Search results for "WIN"

Intermittent release of transients in the slow solar wind: 1. Remote sensing observations

2010

[1] The Heliospheric Imager (HI) instruments on board the STEREO spacecraft are used to analyze the solar wind during August and September 2007. We show how HI can be used to image the streamer belt and, in particular, the variability of the slow solar wind which originates inside and in the vicinity of the streamer belt. Intermittent mass flows are observed in HI difference images, streaming out along the extension of helmet streamers. These flows can appear very differently in images: plasma distributed on twisted flux ropes, V-shaped structures, or “blobs.” The variety of these transient features may highlight the richness of phenomena that could occur near helmet streamers: emergence of…

A spatially consistent downscaling approach for SMOS using an adaptive window

2017

The European Space Agency (ESA)'s Soil Moisture and Ocean Salinity (SMOS) is the first spaceborne mission using L-band radiometry to monitor the Earth's global surface soil moisture (SM). After more than 7 years in orbit, many studies have contributed to improve the quality and applicability of SMOS-derived SM maps. In this research, a novel downscaling algorithm for SMOS is proposed to obtain high-resolution (HR) SM maps at 1 km (L4), from the ∼40 km native resolution of the instrument. This algorithm introduces the concept of a shape adaptive moving window as an improvement of the current semi-empirical downscaling approach at SMOS Barcelona Expert Center, based on the “universal triangle…

Particle surface area dependence of mineral dust in immersion freezing mode: investigations with freely suspended drops in an acoustic levitator and …

2014

Abstract. The heterogeneous freezing temperatures of supercooled drops were measured using an acoustic levitator. This technique allows one to freely suspend single drops in the air without any wall contact. Heterogeneous nucleation by two types of illite (illite IMt1 and illite NX) and a montmorillonite sample was investigated in the immersion mode. Drops of 1 mm in radius were monitored by a video camera while cooled down to −28 °C to simulate freezing within the tropospheric temperature range. The surface temperature of the drops was contact-free, determined with an infrared thermometer; the onset of freezing was indicated by a sudden increase of the drop surface temperature. For compari…

Studies on the impact of winter climate on rubber and wheat cultivation in the mountains of southern China, applying a fuzzy cluster analysis

1992

Data from climatic stations in China, located south of 30° N and > 400 m above sea-level, were analysed in order to study the relationship with winter climate, on the one hand, and with rubber and winter wheat cultivation, on the other. Three relevant agroclimatic parameters were investigated for January, namely mean temperature, precipitation total and sunshine duration. By applying a fuzzy cluster analysis, three agroclimatic regions were found in winter; the boundaries coincide with the macro-scale topography of southern China. In one case the boundary even corresponds with the position of the Kunming quasi-stationary front. Winter climate in the three agroclimatic regions was found to s…

Lagrangian simulations of stable isotopes in water vapor: An evaluation of nonequilibrium fractionation in the Craig-Gordon model

2009

[1] The Craig-Gordon model is the basis for the parameterization of water isotope fractionation during evaporation from the ocean in many atmospheric isotope models. Its exact formulation (e.g., with respect to the nonequilibrium fractionation factor k) is mainly based on theoretical considerations and not very well constrained by observations. This study addresses this issue by combining a recently developed Lagrangian moisture source analysis with a Craig-Gordon fractionation parameterization for the identified evaporation events in order to model isotope ratios in water vapor. This technique is applied to 45 measurement days of isotopes in water vapor at Rehovot (Israel) during the years…

Climatology of convective density currents in the southern foothills of the Atlas Mountains

2010

Density currents fed by evaporationally cooled air are an important dust storm generating feature and can constitute a source of moisture in arid regions. Recently, the existence of such systems has been demonstrated for the area between the High Atlas Mountains and the Sahara desert in southern Morocco on the basis of case studies. Here, a climatological analysis is presented that uses data from the dense climate station network of the IMPETUS project (An Integrated Approach to the Efficient Management of Scarce Water Resources in West Africa) for the 5 year period 20022006. Objective criteria mainly based upon abrupt changes in wind and dew point temperature are defined to identify possib…

Effect of Unidirectional Vertical Wind Shear on Tropical Cyclone Intensity Change—Lower‐Layer Shear Versus Upper‐Layer Shear

2019

Detection of Water Stress in an Olive Orchard with Thermal Remote Sensing Imagery

2006

An investigation of the detection of water stress in non-homogeneous crop canopies such as orchards using high-spatial resolution remote sensing thermal imagery is presented. An airborne campaign was conducted with the Airborne Hyperspectral Scanner (AHS) acquiring imagery in 38 spectral bands in the 0.43–12.5 mm spectral range at 2.5 m spatial resolution. The AHS sensor was flown at 7:30, 9:30 and 12:30 GMT in 25 July 2004 over an olive orchard with three different water-deficit irrigation treatments to study the spatial and diurnal variability of temperature as a function of water stress. A total of 10 AHS bands located within the thermal-infrared region were assessed for the retrieval of…

A new airborne tandem platform for collocated measurements of microphysical cloud and radiation properties

2009

Abstract. A new airborne tandem measurement platform for cloud-radiation interaction studies is introduced in this paper. It consists of a Learjet 35A research aircraft and the AIRcraft TOwed Sensor Shuttle (AIRTOSS), which is an instrumented drag-body towed by the Learjet. Currently, the AIRTOSS is instrumented with a Cloud Imaging Probe (CIP) for measuring cloud microphysical properties and an Inertial Navigation System (INS) for measurements of flight attitudes. The cable dragging AIRTOSS can be as long as four kilometres. Thus, truly collocated measurements in two altitudes above, in, and below clouds can be obtained. Results from first test flights with Learjet and AIRTOSS are reported…

Comparative study on immersion freezing utilizing single-droplet levitation methods

2021

Immersion freezing experiments were performed utilizing two distinct single-droplet levitation methods. In the Mainz vertical wind tunnel, supercooled droplets of 700 µm diameter were freely floated in a vertical airstream at constant temperatures ranging from −5 to −30 ∘C, where heterogeneous freezing takes place. These investigations under isothermal conditions allow the application of the stochastic approach to analyze and interpret the results in terms of the freezing or nucleation rate. In the Mainz acoustic levitator, 2 mm diameter drops were levitated while their temperature was continuously cooling from +20 to −28 ∘C by adapting to the ambient temperature. Therefore, in this case th…