bluuebunny/crossref_metadata_2025 huggingface dataset:
Observation of absorbing aerosols above clouds over the south-east Atlantic Ocean from the geostationary satellite SEVIRI – Part 2: Comparison with MODIS and aircraft measurements from the CLARIFY-2017 field campaign
Authors: Peers Fanny , Francis Peter , Abel Steven J. , Barrett Paul A. , Bower Keith N. , Cotterell Michael I. , Crawford Ian , Davies Nicholas W. , Fox Cathryn , Fox Stuart , Langridge Justin M. , Meyer Kerry G. , Platnick Steven E. , Szpek Kate , Haywood Jim M.
Published: March 2021

Abstract. To evaluate the SEVIRI retrieval for aerosols above
clouds presented in Part 1 of the companion paper, the algorithm is applied
over the south-east Atlantic Ocean during the CLARIFY-2017 field campaign
period. The first step of our analysis compares the retrieved aerosol and
cloud properties against equivalent products from the MODIS MOD06ACAERO
retrieval (Meyer et al., 2015). While the correlation between the two
satellite retrievals of the above-cloud aerosol optical thickness (AOT) is
good (R = 0.78), the AOT retrieved by SEVIRI is 20.3 % smaller than that
obtained from the MODIS retrieval. This difference in AOT is attributed
mainly to the more absorbing aerosol model assumed for the SEVIRI retrieval
compared to MODIS. The underlying cloud optical thickness (COT) derived from
the two satellites is in good agreement (R = 0.90). The cloud droplet
effective radius (CER) retrieved by SEVIRI is consistently smaller than
MODIS by 2.2 µm, which is mainly caused by the use of different
spectral bands of the satellite instruments. In the second part of our
analysis, we compare the forecast water vapour profiles used for the SEVIRI
atmospheric correction as well as the aforementioned aerosol and cloud
products with in situ measurements made from the Facility for Airborne
Atmospheric Measurements (FAAM) aircraft platform during the CLARIFY-2017
campaign. Around Ascension Island, the column water vapour used to correct
the SEVIRI signal is overestimated by 3.1 mm in the forecast compared to
that measured by dropsondes. However, the evidence suggests that the
accuracy of the atmospheric correction improves closer to the African coast.
Consistency is observed between the SEVIRI above-cloud AOT and in situ
measurements (from cavity ring-down spectroscopy instruments) when the
measured single-scattering albedo is close to that assumed in the retrieval
algorithm. On the other hand, the satellite retrieval overestimates the AOT
when the assumed aerosol model is not absorbing enough. Consistency is also
found between the cloud properties retrieved by SEVIRI and the CER measured
by a cloud droplet probe and the liquid water path derived from a microwave
radiometer. Despite the instrumental limitations of the geostationary
satellite, the consistency obtained between SEVIRI, MODIS and the aircraft
measurements demonstrates the ability of the retrieval in providing
additional information on the temporal evolution of the aerosol properties
above clouds.
Performance of open-path GasFinder3 devices for CH4 concentration measurements close to ambient levels
Authors: Häni Christoph , Bühler Marcel , Neftel Albrecht , Ammann Christof , Kupper Thomas
Published: March 2021

Abstract. Open-path measurements of methane (CH4) with the use
of GasFinder systems (Boreal Laser Inc, Edmonton Canada) have been
frequently used for emission estimation with the inverse dispersion method
(IDM), particularly from agricultural sources. It is common to many IDM
applications that the concentration enhancement related to CH4 sources
is small, typically between 0.05 and 0.5 ppm, and accurate measurements of
CH4 concentrations are needed at concentrations close to ambient
levels. The GasFinder3-OP (GF3) device for open-path CH4 measurements
is the latest version of the commercial GasFinder systems by Boreal Laser
Inc. We investigated the uncertainty of six GF3 devices from side-by-side
intercomparison measurements and comparisons to a closed-path quantum
cascade laser device. The comparisons were made at near-ambient levels of
CH4 (85 % of measurements below 2.5 ppm) with occasional phases of
elevated concentrations (max. 8.3 ppm). Relative biases as high as 8.3 %
were found, and a precision for half-hourly data between 2.1 and
10.6 ppm-m (half width of the 95 % confidence interval) was estimated.
These results deviate from the respective manufacturer specifications of 2 % and 0.5 ppm-m. Intercalibration of the GF3 devices by linear regression
to remove measurement bias was shown to be of limited value due to drifts
and step changes in the recorded GF3 concentrations.
Rapid soil organic carbon decomposition in river systems: effects of the aquatic microbial community and hydrodynamical disturbance
Authors: Zhao Man , Jacobs Liesbet , Bouillon Steven , Govers Gerard
Published: March 2021

