scholarly journals Retrieval of the land-sea contrast of cloud liquid water path by applying a physical inversion algorithm to combined zenith and off-zenith ground-based microwave measurements

2022 ◽  
Author(s):  
Vladimir Kostsov ◽  
Dmitry Ionov ◽  
Anke Kniffka
Keyword(s):  
Gulf Of Finland ◽  
Cloud Base ◽  
Microwave Measurements ◽  
Liquid Water Path ◽  
Observational Site ◽  
Control Procedures ◽  
Cloud Liquid Water Path ◽  
The Gulf Of Finland ◽  
Neva Bay ◽  
Cloud Base Height

Abstract. Combined zenith and off-zenith ground-based observations by modern microwave radiometers provide an opportunity to study horizontal inhomogeneities of the humidity field in the troposphere and of the cloud liquid water path (LWP) spatial distribution. However, practical applications are difficult and require thorough analysis of the information content of measurements, assessment of errors of data processing algorithm and the development of the quality control procedures. In this study we analyse the application of our LWP retrieval algorithm based on the inversion of the radiative transfer equation to the problem of detection of the LWP horizontal inhomogeneities by means of ground-based microwave observations in the vicinity of a coastline of a water object of medium size. The study is based on data acquired by the microwave radiometer RPG-HATPRO which is located in the suburbs of St.Petersburg, Russia, at 2.5 km distance from the coastline of the Neva Bay (the Gulf of Finland) and is operating in angular scanning mode in the vertical plane. The retrieval setup is organised in such a way that zenith and off-zenith measurements provide equal sensitivity to atmospheric parameters. The optimal elevation angles for off-zenith observations are selected. The possibility to detect LWP horizontal inhomogeneity, namely the LWP land-sea contrast, for different measurement geometries (elevation angles) and values of cloud base height is analysed. It is shown that ground-based microwave observations in the vicinity of a coastline can be a valuable tool for validation of the space-borne measurements of the LWP land-sea contrast if three principal requirements are met: (a) the multi-parameter physical inversion method is used for retrieving LWP; (b) rigorous bias correction and quality control procedures are applied to the retrieval results; (c) the information on the cloud base height is available. As a result of processing the microwave measurements at the observational site of St.Petersburg State University, the monthly-averaged values of the LWP land-sea difference have been obtained for summer months within the period 2013–2021. For 24 out of 25 months of high quality observations, the LWP land-sea monthly difference is positive (larger values over land and smaller values over water) and can reach 0.06–0.07 kg m−2. The estimations of the LWP land-sea contrast obtained from the ground-based microwave measurements at the observational site of St.Petersburg University are in very good agreement with the values of the LWP land-sea contrast obtained from the multi-year space-borne measurements by the SEVIRI instrument (Spinning Enhanced Visible and InfraRed Imager) in the region of the Neva Bay (the Gulf of Finland) in June and July. For August, the so-called “August anomaly” detected by space-borne observations is not confirmed by the ground-based measurements.

scholarly journals Detection of the cloud liquid water path horizontal inhomogeneity in a coastline area by means of ground-based microwave observations: feasibility study

2020 ◽  
Author(s):  
Vladimir S. Kostsov ◽  
Dmitry V. Ionov ◽  
Anke Kniffka
Keyword(s):  
Liquid Water ◽  
Satellite Observations ◽  
Gulf Of Finland ◽  
Horizontal Gradient ◽  
Liquid Water Path ◽  
Temporal Behaviour ◽  
Cloud Liquid Water ◽  
Water Path ◽  
Cloud Liquid Water Path ◽  
The Gulf Of Finland

