The detection of post-monsoon tropospheric ozone variability over south Asia using IASI data

The ozone (O<sub>3</sub>) variability over south Asia during the 2008 post-monsoon season has been assessed using measurements from the MetOP-A/IASI instrument and O<sub>3</sub> profiles retrieved with the SOftware for a Fast Retrieval of IASI Data (SOFRID). The information content study and error analyses carried out in this paper show that IASI Level 1 data can be used to retrieve tropospheric O<sub>3</sub> columns (TOC, surface-225 hPa) and UTLS columns (225–70 hPa) with errors smaller than 20%. Validation with global radiosonde O<sub>3</sub> profiles obtained during a period of 6 months show the excellent agreement between IASI and radiosonde for the UTLS with correlation coefficient <i>R</i> > 0.91 and good agreement in the troposphere with correlation coefficient <i>R</i> > 0.74. For both the UTLS and the troposphere Relative Standard Deviations (RSD) are lower than 23%. Comparison with in-situ measurements from the MOZAIC program around Hyderabad demonstrates that IASI is able to capture the TOC inter and intra-seasonal variability in central India. Nevertheless, the agreement is mitigated by the fact that the smoothing of the true O<sub>3</sub> profiles by the retrieval results in a reduction of the TOC variability detected by IASI relative to the variability observed by in situ instruments. The post-monsoon temporal variability of the vertical profile of O<sub>3</sub> around Hyderabad has been investigated with MOZAIC observations. These observations from airborne instruments show that tropospheric O<sub>3</sub> is steadily elevated during most of the studied period with the exception of two sharp drops following the crossing of tropical storms over India. Lagrangian simulations with the FLEXPART model indicate that elevated O<sub>3</sub> concentrations in the middle troposphere near Hyderabad are associated with the transport of UTLS air-masses that have followed the Subtropical Westerly Jet (SWJ) and subsided over northern India together with boundary layer polluted air-masses transported from the Indo-gangetic plain by the north-easterly trades. Low O<sub>3</sub> concentrations result from the uplift and westward transport of pristine air-masses from the marine boundary layer of the Bay of Bengal by tropical storms. In order to extend the analysis of tropospheric O<sub>3</sub> variability to the whole of south Asia, we have used IASI-SOFRID O<sub>3</sub> data. We show that IASI O<sub>3</sub> data around Hyderabad were able to capture the fast variability revealed by MOZAIC. Furthermore, their spatio-temporal coverage demonstrates that the behaviour of tropospheric O<sub>3</sub> observed near Hyderabad extended over most of central and south India and part of the Bay of Bengal. This result highlights the ability of the IASI sensor to capture fast changes in chemical composition related to dramatic tropical weather conditions

GEWEX water vapor assessment (G-VAP): final report

Este es un informe dentro del Programa para la Investigación del Clima Mundial (World Climate Research Programme, WCRP) cuya misión es facilitar el análisis y la predicción de la variabilidad de la Tierra para proporcionar un valor añadido a la sociedad a nivel práctica. La WCRP tiene varios proyectos centrales, de los cuales el de Intercambio Global de Energía y Agua (Global Energy and Water Exchanges, GEWEX) es uno de ellos. Este proyecto se centra en estudiar el ciclo hidrológico global y regional, así como sus interacciones a través de la radiación y energía y sus implicaciones en el cambio global. Dentro de GEWEX existe el proyecto de Evaluación del Vapor de Agua (VAP, Water Vapour Assessment) que estudia las medidas de concentraciones de vapor de agua en la atmósfera, sus interacciones radiativas y su repercusión en el cambio climático global.El vapor de agua es, de largo, el gas invernadero más importante que reside en la atmósfera. Es, potencialmente, la causa principal de la amplificación del efecto invernadero causado por emisiones de origen humano (principalmente el CO2). Las medidas precisas de su concentración en la atmósfera son determinantes para cuantificar este efecto de retroalimentación positivo al cambio climático. Actualmente, se está lejos de tener medidas de concentraciones de vapor de agua suficientemente precisas para sacar conclusiones significativas de dicho efecto. El informe del WCRP titulado "GEWEX water vapor assessment. Final Report" detalla el estado actual de las medidas de las concentraciones de vapor de agua en la atmósfera. AEMET ha colaborado en la generación de este informe y tiene a unos de sus miembros, Xavier Calbet, como co-autor de este informe