Abstract. Different erosion processes deliver large amounts of terrestrial
soil organic carbon (SOC) to rivers. Mounting evidence indicates that a
significant fraction of this SOC, which displays a wide range of ages, is
rapidly decomposed after entering the river system. The mechanisms
explaining this rapid decomposition of previously stable SOC still remain
unclear. In this study, we investigated the relative importance of two
mechanisms that possibly control SOC decomposition rates in aquatic systems:
(i) in the river water SOC is exposed to the aquatic microbial community
which is able to metabolize SOC much more quickly than the soil microbial
community and (ii) SOC decomposition in rivers is facilitated due to the
hydrodynamic disturbance of suspended sediment particles. We performed
different series of short-term (168 h) incubations quantifying the rates of
SOC decomposition in an aquatic system under controlled conditions. Organic
carbon decomposition was measured continuously through monitoring dissolved
O2 (DO) concentration using a fiber-optic sensor (FireStingO2,
PyroScience). Under both shaking and standing conditions, we found a
significant difference in decomposition rate between SOC with aquatic
microbial organisms added (SOC + AMO) and without aquatic microbial
organisms (SOC − AMO). The presence of an aquatic microbial community enhanced
the SOC decomposition process by 70 %–128 % depending on the soil type and
shaking–standing conditions. While some recent studies suggested that
aquatic respiration rates may have been substantially underestimated by
performing measurement under stationary conditions, our results indicate
that the effect of hydrodynamic disturbance is relatively minor, under the
temperature conditions, for the soil type, and for the suspended matter
concentration range used in our experiments. We propose a simple conceptual
model explaining these contrasting results.
Influence of land-use on the dynamics, quantity and composition of the organic matter transported across estuaries
Authors: Garcia-Martin E. Elena , Sanders Richard , Evans Chris D. , Kitidis Vassilis , Lapworth Dan J. , Rees Andrew P. , Spears Bryan , Tye Andy , Williamson Jennifer L. , Mayor Daniel J.
Published: March 2021

The flux of terrigenous organic carbon across estuaries is an important and changing component of the global carbon cycle, but it is poorly understood. It has been proposed that estuaries can act either as a transporter of terrestrial dissolved organic carbon (DOC) to the ocean or as a reactor system in which DOC can be buried or transformed into carbon dioxide and released to the atmosphere. However, there is no clear understanding of the factors that drive estuaries to behave in one way or the other. Here we present the results from a study conducted in thirteen British estuaries which drain catchments of diverse land-uses under different hydrological conditions. Our data show that land-use influences the composition of the dissolved organic matter (DOM), the mixing dynamics of DOC and the quantity of DOC exported off the estuaries. Estuaries, whose catchments are less intensively managed and represent more natural ecosystems (average proportion of arable and (sub)-urban land-use ~12 %), contain a higher proportion of biologically-refractory “humic-like” DOM, which is transported conservatively across the salinity gradient. In contrast, estuaries whose catchments are more intensively managed (average proportion of arable and (sub)-urban land-use ~32 %) contain a high fraction of “protein-like” DOM which is transported non-conservatively, and thus suggest the existence of additions and removal processes across the salinity gradient. Furthermore, estuaries with more intensively managed catchments tend to export more DOC to coastal areas than they receive from rivers. Our results indicate that future changes in land-use have the potential to alter aquatic fluxes of terrigenous DOM and the fate of the constituent carbon.
Changes in Water Use on the Lower Colorado River in the USA from 2000-2020
Authors: Nagler Pamela , Barreto-Muñoz Armando , Chavoshi Borujeni Sattar , Nouri Hamideh , Jarchow Christopher , Didan Kamel
Published: March 2021

We studied the health and water use of seven riparian reaches of the Lower Colorado River from Hoover to Morelos Dam over the last 20-years, since 2000, to evaluate trends in the riparian ecosystem. This ecosystem has been in decline based on myriad pressures related to drought, water diversions and land use changes, such as defoliation events from the tamarisk leaf beetle, Diorhabda spp. We provide remotely sensed measurements of vegetation index (VI), daily evapotranspiration (ET, mmd-1) and annualized ET (mmyr-1). We used 250m Moderate Resolution Imaging Spectroradiometer (MODIS) and 30m Landsat EVI2 time-series. We selected EVI2 to parameterize our ET algorithm and tested the ET relationship between sensors by regression approaches and found a significant correlation between EVI2Landsat and EVI2MODIS. A key finding is that riparian health and its water use between Hoover and Morelos Dams has been in decline since 2000, as measured by Landsat with daily water use dropping from 4.79 mmd-1 to 3.18 mmd-1. Our results show that over the past two decades, the average greenness (EVI2Landsat) loss was 29% and total annual ET loss was 34% (-1.61 mmd-1 or -386 mmyr-1; a drop from 1163 mmyr-1 down to 777 mmyr-1). Greenness declined on average 29%, but certain reaches declined 42% or ca. -2.28 mmd-1, or -575 mmyr-1 (Reach 6). Reach 3 showed an ET loss of 39% (-1.94 mmd-1, -410 mmyr-1). Our findings are significant because riparian plant species have declined so drastically, suggesting further deterioration of biodiversity, wildlife habitat and other key ecosystem services.    
Validation of the capability of WRF-Chem model and CAMS to simulate near surface atmospheric CO2 mixing ratio for the territory of Saint-Petersburg
Authors: Nerobelov Georgy , Timofeyev Yury , Smyshlyaev Sergei , Foka Stefani , Mammarella Ivan , Virolainen Yana
Published: March 2021