Abstract. The improvement of cloud modelling for global and regional climate and weather studies requires comprehensive information on many cloud parameters. This information is delivered by remote observations of clouds from ground-based and space-borne platforms using different methods and processing algorithms. Cloud liquid water path (LWP) is one of the main obtained quantities. Previously, the measurements of LWP by the SEVIRI and AVHRR satellite instruments provided the evidences of the systematic differences between LWP values over land and water areas in Northern Europe. An attempt is made to detect such differences by means of ground-based microwave observations performed near the coastline of the Gulf of Finland in the vicinity of St. Petersburg, Russia. The microwave radiometer RPG HATPRO located 2.5 km from the coastline is functioning in the angular scanning mode and is probing the air portions over land (at elevation angle 90°) and over water area (at 7 elevation angles in the range 4.8°–30°). The problem of the LWP horizontal gradient detection is examined in the measurement domain: the brightness temperatures of the microwave radiation measured at different elevation angles in the 31.4 GHz and 22.24 GHz spectral channels are analysed and compared with the corresponding values which were calculated under the assumption of horizontal homogeneity of the atmosphere. Several specific cases, selected on the basis of the analysis of the satellite observations by the SEVIRI instrument were considered in detail including: clear-sky conditions, the presence of clouds over the radiometer and at the same time the absence of clouds over the Gulf of Finland, and overcast conditions over the radiometer and over the opposite shore of the Gulf of Finland. The influence of the land-sea LWP difference on the brightness temperature values in the 31.4 GHz spectral channel has been demonstrated and the following features have been detected: (1) an interfering systematic signal is present in the 31.4 GHz channel which can attributed to the humidity horizontal gradient; (2) clouds over the opposite shore of the Gulf of Finland mask the LWP gradient effect. Preliminary results of the retrieval of LWP over water by statistical regression method are presented. These monthly averaged results are compared to the corresponding values derived from the satellite observations by the SEVIRI instrument. The agreement between satellite and ground-based results is very good for warm season in terms of temporal behaviour if systematic difference is neglected.

scholarly journals Detection of the cloud liquid water path horizontal inhomogeneity in a coastline area by means of ground-based microwave observations: feasibility study

2020 ◽  
Vol 13 (8) ◽  
pp. 4565-4587
Author(s):  
Vladimir S. Kostsov ◽  
Dmitry V. Ionov ◽  
Anke Kniffka
Keyword(s):  
Liquid Water ◽  
Elevation Angle ◽  
Gulf Of Finland ◽  
Horizontal Gradient ◽  
Statistical Regression ◽  
Liquid Water Path ◽  
Cloud Liquid Water ◽  
Water Path ◽  
Cloud Liquid Water Path ◽  
The Gulf Of Finland

Abstract. Improvement of cloud modelling for global and regional climate and weather studies requires comprehensive information on many cloud parameters. This information is delivered by remote observations of clouds from ground-based and space-borne platforms using different methods and processing algorithms. Cloud liquid water path (LWP) is one of the main obtained quantities. Previously, measurements of LWP by the SEVIRI (Spinning Enhanced Visible and InfraRed Imager) and AVHRR (Advanced Very High Resolution Radiometer) satellite instruments provided evidence for the systematic differences between LWP values over land and water areas in northern Europe. An attempt is made to detect such differences by means of ground-based microwave observations performed near the coastline of the Gulf of Finland in the vicinity of St Petersburg, Russia. The microwave radiometer (RPG-HATPRO, Radiometer Physics GmbH – Humidity And Temperature PROfiler), located 2.5 km from the coastline, is functioning in the angular scanning mode and is probing the air portions over land (at an elevation angle of 90∘) and over water (at seven elevation angles in the range 4.8–30∘). The influence of the land–sea LWP difference on the brightness temperature values in the 31.4 GHz spectral channel has been demonstrated, and the following features have been detected: (1) an interfering systematic signal is present in the 31.4 GHz channel, which can be attributed to the humidity horizontal gradient, (2) clouds over the opposite shore of the Gulf of Finland mask the LWP gradient effect. Preliminary results of the retrieval of LWP over water by the statistical regression method applied to the microwave measurements by HATPRO in the 31.4 and 22.24 GHz channels are presented. The monthly averaged results are compared to the corresponding values derived from the satellite observations by the SEVIRI instrument and from the reanalysis data.