Estimating Analysis Temperature And Humidity Biases Due To Assimilation Of Aerosol & Cloud Contaminated Hyperspectral Infrared Radiances

Observations from hyperspectral infrared sounder (HIS) instruments aboard earth-observing satellites have become a cornerstone of numerical weather prediction assimilation efforts – providing the largest decrease in forecast error of any assimilated satellite observations. The assimilation of infrared (IR) radiances is predicated on the assumption of clear-sky observations. Thus, any signal imparted upon the HIS radiances due to cloud or aerosol will likely result in unexpected and uncharacterized biases in analyzed temperature and humidity fields. Forecasts based upon these biased fields may have large inherent inaccuracies. The process of cloud and aerosol screening of passive satellite products and radiances is imperfect. Residual aerosol and cirrus clouds are found to contaminate HIS radiances assimilated from presumed clear-sky scenes at concerning rates (approximately 30% and 8% for the Naval Research Laboratory Variational Data Assimilation System, respectively). As such, the presence of an uncharacterized bias exists within model analyses. To determine the biases a modified one-dimensional variational (1DVar) assimilation system is used for two studies: one for aerosol, one for cloud. For the aerosol study, observations of dust from the Island of Tenerife, Spain are used to create synthetic dust contaminated HIS observations. For the cloud study, a series of clouds of varying optical depth and cloud top altitude are simulated. Analysis biases greater than expected forecast uncertainties are found for both studies. Aerosol biases are smaller, likely due to lower thermal contrast with the lower atmosphere. For instance, at an average aerosol optical depth of 0.30 a peak temperature bias of 0.5 K and dew point bias of 1.0 K is found. Meanwhile, for cloud optical depths as small as 0.1, maximum temperature and dew point biases of 3 K and 10 K are shown. Finally, a third study in similar vein to the first two simplifies the impact of aerosols on numerical weather prediction by examining the impact of aerosol optical model on broadband radiative properties. Observations above and within a dust aerosol plume collected during the Studies of Emissions and Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys (SEAC4RS) field campaign are used to attempt radiative closure. Large variability for different commonly used aerosol optical models is shown for shortwave fluxes and heating rates of up to 50% and 400%, respectively. In the IR, variability is still relatively smaller, but still very large at 3% for flux and 25-50% for heating rates. Finally, it is determined that aerosol analyses from models are not sufficiently accurate to provide accurate fluxes or heating rates

Improvement and interpretation of the tropospheric ozone columns retrieved based on SCIAMACHY Limb-Nadir Matching approach