The growing content of greenhouse gases (GHGs) influences the radiation balance of the planet causing the rise of air temperature in lower atmosphere. This circumstance triggers researchers to create and develop the new methods of estimation of anthropogenic CO2 emissions. One of such method is top-down estimation which is based on measurements and chemical transport modelling. Since the errors of the top-down approach depend on quality of the modelled data it requires validation by complex observations. In current study we investigated the performance of regional numerical weather prediction and chemistry transport model WRF-Chem and CAMS service in simulating spatio-temporal variation of near surface atmospheric CO2 mixing ratio in March and April 2019 for the Saint-Petersburg area (Russia). To validate the modelled data, we used local observations obtained on Peterhof (St. Petersburg) station. The analysis demonstrates that WRF-Chem model can adequate simulate the transport of CO2 in near-surface layer with spatial resolution of 3 km. Average difference and correlation coefficient are in range 0.8-1.6% and 0.55-0.72 respectively. It was found that the WRF-Chem modelled data where biogenic and anthropogenic fluxes were considered fit the observation data worse than the WRF-Chem simulation where only anthropogenic emissions were used. It can be linked to the errors of the biogenic flux calculation. However, to prove that investigations for two contrast periods (in summer and winter) are needed. Despite the rude spatial resolution of the CAMS data (approximately 200x400 km) we found that in general the trend of surface atmospheric CO2 mixing ratio in March and April 2019 for the Saint-Petersburg area from the CAMS dataset fits the observations.
GeoGravGOCE: A GOCE SGG processing software for datum transformations and filtering
Authors: Mamagiannou Elisavet Maria G. , Pitenis Eleftherios A. , Natsiopoulos Dimitrios A. , Vergos Georgios S. , Tziavos Ilias N.
Published: March 2021

Whilst GOCE SGG data have been widely processed and used in geodetic research, one of the key points of their use is to have a one-stop software for their pre-processing and basic manipulations in terms of frame transformations and filtering operations. Within the GeoGravGOCE project, funded by the Hellenic Foundation for Research Innovation, the main goal is the optimal combination of GOCE Satellite Gravity Gradiometry (SGG) data with in-situ observations for geoid determination. During the project development, it became apparent that GOCE SGG data after using the GOCEPARSER, had to be pre- and post-processed via several own-developed routines in order to perform data quality checks, data consistency tests, reference frame transformations, data reductions and filtering. With that in mind, a standalone open-source software has been developed in MATLAB consisting of a Graphical User Interface (GUI) to perform the aforementioned operation. The software is divided in four tabs and is designed to process the original GOCE gravity gradients, which are the second-order derivatives of the gravitational potential. The first tab of the software is designed to allow the pre-processing of the Level 2 Electrostatic Gravity Gradiometer nominal gravity gradients (EGG_NOM) and Satellite to Satellite Tracking Precise Science Orbits (SST_PSO) products. The second tab enables the transformation of gravity gradients from a Global Geopotential Model (GGM) from the Local North Oriented Frame (LNOF) to the Gradiometer Reference Frame (GRF). The third tab provides filtering options for the reduced SGG observations and encompasses three different methods: Finite Impulse Response (FIR), Infinite Impulse Response (IIR), and Wavelet Multi-Resolution Analysis (WL-MRA). Finally, the fourth tab allows the transformation of SGG data from the GRF to the LNOF and vice versa. In this work, we present the basic software development procedure and outline its basic functionality and results.
A full year of extreme sea-ice and atmosphere conditions in the Eurasian Arctic: the OCEAN environment during MOSAiC
Authors: Rabe Benjamin , Heuzé Céline ,   MOSAiC OCEAN Team
Published: March 2021

The Arctic Ocean, although remote to most of us, is linked to lower latitudes by way of climate, physics, biology and biogeochemistry. Strongly coupled to the rapidly changing Arctic atmosphere and sea-ice, the ocean is subject to amplification of change amid global trends in climate. The relatively fresh and cold upper mixed-layer in the Arctic basin exhibits a strong seasonal cycle, yet the deeper warm water of Atlantic origin largely stays isolated from the ice. Further, changes in heat, salt and momentum due to exchange with ice and atmosphere cannot penetrate to great depth due to a strong halocline. Nevertheless, we observed changes in the upper water column stratification and mixing, due to storms and freeze-induced brine release during the year-long MOSAiC experiment. This was further expressed by significant variability in (sub)mesoscale processes, including eddies and frontal adjustment. We will present results from ocean observations during the MOSAiC drift using a variety of manually-operated devices and autonomous platforms within several 10s of kilometres from the drifting icebreaker Polarstern. Preliminary analyses of our data highlight a pronounced seasonal cycle in mixed-layer depth and upper ocean stratification characteristics connected to brine release, turbulent events triggered by storms, and geographic background variability. We will further detail the observed full-depth water mass distribution and attempt to untangle temporal and spatial variability. Finally, we will give an overview of Team-OCEAN analyses and interdisciplinary projects.
Emirates Mars Mission (EMM) 2020 Overview and Status
Authors: Sharaf Omran , Amiri Sarah , Almatroushi Hessa , AlRais Adnan , Wali Mohammad , AlShamsi Zakareyya , AlTeneiji Nour , McGrath Michael , Withnell Pete , Brain David , Ferrington Nicolas , Reed Heather , Landin Brett , Ryan Sean , Pramann Brian , Holsclaw Gregory , Edwards Christopher , Wolff Michael ,   EMM Team
Published: March 2021

