The overarching theme of the research unit's work will be the analysis and understanding of the freshwater budget of the ocean, including the role, which surface freshwater fluxes (net evaporation minus precipitation plus run-off and sea ice melting) play in changing the salt content in the upper ocean.


New FOR1740 puplication

Our PhD Yao Fu puplished an article entitled: "Atlantic Meridional Overturning Circulation at 14.5° N in 1989 and 2013 and 24.5° N in 1992 and 2015: volume, heat, and freshwater transports"

Abstract: The Atlantic Meridional Overturning Circulation (AMOC) is analyzed by applying a box inverse model to hydrographic data from transatlantic sections along 14.5°N, occupied in 1989 and 2013, and along 24.5°N, occupied in 1992 and 2015. Direct comparison of water mass properties among the different realizations at the respective latitudes shows that the Antarctic Intermediate Water (AAIW) became warmer and saltier at 14.5°N, and the densest Antarctic Bottom Water became lighter, while the North Atlantic Deep Water freshened at both latitudes. The inverse solution shows that the intermediate layer transport at 14.5°N was also markedly weaker in 2013 than in 1989, indicating that the AAIW property changes at this latitude may be related to changes in the circulation. The inverse solution was validated using the RAPID and MOVE array data, and the GECCO2 ocean state estimate. Comparison among these datasets indicates that the AMOC has not significantly weakened over the past 2 decades at both latitudes. Sensitivity tests of the inverse solution suggest that the overturning structure and heat transport across the 14.5°N section are sensitive to the Ekman transport, while freshwater transport is sensitive to the transport-weighted salinity at the western boundary.

The full article can be found here


"What do I want from my future?"

Our PhD students and the FOR1740 coordination participated to the second “I, Scientist” conference which was hosted in Berlin between the 25-26 May 2018. 

Only few people are aware of gender- based obstacles and prejudices with which even highly educated woman have to deal with. Therefore, one goal is to increase the visibility of these problems and to develop and discuss possible solutions.  The conference sees itself as a platform for orientation for young scientists to a variety of options in science, industry, and alternative fields and providing protected spaces where the female participants can network among themselves.

Motivational talks from female role models and discussions covered a wide range of gender equality topics, such as the compatibility of family and work, the under-representation of woman in leadership, ways to detect gender-related stereotypes and discrimination, the "imposter syndrome" among females and its overcoming as well as practices to empower and encourage female students. 

Moreover, the participants had the opportunity to network and to inform themselves about possible career path during the "career speed dating", networking events, workshops and discussion sessions, and where motivated not just thinking about what I really want to work on, but also how I want to work and what my future should look like.

The final public panel discussion with

concerned the “Equal rites- Why do we still talk about gender (in)equality in 2018”.

I, Scientist was initiated in 2016 by a group of PhD-students with the aim to take action for equal opportunities in the sciences and thus founded the Lise-Meitner Society e.V. as the conference host.


 (left) Photo by Eleni Tzortzi


New FOR1740 puplication

Our researcher Julian Liman puplished an article entitled: "Uncertainty characterization of HOAPS 3.3 latent heat-flux-related parameters"

Abstract:Latent heat flux (LHF) is one of the main contributors to the global energy budget. As the density of in situ LHF measurements over the global oceans is generally poor, the potential of remotely sensed LHF for meteorological applications is enormous.  However, to date none of the available satellite products have included estimates of systematic, random, and sampling uncertainties, all of which are essential for assessing their quality.  Here, the challenge is taken on by matching
LHF-related pixel-level data of the Hamburg Ocean Atmosphere Parameters and Fluxes from Satellite (HOAPS) climatology (version 3.3) to in situ measurements originating from a high-quality data archive of buoys and selected ships. Assuming the ground reference to be bias-free, this allows for deriving instantaneous systematic uncertainties as a function of four atmospheric predictor variables. The approach is regionally independent and therefore overcomes the issue of sparse in situ data densities over large oceanic areas. Likewise, random uncertainties are derived, which include not only a retrieval component but also contributions from in situ measurement noise and the collocation procedure.  A recently published random uncertainty decomposition approach is applied to isolate the random retrieval uncertainty of all LHF-related HOAPS parameters.  It makes use of two combinations
of independent data triplets of both satellite and in situ data, which are analysed in terms of their pairwise variances of differences.  Instantaneous uncertainties are finally aggregated, allowing for uncertainty characterizations on monthly to multi-annual timescales.  Results show that systematic LHF uncertainties range between 15 and 50 Wm^(-2) with a global mean of 25 Wm^(-2). Local maxima are mainly found over the subtropical ocean basins as well as along the western boundary currents. Investigations indicate that contributions from qa (U) to the overall LHF uncertainty are on the order of 60 % (25 %). From an instantaneous point of view, random retrieval uncertainties are specifically large over the subtropics with a global average of 37 Wm-2.  In a climatological sense, their magnitudes become negligible, as do respective sampling uncertainties.  Regional and seasonal analyses suggest that largest total LHF uncertainties are seen over the Gulf Stream and the Indian monsoon region during boreal winter.  In light of the uncertainty measures, the observed continuous global mean LHF increase up to 2009 needs to be treated with caution. The demonstrated approach can easily be
transferred to other satellite retrievals, which increases the significance of the present work.

