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A hyperspectral infrared (IR) sounder from geostationary orbit provides nearly continuous measurements of atmospheric thermodynamic and dynamic information within a weather cube, specifically the atmospheric temperature, moisture, and wind information at different pressure levels that are critical for improving high-impact weather (HIW) nowcasting and numerical weather prediction (NWP). Geostationary hyperspectral IR sounders (GeoHIS) have been on board China's Fengyun-4 series since 2016 and will be on board Europe's Meteosat Third Generation (MTG) series in the 2024 time frame; the United States and other countries are also planning to include GeoHIS instruments on their next generation of geostationary weather satellites. Although availability of on-orbit GeoHIS data are limited currently, studies have been conducted and progress has been made on developing the applications of high-temporal-resolution GeoHIS observations. These include but are not limited to deriving three-dimensional wind fields for nowcasting and NWP applications, trending atmospheric instability for warning in preconvective environments, conducting impact studies with data from the experimental Geostationary Interferometric Infrared Sounder (GIIRS) on board Fengyun-4A, preparing observing system simulation experiments (OSSEs), and monitoring diurnal variation of atmospheric composition. This paper provides an overview of the current applications of GeoHIS, discusses the data processing challenges, and provides perspectives on future development. The purpose is to provide direction on utilization of the current and assist preparation for the upcoming GeoHIS observations for nowcasting, NWP and other applications. [ABSTRACT FROM AUTHOR]

The marine icicles that form on coastal constructions (e.g., piers and railings) are very common in polar and subpolar areas. The occasional formation of icicles in the coastal zones of the Mediterranean Sea occurs in relation to cold-air outbreaks from the polar region, such as the one presented in this paper in February 2018. The air temperatures over the northern Adriatic Sea, the northernmost part of the Mediterranean, dropped below –2.1°C, a necessary condition for seawater to freeze, with salinity between 38.0 and 38.5 PSU. The formation of icicles on the coastal structures was further enabled by the bora wind and related high seas along the coast. Measurements presented in this paper confirm that the icicles in the Bay of Piran in the Gulf of Trieste (45.55°N) were formed from the seawater. The measured salinity level of the melted icicles, around 9 PSU, is a typical value reported for marine icicles in polar regions. [ABSTRACT FROM AUTHOR]

Clouds play an important role in Arctic amplification. This term represents the recently observed enhanced warming of the Arctic relative to the global increase of near-surface air temperature. However, there are still important knowledge gaps regarding the interplay between Arctic clouds and aerosol particles, and surface properties, as well as turbulent and radiative fluxes that inhibit accurate model simulations of clouds in the Arctic climate system. In an attempt to resolve this so-called Arctic cloud puzzle, two comprehensive and closely coordinated field studies were conducted: the Arctic Cloud Observations Using Airborne Measurements during Polar Day (ACLOUD) aircraft campaign and the Physical Feedbacks of Arctic Boundary Layer, Sea Ice, Cloud and Aerosol (PASCAL) ice breaker expedition. Both observational studies were performed in the framework of the German Arctic Amplification: Climate Relevant Atmospheric and Surface Processes, and Feedback Mechanisms (AC) project. They took place in the vicinity of Svalbard, Norway, in May and June 2017. ACLOUD and PASCAL explored four pieces of the Arctic cloud puzzle: cloud properties, aerosol impact on clouds, atmospheric radiation, and turbulent dynamical processes. The two instrumented Polar 5 and Polar 6 aircraft; the icebreaker Research Vessel (R/V) Polarstern; an ice floe camp including an instrumented tethered balloon; and the permanent ground-based measurement station at Ny-Ålesund, Svalbard, were employed to observe Arctic low- and mid-level mixed-phase clouds and to investigate related atmospheric and surface processes. The Polar 5 aircraft served as a remote sensing observatory examining the clouds from above by downward-looking sensors; the Polar 6 aircraft operated as a flying in situ measurement laboratory sampling inside and below the clouds. Most of the collocated Polar 5/6 flights were conducted either above the R/V Polarstern or over the Ny-Ålesund station, both of which monitored the clouds from below using similar but upward-looking remote sensing techniques as the Polar 5 aircraft. Several of the flights were carried out underneath collocated satellite tracks. The paper motivates the scientific objectives of the ACLOUD/PASCAL observations and describes the measured quantities, retrieved parameters, and the applied complementary instrumentation. Furthermore, it discusses selected measurement results and poses critical research questions to be answered in future papers analyzing the data from the two field campaigns. [ABSTRACT FROM AUTHOR]

The article reports on the climate impacts of anthropogenic carbon dioxide emissions. In its Fourth Assessment Report, the Intergovernmental Panel on Climate Change (IPCC) suggests that about 50 percent of a carbon dioxide increase will be removed from the atmosphere within 30 years. It is reported that the logarithmic relationship between carbon dioxide and its radiative forcing implies that the time scale at which atmospheric temperature declines will be longer.