The Emirates Mars Mission (EMM) is the United Arab Emirates’ (UAE) first mission to Mars and is the first Arab mission to another planet. It launched an unmanned observatory called “Hope” into an elliptical orbit around Mars on July 20, 2020  carrying three scientific instruments to study the Martian atmosphere in visible, ultraviolet, and infrared wavelengths. EMM will be the first mission to provide the first truly global picture of the Martian atmosphere, revealing important information about how atmospheric processes drive diurnal variations for a period of one Martian year. This will provide scientists with valuable understanding of the changes to the Martian atmosphere today through the achievement of three scientific objectives:

Characterize the state of the Martian lower atmosphere on global scales and its geographic, diurnal and seasonal variability.

Correlate rates of thermal and photochemical atmospheric escape with conditions in the collisional Martian atmosphere.

Characterize the spatial structure and variability of key constituents in the Martian exosphere.

The mission is led by Emiratis from Mohammed Bin Rashid Space Centre (MBRSC) and is expanding the nation’s human capital through knowledge transfer programs set with international partners from the University of Colorado Laboratory for Atmospheric and Space Physics (LASP), Arizona State University (ASU) School of Earth and Space Exploration, and University of California Berkeley Space Sciences Laboratory (SSL). The presentation will review the status of the mission up to and beyond a successful Mars Orbit Insertion on Feb 9, 2021, including activities from Mars orbit in preparation for the start of mission science in May 2021.
Trace element geochemistry of iron oxides from the Per Geijer apatite iron ores in the Kiruna district, northern Sweden: Implications for ore genesis
Authors: Krolop Patrick , Niiranen Kari , Gilbricht Sabine , Schulz Bernhard , Oelze Marcus , Seifert Thomas
Published: March 2021

Iron oxide-apatite (IOA) deposits are an important source of iron ore based on the modal abundance of magnetite > 90 vol.%. Further interest is generated due to the high variability of apatite and hematite in some of these ores. The origin of the so-called Kiruna-type deposits has been subject to controversy for more than a century. Models range from a purely magmatic origin to ore-forming processes that involve variable stages of hydrothermal fluid involvement to a not widely accepted sedimentary-exhalative origin. In contribution of understanding ore-forming processes of this deposit type, we performed mineral chemistry and trace element analyses on samples from the Per Geijer deposits. They account for the lesser studied deposits in the Kiruna district of northern Sweden. A comprehensive mineral-chemical dataset of magnetite and hematite obtained by electron microprobe analysis (EPMA) and LA-ICP-MS from representative drill core samples is presented. Magnetite and four different types of hematite constitute the massive orebodies: Primary and pristine magnetite with moderate to high concentrations of Ti (∼61–2180 ppm), Ni (∼11–480 ppm), Co (∼5–300 ppm) and V (∼553–1831 ppm) indicate a magmatic origin for magnetite. Hematite type I appears as a replacement of magnetite with high Ti (∼15,700–42,300 ppm), relatively constant V (∼1460–2160 ppm) and moderate Sn (∼29–105 ppm) concentrations. Moderate and variable Ti (∼369–12,490 ppm) and low Sn (∼1.4–19 ppm) concentrations are representative for hematite type II. Hematite type III has lowest Ti (∼99–1250 ppm) concentrations. Significantly high Ti concentrations (∼12,100–78,700 ppm), low V (∼132–381 ppm) and high Sn (∼129–456 ppm) concentrations account for type IV. The presence of fluorapatite and disseminated pyrite with high Co:Ni ratios (> 1–10) in massive magnetite ores are consistent with a high temperature (∼ 800°C) genesis for the deposit. The different and abundant types of hematite state subsequent hydrothermal events.
Estimation water status of the vineyard by calculating multispectral index from satellite images
Authors: Rodríguez-Fernández Marta , Fandiño María , González Xesús Pablo , Cancela Javier J.
Published: March 2021

The estimation of the water status in the vineyard, is a very important factor, in which every day the winegrowers show more interest since it directly affects the quality and production in the vineyards. The situation generated by COVID-19 in viticulture, adds importance to tools that provide information of the hydric status of vineyard plants in a telematic way.

In the present study, the stem water potential in the 2018 and 2019 seasons, is analysed in a vineyard belonging to the Rias Baixas wine-growing area (Vilagarcia de Arousa, Spain), with 32 sampling points distributed throughout the plot, which allows the contrast and validation with the remote sensing methodology to estimate the water status of the vineyard using satellite images.

The satellite images have been downloaded from the Sentinel-2 satellite, on the closets available dates regarding the stem water potential measurements, carried out in the months of June to September, because this dates are considered the months in which vine plants have higher water requirements.