Tropospheric ozone, one of the most important green-house gases and one of the most essential components of photochemical smog, has been monitored from space by different retrieval techniques since the late 1980s. Satellite measurements are well suitable to investigate sources and transport mechanisms of tropospheric ozone, as well as its atmospheric chemistry on regional and global scales. Nevertheless, the retrieval of tropospheric ozone columns (TOCs) from satellite data constitutes a big challenge since approximately 90% of the total ozone amount is located in the stratosphere, and only the remaining 10% is located in the troposphere. The Limb-Nadir Matching technique is one of the methods that has been widely used to re-trieve TOCs from space borne measurements. In previous studies, this approach has been applied to measurements from the SCIAMACHY instrument, which alternates limb and nadir geometry. An accurate tropopause height, retrieved from the ECMWF database, was used to subtract the stratospheric ozone column from the total ozone column. In this thesis, a three-step approach is shown that was developed to improve the current Limb-Nadir Matching TOC retrieval technique, and resulted in the new database version 1.2. Several improvements in the V1.2 TOC data have been achieved. The obtained amount of TOC V1.2 data has increased by a factor of two in comparison to the original dataset. Fur-thermore, the data quality has improved in many aspects. First of all, the V1.2 TOC data set reduces the negative (>10 DU) and positive (~10 DU) biases over tropics and high latitudes, respectively. The reduction is achieved by use of the improved limb ozone data set V3.0, which was tested and validated against the previous version V2.9 in this thesis. The TOC values were also optimized over the midlatitudes by decreasing its positive biases. The yearly averaged V1.2 TOC data set agrees well with ozonesonde measurements within 5 DU globally. More details on the TOC distribution were successfully captured because of the improved accuracy of the data. The clear observation of the spring TOC maxima (~42 DU) over the Arabian Sea (AS) during the pre-monsoon is one of the benefits of using the V1.2 TOC product. In the present thesis, the potential sources of the AS spring ozone pool are investigated by use of multiple data sets (e.g., SCIAMACHY Limb-Nadir-Matching TOC, OMI/MLS TOC, TES TOC, MACC reanalysis data, MOZART-4 model and HYSPLIT model). 3/4 of the enhanced ozone concentrations are attributed to the 0-8 km height range. The main source of the ozone enhancement is considered to be caused by long range transport of pollutants from India (~ 50% contributions to the lowest 4 km, ~ 20% contributions to the 4-8 km height range), the Middle East, Africa and Europe (~30% in total). In addition, the vertical pollution accumulation in the lower troposphere, especially at 4-8 km, was found to be important for the AS spring ozone pool. Local photochemistry, on the other hand, plays a negligible role in producing ozone at the 4-8 km height range. In the 0-4 km height range, ozone is quickly removed by wet-deposition. The AS spring TOC maxima are influenced by the dynamical variations caused by the sea surface temperature (SST) anomaly during the El Nino period in 2005 and 2010 with a ~5 DU decrease. The Limb-Nadir Matching retrieval improvement scheme developed in this thesis leads to a much more accurate TOC product measured by SCIAMACHY and a better understanding of tropospheric ozone distributions

Cumulus boundary layers in the atmosphere : high resolution models and satellite observations

