Missing North Atlantic cyclonic precipitation in ECMWF numerical weather prediction and ERA-40 data detected through the satellite climatology HOAPS II

Klepp, C.; Bakan, Stephan; Graßl, Hartmut

doi:10.1127/0941-2948/2005/0088

Cited by 8 publications

(7 citation statements)

References 8 publications

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“…To answer the question we analyzed data from two different precipitation climatologies, namely the Global Precipitation Climatology Project (GPCP) [ Adler et al , 2003] and the Hamburg Ocean Atmosphere Parameters and Fluxes from Satellite Data (HOAPS‐3). Preceding studies for midlatitude cyclones confirm that precipitation structures and intensities in HOAPS‐3 are in good agreement with observations of various precipitation types, including postfrontal lows (PFL) [ Klepp et al , 2005].…”

Section: Analysis Of Satellite Datasupporting

confidence: 62%

Southern Ocean phytoplankton increases cloud albedo and reduces precipitation

Krüger

Graßl

2011

Geophys. Res. Lett.

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[1] Effects of natural and anthropogenic aerosol particles on the radiation budget in cloudy atmospheres are still a major research topic. For example, can an increase or decrease in aerosol particle number, originating from changed dimethylsulfide (DMS) and isoprene emissions by marine phytoplankton, impact the earth radiation budget via increasing or decreasing planetary albedo and lifetime of clouds? And if so, is a shifted cloud droplet spectrum accompanied by a regional change in precipitation? Here, we show by a synergistic analysis of satellite observations (MODIS, SeaWiFS, AIRS, SSM/I and CERES) that the phytoplankton related emission of the mentioned gases into the atmosphere strongly influences cloud properties within a broad latitude belt in the Southern Hemisphere during the austral summer. For this season we detected indirect aerosol effects over the Southern Ocean from 45°S to 65°S, especially in regions with plankton blooms, indicated by high chlorophyll-a concentration in seawater. The strong increase in cloud condensation nuclei column content from 2.0 × 10 8 to more than 5.0 × 10 8 CCN/cm 2 for a chlorophyll increase from 0.3 to about 0.5 mg/m 3 in these regions decreases cloud droplet effective radius and increases cloud optical thickness for water clouds. Consequently, the upward short-wave radiative flux at the top of the atmosphere increases. Our analysis also reveals reduced precipitation over the Antarctic Polar Frontal Zone during strong plankton blooms. We suggest that due to fine particles formed in the atmosphere originating from gaseous DMS and possibly isoprene emissions the reduction of precipitation is caused by delayed homogeneous freezing in water clouds.Citation: Krüger, O., and H. Graßl (2011), Southern Ocean phytoplankton increases cloud albedo and reduces precipitation, Geophys. Res. Lett., 38, L08809,

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Section: Analysis Of Satellite Datasupporting

confidence: 62%

Southern Ocean phytoplankton increases cloud albedo and reduces precipitation

Krüger

Graßl

2011

Geophys. Res. Lett.

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“…Utilizing in situ voluntary observing ship data, it was shown that, in contrast to other satellite products, HOAPS recognizes smallscale intensive precipitation systems in cold air outbreaks with reliable patterns and intensities. This type of precipitation is also mostly missing in a large sample of events investigated in the ECMWF numerical weather prediction and ERA-40 reanalysis datasets (Klepp et al 2005). Furthermore, Klepp et al (2010) demonstrate the ability of HOAPS to detect even light amounts of cold season snowfall with a high accuracy of 96% between point-to-area collocations of ship-based optical disdrometers and satellite data.…”

Section: E Precipitationmentioning

confidence: 95%

“…This is in agreement with previous intercomparison studies that included satellite-based as well as model-based precipitation estimates. These showed regionally large differences among the individual products that are up to 50% in regions of strong precipitation and at high latitudes (e.g., Adler et al 2001;Klepp et al 2005;Beranger et al 2006). Particularly in the tropical regions model-based data (e.g., reanalysis products) are found to perform significantly poorer than satellite-derived fields (Trenberth and Guillemot 1998;Janowiak et al 1998;Shinoda et al 1999).…”

Section: E Precipitationmentioning

confidence: 99%

“…For the mid-high latitudes detailed case study analyses on midlatitude cyclones with intense postfrontal mesoscale convective mixed-phase precipitation were carried out by Klepp et al (2003). Utilizing in situ voluntary observing ship data, it was shown that, in contrast to other satellite products, HOAPS recognizes smallscale intensive precipitation systems in cold air outbreaks with reliable patterns and intensities.…”