With satellite images, two spectral index related to the detection of water stress have been calculated: NDWI (Normalized Difference Water Index) and MSI (Moisture Stress Index). Stem water potential measurements, have allowed a linear regression with both index, to validate the use of these multispectral index to determine water stress in the vineyard.

Determination coefficients of r2=0.62 and 0.67, have been obtained in July and August 2018 and 0.54 in June of 2019 for the NDWI index, as well as values of 0.53 and 0.63 in July 2018 and June 2019 respectively, when it has been analysed the MSI index.

Between both seasons, the difference observed, that implies slightly greater water stress in 2019, is reflected in the climate conditions during the summer months, with an average accumulated rainfall that doesn’t exceed 46 mm of water. Although, the NDWI index has allowed to establish better relationships in the 2018 season respect to the MSI index and the 2019 season, (r2=0.60 NDWI in 2018), as well as greater differences in terms of water stress presented in the vineyard.

With the spectral index calculated, it has been possible to validate the use of these index for the determination of the water stress of the vineyard plants, as an efficient, fast and less expensive method, which allows the application of an efficient irrigation system in the vineyard.
Comparison of urban climate measurements in Berlin and LES model output for a special observation period
Authors: langer Ines , Pasternack Alexander , Ulbrich Uwe , Rust Henning
Published: March 2021

Surface (2 m) temperature and specific humidity data are measured at 5-minute intervals in a network comprising 33 stations distributed across the city of Berlin, Germany. These data are utilized in order to validate a LES (large eddy simulation) model designed to assess the local climate at a very high resolution of 10 m to 1 m. This model, was developed at the ​Institute of Meteorology and Climatology (IMUK) of the Leibniz Universität Hannover, Germany, and is developed into an application tool for city planners within the funding programme "[UC²] - Urban Climate under Change", of the German Federal Ministry of Education and Research (BMBF).

The evaluation distinguishes between the different Local climate zones (LCZ) in the city, which are defined following the concept of Stewart & Oke (2012). For Berlin, the following LCZ have been identified: 2 (compact midrise), 4 (open high-rise), 6 (open low-rise), 8 (large low-rise), A (dense trees), B (scattered trees), D (low Plants), G (water).

We analyzed one cold winter day during an intensive observation period from 06 UTC on 17th January to 06 UTC on 18th January, 2017. The minimum and maximum recorded temperatures were -8.1 °C and +2 °C, respectively, the sun shine duration was 6.5 hours. Daily and hourly mean absolute error, mean square error and root mean square error confirm that the deviation between measurements and the PALM-4U model differs between the LCZ for Berlin, with particularly large negative deviations of up to 5 K in forest areas, as they are not yet well represented in the model. Smallest deviations are found for the industrial zone. In all cases, the observed amplitude of the diurnal cycle is underestimated. The role of the driving model for the deviations found is addressed.

Stewart, I.D., Oke, T.R. (2012) Local climate zones for urban temperature studies. Bull. Amer. Meteor. Soc. 93 1879-1900. DOI: 10.1175/BAMS-D-11-00019.1.

 
The IDS Contribution to the ITRF2020
Authors: Moreaux Guilhem , Lemoine Frank , Capdeville Hugues , Stepanek Petr , Otten Michiel , Saunier Jérôme , Ferrage Pascale
Published: March 2021

In the context of the realization of the next International Terrestrial Reference Frame (ITRF2020), the International DORIS Service (IDS) is involved in the estimation of DORIS station positions/velocities as well as Earth orientation parameters from DORIS data. Thus, the 4 IDS Analysis Centers  have re-analyzed all the DORIS observations from the fifteen DORIS satellites from January 1993 to December 2020.0.

The primary objective of this study is to analyze the DORIS contribution to ITRF2020 in terms of (1) geocenter and scale solutions; (2) station positions and week-to-week repeatability; (3) Earth orientation parameters; (4) a cumulative position and velocity solution.

Comparisons with the IDS contribution to ITRF2014 will address the benefits of the new antenna models, new models, including improved methods to handle non-conservative force model error on the Jason satellites, as well as the addition of data (compared to ITRF2014) from the latest DORIS missions (e.g. Jason-3, Sentinel-3A/B) in the IDS combination.
Adriatic mix layer depth changes in September in the recent years
Authors: Ćatipović Leon , Udovičić David , Džoić Tomislav , Matić Frano , Kalinić Hrvoje , Juretić Tea , Tičina Vjekoslav
Published: March 2021

