Maia L. Mitnik

Atmospheric Water Vapor and Cloud Liquid Water Retrieval Over the Arctic Ocean Using Satellite Passive Microwave Sensing

New algorithms for total atmospheric water vapor content (Q) and total cloud liquid water content (W) retrieval from satellite microwave radiometer data, based on neural networks (NNs) and applicable for high-latitude open-water areas, were developed. For algorithm development, a radiative transfer equation numerical integration was carried out for Special Sensor Microwave/Imager (SSM/I) and Advanced Microwave Scanning Radiometer-Earth Observing System (AMSR-E) channel characteristics for nonprecipitating conditions over the open ocean. Sets of sea surface temperatures less than 15°C, surface winds, and radiosonde (r/s) reports collected by Russian research vessels served as input data for integration. It was shown that NNs perform better than the conventional regression techniques. Q retrieval algorithms were validated both for the SSM/I and AMSR-E instruments using satellite radiometric measurements collocated in space and time with polar station r/s data. The resulting SSM/I and AMSR-E retrieval errors proved to be 1.09 and 0.90 kg/m2 correspondingly. For SSM/I Q retrievals, the algorithms were compared with the Wentz global operational algorithm. This comparison demonstrated the advantages of NN-based polar regional algorithms in comparison with the Wentz global one. The retrieval errors proved to be 1.34 and 1.90 kg/m2 ( ~ 40% worse) for the NN and Wentz algorithms correspondingly.

Arctic Polar Low Detection and Monitoring Using Atmospheric Water Vapor Retrievals from Satellite Passive Microwave Data

An approach for detecting and tracking polar lows (PLs) is developed based on satellite passive microwave data from two sensors: Special Sensor Microwave Imager (SSM/I) on board the Defense Meteorological Satellite Program satellite and Advanced Microwave Scanning Radiometer-Earth Observing System (AMSR-E) on board the Aqua satellite. This approach consists of two stages. During the first stage, the total atmospheric water vapor fields are retrieved from SSM/I and AMSR-E measurement data using precise Arctic polar algorithms, applicable over open water and having high retrieval accuracies under a wide range of environmental conditions previously developed. During the second stage, the vortex structures are detected by visual analysis in these fields, and PLs are identified and tracked. A few case studies are comprehensively conducted based on multisensor data usage. SSM/I and AMSR-E measurements and other satellite data, including visible, infrared, and synthetic aperture radar images, scatterometer wind fields, surface analysis maps, and reanalysis data, have been used for PL study. It has been shown that multisensor data provide the most complete information about these weather events. Through this, advantages of satellite passive microwave data are demonstrated.

AMSR-E advanced wind speed retrieval algorithm and its application to marine weather systems

The physical-based algorithm for the sea surface wind speed W retrieval from Aqua AMSR-E passive microwave measurements is considered. The brightness temperatures T<inf>B</inf>^V(24) at 23.8 GHz and T<inf>B</inf>^V(36) at 36.5 GHz with vertical (V) polarization and T<inf>B</inf>^H(11) at 10.7 GHz with horizontal (H) polarization and results of computations of the brightness temperature of the calm ocean surface T<inf>Boc</inf>^H(11) are used at first to estimate contribution of the atmosphere to T<inf>B</inf>^H(11), then increment of T<inf>Boc</inf>^H(11) caused by wind action and at last wind speed. The developed algorithm is applied to AMSR-E data obtained in the Northwest Pacific Ocean over extratropical cyclones with gale winds. The retrieved fields of wind speed are compared with scatterometer-derived fields and the surface analysis maps.

On-orbit calibration of the “Meteor-M” microwave imager/sounder

Multichannel microwave radiometer MTVZA-GY onboard of meteorological satellite Meteor-M N 1 performs carries out measurements of outgoing radiation of the atmosphere-underlying system. Both internal and external calibrations of the measured radiation as well as the results of numerical integration of microwave radiative transfer equation are used to derive brightness temperatures TBs at vertical (V) and horizontal (H) polarizations at MTVZA-GY frequencies. Radiosonde data for TBs modeling and comparison with the measured values were selected for various physical-geographical regions. The spatial structures of the marine weather systems measured by MTVZA-GY and AMSR-E were mainly similar. Their differences were due to the differences in the incidence angle: 55° for AMSR-E and 65° for MTVZA-GY.

Sea surface wind and Sea ice in the Barents Sea using microwave sensing data from Meteor-M N1 and GCOM-W1 satellites in January–March 2013

Application of satellite passive microwave sensing for the retrieval of key climatic parameters in the Barents Sea is considered. Fields of surface wind, atmosphere water vapor content and cloud liquid water content were found from MTVZA-GY radiometer onboard the Meteor-M N1 satellite and AMSR2 onboard the GCOM-W1 satellite with the use of original algorithms. The fields are in a good agreement with the ancillary remote and in situ measurements, which follows from the analysis of the evolution of the extra tropical and polar cyclones and cold air outbreaks with storm winds leading to intense air-sea interaction, and the formation and drift of sea ice.

