Mars Science Laboratory Curiosity rover observations of the 2018/Mars year 34 global/planet‐encircling dust storm represent the first in situ measurements of a global dust storm with dedicated meteorological sensors since the Viking Landers. The Mars Science Laboratory team planned and executed a science campaign lasting approximately 100 Martian sols to study the storm involving an enhanced cadence of environmental monitoring using the rover's meteorological sensors, cameras, and spectrometers. Mast Camera 880‐nm optical depth reached 8.5, and Rover Environmental Monitoring Station measurements indicated a 97% reduction in incident total ultraviolet solar radiation at the surface, 30K reduction in diurnal range of air temperature, and an increase in the semidiurnal pressure tide amplitude to 40 Pa. No active dust‐lifting sites were detected within Gale Crater, and global and local atmospheric dynamics were drastically altered during the storm. This work presents an overview of the mission's storm observations and initial results.

This study constrains the lower bound of the scattering phase function of Martian water ice clouds (WICs) through the implementation of a new observation aboard the Mars Science Laboratory (MSL). The Phase Function Sky Survey (PFSS) was a multiple pointing all-sky observation taken with the navigation cameras (Navcam) aboard MSL. The PFSS was executed 35 times during the Aphelion Cloud Belt (ACB) season of Mars Year 34 over a solar longitude range of s = 61.4°− 156.5°. Twenty observations occurred in the morning hours between 06:00 and 09:30 LTST, and 15 runs occurred in the evening hours between 14:30 and 18:00 LTST, with an operationally required 2.5 hour gap on either side of local noon due the sun being located near zenith. The resultant WIC phase function was derived over an observed scattering angle range of 18.3° to 152.61°, normalized, and compared with 9 modeled phase functions: seven ice crystal habits and two Martian WIC phase functions currently being implemented in models. Through statistical chi-squared probability tests, the five most probable ice crystal geometries observed in the ACB WICs were aggregates, hexagonal solid columns, hollow columns, plates, and bullet rosettes with p-values greater than or equal to 0.60, 0.57,0.56,0.56, and 0.55, respectively. Droxtals and spheres had p-values of 0.35, and 0.2, making them less probable components of Martian WICs, but still statistically possible ones. Having a better understanding of the ice crystal habit and phase function of Martian water ice clouds directly benefits Martian climate models which currently assume spherical and cylindrical particles.

No abstract

Samples of agricultural soils were collected across North Carolina in 1992 and Nebraska in 1993 to determine which indices of nematode communities could be applied to distinguish ecological pattern at regional geographic scales. Sampling density was proportional to the area of agriculture in each region of each state. Maturity indices (based on life-history characteristics) were calculated to determine the successional status of nematode communities, and diversity indices were calculated to estimate relative abundance of nematode trophic groups. Population densities of nematode families were also compared between states and among regions within states. The range of maturity-index values for free-living and plant-parasitic nematodes was greater for soils in North Carolina than in Nebraska. The relative distribution of nematode trophic groups (bacterial feeders, fungal feeders, plant parasites, omnivores, and predators) was similar in the two states. Significant differences in maturity-index values for free-living and plant-parasitic nematodes were found between but not within states. We conclude that regional or national assessments of soil ecological condition based on measures of nematode community structure can be made at a geographic resolution of 125 000-200 000 km 2 of land area.

The Mars Science Laboratory (MSL) landed on Mars in Gale crater in 2012, and, since then, the rover has been almost continuously observing the meteorology within the crater using the Rover Environmental Monitoring Station (REMS; Gómez-Elvira et al., 2012). Among the regular observations by REMS have been surface pressure, UV radiation flux, air temperature, humidity, and ground temperature (measurements of wind speed and direction were constrained to moments when the wind was blowing onto the front of the rover after a second, complementary wind sensor was damaged upon landing). Additionally, MSL cameras provide atmospheric information that includes estimates of atmospheric dust loading and detection of dust devils and water ice clouds (Guzewich