PROBLEM OF HEAVY METAL SURFACE SEDIMENT CONTAMINATION IN THE EASTERN GULF OF FINLAND

2017 ◽  
Author(s):  
N Derugina ◽  
N Derugina ◽  
А Grigoriev ◽  
A Grigoriev ◽  
Дарья Рябчук ◽  
...  
Keyword(s):  
Heavy Metals ◽  
Heavy Metal ◽  
Bottom Sediments ◽  
Late Holocene ◽  
Sediment Contamination ◽  
Gulf Of Finland ◽  
Slow Decline ◽  
Contamination Levels ◽  
The Gulf Of Finland ◽  
Neva Bay

This project defines the pre-industrial quantities of heavy metals in sediment sequences of the Late Holocene from the Eastern Gulf of Finland. A comparative analysis reveals differences and similarities in the current concentrations of heavy metals in bottom sediments and pre-industrial levels. It is found that the maximum concentrations of heavy metals in the bottom sediments of the Gulf of Finland and Neva Bay occurred in the period of 1950-1990. Since the 1990s, the trend has been a slow decline in the contamination levels; however, the concentrations of some heavy metals in bottom sediments remain high.

scholarly journals Climatology of Warm Boundary Layer Clouds at the ARM SGP Site and Their Comparison to Models

2004 ◽  
Vol 17 (24) ◽  
pp. 4760-4782 ◽  
Author(s):  
Manajit Sengupta ◽  
Eugene E. Clothiaux ◽  
Thomas P. Ackerman
Keyword(s):  
Liquid Water ◽  
Solar Flux ◽  
Cloud Base ◽  
Liquid Water Path ◽  
Cloud Liquid Water ◽  
Water Path ◽  
Cloud Forcing ◽  
Cloud Liquid Water Path ◽  
Ecmwf Model ◽  
Cloud Thickness

Abstract A 4-yr climatology (1997–2000) of warm boundary layer cloud properties is developed for the U.S. Department of Energy Atmospheric Radiation Measurement (ARM) Program Southern Great Plains (SGP) site. Parameters in the climatology include cloud liquid water path, cloud-base height, and surface solar flux. These parameters are retrieved from measurements produced by a dual-channel microwave radiometer, a millimeter-wave cloud radar, a micropulse lidar, a Belfort ceilometer, shortwave radiometers, and atmospheric temperature profiles amalgamated from multiple sources, including radiosondes. While no significant interannual differences are observed in the datasets, there are diurnal variations with nighttime liquid water paths consistently higher than daytime values. The summer months of June, July, and August have the lowest liquid water paths and the highest cloud-base heights. Model outputs of cloud liquid water paths from the European Centre for Medium-Range Weather Forecasts (ECMWF) model and the Eta Model for 104 model output location time series (MOLTS) stations in the environs of the SGP central facility are compared to observations. The ECMWF and MOLTS median liquid water paths are greater than 3 times the observed values. The MOLTS data show lower liquid water paths in summer, which is consistent with observations, while the ECMWF data exhibit the opposite tendency. A parameterization of normalized cloud forcing that requires only cloud liquid water path and solar zenith angle is developed from the observations. The parameterization, which has a correlation coefficient of 0.81 with the observations, provides estimates of surface solar flux that are comparable to values obtained from explicit radiative transfer calculations based on plane-parallel theory. This parameterization is used to estimate the impact on the surface solar flux of differences in the liquid water paths between models and observations. Overall, there is a low bias of 50% in modeled normalized cloud forcing resulting from the excess liquid water paths in the two models. Splitting the liquid water path into two components, cloud thickness and liquid water content, shows that the higher liquid water paths in the model outputs are primarily a result of higher liquid water contents, although cloud thickness may a play a role, especially for the ECMWF model results.

scholarly journals New data on the flora of Centrophyceae (Bacillariophyta) in the Neva Bay of the Gulf of Finland (Russia)

Algologia ◽  
2021 ◽  
Vol 31 (4) ◽  
pp. 382-389
Author(s):  
S.I. Genkal ◽  
◽  
I.S. Trifonova ◽  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Microscopy Study ◽  
Systematic Position ◽  
Electron Microscopy Study ◽  
Gulf Of Finland ◽  
Centric Diatoms ◽  
The Gulf Of Finland ◽  
Neva Bay ◽  
Scanning Electron