In the recent years Adriatic Sea witnessed to different microbiological, termohaline with also the sea surface temperature changes interleaved with human impact, climate change and shifts in synoptical patterns. Adriatic Sea is under permanently modulated with Adriatic-Ionian Bimodal Oscillating System and North Atlantic Oscillation. This paper shows changes in termohaline properties in September, the period between Summer and Autumn. During summer months most cyclones that are appearing in the Adriatic basin and their tracks are classified as Genoa cyclones with a smaller number of Adriatic Cyclones. Autumn shows a different picture, with an equal number of Genoa, Adriatic, and non-Genoa and non-Adriatic cyclones. Large-scale air flow superimposed with Adriatic circulation have an impact during the transition from summer to autumn. The mix layer depth and termohaline conditions over Eastern Adriatic in the September in the period 2005 – 2020 are detected form a large database of CTD measurements. The data used in this study were collected during acoustic surveys conducted within framework of projects PELMON (2005-2012) and MEDIAS (2013-2020), carried out by Institute of Oceanography and Fisheries and supported by Croatia's Ministry of Agriculture. The CTD SBE25 probes used in the experiment were regularly calibrated and all measurements was quality controlled. In order to extract characteristic patterns from temperature and salinity vertical profiles and to connect them to wind and sea surface air pressure obtained from ERA5 reanalysis the unsupervised learning approach was utilized and the Neural gas algorithm was applied. The results show that the changes in mix layer depth are connected with interannual changes in cyclone path are connected with wind regime.

This work has been supported in part by Croatian Science Foundation under the project UIP-2019-04-1737 and project MAUD (grant number HRZZ-IP-2018-01-9849).
A clock for the Sun's magnetic Hale cycle and 27 day recurrences in the aa geomagnetic index
Authors: Chapman Sandra , McIntosh Scott , Leamon Robert , Watkins Nicholas
Published: March 2021

We construct a new solar cycle phase clock which maps each of the last 18 solar cycles onto a single normalized epoch for the approximately 22 year Hale (magnetic polarity) cycle, using the Hilbert transform of daily sunspot numbers (SSN) since 1818. We use the clock to study solar and geomagnetic climatology as seen in datasets available over multiple solar cycles. The occurrence of solar maxima on the clock shows almost no Hale cycle dependence, confirming that the clock is synchronized with polarity reversals.  The odd cycle minima lead the even cycle minima by ~ 1.1 normalized years, whereas the odd cycle terminators (when sunspot bands from opposite hemispheres have moved to the equator and coincide, thus terminating the cycle, McIntosh(2019)) lag the even cycle terminators  by ~ 2.3 normalized years.  The average interval between each minimum and terminator  is thus relatively extended for odd cycles and shortened for even ones. We re-engineer the R27 index that was orignally proposed by Sargent(1985) to parameterize 27 day recurrences in the aa index. We perform an epoch analysis of autocovariance in the aa index using the Hale cycle clock to obtain a high time resolution parameter for 27 day recurrence, . This reveals that the transition to recurrence, that is, to an ordered solar wind dominated by high speed streams, is fast, occurring within 2-3 solar rotations or less. It resolves an extended late declining phase which is approximately twice as long on even Schwabe cycles as odd ones. We find that Galactic Cosmic Ray flux rises in step with  but then stays high. Our analysis also identifies a slow timescale trend in SSN that simply tracks the Gleissberg cycle. We find that this trend is in phase with the slow timescale trend in the modulus of sunspot latitudes, and in antiphase with that of the R27 index.
A global climatological perspective on the importance of Rossby wave breaking and intense moisture transport for extreme precipitation events
Authors: De Vries Andries Jan
Published: March 2021

Extreme precipitation events (EPEs) frequently cause flooding with dramatic socioeconomic impacts in many parts of the world. Previous studies considered two synoptic-scale processes, Rossby wave breaking and intense moisture transport, typically in isolation, and their linkage to such EPEs in several regions. This study presents for the first time a global and systematic climatological analysis of these two synoptic-scale processes, in tandem and in isolation, for the occurrence of EPEs. To this end, we use 40-year ERA-Interim reanalysis data (1979-2018) and apply object-based identification methods for (i) daily EPEs, (ii) stratospheric potential vorticity (PV) streamers as indicators of Rossby wave breaking, and (iii) structures of high vertically integrated horizontal water vapor transport (IVT). First, the importance of these two synoptic-scale processes is demonstrated by case studies of previously documented flood events that inflicted catastrophic impacts in different parts of the world. Next, a climatological quantification shows that Rossby wave breaking is associated with > 90 % of EPEs near high topography and over the Mediterranean, whereas intense moisture transport is linked to > 95 % of EPEs over many coastal zones, consistent with findings of atmospheric river-related studies. Combined Rossby wave breaking and intense moisture transport contributes up to 70 % of EPEs in several subtropical and extratropical regions, including (semi)arid desert regions where tropical-extratropical interactions are of key importance for (heavy) rainfall. A detailed analysis shows that five categories with different combinations of wave breaking and intense moisture transport can reflect a large range of EPE-related weather systems across various climate zones. Odds ratios of EPEs linked to the two synoptic-scale processes suggest that intense moisture transport is stronger associated with the occurrence of EPEs than wave breaking. Furthermore, the relationship between the PV and IVT characteristics and the precipitation volumes shows that the depth of the wave breaking and moisture transport intensity are intimately connected with the extreme precipitation severity. Finally, composites reveal that subtropical and extratropical EPEs, linked to Rossby wave breaking, go along with the formation of upper-level troughs and cyclogenetic processes near the surface downstream, reduced static stability beneath the upper-level forcing (only over water), and dynamical lifting ahead (over water and land). This study concludes with a concept that reconciles well-established meteorological principles with the importance of Rossby wave breaking and intense moisture transport for extreme precipitation events. The findings of this study may contribute to an improved understanding of the atmospheric processes that lead to EPEs, and may find application in climatic studies on extreme precipitation changes in a warming climate.
Trends in ice sheet mass balance
Authors: Shepherd Andrew , Ivins Erik ,   IMBIE Team
Published: March 2021