The full article can be found here


FOR1740 @Ocean Sciences Meeting 2018

The Ocean Science Meeting 2018 brought  together marine scientists from all over the world.  It was held in Portland, February 11 to 16.

Our postdoctoral researcher Ilaria Stendardo was represented with a poster entitled "Long-Term Observations of Salinity Transport Along the Pathway of the North Atlantic Current at 47°N".

Also Julia Köhler presented her latest findings about salinity seasonal variability in the Indian Ocean and their underlying mechanisms at the poster session.

More informations about the salinity session program can be found here


News from Climate Science

Interview with Christian Klepp in "DAS!" at NDR

Christian Klepp was accompanied by a film team and gives an insight into his research on oceanic precipitation measured by optical disdrometers from long-term equipped Research Vessels (RV).

Have a look at the Interview (start after ~21min., only german)


New FOR1740 puplication

Our postdoctoral researcher Julia Köhler puplished an article entitled: "Mechanisms of Mixed-layer Salinity Seasonal Variability in the Indian Ocean"

Abstract: Based on a joint analysis of an ensemble mean of satellite sea surface salinity retrievals and the output of a high-resolution numerical ocean circulation simulation, physical processes are identified that control seasonal variations of mixed layer salinity (MLS) in the Indian Ocean, a basin where salinity changes dominate changes in density. In the northern and near-equatorial Indian Ocean, annual salinity changes are mainly driven by respective changes of the horizontal advection. South of the equatorial region, between 45°E and 90°E, where evaporation minus precipitation has a strong seasonal cycle, surface freshwater fluxes control the seasonal MLS changes. The influence of entrainment on the salinity variance is enhanced in mid-ocean upwelling regions, but remains small. The model and observational results reveal that vertical diffusion plays a major role in precipitation and river runoff dominated regions balancing the surface freshwater flux. Vertical diffusion is important as well in regions where the advection of low salinity leads to strong gradients across the mixed layer base. There, vertical diffusion explains a large percentage of annual MLS variance. The simulation further reveals that 1) high-frequency small-scale eddy processes primarily determine the salinity tendency in coastal regions (in particular in the Bay of Bengal), and 2) shear horizontal advection, brought about by changes in the vertical structure of the mixed layer, acts against mean horizontal advection in the equatorial salinity frontal regions. Observing those latter features with the existing observational components remains a future challenge.

The full article can be found here


News from Climate Science

Once a month, climate researchers report on their latest findings in the newspaper "Hamburger Abendblatt".

Christian Klepp explains, how to measure oceanic precipitation with an optical disdrometer from long-term equipped Research Vessels (RV) to validate satellite-precipitation products.

Have a look at the Welt article and Hamburger Abendblatt article (only german).


Release of HOAPS 4.0

HOAPS 4.0 surface freshwater flux data has finally been officially released (period 1987-2014).

Data sets and further informations can be found here . Please contact the "User Help Desk" if you want to access these data.


