MWRRETV2 Value-Added Product Report: The Retrieval of Liquid Water Path and Precipitable Water Vapor from Microwave Radiometer – 3-Channel (MWR3C) Data Sets

Abstract. Feng-Yun 3D (FY-3D) satellite is the latest polar-orbiting meteorological satellite launched by China and carry 10 instruments onboard. Its microwave temperature sounder (MWTS) and microwave humidity sounder (MWHS) can acquire a total of 28 channels of brightness temperatures, providing rich information for profiling atmospheric temperature and moisture. However, due to a lack of two important frequencies at 23.8 and 31.4 GHz, it is difficult to retrieve the total precipitable water vapor (TPW) and cloud liquid water path (CLW) from FY-3D microwave sounder data as commonly done for other microwave sounding instruments. Using the channel similarity between Suomi NPP advanced technology microwave sounder (ATMS) and FY-3D microwave temperature and humidity sounders, a machine learning technique is used to generate the two missing low frequency channels of MWTS and MWHS. Then, a new data set named as a combined microwave sounder (CMWS) is obtained and has the same channel setting as ATMS but the spatial resolution is consistent with MWTS. It is shown that the mean absolute errors of the two simulated channels are both between 3 and 4 K. The simulation errors mainly distribute in the high latitude regions, coastlines and the boundaries of some heavy rainfall. A statistical inversion method is adopted to retrieve TPW and CLW over oceans from the FY-3D CMWS. The inter-comparison between different satellites shows that the inversion products of FY-3D CMWS and Suomi NPP ATMS have good consistency in magnitude and distribution.

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Ground-based observations of cloud and drizzle liquid water path in stratocumulus clouds

Atmospheric Measurement Techniques ◽

10.5194/amt-13-1485-2020 ◽

2020 ◽

Vol 13 (3) ◽

pp. 1485-1499 ◽

Cited By ~ 1

Author(s):

Maria P. Cadeddu ◽

Virendra P. Ghate ◽

Mario Mech

Keyword(s):

Liquid Water ◽

Microwave Radiometer ◽

Precipitable Water ◽

Cloud Base ◽

Radiative Cooling ◽

Liquid Water Path ◽

Cell Systems ◽

Water Path ◽

Closed Cell ◽

Stratocumulus Clouds

Abstract. The partition of cloud and drizzle water path in precipitating clouds plays a key role in determining the cloud lifetime and its evolution. A technique to quantify cloud and drizzle water path by combining measurements from a three-channel microwave radiometer (23.8, 30, and 90 GHz) with those from a vertically pointing Doppler cloud radar and a ceilometer is presented. The technique is showcased using 1 d of observations to derive precipitable water vapor, liquid water path, cloud water path, drizzle water path below the cloud base, and drizzle water path above the cloud base in precipitating stratocumulus clouds. The resulting cloud and drizzle water path within the cloud are in good qualitative agreement with the information extracted from the radar Doppler spectra. The technique is then applied to 10 d each of precipitating closed and open cellular marine stratocumuli. In the closed-cell systems only ∼20 % of the available drizzle in the cloud falls below the cloud base, compared to ∼40 % in the open-cell systems. In closed-cell systems precipitation is associated with radiative cooling at the cloud top <-100Wm-2 and a liquid water path >200 g m−2. However, drizzle in the cloud begins to exist at weak radiative cooling and liquid water path >∼150 g m−2. Our results collectively demonstrate that neglecting scattering effects for frequencies at and above 90 GHz leads to overestimation of the total liquid water path of about 10 %–15 %, while their inclusion paves the path for retrieving drizzle properties within the cloud.

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Measurement of Vertical Liquid Water Path by Means of an Airborne Radiometer and the Shortwave Albedo of Marine Low-Level Clouds during WENPEX in Japan

Journal of Applied Meteorology ◽

10.1175/1520-0450-34.2.471 ◽

1995 ◽

Vol 34 (2) ◽

pp. 471-481 ◽

Cited By ~ 4

Author(s):

Y. Fujiyoshi ◽

Y. Ishizaka ◽

T. Takeda ◽

T. Hayasaka ◽

M. Tanaka

Keyword(s):