Tese de doutoramento, Ciências Geofísicas e da Geoinformação (Meteorologia), Universidade de Lisboa, Faculdade de Ciências, 2011This project intends to explore some of the challenges on the representation of the Planetary Boundary Layer (PBL) using both high resolution models and state of the art observations. Some of the issues related the different types of boundary layers are highlighted in the context of a model intercomparison at a transect in the northeast Pacific that served as a benchmark for studying cloud regimes and transitions between them. Several model biases were detected and even reanalysis products do not show reasonable comparisons against observations in terms of low-cloud related variables. The transition from shallow to deep convection over land is a key process in the diurnal cycle of convection over land. High resolution simulations were analyzed the ability of the model to reproduce observed precipitation characteristics and its sensitivity to horizontal resolution and to the evaporation of precipitation. The latter physical process influences the development of new convection by increasing the thermodynamic heterogeneities at the PBL through the formation of cold pools which result from convective downdrafts. At the later stages of the transition these features dominate the PBL behavior, as the turbulent length scales increase up to several times the size of the PBL height. Results are however quite sensitive to model resolution. At the observational perspective, the Atmospheric Infrared Sounder was used to characterize the PBL properties in a variety of situations. An algorithm for PBL height determination was developed and validated against radiosondes launched at the Rain in Cumulus over the Ocean campaign. The encouraging results of the validation led to the calculation of a PBL height climatology over the tropical, subtropical and midlatitude oceans. Results were then compared to similar estimates from collocated profiles from ERA-Interim, revealing similar geographical distribution and seasonal variations. Diurnal variability is much different between both datasets which warrants further investigations.A camada limite planetária (CLP) apresenta desafios tanto em termos observacionais como em termos da sua modelação numérica. O seu papel no sistema climático traduz-se na mediação das interacções entre a superfície e a troposfera livre, através de fluxos turbulentos de calor, humidade , momento e outros constituintes químicos e aerossóis. A estrutura da CLP encontra-se profundamente relacionada com as condições climatéricas de uma dada região, em particular com tipo de nuvens predominantes. A intercomparação de modelos realizada sobre uma secção no Pacífico nordeste pretendeu avaliar a capacidade dos modelos de representar os diversos processos associados aos diversos regimes de nuvens presentes na região. A secção mostrou-se indicada para este exercício, pois além de amostrar as características principais das células de Walker e Hadley, é também representativa das transições que ocorrem entre nuvens estratiformes que ocorrem ao largo da costa da California, nuvens tipo cumulus pouco profundos na região dos Alíseos e nuvens tipo cumulonimbos que ocorrem preferencialmente na Zona Intertropical de Convergência (ITCZ). Os resultados da comparação evidenciaram as enormes discrepâncias que existem entre modelos em termos da representação dos processos associados às nuvens. Além dos modelos, a própria reanálise ERA-40 mostrou diferenças significativas quando comparada com observações de detecção remota dedicadas a esses processos. A transição de entre convecção pouco profunda para convecção profunda é o processo que domina a fase matinal do ciclo diurno da convecção sobre terra nos trópicos, e a sua representação na maioria dos modelos de larga escala apresenta graves deficiências, com o pico da precipitação a ocorrer no período na manhã, enquanto as observações mostram que o mesmo ocorre a meio da tarde. Os modelos tendem a usar um fecho para a parameterização da convecção baseado no conceito de energia potencial disponível para a convecção (CAPE), que activa a convecção profunda demasiado cedo, sendo que as simulações de alta resolução têm mostrado que o processo é bastante mais gradual: inicia-se com a formação de uma camada limite bem misturada, seguida da formação de cumulus pouco profundos que humidificam as camadas inferiores da troposfera, para então se dar a transição para convecção profunda. Neste projecto realizaram-se simulações de alta resolução deste processo usando o modelo MesoNH, por forma a estudar a capacidade do modelo de reproduzir as características da precipitação e a sensibilidade dos resultados à resolução do modelo e à evaporação da precipitação. Este vi último processo físico desempenha um papel fundamental no estabelecimento da fase madura do regime de convecção profunda. Isto porque ao evaporar, a precipitação arrefece o ar, causando fortes correntes descendentes que ao atingir a superfície se espraiam sob a forma de correntes gravíticas. Nos limites destas correntes, fortes gradientes termodinâmicos forçam o ar da CLP a subir, originando novas térmicas