New FOR1740 puplications

The postdoctoral researcher Jörg Burdanowitz puplished a paper entitled " Simulation of Ship-Track versus Satellite-Sensor Differences in oceanic Precipitation using an Island-Based Radar"


The point-to-area problem strongly complicates the validation of satellite-based precipitation estimates, using surface-based point measurements. We simulate the limited spatial representation of light-to-moderate oceanic precipitation rates along ship tracks with respect to areal passive microwave satellite estimates using data from a subtropical island-based radar. The radar data serves to estimate the discrepancy between point-like and areal precipitation measurements. From the spatial discrepancy, two statistical adjustments are derived so that along-track precipitation ship data better represent areal precipitation estimates from satellite sensors. The first statistical adjustment uses the average duration of a precipitation event as seen along a ship track, and the second adjustment uses the median-normalized along-track precipitation rate. Both statistical adjustments combined reduce the root mean squared error by 0.24 mm/h (55%) compared to the unadjusted average track of 60 radar pixels in length corresponding to a typical ship speed of 24–34 km/h depending on track orientation. Beyond along-track averaging, the statistical adjustments represent an important step towards a more accurate validation of precipitation derived from passive microwave satellite sensors using point-like along-track surface precipitation reference data

Öffnet externen Link in neuem FensterYou can read the full article here


Our PhD candidate Xin Liu and the PIs Armin Köhl and Detlef Stammer puplished a new paper in "Journal of Geophysical Research" titled: "Dynamical ocean response to projected changes of the global water cycle"  


Over the next century substantial changes will occur in the ocean as a consequence of an accelerated global hydrological cycle and the associated net surface freshwater flux change is projected to result from global warming. This paper is concerned with the dynamical response to the associated surface volume flux anomalies. Based on ocean model runs driven by RCP8.5 surface freshwater flux anomalies over the period 2081–2100 relative to 1986–2005, we show that the adjustment of the circulation involves a barotropic circulation response as predicted from the Goldsbrough-Stommel theory. The corresponding barotropic circulation intensifies by approximately 20% with a stronger intensification of about 50% in the Southern Ocean, comparing to the present-day Goldsbrough-Stommel Circulation. The barotropic circulation anomaly induced by intensified freshwater flux reaches to 0.6 Sv in the Antarctic Circumpolar Current region. The adjustment also involves changes in the meridional overturning circulation mirroring the basin-wide averages of changes in the convergence and divergence of the mass transport driven by the surface volume flux. The subsequent pathways of fresh water match with the spreading of volume flux in the shallow cells but diverge substantially with depth. Associated with changes of the flow field are the changes in meridional heat and freshwater transports. Changes in the circulation also lead to a redistribution of temperature and salinity from which a significant contribution results in form of regional steric sea level changes. These changes are of the order of 0.5 cm and can be largely attributed to the displacement of the isopycnals.

Öffnet externen Link in neuem FensterThe full article can be downloaded here


 Have a look on what has been published so far


FOR1740 young researcher at the GODAE OceanView International School 2017

Our PhD student Aurpita Saha participated at the "GODAE OceanView International School 2017: New Frontiers in Operational Oceanography" , which took place between 2nd October and 13th October in Mallorca, Spain, under the auspices of IMEDEA (CSIC-UIB) and SOCIB. The summer school for observing, assimilating and forecasting the ocean was offered to early career scientists, professionals and students on the current state of the art in operational oceanography and related advances in the ocean sciences.

During the poster session, Aurpita had the opportunity to present and discuss her PhD research work and develop her professional network. Her impressions about the two week summer school:  "It was enriching to talk and learn during discussions and poster session along with students and scientists in the various disciplines of oceanography from all around the world. I was excited to hear talks in the advances in ocean observing systems, methods and techniques for analysis and ocean modeling."

Further informations about the summer school objectives, program and participants can be found here.


Workshop on global ocean salinity and the watercycle

The 2017 salinity workshop will take place at Woods Hole Oceanographic Institution, Woods Hole, Mass., USA from May 22 to May 26, 2017.

FOR1740 scientists will present their work there.

Scientific program and further informations can be accessed here


FOR1740 scientists present their new findings at the 2016 AGU Fall Meeting

Presenting a poster and talk with scientific results from satellite-retrived salinity data, the FOR1740 project participates in the AGU 2016 conference.


Jörg Burdanowitz successfully defended his PhD thesis

Yesterday,  our PhD candidate Jörg Burdanowitz successfully defended his PhD thesis titled "Point-to-area validation of passive microwave satellite precipitation with shipboard disdrometers".