Boundary Layer ◽

Planetary Boundary Layer ◽

Liquid Water ◽

Microwave Radiometer ◽

Cloud Droplet ◽

Precipitable Water ◽

Horizontal Distribution ◽

Liquid Water Path ◽

Water Path ◽

Boundary Layer Clouds

Abstract Special observations were made over the southwest island area of the East China Sea from 12 to 27 January 1991 as part of the World Climate Research Program in Japan (WENPEXWestern North Pacific CloudRadiation Experiment). Two aircraft were used to determine the air truth of the total vertical liquid water path (LWP) using a microwave radiometer. One airplane was fitted with a 37-GHz radiometer and flew above planetary boundary layer clouds. The other flew inside the clouds with a cloud droplet spectrometer. These aircraft flew simultaneously along the same flight path when planetary boundary layer clouds were formed over the warm sea during an outbreak of cold air. The result of the air truth of the LWPradiometer indicates that the 37-GHZ microwave radiometer gives an estimation of the LWP accurate to 100 mg cm−2. The shortwave cloud albedo was related to the LWPradiometer. The albedo increases with the LWP, independent of cloud type, when measured just above the cloud tops. The measured albedo is nearly the same as the calculated albedo when the LWPradiometer is larger than 60 mg cm−2 but much smaller than the calculated albedo when the LWPradiometer is less than 40 mg cm−2. Cloud-top irregularity is suggested to be the primary cause of this discrepancy. The degree of inhomogeneity of the horizontal distribution of liquid water appears to be correlated with the amount of precipitable water in the planetary boundary layer.

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The influence of water vapor anomalies on clouds and their radiative effect at Ny-Ålesund

Atmospheric Chemistry and Physics ◽

10.5194/acp-20-5157-2020 ◽

2020 ◽

Vol 20 (8) ◽

pp. 5157-5173 ◽

Cited By ~ 1

Author(s):

Tatiana Nomokonova ◽

Kerstin Ebell ◽

Ulrich Löhnert ◽

Marion Maturilli ◽

Christoph Ritter

Keyword(s):

Water Vapor ◽

Liquid Water ◽

Microwave Radiometer ◽

The Arctic ◽

Radiative Effect ◽

Liquid Water Path ◽

Surface Cooling ◽

Water Path ◽

Cloud Properties ◽

The Mean

Abstract. The occurrence of events with increased and decreased integrated water vapor (IWV) at the Arctic site Ny-Ålesund, their relation to cloud properties, and the surface cloud radiative effect (CRE) is investigated. For this study, we used almost 2.5 years (from June 2016 to October 2018) of ground-based cloud observations processed with the Cloudnet algorithm, IWV from a microwave radiometer (MWR), long-term radiosonde observations, and backward trajectories FLEXTRA. Moist and dry anomalies were found to be associated with North Atlantic flows and air transport within the Arctic region, respectively. The amount of water vapor is often correlated to cloud occurrence, presence of cloud liquid water, and liquid water path (LWP) and ice water path (IWP). In turn, changes in the cloud properties cause differences in surface CRE. During dry anomalies, in autumn, winter, and spring, the mean net surface CRE was lower by 2–37 W m−2 with respect to normal conditions, while in summer the cloud-related surface cooling was reduced by 49 W m−2. In contrast, under moist conditions in summer the mean net surface CRE becomes more negative by 25 W m−2, while in other seasons the mean net surface CRE was increased by 5–37 W m−2. Trends in the occurrence of dry and moist anomalies were analyzed based on a 25-year radiosonde database. Dry anomalies have become less frequent, with rates for different seasons ranging from −12.8 % per decade to −4 % per decade, while the occurrence of moist events has increased at rates from 2.8 % per decade to 6.4 % per decade.

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Ground-based Observations of Cloud and Drizzle Liquid Water Path in Stratocumulus Clouds

10.5194/amt-2019-346 ◽

2019 ◽

Author(s):

Maria P. Cadeddu ◽

Virendra P. Ghate ◽

Mario Mech

Keyword(s):

Liquid Water ◽

Microwave Radiometer ◽

Precipitable Water ◽

Cloud Base ◽

Radiative Cooling ◽

Liquid Water Path ◽

Cell Systems ◽

Water Path ◽

Closed Cell ◽

Stratocumulus Clouds

Abstract. The partition of cloud and drizzle liquid water path in precipitating clouds plays a key role in determining the cloud lifetime and its evolution. A technique to quantify cloud and drizzle liquid water path by combining measurements from a three-channel microwave radiometer (23.8, 30, and 90 GHz) with those from a vertically pointing Doppler cloud radar and a ceilometer is presented. The technique is showcased using one-day of observations to derive precipitable water vapor, liquid water path, cloud water path, drizzle water path below the cloud base, and drizzle water path above the cloud base in precipitating stratocumulus clouds. The resulting cloud and drizzle water path within the cloud are in good qualitative agreement with the information extracted from the radar Doppler spectra. The technique is then applied to ten days each of precipitating closed and open cellular marine stratocumuli. In the closed cell systems only ~20% of the available drizzle in the cloud falls below the cloud base, compared to ~40% in the open cell systems. In closed cell systems precipitation is associated with radiative cooling at the cloud top < −100 W/m2 and liquid water path > 200 g/m2. However, drizzle in the cloud begins to exists at weak radiative cooling and liquid water path > ~150 g/m2. Our results collectively demonstrate that neglecting scattering effects for frequencies at and above 90 GHz leads to overestimation of the total liquid water path of about 10–15%, while their inclusion paves the path for retrieving drizzle properties within the cloud.

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