que eventualmente formam novas células convectivas. Nas fases finais da transição, estas perturbações dominam o comportamento da CLP, tal como indicam os diagnósticos espectrais das escalas de comprimento dominantes. Esta análise mostra que o tamanho dos turbilhões na CLP varia desde a dimensão típica da altura da CLP na fase de convecção pouco profunda até dimensões que superam várias vezes essa escala típica na fase de convecção profunda. Esse comportamento é totalmente distinto na simulação sem evaporação de precipitação, com os turbilhões a manterem dimensões associadas à altura da CLP durante todo o processo. Os resultados revelam contudo uma grande sensibilidade à resolução do modelo, com evoluções bastante distintas no alcance vertical da convecção nas simulações com diferentes resoluções. As diferenças são atribuidas à diferente representação dos processos turbulentos por parte do modelo de turbulência de subescala, mas os resultados são ainda inconclusivos. A observação da CLP por métodos de detecção remota apresenta também desafios próprios. Neste projecto, a base de dados do Atmospheric Infrared Sounder (AIRS) V5 L2 Support Product foi usada para estimar parâmetros da camada limite. Este produto apresenta um espaçamento de grelha vertical superior ao dos produtos AIRS convencionais, o que o torna mais indicado para estudar a CLP. Um algoritmo para determinação da altura da CLP foi desenvolvido e validado contra dados das sondagens lançadas no contexto da campanha Rain in Cumulus over the Ocean, ocorrida nas Caraíbas no Inverno de 2004-2005. Essa área é dominada nessa altura do ano por convecção pouco profunda embebida nos ventos alíseos, o que a torna ideal para a validação dos perfis obtidos com o AIRS, dado que o sensor utiliza radiâncias da banda do infravermelho, fortemente atenuadas pela presença de nuvens. Os perfis utilizados foram comparados com os das radiossondagens e revelaram a sua capacidade de ilustrar as principais características da CLP, com margens de erro dentro do aceitável de acordo com as características desejáveis para o instrumento. Os resultados mostraram-se insensíveis a diversos factores como a fracção de nuvens e de píxeis terrestes no campo de visão, radiação de longo comprimento de onda no topo da atmosfera e distância entre vii a radiossonda e o pixel do satélite. As alturas da CLP são determinadas a partir de perfis de temperatura potencial e humidade relativa, a partir da localização do nível com maiores gradientes verticais dessas propriedades. Os métodos utilizados na determinação da altura da CLP são ainda objecto de debate e dependem da base de dados utilizada; este foi o método escolhido por ser o mais simples, mais adequado aos dados disponíveis e com maior aplicabilidade em diferentes regiões do globo. A comparação entre as estimativas dos dados de satélite e das radiossondas revela erros médios quadráticos da ordem de 50 hPa, o que mostra que o produto é capaz de caracterizar de forma aceitável a altura da CLP. Uma climatologia da altura da CLP foi calculada usando toda a base de dados do AIRS (2003-2010) ao longo dos oceanos das regiões tropicais, subtropicais e das latitudes médias. Essa climatologia foi comparada com estimativas semelhantes obtidas a partir de perfis da reanálise ERA-Interim extraídos da localização mais próxima e da hora mais próxima da hora de passagem do satélite. Ambas as estimativas revelaram distribuições realísticas da altura da CLP, com valores mínimos a coincidir com as áreas dominadas por nuvens estratiformes ao largo da costa oeste dos continentes subtropicais e valores mais altos nas zonas dominadas por convecção profunda. As variações sazonais são também realistas em ambos as bases de dados, com características como a migração da ITCZ ao longo do ano e o estabelecimento das características típicas de monções sazonais em determinadas regiões do globo. Contudo, o ciclo diurno aparece representado nas duas bases de dados de forma bastante distinta: enquanto o AIRS mostra variações realísticas da altura da CLP ao longo do ciclo diurno, a ERA-Interim não apresenta variações diurnas significativas, o que indica a presença de algumas deficiências na representação de processos de camada limite sobre o oceano nessa base de dados. Os dados foram analisados em particular sobre a secção no Pacífico nordeste com objectivo de explicar alguns dos desvios encontrados. Essa análise evidenciou a tendência do instrumento para amostrar principalmente pixeis com características de céu limpo ou com nebulosidade reduzida, pois ao aplicar amostragem condicional aos dados ERA-Interim de modo a isolar os perfis característicos de baixas coberturas nebulosas, mostra-se que existe uma correspondência bastante melhor entre as duas bases de dados. Neste trabalho mostra-se que tanto modelos como observações da CLP sofrem dos seus problemas e que avanços significativos no conhecimento desta camada tão importante da atmosfera só podem ser atingidos combinando eficazmente ambas as estratégias.Fundação para a Ciência e a Tecnologia (FCT, SFRH/BD/37800/2007 e projectos (PTDC/CLI/73814/2006);(PEst-OE/CTE/LA0019/2011/2012) e Fundação Calouste Gulbenkia

