Gary K. Corlett

A 20 year independent record of sea surface temperature for climate from Along Track Scanning Radiometers

A new record of sea surface temperature (SST) for climate applications is described. This record provides independent corroboration of global variations estimated from SST measurements made in situ. Infra-red imagery from Along-Track Scanning Radiometers (ATSRs) is used to create a 20 year time series of SST at 0.1deg latitude- longitude resolution, in the ATSR Reprocessing for Climate (ARC) project. A very high degree of independence of in situ measurements is achieved via physics-based techniques. Skin SST and SST estimated for 20 cm depth are provided, with grid cell uncertainty estimates. Comparison with in situ datasets establishes that ARC SSTs generally have bias of order 0.1 K or smaller. The precision of the ARC SSTs is 0.14 K during 2003 to 2009, from three-way error analysis. Over the period 1994 to 2010, ARC SSTs are stable, with better than 95% confidence, to within 0.005 K/yr (demonstrated for tropical regions). The dataset appears useful for cleanly quantifying inter-annual variability in SST and major SST anomalies. The ARC SST global anomaly time series is compared to the in situ-based Hadley Centre SST dataset version 3 (HadSST3). Within known uncertainties in bias adjustments applied to in situ measurements, the independent ARC record and HadSST3 present the same variations in global marine temperature since 1996. Since the in situ observing system evolved significantly in its mix of measurement platforms and techniques over this period, ARC SSTs provide an important corroboration that HadSST3 accurately represents recent variability and change in this essential climate variable.

The Global Trend in Sea Surface Temperature from 20 Years of Advanced Very High Resolution Radiometer Data

The trend in sea surface temperature has been determined from 20 yr of Advanced Very High Resolution Radiometer Pathfinder data (version 5). The data span the period from January 1985 to December 2004, inclusive. The linear trends were calculated to be 0.18° 0.04° and 0.17° 0.05°C decade 1 from daytime and nighttime data, respectively. However, the measured trends were found to be somewhat smaller if version 4.1 of the Pathfinder data was used, or if the time series of data ended earlier. The influence of El Nino on global temperatures can be seen clearly in the data. However, it was not found to affect the trend measurements significantly. Evidence of cool temperatures after the eruption of Mount Pinatubo in 1991 was also observed.

Evaluation of AATSR and TMI Satellite SST Data

Abstract The purpose of this paper is to investigate two satellite instruments for SST: the infrared (IR) Advanced Along Track Scanning Radiometer (AATSR) and the microwave (MW) Tropical Rainfall Measuring Mission (TRMM) Microwave Imager (TMI). Because of its dual view, AATSR has a potential for lower biases than other IR products such as the Advanced Very High Resolution Radiometer (AVHRR), while the tropical TMI record was available for a longer period of time than the global MW instrument, the Advanced Microwave Scanning Radiometer (AMSR). The results show that the AATSR IR retrievals are good quality with biases lower than or as low as other satellite retrievals between 50°S and 50°N. Furthermore, the dual-view algorithm reduces the influence of aerosol contamination. However, the AATSR coverage is roughly half that of AVHRR. North of 50°N there appear to be biases and high variability in summer daytime retrievals, with smaller but consistent biases observed below 50°S. TMI data can significantly impr...

Use of satellite observations for operational oceanography: recent achievements and future prospects

The paper gives an overview of the development of satellite oceanography over the past five years focusing on the most relevant issues for operational oceanography. Satellites provide key essential variables to constrain ocean models and/or serve downstream applications. New and improved satellite data sets have been developed and have directly improved the quality of operational products. The status of the satellite constellation for the last five years was, however, not optimal. Review of future missions shows clear progress and new research and development missions with a potentially large impact for operational oceanography should be demonstrated. Improvement of data assimilation techniques and developing synergetic use of high resolution satellite observations are important future priorities.

The rotational spectrum of the benzene hydrogen bromide complex

Abstract Ground-state rotational spectra of six symmetric-top isotopomers, C 6 H 6 ⋯ H 79 Br, C 6 H 6 ⋯ H 81 Br, C 6 D 6 ⋯ H 79 Br, C 6 D 6 ⋯ H 81 Br, C 6 H 6 ⋯ D 79 Br and C 6 H 6 ⋯ D 81 Br, of the benzene-hydrogen bromide complex were observed and analysed to give the rotational constant B 0 , the centrifugal distortion constants D J and D JK , and the Br nuclear quadrupole and spin-rotation coupling constants X aa and M bb in each case. It is concluded that in the zero-point state the complex has effective C 6v symmetry, with HBr oriented so that H lies closest to the benzene ring and undergoes a circular motion which allows it to sample the π-electron density of the ring.

Concurrent multiaxis differential optical absorption spectroscopy system for the measurement of tropospheric nitrogen dioxide

The development of a new concurrent multiaxis (CMAX) sky viewing spectrometer to monitor rapidly changing urban concentrations of nitrogen dioxide is detailed. The CMAX differential optical absorption spectroscopy (DOAS) technique involves simultaneous spectral imaging of the zenith and off-axis measurements of spatially resolved scattered sunlight. Trace-gas amounts are retrieved from the measured spectra using the established DOAS technique. The potential of the CMAX DOAS technique to derive information on rapidly changing concentrations and the spatial distribution of NO2 in an urban environment is demonstrated. Three example data sets are presented from measurements during 2004 of tropospheric NO2 over Leicester, UK (52.62 degrees N, 1.12 degrees W). The data demonstrate the current capabilities and future potential of the CMAX DOAS method in terms of the ability to measure real-time spatially disaggregated urban NO2.