The Ice Sheet Mass Balance Inter-Comparison Exercise (IMBIE) is a community effort supported by ESA and NASA that aims to provide a consensus estimate of ice sheet mass balance. In its first phase, IMBIE showed that estimates of ice sheet mass balance derived from satellite gravimetry, altimetry and the mass budget method could be reconciled within their respective uncertainties. In its second phase, IMBIE showed that rates of ice loss from Antarctica and Greenland have increased by a factor 6 during the satellite era and are tracking the high-end (worst-case) projections reported in the IPCC’s fifth assessment report (AR5). The project now involves 96 individual participants based in 50 institutes from 13 nations and includes 26 satellite estimates of ice sheet mass balance, 11 models of glacial isostatic adjustment, and 10 models of surface mass balance. IMBIE has now begun its third phase, and the objectives are to (i) include measurements from new satellite missions, (ii) to report annual assessments, (iii) to partition changes in mass due to ice dynamics and surface mass balance, (iv) to produce regional assessments in areas of imbalance, and to (v) explore remaining biases between the various geodetic techniques involved. Participation is open to the full community, and the quality and consistency of submissions is regulated through a series of data standards and documentation requirements. This paper will introduce the objectives of IMBIE-3 and present the latest assessment of ice sheet mass balance. which has been updated for the IPCC's sixth assessment report.
Significant climate benefits from near-term climate forcer mitigation in spite of aerosol reductions
Authors: Allen Robert , Horowitz Larry , Naik Vaishali , Oshima Naga , O'Connor Fiona , Turnock Steven , Shim Sungbo , Le Sager Philippe , van Noije Twan , Tsigaridis Kostas , Bauer Susanne , Sentman Lori , John Jasmin , Broderick Conor , Deushi Makoto , Folberth Gerd , Fujimori Shinichiro , Collins William
Published: March 2021

Near-term climate forcers (NTCFs), including aerosols and chemically reactive gases such as tropospheric ozone and methane, offer a potential way to mitigate climate change and improve air quality--so called "win-win" mitigation policies.   Prior studies support improved air quality under NTCF mitigation, but with conflicting climate impacts that range from a significant reduction in the rate of global warming to only a modest impact.  Here, we use state-of-the-art chemistry-climate model simulations conducted as part of the Aerosol and Chemistry Model Intercomparison Project (AerChemMIP) to quantify the 21st-century impact of NTCF reductions, using a realistic future emission scenario with a consistent air quality policy.  Non-methane NTCF (NMNTCF; aerosols and ozone precursors) mitigation improves air quality, but leads to significant increases in global mean precipitation of 1.3% by mid-century and 1.4% by end-of-the-century, and corresponding surface warming of 0.23 and 0.21 K.  NTCF (all-NTCF; including methane) mitigation further improves air quality, with larger reductions of up to 45% for ozone pollution, while offsetting half of the wetting by mid-century (0.7% increase) and all the wetting by end-of-the-century (non-significant 0.1% increase) and leading to surface cooling of -0.15 K by mid-century and -0.50 K by end-of-the-century.  This suggests that methane mitigation offsets warming induced from reductions in NMNTCFs, while also leading to net improvements in air quality.
The changes in Mulberry-based fish ponds in the Guangdong-Hong Kong-Macao Greater Bay Area over the past 40 years
Authors: Zhang Wenxin , Cheng Zihao , Liu Xianfeng , Lin Gangte , He Junan , Huang Fangyuan , Yang Xiankun
Published: March 2021

Mulberry-based fish ponds are representative traditional eco-agriculture in the Guangdong-Hong Kong-Macao Greater Bay Area (GBA). Investigations about the changes in such ponds and their relevant water environment under the background of rapid urbanization can provide a reference for the protection and development of these ponds. Using the Landsat images obtained after 1986, this study employed supervised classification and visual interpretation approaches and water intensity index as well as calculating synthesized index to identify the spatial patterns of changes in Mulberry-based fish ponds in the GBA. The results indicated that the year of 2013 was the inflection point of fish pond changes, which can also be proved by calculating synthesized index. The causes to the changes in fish ponds were further explored from four aspects: land use change, industrial transfer, government guidance and financial motives.
Impacts of Atlantic Multidecadal Variability on the Tropical Pacific: a multi-model study
Authors: Ruprich-Robert Yohan ,   the AMV - Tropical Pacific study team
Published: March 2021

