Ice Water Path Estimation and Characterization Using Passive Microwave Radiometry

1991 ◽  
Vol 30 (10) ◽  
pp. 1407-1421 ◽  
Author(s):  
J. Vivekanandan ◽  
J. Turk ◽  
V. N. Bringi
Keyword(s):  
Passive Microwave ◽  
Microwave Radiometry ◽  
Water Path ◽  
Ice Water Path ◽  
Passive Microwave Radiometry ◽  
Ice Water

scholarly journals Potential of Hyperspectral Thermal Infrared Spaceborne Measurements to Retrieve Ice Cloud Physical Properties: Case Study of IASI and IASI-NG

2020 ◽  
Vol 13 (1) ◽  
pp. 116
Author(s):  
Lucie Leonarski ◽  
Laurent C.-Labonnote ◽  
Mathieu Compiègne ◽  
Jérôme Vidot ◽  
Anthony J. Baran ◽  
...  
Keyword(s):  
Radiative Transfer ◽  
Signal To Noise Ratio ◽  
Thermal Infrared ◽  
Radiative Transfer Model ◽  
Retrieval Algorithm ◽  
Transfer Model ◽  
Water Path ◽  
Ice Cloud ◽  
Ice Water Path ◽  
Ice Water

The present study aims to quantify the potential of hyperspectral thermal infrared sounders such as the Infrared Atmospheric Sounding Interferometer (IASI) and the future IASI next generation (IASI-NG) for retrieving the ice cloud layer altitude and thickness together with the ice water path. We employed the radiative transfer model Radiative Transfer for TOVS (RTTOV) to simulate cloudy radiances using parameterized ice cloud optical properties. The radiances have been computed from an ice cloud profile database coming from global operational short-range forecasts at the European Center for Medium-range Weather Forecasts (ECMWF) which encloses the normal conditions, typical variability, and extremes of the atmospheric properties over one year (Eresmaa and McNally (2014)). We performed an information content analysis based on Shannon’s formalism to determine the amount and spectral distribution of the information about ice cloud properties. Based on this analysis, a retrieval algorithm has been developed and tested on the profile database. We considered the signal-to-noise ratio of each specific instrument and the non-retrieved atmospheric and surface parameter errors. This study brings evidence that the observing system provides information on the ice water path (IWP) as well as on the layer altitude and thickness with a convergence rate up to 95% and expected errors that decrease with cloud opacity until the signal saturation is reached (satisfying retrievals are achieved for clouds whose IWP is between about 1 and 300 g/m2).

Variational Assimilation of Cloud Liquid/Ice Water Path and Its Impact on NWP

2015 ◽  
Vol 54 (8) ◽  
pp. 1809-1825 ◽  
Author(s):  
Yaodeng Chen ◽  
Hongli Wang ◽  
Jinzhong Min ◽  
Xiang-Yu Huang ◽  
Patrick Minnis ◽  
...  
Keyword(s):  
Data Assimilation ◽  
Liquid Water ◽  
Weather Prediction ◽  
Wrf Model ◽  
Liquid Water Path ◽  
Cloud Liquid Water ◽  
Water Path ◽  
Ice Water Path ◽  
Ice Water ◽  
The Impact

AbstractAnalysis of the cloud components in numerical weather prediction models using advanced data assimilation techniques has been a prime topic in recent years. In this research, the variational data assimilation (DA) system for the Weather Research and Forecasting (WRF) Model (WRFDA) is further developed to assimilate satellite cloud products that will produce the cloud liquid water and ice water analysis. Observation operators for the cloud liquid water path and cloud ice water path are developed and incorporated into the WRFDA system. The updated system is tested by assimilating cloud liquid water path and cloud ice water path observations from Global Geostationary Gridded Cloud Products at NASA. To assess the impact of cloud liquid/ice water path data assimilation on short-term regional numerical weather prediction (NWP), 3-hourly cycling data assimilation and forecast experiments with and without the use of the cloud liquid/ice water paths are conducted. It is shown that assimilating cloud liquid/ice water paths increases the accuracy of temperature, humidity, and wind analyses at model levels between 300 and 150 hPa after 5 cycles (15 h). It is also shown that assimilating cloud liquid/ice water paths significantly reduces forecast errors in temperature and wind at model levels between 300 and 150 hPa. The precipitation forecast skills are improved as well. One reason that leads to the improved analysis and forecast is that the 3-hourly rapid update cycle carries over the impact of cloud information from the previous cycles spun up by the WRF Model.

scholarly journals The Impacts of Atmospheric and Surface Parameters on Long-Term Variations in the Planetary Albedo

2018 ◽  
Vol 31 (21) ◽  
pp. 8705-8718 ◽  
Author(s):  
Bida Jian ◽  
Jiming Li ◽  
Guoyin Wang ◽  
Yongli He ◽  
Ying Han ◽  
...  
Keyword(s):  
Liquid Water ◽  
Surface Albedo ◽  
Cloud Fraction ◽  
Liquid Water Path ◽  
Water Path ◽  
Ice Water Path ◽  
Planetary Albedo ◽  
Ice Water ◽  
Long Term Variations