His PhD thesis can be downloaded here


News from Climate Science

Once a month, climate researchers report on their latest findings in the newspaper "Hamburger Abendblatt".

Our postdoctoral researcher Julia Köhler explains, how satellite-retrieved salinity measurements can help to understand the global hydrological cycle.

The article can be found here (german and english)

"Salinity and Freshwater Changes in the Ocean" Conference a great success!

Last week the "Salinity and Freshwater Changes in the Ocean" conference was held at the Museum für Völkerkunde in Hamburg.

About 80 international scientist came together, presented their work and discussed future developments regarding the freshwater cycle.

We like to thank all participants for the frutiful discussions and interesting talks as well as posters.

Conference Registration Closed

The conference registration is now closed. We are looking forward to welcome about 100 scientists to Hamburg in October!

Warning: Suspect fraud EHS for the conference "Salinity and Freshwater Changes in the Ocean"

If you get called by a travel agency urging you to book your accommodation since it the date was expiring of a block booking for hotels related to the conference or to change your existing booking, please do not provide your personal or credit card information! We did not assign a travel agency to do this for us, since every participant is responsible for their own booking.

The alleged travel agency is called EHS ( and it seems they have been reported in several scam attempts (

If you already got called and provided your information, please block your credit card so that you do not loose money.

Final conference program

The abstracts have been sorted out and the talks have been selected. We want to thank everyone who submitted an abstract for the conference.

Have a look at the Initiates file downloadconference program.

Get registered now!

The registration for the open science conference on "Ocean Salinity and Freshwater Changes in the Ocean" is only open until the 31. August 2015.

So get registered now! Information about the objectives and the program can be found here.

Research Group PhD wins "EGU Outstanding Student Poster" award

At the EGU General Assembly 2015 in Vienna,  Yao Fu (FOR1740 PhD student in WP 1.3), won the Outstanding Student Poster award (link to

The poster “Estimation of the Meridional Ekman Transport in the Tropical Atlantic” by Yao Fu, Johannes Karstensen and Peter Brandt, presents an analysis of Ekman transport and associated salinity and heat fluxes in the tropical Atlantic. See Poster.

International conference in planning

"Salinity and Freshwater Changes in the Ocean"

Date: 12. - 15. October 2015

Location: Museum für Völkerkunde, Hamburg

More information about registration and abstract submission will follow soon.

Impressions from FOR1740 PhDs and Post docs about the Research group meeting

"For me as a meteorologist the recent FOR1740 project meeting at Geomar in Kiel was particularly helpful to get detailed insights into the field of oceanography. In addition, I had the chance to getting in touch with my colleagues within this interdisciplinary project. In that sense, regular meetings do not only support the exchange of ideas and information but are therefore a vital part of everyday science."

Jörg Burdanowitz, Ph.D. student WP 2.1


"The topics presented in the meeting covered a much larger field than what I am doing. I think it is really helpful for me to look at a greater picture rather than just focusing on my own work. Since I am working on the meridional transport estimation from the observational aspect, it would be interesting to compare the observed results with the modelling results, e.g. GECCO reanalysis."

Yao Fu, Ph.D. student, WP 1.3


"The project meeting was very meaningful, as it allowed for a great overview of ongoing progress within the individual working groups. The ‘big picture’ and pursued aims are much clearer to me now! Towards the end, fruitful discussions and newly defined goals motivated everyone to continue their research. I am looking forward to the next progress meeting early next year!"

Julian Kinzel, Ph.D. student, WP 2.1


"I’ve benefited a lot from this project meeting. It is always exciting to know other oceanographers and PhD students, and the research they are doing. Besides, preparing for the presentation helped me to have a better understanding of my own work."

Xin Lui, Ph.D. student, WP 3.1


"I think the meeting was really useful to learn more about what the other working groups have been working during this last year and how their studies are progressing. I also presented some preliminary results from my analysis and I am really looking forward to have the opportunity to combine with the results from the HOAPS climatology (W.P. 2.1), to be able to see if some of the salinity anomalies observed can be explained by evaporation and/or precipitation"

Dr. Ilaria Stendardo, Post doc, WP 1.2

Research group meeting in Kiel

On the 23rd of September, the DFG research group 1740 met in Kiel for an exchange of results and recent research efforts.

Participants of the DFG Research Group Meeting in Kiel.