Angular geometries of complexes containing the O⋯Cl–F linkage: Rotational spectrum of formaldehyde⋯chlorine monofluoride

Ground-state rotational spectra of the three isotopomers H2CO⋯35ClF, H2CO⋯37ClF and D2CO⋯35ClF of a complex formed by formaldehyde and chlorine monofluoride were observed with a Balle–Flygare, Fourier-transform microwave spectrometer. A fast-mixing nozzle, specially modified to generate a continuous supply of H2CO from paraformaldehyde in situ close to the nozzle exit, was used to preclude the chemical reaction of H2CO and ClF. The rotational constants A0, B0, and C0, centrifugal distortion constants ΔJ, ΔJK, and δJ, components χaa, χbb−χcc, χab of the Cl-nuclear quadrupole tensor, and the spin–rotation coupling constant 1/2(Mbb+Mcc) were determined. Interpretation of the spectroscopic constants led to the conclusion that H2CO⋯ClF is a planar complex of Cs symmetry with r(O⋯Cl)=2.523(7) A, with an angle 180−φ=69.1(7)° between the C2 axis of H2CO and the O⋯Cl internuclear line, but with a deviation θ of the O⋯Cl–F nuclei from collinearity of only 3.2(7)°. A family relationship between the angular geometrie...

Determination of AATSR Biases Using the OSTIA SST Analysis System and a Matchup Database

Abstract Sea surface temperature (SST) analyses are produced on a daily basis at the Met Office using the Operational SST and Sea Ice Analysis (OSTIA) system. OSTIA uses satellite SST data, provided by international agencies via the Global Ocean Data Assimilation Experiment (GODAE) High-Resolution SST Pilot Project (GHRSST-PP) regional/global task sharing (R/GTS) framework, which includes an estimate of bias error (available online at http://www.ghrsst-pp.org). The OSTIA system produces a foundation SST estimate (SSTfnd), which is the SST that is free of diurnal variability, at a resolution of 1/20° (∼6 km). Global coverage outputs are provided each day in GHRSST-PP L4 netCDF format. The verification and intercomparison of the OSTIA analysis, with observations and analyses, has revealed a cold bias of approximately 0.1 K in the OSTIA outputs. Because OSTIA uses the operational 1-km Envisat Advanced Along-Track Scanning Radiometer (AATSR) ATS_NR_2P data [via the GHRSST-PP/European Space Agency (ESA) Medspi...

LIF spectroscopy of the MgCCH free radical

Abstract We report first observation of the electronic spectrum of the free radical MgCCH. This molecule was prepared in a supersonic expansion by laser ablation of magnesium in the presence of methane. A strong laser-induced fluorescence excitation spectrum was found in the 415–440 nm region and was assigned to part of the A 2 Π− X 2 Σ + system. The spectrum is dominated by a single vibrational progression of interval 552 cm −1 which has been assigned to the MgC stretch in the A state. A prelimiry rotational analysis has shown that the rotational constant, B O , in the A 2 Π state is larger than that in the X 2 Σ + state, indicating a stronger MgC bond in the excited electronic state.

A Comparison of Total Column Ozone Values Derived from the Global Ozone Monitoring Experiment (GOME), the Tiros Operational Vertical Sounder (TOVS), and the Total Ozone Mapping Spectrometer (TOMS)

A comparison of total column ozone data retrieved from the Global Ozone Monitoring Experiment (GOME), the Tiros Operational Vertical Sounder (TOVS), and the Total Ozone Mapping Spectrometer (TOMS) for the years 1996, 1997, 1998, and 1999 is presented. A statistical analysis and a spatial difference analysis were performed on a range of temporally and spatially averaged datasets. An analysis of globally averaged column ozone values showed a consistent offset with TOVS and TOMS values being consistently higher than GOME by ;10‐13 DU averaged over the 4-yr period. A 4%‐5% drift was noted between the years 1996/97 and 1998/ 99 in the magnitude of the offset. The drift was identified as an increased offset of 125‐30 DU between TOVS/ TOMS and GOME occurring over latitudes above 708N during 1998/99, and is a result of TOVS/TOMS ozone columns being higher during 1998/99 than in 1996/97. Seasonal and latitudinal trends were noted in the global differences. In particular, TOMS and TOVS ozone values are consistently higher than GOME in the Southern Hemisphere from 308‐908S. TOVS and GOME ozone columns show good agreement between 208S and 208N, with TOMS values approximately 10‐15 DU higher than both TOVS and GOME in the same region. All three sensors show reasonable agreement between 208 and 608N. However, there is no agreement above 608N, where TOVS columns are higher than TOMS columns that in turn are higher than GOME columns. Results from a spatial difference analysis indicated further differences between GOME and TOVS ozone values that were not obvious from the global or latitudinal analysis owing to cancellation effects, including an area over Indonesia where GOME columns are higher than TOVS columns.