on a map of the region. Information was imported into ArcGIS for analysis and display of vessel distribution and density. The resultant spatial dataset has a number of applications for marine spatial planning and management. Strengths of this method include collection of entire vessel routes, linking spatial data to questionnaire variables, and a high response rate. Limitations include some bias towards sample sites and issues of respondent accuracy, as well as cost and effort. Recommendations for management and research are made.     

The slow rotation of 253 Mathilde

CCD photometry of the NEAR mission fly-by target 253 Mathilde is presented. Measurements taken during 52 nights of observations, from February to June 1995, allow a rotation period of 17.406±0.010 days and a lightcurve amplitude of 0.45±0.02 mag to be determined. A B-V color index of 0.67±0.02 and a V-R of 0.35±0.02 are measured, which are compatible with C-type membership. The determination of the phase relation results in H = 10.28±0.03 and G = 0.12±0.06. Indications that the lightcurve is not strictly singly-periodic are found. A power-spectrum analysis detects a secondary frequency f₂ = 0.0322±0.0010 d⁻¹, which is interpreted as evidence for a complex rotation state.     

Remote sensing of coral reefs and their physical environment

There has been a vast improvement in access to remotely sensed data in just a few recent years. This revolution of information is the result of heavy investment in new technology by governments and industry, rapid developments in computing power and storage, and easy dissemination of data over the internet. Today, remotely sensed data are available to virtually anyone with a desktop computer. Here, we review the status of one of the most popular areas of marine remote sensing research: coral reefs. Previous reviews have focused on the ability of remote sensing to map the structure and habitat composition of coral reefs, but have neglected to consider the physical environment in which reefs occur. We provide a holistic review of what can, might, and cannot be mapped using remote sensing at this time. We cover aspects of reef structure and health but also discuss the diversity of physical environmental data such as temperature, winds, solar radiation and water quality. There have been numerous recent advances in the remote sensing of reefs and we hope that this paper enhances awareness of the diverse data sources available, and helps practitioners identify realistic objectives for remote sensing in coral reef areas.     

Mean meridional currents in the central and eastern equatorial Atlantic

Ship-based acoustic Doppler current profiler (ADCP) velocity measurements collected by several major field programs in the tropical Atlantic are averaged and combined with estimates of the mean near-surface velocity derived from drifters and Argo float surface drifts (ADCP+D) to describe the mean cross-equatorial and vertical structure of the meridional currents along 23°W and 10°W. Data from moored ADCPs and fixed-depth current meters, a satellite-derived velocity product, and a global ocean reanalysis were additionally used to evaluate the mean ADCP+D meridional velocity. The dominant circulation features in the long-term mean ADCP+D meridional velocity in the upper 100 m are the tropical cells (TCs) located approximately between 5°S and 5°N, with near-surface poleward flow and subsurface equatorward flow that is stronger and shallower in the northern cell compared to the southern cell. The thickness of the surface limb of the TCs decreases and the northern cell is found to shift further south of the equator from the central to eastern tropical Atlantic. Analysis of two-season means estimated from the ship-based ADCP, near-surface drift, and moored velocity data, as well as the simulated fields, indicates that the maximum poleward velocity in the surface limb of the TCs intensifies during December–May along 23°W largely due to seasonal compensation between the geostrophic and ageostrophic (or wind-driven) components of the meridional velocity, whereas the maximum equatorward flow in the subsurface limb of the northern cell intensifies during June–November along both 23°W and 10°W due to the seasonality of the geostrophic meridional velocity.     

Retrieving daily global solar radiation from routine climate variables

Solar radiation is an important variable for studies related to solar energy applications, meteorology, climatology, hydrology, and agricultural meteorology. However, solar radiation is not routinely measured at meteorological stations; therefore, it is often required to estimate it using other techniques such as retrieving from satellite data or estimating using other geophysical variables. Over the years, many models have been developed to estimate solar radiation from other geophysical variables such as temperature, rainfall, and sunshine duration. The aim of this study was to evaluate six of these models using data measured at four independent worldwide networks. The dataset included 13 stations from Australia, 25 stations from Germany, 12 stations from Saudi Arabia, and 48 stations from the USA. The models require either sunshine duration hours (Ångstrom) or daily range of air temperature (Bristow and Campbell, Donatelli and Bellocchi, Donatelli and Campbell, Hargreaves, and Hargreaves and Samani) as input. According to the statistical parameters, Ångstrom and Bristow and Campbell indicated a better performance than the other models. The bias and root mean square error for the Ångstrom model were less than 0.25 MJ m² day^?1 and 2.25 MJ m² day^?1, respectively, and the correlation coefficient was always greater than 95 %. Statistical analysis using Student’s t test indicated that the residuals for Ångstrom, Bristow and Campbell, Hargreaves, and Hargreaves and Samani are not statistically significant at the 5 % level. In other words, the estimated values by these models are statistically consistent with the measured data. Overall, given the simplicity and performance, the Ångstrom model is the best choice for estimating solar radiation when sunshine duration measurements are available; otherwise, Bristow and Campbell can be used to estimate solar radiation using daily range of air temperature.     

The Acre Basin basement (NW Brazil) and the transition from the intracratonic to retroarc foreland basin system

The understanding of the crustal transition between orogenic zones and cratonic portions in distal regions of foreland basins has received increasing attention, but the analysis is often hampered by the sedimentary cover. Despite the peculiar location of the Acre Basin, specifically between the Amazonian Craton and the sub-Andean zone, local basement studies are still scarce due to lacking seismic data and exploratory wells. Therefore, this work aims to map basement depths, estimate crustal compositions and identify the main depocenters, structures and limits of Acre Basin using an integrated analysis to understand better the region lithospheric evolution, its relationship with the Amazonian Craton and its positioning within the Andean orogeny. For that, we used well, 2D seismic reflection, airborne and ground gravity and magnetic data as well as the EMG2008. Tilt Depth estimates indicate basement depths between 500 and 7800 m and larger sedimentary thicknesses in the northern portion. Additionally, we modelled groups of potential sources between 0.1 and 22 km and Moho depths between 26 and 37 km. Compositionally, the upper crust consists dominantly of meta-sedimentary and low-grade metamorphic rocks and granites, indicating that the sub-Andean and Acre Basins share a similar basement. Thus, there are indications that the basement of the Acre Basin is essentially formed by the Sunsás province in the Amazonian Craton. However, local differences in basement depth, magnetic susceptibility and exploratory potential led to the subdivision into Divisor and Xapuri sub-basins, north and south of the Fitzcarrald Arch, respectively. Finally, it was possible to establish the limits of the Andean orogeny influence in the Acre Basin and delimit the area of the Western Amazon Foredeep installed during the Neogene.     

Monitoring US agriculture: the US Department of Agriculture,National Agricultural Statistics Service,Cropland Data Layer Program

The National Agricultural Statistics Service (NASS) of the US Department of Agriculture (USDA) produces the Cropland Data Layer (CDL) product, which is a raster-formatted, geo-referenced, crop-specific, land cover map. CDL program inputs include medium resolution satellite imagery, USDA collected ground truth and other ancillary data, such as the National Land Cover Data set. A decision tree-supervised classification method is used to generate the freely available state-level crop cover classifications and provide crop acreage estimates based upon the CDL and NASS June Agricultural Survey ground truth to the NASS Agricultural Statistics Board. This paper provides an overview of the NASS CDL program. It describes various input data, processing procedures, classification and validation, accuracy assessment, CDL product specifications, dissemination venues and the crop acreage estimation methodology. In general, total crop mapping accuracies for the 2009 CDLs ranged from 85% to 95% for the major crop categories.