New Russian meteorological satellite Meteor-M N 2: sensing of the subsurface, surface and atmospheric characteristics by MTVZA-GY microwave imager/sounder

The Meteor-M N 2 spacecraft with microwave radiometer MTVZA-GY has been launched on July 8, 2014 on sun-synchronous orbit at an altitude of 830 km. MTVZA-GY is a 29 channel microwave imager/sounder for remote sensing of the ocean and land surface parameters as well as for measuring total atmospheric water vapor content, total cloud liquid water content, air temperature and humidity profiles. MTVZA GY operates at frequencies10-190 GHz. The total power radiometer configuration is employed. The antenna system of MTVZA-GY consists of an offset parabolic reflector of dimension 65 cm, illuminated by four feed-horns antenna. Results of vicarious calibration and longtime stability study are discussed. Globe MTVZA-GY data are presented. The examples of joint analysis of MTVZA-GY and other remote and ground-based observations of severe marine weather systems and Antarctica are discussed.

Severe Weather Study in Middle and High Oceanic Latitudes using Aqua AMSR-E

A variety of severe weather events impact the coastal zones, ships and offshore industry year round, however, only part of mesoscale events was marked on the weather maps. The Aqua AMSR-E higher spatial resolution and availability of simultaneous visible and infrared MODIS data have produced measurements of the marine weather systems that are not available from any other satellite. Efficiency of AMSR-E measurements is shown by detailed consideration of severe weather events over the Northwest Pacific Ocean. They include heavy rains and snowfalls caused by passing of cyclones from the Yellow Sea to the Japan Sea, strong winds in the areas of polar lows and cold air outbreaks over the Asian Marginal Seas and in the Northwest Pacific. QuikSCAT-derived wind fields and Aqua MODIS images and surface analysis maps are used as supplementary information. The satellite information provided by AMSR-E and other sensors is a good tool for monitoring the events and issuing a reasonable nowcast.

Passive microwave observations of South America and surrounding oceans from Russian Meteor-M No. 2 and Japan GCOM-W1 satellites

ABSTRACT A new Russian Meteorological Satellite Meteor-M No. 2 with onboard multichannel microwave radiometer MTVZA-GY was launched on sun synchronous orbit in July 2014. The radiometer receives the outgoing radiation of the Earth at 29 channels at the frequency ranges ν = 10–48, 52–57, 90–93 and 176–190 GHz. Conical scanning is performed at the incidence angle 65°. The data derived over the Amazon basin rain forest and the cloudless calm areas in the South Atlantic and South Pacific Ocean and the computed brightness temperatures (TBs) served for the MTVZA-GY external calibration. A comparison of the TB time series obtained by the MTVZA-GY and well-calibrated AMSR2 radiometer onboard GCOM-W1 was used for assessment of the long-term stability of the MTVZA-GY in flight. The joint analysis of the TB time series at ν = 10.6, 42.0 and 91.6 GHz allowed to reveal the variations associated with the wet and dry seasons in the Amazon forest as well as events caused by the rain and heavy clouds during satellite observations. The multichannel approach was also used to study structure, evolution and fields of the sea surface wind, total water vapour content and total cloud liquid water content in the cyclonic formations over the South Atlantic and South Pacific Oceans.

Microwave Scanner-Sounder MTVZA-GY on New Russian Meteorological Satellite Meteor-M No. 2: Modeling, Calibration, and Measurements

On July 8, 2014 meteorological satellite “Meteor-M” no. 2 with a module of temperature and humidity atmospheric sensing MTVZA-GY was launched on a circular sun-synchronous orbit. Microwave radiometer MTVZA-GY has 16 imaging channels at frequencies of 10.65, 18.7, 23.8, 31.5, 36.5, 42.0, 48.0, and 91.65 GHz and 13 sounder channels at frequencies in the ranges of 52–57 and 176–191 GHz and carries out conical scanning of the Earth at the angle of incidence 65°. Swath width is 1500 km. The brightness temperatures TBs were computed by numerical integration of microwave radiative transfer equation using the radiosonde and reanalysis atmospheric profiles as the input information. The TBs for the Amazon forest and the calm Ocean under clear sky served for the vicarious calibration of MTVZA channels. The long-term stability of MTVZA-GY operation was examined by the analysis of time series of TBs measured over the test areas around the Eastern Antarctic Dome C station, Greenland GEOSummit station and Amazon rainforest. TBs time series obtained by the GCOM-W1 AMSR2 radiometer for the same test areas served as a reference and were used for a comparison with MTVZA-GY time series. Examples are given of the global MTVZA-GY measurements.

Polar low study using satellite passive and active microwave remote sensing

An approach for detection and tracking polar lows is developed utilizing the data from two sensors: Special Sensor Microwave Imager (SSM/I) onboard Defense Meteorological Satellite Program (DMSP) satellite and Advanced Microwave Scanning Radiometer – Earth Observing System (AMSR-E) onboard Aqua satellite. This approach consists of two stages. At the first stage total atmospheric water vapor fields are retrieved from SSM/I and AMSRE-E measurement data using precise Arctic polar algorithms, developed at NIERSC. These algorithms are applicable over open water. They have high retrieval accuracies under a wide range of environmental conditions. Algorithms are based on numerical simulation of brightness temperatures and their inversion by means of Neural Networks. At the second stage the vortex structures are detected in these fields, Polar Lows are identified and tracked and some of their parameters are calculated. A few case studies are comprehensively conducted based on SSM/I and AMSRE-E measurements and using other satellite data including visible, infrared and SAR images, QuickScat Scatterometer wind fields, surface analysis maps and re-analysis data, which demonstrated the advantages of satellite passive microwave data usage in the Polar Low studies.