A total solar eclipse traversed the continental United States on 21 August 2017. It was the first such event in 99 years and provided a rare opportunity to observe the atmospheric response from a variety of instrumented observational platforms. This paper discusses the highquality observations collected by the Kentucky Mesonet (www.kymesonet.org), a research-grade meteorological and climatological observation network consisting of 72 stations and measuring air temperature, precipitation, relative humidity, solar radiation, wind speed, and wind direction. The network samples the atmosphere, for most variables, every 3 s and then calculates and records observations every 5 min. During the total solar eclipse, these observations were complemented by observations collected from three atmospheric profiling systems positioned in the path of the eclipse and operated by the University of Alabama in Huntsville (UAH). Observational data demonstrate that solar radiation at the surface dropped from >800 to 0 W m-2, the air temperature decreased by about 4.5°C, and, most interestingly, a land-breeze-sea-breeze-type wind developed. In addition, due to the high density of observations, the network recorded a detailed representation of the spatial variation of surface meteorology. The UAH profiling system captured collapse and reformation of the planetary boundary layer and related changes during the total solar eclipse. [ABSTRACT FROM AUTHOR]

This paper describes the formation of, and initial results for, a new FLUXNET coordination network for ecosystem-scale methane (CH4) measurements at 60 sites globally, organized by the Global Carbon Project in partnership with other initiatives and regional flux tower networks. The objectives of the effort are presented along with an overview of the coverage of eddy covariance (EC) CH4 flux measurements globally, initial results comparing CH4 fluxes across the sites, and future research directions and needs. Annual estimates of net CH4 fluxes across sites ranged from −0.2 ± 0.02 g C m–2 yr–1 for an upland forest site to 114.9 ± 13.4 g C m–2 yr–1 for an estuarine freshwater marsh, with fluxes exceeding 40 g C m–2 yr–1 at multiple sites. Average annual soil and air temperatures were found to be the strongest predictor of annual CH4 flux across wetland sites globally. Water table position was positively correlated with annual CH4 emissions, although only for wetland sites that were not consistently inundated throughout the year. The ratio of annual CH4 fluxes to ecosystem respiration increased significantly with mean site temperature. Uncertainties in annual CH4 estimates due to gap-filling and random errors were on average ±1.6 g C m–2 yr–1 at 95% confidence, with the relative error decreasing exponentially with increasing flux magnitude across sites. Through the analysis and synthesis of a growing EC CH4 flux database, the controls on ecosystem CH4 fluxes can be better understood, used to inform and validate Earth system models, and reconcile differences between land surface model- and atmospheric-based estimates of CH4 emissions. [ABSTRACT FROM AUTHOR]

Although the large U.S. meteorological community has made significant strides in weather diagnosis and prediction, progress has been slowed by a lack of cooperation, coordination, and pooling of resources. This paper analyzes such problems in a number of areas, ranging from numerical weather prediction to forecast dissemination, and proposes an alternative approach of greater community involvement in decision making, coupled with closely coordinated research and application, which might facilitate improvement in our ability to predict the weather and to apply weather information to societal needs. [ABSTRACT FROM AUTHOR]

The article presents comments and criticisms on the published paper "Hurricanes and global warming. This is presentation of the views and scientific perspectives as well as the perspectives on structure and function of scientific assessments given by Anthes et al.(2006) and Pielke et al. (2005). The policy action in question here deals with what could be the most effective policy with regards to tropical cyclone that have an impact in the societal vulnerability. There is an on-going investigation on the issues of research in climate changes and tropical cyclones. Also, a brief enumeration on the criticisms by Pielke et al.(2005) and Anthes et al.(2006) is emphasized.

The formula used in the U.S. and Canada to express the combined effect of wind and low temperature on how cold it feels was changed in November 2001. Many had felt that the old formula for equivalent temperature, derived in the 1960s from Siple and Passel's flawed but quite useful Wind Chill Index, unnecessarily exaggerated the severity of the weather. The new formula is based on a mathematical model of heat flow from the upwind side of a head-sized cylinder moving at walking speed into the wind. The paper details the assumptions that were made in generating the new wind chill charts. It also points out weaknesses in the concept of wind chill equivalent temperature, including its steady-state character and a seemingly paradoxical effect of the internal thermal resistance of the cylinder on comfort and equivalent temperature. Some improvements and alternatives are suggested. [ABSTRACT FROM AUTHOR]

This paper presents a method for predicting the onset of finger freezing. It is an extension of a tissue-cooling model originally developed to predict the onset of cheek freezing. The extension to the finger is presented as a more conservative warning of wind chill. Indeed, guidance on the risk of finger freezing is important not only to safeguard the finger, but also because it pertains more closely to susceptible facial features, such as the nose, than if only the risk of cheek freezing was provided. The importance of blood flow to the finger and the modeling of vaso-constriction are demonstrated through cooling predictions that agree reasonably well with several reported observations. Differences in the prediction between the present physiologic-based model and the engineering model used to develop the wind chill index are also discussed. New wind chill charts are presented that tabulate the mean cooling rates and corresponding onset times to freezing of the finger for various combinations of air temperature and wind speed. Results indicate that the surface of the finger cools to its freezing point in approximately one-eighth of the time predicted for the cheek. For combinations that result in the same wind chill temperature (WCT), the rate of finger cooling is faster at the higher wind speed. This asymmetry was previously disclosed through the application of the model to cheek cooling, and it reiterates the ambiguity associated with the reporting of WCT. It is further emphasized that the reporting of onset times to freezing, or safe exposure limits, is a more logical and meaningful alternative to the WCT. [ABSTRACT FROM AUTHOR]

This article discusses climate change and hurricanes. Papers that appeared in the scholarly journals "Nature" and "Science" during the summer of 2005 raised the question of global warming being the cause of the record-breaking hurricane season of 2005. The article examines that argument, noting that many scientists believe that human-induced climate warming is indeed real. Also discussed is the increasing intensity of hurricanes since 1975, as well as the rise in seas surface temperatures and greenhouse gases in the atmosphere.