Section: E Precipitationmentioning

confidence: 99%

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Evaluation of HOAPS-3 Ocean Surface Freshwater Flux Components

Andersson

Klepp

Fennig

et al. 2011

Journal of Applied Meteorology and Climatology

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Today, latent heat flux and precipitation over the global ocean surface can be determined from microwave satellite data as a basis for estimating the related fields of the ocean surface freshwater flux. The Hamburg Ocean Atmosphere Parameters and Fluxes from Satellite Data (HOAPS) is the only generally available satellite-based dataset with consistently derived global fields of both evaporation and precipitation and hence of freshwater flux for the period 1987-2005. This paper presents a comparison of the evaporation E, precipitation P, and the resulting freshwater flux E 2 P in HOAPS with recently available reference datasets from reanalysis and other satellite observation projects as well as in situ ship measurements. In addition, the humidity and wind speed input parameters for the evaporation are examined to identify sources for differences between the datasets. Results show that the general climatological patterns are reproduced by all datasets. Global mean time series often agree within about 10% of the individual products, while locally larger deviations may be found for all parameters. HOAPS often agrees better with the other satellite-derived datasets than with the in situ or the reanalysis data. The agreement usually improves in regions of good in situ sampling statistics. The biggest deviations of the evaporation parameter result from differences in the nearsurface humidity estimates. The precipitation datasets exhibit large differences in highly variable regimes with the largest absolute differences in the ITCZ and the largest relative biases in the extratropical storm-track regions. The resulting freshwater flux estimates exhibit distinct differences in terms of global averages as well as regional biases. In comparison with long-term mean global river runoff data, the ocean surface freshwater balance is not closed by any of the compared fields. The datasets exhibit a positive bias in E 2 P of 0.2-0.5 mm day 21 , which is on the order of 10% of the evaporation and precipitation estimates.* Current affiliation:

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“…State‐of‐the‐art satellite retrievals and reanalysis data sets still disagree on global precipitation amounts, patterns, variability and temporal behaviour (Andersson, 2009), with the relative differences increasing in the poleward direction. The estimation of frequency of occurrence and amounts of mixed‐phase precipitation and snowfall is most challenging as results by Klepp et al (2003 and 2005) indicate for North Atlantic cyclones and its post‐frontal precipitation. Hence, satellite based retrievals for the estimation of instantaneous pixel‐level mixed‐phase precipitation need to be ground validated to assess retrieval accuracy across the wide range of synoptic conditions that lead to precipitation.…”

Section: Introductionmentioning

confidence: 99%

Ground validation of oceanic snowfall detection in satellite climatologies during LOFZY

Klepp¹,

Bumke²,

Bakan³

et al. 2010

Tellus A

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A B S T R A C T A thorough knowledge of global ocean precipitation is an indispensable prerequisite for the understanding of the water cycle in the global climate system. However, reliable detection of precipitation over the global oceans, especially of solid precipitation, remains a challenging task. This is true for both, passive microwave remote sensing and reanalysis based model estimates. The optical disdrometer ODM 470 is a ground validation instrument capable of measuring rain and snowfall on ships even under high wind speeds. It was used for the first time over the Nordic Seas during the LOFZY 2005 campaign. A dichotomous verification of precipitation occurrence resulted in a perfect correspondence between the disdrometer, a precipitation detector and a shipboard observer's log. The disdrometer data is further pointto-area collocated against precipitation from the satellite based Hamburg Ocean Atmosphere Parameters and fluxes from Satellite data (HOAPS) climatology. HOAPS precipitation turns out to be overall consistent with the disdrometer data resulting in a detection accuracy of 0.96. The collocated data comprises light precipitation events below 1 mm h -1 . Therefore two LOFZY case studies with high precipitation rates are presented that indicate plausible HOAPS satellite precipitation rates. Overall, this encourages longer term measurements of ship-to-satellite collocated precipitation in the near future.

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Missing North Atlantic cyclonic precipitation in ECMWF numerical weather prediction and ERA-40 data detected through the satellite climatology HOAPS II

Cited by 8 publications

References 8 publications

Southern Ocean phytoplankton increases cloud albedo and reduces precipitation

Southern Ocean phytoplankton increases cloud albedo and reduces precipitation

Evaluation of HOAPS-3 Ocean Surface Freshwater Flux Components

Ground validation of oceanic snowfall detection in satellite climatologies during LOFZY

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