Planetary albedo (PA; shortwave broadband albedo) and its long-term variations, which are controlled in a complex way by various atmospheric and surface properties, play a key role in controlling the global and regional energy budget. This study investigates the contributions of different atmospheric and surface properties to the long-term variations of PA based on 13 years (2003–15) of albedo, cloud, and ice coverage datasets from the Clouds and the Earth’s Radiant Energy System (CERES) Single Scanner Footprint edition 4A product, vegetation product from Moderate Resolution Imaging Spectroradiometer (MODIS), and surface albedo product from the Cloud, Albedo, and Radiation dataset, version 2 (CLARA-A2). According to the temporal correlation analysis, statistical results indicate that variations in PA are closely related to the variations of cloud properties (e.g., cloud fraction, ice water path, and liquid water path) and surface parameters (e.g., ice/snow percent coverage and normalized difference vegetation index), but their temporal relationships vary among the different regions. Generally, the stepwise multiple linear regression models can capture the observed PA anomalies for most regions. Based on the contribution calculation, cloud fraction dominates the variability of PA in the mid- and low latitudes while ice/snow percent coverage (or surface albedo) dominates the variability in the mid- and high latitudes. Changes in cloud liquid water path and ice water path are the secondary dominant factor over most regions, whereas change in vegetation cover is the least important factor over land. These results verify the effects of atmospheric and surface factors on planetary albedo changes and thus may be of benefit for improving the parameterization of the PA and determining the climate feedbacks.

Intraseasonal Forcing of Convection and Lightning Activity in the Southern Amazon as a Function of Cross-Equatorial Flow

2006 ◽  
Vol 19 (13) ◽  
pp. 3180-3196 ◽  
Author(s):  
Walter A. Petersen ◽  
Rong Fu ◽  
Mingxuan Chen ◽  
Richard Blakeslee
Keyword(s):  
Wind Shear ◽  
Lightning Activity ◽  
Lightning Flash ◽  
Easterly Wind ◽  
Water Path ◽  
Low Level ◽  
Ice Water Path ◽  
Stratiform Precipitation ◽  
Ice Water ◽  
Thermodynamic Instability

Abstract This study focuses on modulation of lightning and convective vertical structure in the southern Amazon as a function of the South American monsoon V index (VI). Four wet seasons (December–March 1998–2001) of Tropical Rainfall Measuring Mission (TRMM) Lightning Imaging Sensor (LIS) and Precipitation Radar (PR) data are examined together with two wet seasons (2000–01) of ground-based Brazilian Lightning Detection Network (BLDN) data. These observations are composited by VI phase (northerly or southerly) for a region of the southern Amazon and discussed relative to VI-regime environmental characteristics such as thermodynamic instability and wind shear. Relative comparisons of VI-regime convective properties reveal 1) slightly larger (20%–25%) PR pixel-mean rainfall during periods of northerly VI due to increased stratiform precipitation, 2) a factor of 2 or more increase in lightning flash density and the lightning diurnal cycle amplitude during periods of southerly VI, 3) a factor of 1.5–2 increase in the conditional probability of any PR radar reflectivity pixel exceeding 30 dBZ above the −10°C level during periods of southerly VI, and 4) an associated factor of 2 or more increase in southerly VI pixel-mean ice water path, with the ice water path being highly correlated to trends in lightning activity. During periods of southerly VI, convection occurs in an environment of increased thermodynamic instability, weak southeasterly low-level, and deep upper-tropospheric easterly wind shear. During periods of northerly VI, low-level westerly shear opposes stronger deep tropospheric easterly shear in a relatively moist environment of weaker thermodynamic instability, consistent with the occurrence of more widespread stratiform precipitation. The composite results of this study point to 1) regime differences in convective forcing that alter the prevalence of ice processes and, by inference, the vertical profile of latent heating and 2) the utility of lightning observations in delineating convective regime changes.

scholarly journals Low-level mixed-phase clouds in a complex Arctic environment

2020 ◽  
Vol 20 (6) ◽  
pp. 3459-3481 ◽  
Author(s):  
Rosa Gierens ◽  
Stefan Kneifel ◽  
Matthew D. Shupe ◽  
Kerstin Ebell ◽  
Marion Maturilli ◽  
...  
Keyword(s):  
Large Scale ◽  
Local Wind ◽  
Liquid Water Path ◽  
Water Path ◽  
Local Boundary ◽  
Low Level ◽  
Ice Water Path ◽  
Mixed Phase Clouds ◽  
Ice Water ◽  
Surface Coupling

Abstract. Low-level mixed-phase clouds (MPCs) are common in the Arctic. Both local and large-scale phenomena influence the properties and lifetime of MPCs. Arctic fjords are characterized by complex terrain and large variations in surface properties. Yet, not many studies have investigated the impact of local boundary layer dynamics and their relative importance on MPCs in the fjord environment. In this work, we used a combination of ground-based remote sensing instruments, surface meteorological observations, radiosoundings, and reanalysis data to study persistent low-level MPCs at Ny-Ålesund, Svalbard, for a 2.5-year period. Methods to identify the cloud regime, surface coupling, and regional and local wind patterns were developed. We found that persistent low-level MPCs were most common with westerly winds, and the westerly clouds had a higher mean liquid (42 g m−2) and ice water path (16 g m−2) compared to those with easterly winds. The increased height and rarity of persistent MPCs with easterly free-tropospheric winds suggest the island and its orography have an influence on the studied clouds. Seasonal variation in the liquid water path was found to be minimal, although the occurrence of persistent MPCs, their height, and their ice water path all showed notable seasonal dependency. Most of the studied MPCs were decoupled from the surface (63 %–82 % of the time). The coupled clouds had 41 % higher liquid water path than the fully decoupled ones. Local winds in the fjord were related to the frequency of surface coupling, and we propose that katabatic winds from the glaciers in the vicinity of the station may cause clouds to decouple. We concluded that while the regional to large-scale wind direction was important for the persistent MPC occurrence and properties, the local-scale phenomena (local wind patterns in the fjord and surface coupling) also had an influence. Moreover, this suggests that local boundary layer processes should be described in models in order to present low-level MPC properties accurately.

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