Extended validation and evaluation of the OLCI–SLSTR SYNERGY aerosol product (SY_2_AOD) on Sentinel-3

We present the first extended validation of a new SYNERGY global aerosol product (SY_2_AOD), which is based on synergistic use of data from the Ocean and Land Color Instrument (OLCI) and the Sea and Land Surface Temperature Radiometer (SLSTR) sensors aboard the Copernicus Sentinel-3A (S3A) and Sentinel-3B (S3B) satellites. Validation covers period from 14 January 2020 to 30 September 2021. Several approaches, including statistical analysis, time series analysis, and comparison with similar aerosol products from the other spaceborne sensor, the Moderate Resolution Imaging Spectroradiometer (MODIS), were applied for validation and evaluation of S3A and S3B SY_2 aerosol products, including aerosol optical depth (AOD) provided at different wavelengths, AOD pixel-level uncertainties, fine-mode AOD, and Angström exponent.Over ocean, the performance of SY_2 AOD (syAOD) retrieved at 550 nm is good: for S3A and S3B, Pearson correlation coefficients with the Maritime Aerosol Network (MAN) component of the AErosol RObotic NETwork (AERONET) are 0.88 and 0.85, respectively; 88.6 % and 89.5 % of pixels fit into the MODIS error envelope (EE) of ±0.05 ± 0.2 × AOD.Over land, correlation coefficients with AERONET AOD (aAOD) are 0.60 and 0.63 for S3A and S3B, respectively; 51.4 % and 57.9 % of pixels fit into MODIS EE. Reduced performance over land is expected since the surface reflectance and angular distribution of scattering are higher and more difficult to predict over land than over ocean. The results are affected by a large number of outliers.Evaluation of the per-retrieval uncertainty with the χ2 test indicates that syAOD prognostic uncertainties (PU) are slightly underestimated (χ2 = 3.1); if outliers are removed, PU describes the syAOD error well (χ2 = 1.6).The regional analysis of the Angström exponent, which relates to the aerosol size distribution, shows spatial correlation with expected sources. For 40 % of the matchups with AERONET in the Northern Hemisphere (NH) and for 60 % of the matchups in the Southern Hemisphere (SH), which fit into the AE size range of [1, 1.8], an offset between SY_2 AE (syAE) and AERONET AE (aAE) is within ±0.25. General overestimation of low ( 1.8) syAE results in high (0.94, globally) overall bias.Good agreement (bias  1, syFMAOD is considerably underestimated (by 0.3–0.5 in different aFMAOD ranges) in the NH. In the SH, only a few aFMAOD values above 1 are measured. The fine-mode fraction (FMF) in the SY_2 AOD product (syFMF) in the range of [0, 0.7] is overestimated; the positive offset of 0.3–0.5 for low (< 0.25) FMF gradually decreases.Differences between the annual and seasonal AOD values from SY_2 and MODIS (mod) Dark Target and Deep Blue products are within 0.02 for the study area (30∘ S–60∘ N, 80∘ W–45∘ E). The agreement is better over ocean; however, a difference up to 0.6 exists between syFMF and modFMF. Over bright land surface (Saharan desert) the difference in AOD between the two products is highest (up to 0.11); the sign of the difference varies over time and space.For both S3A and S3B AOD products, validation statistics are often slightly better in the Southern Hemisphere. In general, the performance of S3B is slightly better

Hague Conventions and the Reform of English Conflict of Laws

Over twenty years ago, Horace Read said: The first half of this century has seen the emergence of legislation as the chief instrument of change and innovation in the law .2 True though this comment was in 1959, it has received added force in the common law world, especially in the Commonwealth, by the \u27explosion of law reform\u27 3 which has taken place since the mid-sixties. The creation of permanent statutory law reform agencies has tilted the balance even further towards legislation as the instrument of legal change. This is for two reasons. Despite the occasional judicial attempt to jump the legislative gun,4 the means of implementing proposals from law reform commissions is by means of legislation, and this is assisted by the practice of many such bodies of appending draft Bills to their final reports. The fact that such agencies exist seems in recent years, in England at least, to have caused the judges in a number of instances to argue that major change in the law is not for them, but for the legislature

War Stories': morality, curiosity, enthusiasm and commitment as facilitators of SME owners' engagement in low carbon transitions

The ‘urban’ has emerged as a key site for policies to reduce greenhouse gasses in order to avoid dangerous climate change, especially given concerns at a lack of action at international and national levels. In cities, the private sector, especially SME owners, are a key actors central to driving through emissions reduction at the level of the firm: yet they are often seen as laggards in emissions reduction. Drawing on data collected as a result of a recent Knowledge Exchange programme in Liverpool, UK, and on cultural and diverse economies perspectives, the paper argues that those SME owners can be effective change agent through their mobilisation of what they call 'war stories', through which they 'show and tell' other perhaps less convinced business people about the changes they have made

The Development of the Academic Dress of the University of Oxford 1920–2012

One might expect that the well-trodden ground of Oxford academic dress would yield nothing new or surprising, but this is far from the truth. With an institution as old as Oxford, many onlookers assume that because they know Oxford’s traditions that they know Oxford’s rules and so do not need to consult statute. An excellent example is the number of undergraduates these days who profess that one may not wear the square cap until graduation, whereas the most cursory glance at University regulations would show their belief false. Also, I would argue that the academic dress of Oxford is of particular importance as its gowns and hoods are used as templates for many other universities in the United Kingdom and further afield. Thus an understanding of the nature and origin of the current state of academic dress is essential. [Excerpt]

The effect of a scanning flat fold mirror on a CMB B-mode experiment

We investigate the possibility of using a flat-fold beam steering mirror for a CMB B-mode experiment. An aluminium flat-fold mirror is found to add $\sim$0.075% polarization, which varies in a scan synchronous way. Time-domain simulations of a realistic scanning pattern are performed, and the effect on the power-spectrum illustrated and a possible method of correction applied.Comment: 8 pages, 5 figures. Accepted for publication in Rev Sci Ins

The Road Less Travelled in Access to Higher Education

Peer reviewedPublisher PD