This scanning electron microscopy study of phytoplankton from the Neva Bay and analysis of valve images from S.I. Genkal’s iconotheka have provided new data on centric diatoms of the Neva Bay. Representatives of the genera Aulacoseira scalaris and Stephanodiscus lacustris, new to the flora of the Bay, have been identified. The systematic position and distribution of 14 species and varieties of Centrophyceae from the genera Aulacoseira, Conticribra, Cyclostephanos, Ellerbeckia, Handmannia, Pantocsekiella, Stephanodiscus, Thalassiosira have been refined and specified. The species composition of the class Centrophyceae of the Neva Bay has been expanded. Now it includes 42 species and varieties from 17 genera.

PROBLEM OF HEAVY METAL SURFACE SEDIMENT CONTAMINATION IN THE EASTERN GULF OF FINLAND

2017 ◽  
Author(s):  
N Derugina ◽  
N Derugina ◽  
А Grigoriev ◽  
A Grigoriev ◽  
Дарья Рябчук ◽  
...  
Keyword(s):  
Heavy Metals ◽  
Heavy Metal ◽  
Bottom Sediments ◽  
Late Holocene ◽  
Sediment Contamination ◽  
Gulf Of Finland ◽  
Slow Decline ◽  
Contamination Levels ◽  
The Gulf Of Finland ◽  
Neva Bay

This project defines the pre-industrial quantities of heavy metals in sediment sequences of the Late Holocene from the Eastern Gulf of Finland. A comparative analysis reveals differences and similarities in the current concentrations of heavy metals in bottom sediments and pre-industrial levels. It is found that the maximum concentrations of heavy metals in the bottom sediments of the Gulf of Finland and Neva Bay occurred in the period of 1950-1990. Since the 1990s, the trend has been a slow decline in the contamination levels; however, the concentrations of some heavy metals in bottom sediments remain high.

scholarly journals Impact of the Vertical Variation of Cloud Droplet Size on the Estimation of Cloud Liquid Water Path and Rain Detection

2007 ◽  
Vol 64 (11) ◽  
pp. 3843-3853 ◽  
Author(s):  
Ruiyue Chen ◽  
Fu-Lung Chang ◽  
Zhanqing Li ◽  
Ralph Ferraro ◽  
Fuzhong Weng
Keyword(s):  
Liquid Water ◽  
Cloud Droplet ◽  
Cloud Base ◽  
Liquid Water Path ◽  
Vertical Variation ◽  
Water Path ◽  
Moderate Resolution ◽  
Moderate Resolution Imaging Spectroradiometer ◽  
Cloud Liquid Water Path ◽  
Mean Square Errors

Abstract Cloud droplet effective radius (DER) and liquid water path (LWP) are two key parameters for the quantitative assessment of cloud effects on the exchange of energy and water. Chang and Li presented an algorithm using multichannel measurements made at 3.7, 2.1, and 1.6 μm to retrieve a cloud DER vertical profile for improved cloud LWP estimation. This study applies the multichannel algorithm to the NASA Moderate Resolution Imaging Spectroradiometer (MODIS) data on the Aqua satellite, which also carries the Advanced Microwave Scanning Radiometer (AMSR-E) for measuring cloud LWP and precipitation. By analyzing one day of coincident MODIS and AMSR-E observations over the tropical oceans between 40°S and 40°N for overcast warm clouds (>273 K) having optical depths between 3.6 and 23, the effects of DER vertical variation on the MODIS-derived LWP are reported. It is shown that the LWP tends to be overestimated if the DER increases with height within the cloud and underestimated if the DER decreases with height within the cloud. Despite the uncertainties in both MODIS and AMSR-E retrievals, the result shows that accounting for the DER vertical variation reduces the mean biases and root-mean-square errors between the MODIS- and AMSR-E–derived LWPs. Besides, the manner in which the DER changes with height has the potential for differentiating precipitative and nonprecipitative warm clouds. For precipitating clouds, the DER at the cloud top is substantially smaller than the DER at the cloud base. For nonprecipitating clouds, however, the DER differences between the cloud top and the cloud base are much less.

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