The Atlantic Multidecadal Variability (AMV) has been linked to the observed slowdown of global warming over 1998-2012 through its impact on the tropical Pacific. Given the global importance of tropical Pacific variability, better understanding this Atlantic-Pacific teleconnection is key for improving climate predictions, but the robustness and strength of this link is uncertain. Analysing a multi-model set of sensitivity experiments, we find that models differ by a factor 10 in simulating the amplitude of the Equatorial Pacific cooling response to observed AMV warming. The inter-model spread is mainly driven by different amounts of moist static energy injection from the tropical Atlantic surface into the upper troposphere. We reduce this inter-model uncertainty by analytically correcting models for their mean precipitation biases and we quantify that, following an observed 0.26ºC AMV warming, the equatorial Pacific cools by 0.16ºC with an inter-model standard deviation of 0.03ºC.
ETAS Space time modelling of Chile induced seismicity using covariates.
Authors: Chiodi Marcello , Nicolis Orietta , Adelfio Giada , D'angelo Nicoletta , Gonzàlez Alex
Published: March 2021

Chilean seismic activity is among the strongest ones in the world. As already shown in previous papers, seismic activity can be usefully described by a space-time branching process, like the ETAS (Epidemic Type Aftershock Sequences) model, which is a semiparametric model with a large time scale component for the background seismicity and a small time scale component for the induced seismicity. The large-scale component intensity function  is usually estimated by  nonparametric techniques, specifically in our paper we used the Forward Likelihood Predictive approach (FLP); the induced seismicity is modelled with a parametric space-time function. In classical ETAS models the expected number of induced events depends only on the magnitude of the main event. From a statistical point of view, forecast of induced seismicity can be performed in the days following a big event; of course the estimation of this component is very important to forecast the evolution, in space and time domain, of a seismic sequence. Together with magnitude, to explain the expected number of induced events we also used other covariates. According to this formulation, the expected number of events induced by event Ei is a function of a linear predictor ηi=xiβ, where xi is the vector of covariates observed for the i-th event (the first is usually the magnitude mi), and β is a vector of parameters to be estimated together with the other parametric and nonparametric components of the ETAS model. We obtained some interesting result using some covariates related to the depth of events and to some GPS measurement, corresponding to earth movement observed before main events. We find that some of these models can improve the description and the forecasting of the induced seismicity in Chile, after a subdivision of the country in different spatial regions. We used open-source software (R package etasFLP) to perform the semiparametric estimation of the ETAS model with covariates.
Uncertainty Estimation for Magnetic Maps
Authors: Saltus Richard , Chulliat Arnaud , Meyer Brian , Amante Christopher
Published: March 2021

Magnetic maps depict spatial variations in the Earth’s magnetic field.  These variations occur at a wide range of scales and are produced via a variety of physical processes related to factors including structure and evolution of the Earth’s core field and the geologic distribution of magnetic minerals in the lithosphere.  Mankind has produced magnetic maps for 100’s of years with increasing fidelity and accuracy and there is a general understanding (particularly among the geophysicists who produce and use these maps) of the approximate level of resolution and accuracy of these maps.  However, few magnetic maps, or the digital grids that typically underpin these maps, have been produced with accompanying uncertainty quantification.  When uncertainty is addressed, it is typically a statistical representation at the grid or survey level (e.g., +- 10 nT overall uncertainty based on line crossings for a modern airborne survey) and not at the cell by cell local level.

As magnetic map data are increasingly used in complex inversions and in combination with other data or constraints (including in machine learning applications), it is increasingly important to have a handle on the uncertainties in these data.  An example of an application with need for detailed uncertainty estimation is the use of magnetic map information for alternative navigation.  In this application data from an onboard magnetometer is compared with previously mapped (or modeled) magnetic variations.  The uncertainty of this previously mapped information has immediate implications for the potential accuracy of navigation.

We are exploring the factors contributing to magnetic map uncertainty and producing uncertainty estimates for testing using new data collection in previously mapped (or modeled) map areas.  These factors include (but are likely not limited to) vintage and type of measured data, spatial distribution of measured data, expectation of magnetic variability (e.g., geologic or geochemical environment), statistics of redundant measurement, and spatial scale/resolution of the magnetic map or model.  The purpose of this talk is to discuss the overall issue and our initial results and solicit feedback and ideas from the interpretation community.
Effects of ozone and climate on historical (1980-2015) crop yields in the United States: Implication for mid-21st century projection
Authors: Da Yabin , Xu Yangyang , McCarl Bruce
Published: March 2021

Surface ozone pollution has been proven to impose significant damages on crops. However, the quantification of the damages was extensively derived from chamber experiments, which is not representative of actual results in farm fields due to the limitations of spatial scale, time window, etc. In this work, we attempt to empirically fill this gap using county-level data in the United States from 1980 to 2015. We explore ozone impacts on corn, soybeans, spring wheat, winter wheat, barley, cotton, peanuts, rice, sorghum, and sunflower. We also incorporate a variety of climate variables to investigate potential ozone-climate interactions. More importantly, we shed light on future yield consequences of ozone and climate change individually and jointly under a moderate warming scenario. Our findings suggest significant negative impacts of ozone exposure for eight of the ten crops we examined, excepting barley and winter wheat, which contradicts experimental results. The average annual damages were estimated at $6.03 billion (in 2015 U.S. dollar) from 1980 to 2015. We also find rising temperatures tend to worsen ozone damages while water supply would mitigate that. Finally, elevated ozone driven by future climate change would cause much smaller damages than the direct effects of climate change itself.