Izaña Atmospheric Research Center. Activity Report 2015-2016

This report is a summary of the many activities at the Izaña Atmospheric Research Center to the broader community. The combination of operational activities, research and development in state-of-the-art measurement techniques, calibration and validation and international cooperation encompass the vision of WMO to provide world leadership in expertise and international cooperation in weather, climate, hydrology and related environmental issues

Validation practices for satellite based earth observation data across communities

Assessing the inherent uncertainties in satellite data products is a challenging task. Different technical approaches have been developed in the Earth Observation (EO) communities to address the validation problem which results in a large variety of methods as well as terminology. This paper reviews state-of-the-art methods of satellite validation and documents their similarities and differences. First the overall validation objectives and terminologies are specified, followed by a generic mathematical formulation of the validation problem. Metrics currently used as well as more advanced EO validation approaches are introduced thereafter. An outlook on the applicability and requirements of current EO validation approaches and targets is given

Mesure du protoxyde d'azote (N2O) depuis l'espace

Cette thèse porte sur la mesure du protoxyde d'azote (N2O) à partir de capteurs spatiaux. Dans un premier temps, nous avons étudié les processus d'émissions et de transport de N2O depuis l'Asie jusqu'au bassin méditerranéen. Pour cette étude, nous avons utilisé des sorties du modèle de chimie-transport LMDz-Or-INCA ansi que des profils de N2O estimés à partir d'observations du capteur spatial TANSO-FTS (Thermal And Near infrared Sensor for carbon Observation Fourier Transform Spectrometer) de la plateforme GOSAT (Greenhouses gases Observing SATellite). Ensuite, nous avons mis en place un système de restitution des profils troposphériques de N2O à partir des mesures du capteur spatial infrarouge IASI (Infrared Atmospheric Sounding Interferometer) des plateformes MetOp. Ce système a ensuite été validé en utilisant les mesures in-situ des campagnes aéroportées HIPPO (High performance Instrumented airborne platform for environmental research Pole-to-Pole Observations). Enfin, nous avons étudié l'apport théorique du capteur IASI-NG (IASI-New Generation) par rapport à IASI pour la mesure du N2O troposphérique.This thesis focuses on the measurement of nitrous oxide (N2O) from space sensors. Firstly, we studied the transport and emission processes of N2O from Asia to the Mediterranean Basin (MB). For this study, we used N2O profiles over the period 2010-2013 retrieved from TANSO-FTS (Thermal And Near infrared Sensor for carbon Observation Fourier Transform Spectrometer) observations onboard the platform GOSAT (Greenhouses gases Observing SATellite) . We also used outputs of the chemistry-transport model LMDz-Or-INCA over the same period. Secondly, we built an algorithm to retrieve N2O profiles using observations from IASI (Infrared Atmospheric Sounding Interferometer) onboard the MetOp platforms. This algorithm was validated by comparing the retrieved profiles with in-situ measurements from HIPPO (High performance Instrumented airborne platform for environmental research Pole-to-Pole Observations) airborne campaigns. Finally, we performed a theoretical intercomparison between IASI-NG (IASI-New Generation) and IASI concerning the tropospheric N2O measurements

Evaluating spectral radiances simulated by the HadGEM2 global climate model using longwave satellite measurements

A 'model-to-radiance' comparison of simulated brightness temperatures and radiances from the Hadley Centre Global Environmental Model 2 (HadGEM2-A) with longwave measurements from the High Resolution Infrared Radiation Sounder/4 (HIRS/4) and the Infrared Atmospheric Sounding Interfermeter (IASI) onboard the MetOp-A satellite is presented for all-sky and clear-sky global means. The fast Radiative Transfer model for TOVS 10 (RTTOV-10) is applied to HadGEM2 output to simulate observational-equivalent data. The results are compared with corresponding broadband analyses. A method is developed to extend hyperspectral IASI radiances to cover the whole outgoing terrestrial spectrum, in order to identify any compensating biases, and explore wavebands in the unobserved Far Infrared (FIR) region. For the all-sky HIRS analysis, the model overestimates brightness temperatures in the atmospheric window region with the greatest biases over areas associated with deep convective cloud. In contrast to many global climate models, much smaller clear-sky biases are found indicating that model clouds are the dominating source of error. Simulated values in upper atmospheric CO2 channels approximate observations better as a result of compensating cold biases at the poles and warm biases at lower latitudes, due to a poor representation of the Brewer Dobson circulation in the 38 level 'low-top' configuration of the model. Simulated all and clear-sky outgoing longwave radiation evaluated against the Clouds and the Earth's Radiant Energy System (CERES) and HIRS OLR products reveal good agreement, in part due to cancellation of positive and negative biases. Through physical arguments relating to the spectral energy balance within a cloud, it is suggested that broadband agreement could be the result of a balance between positive window biases and unseen negative biases originating from the water vapour rotational band in the FIR (not sampled by HIRS). Simple sensitivity tests show that dramatically altering existing cloud properties has little effect on the prominent window biases, however raising clouds a maximum of 5 atmospheric levels minimises the error in cloud contaminated channels, due to the introduction of spatially compensating errors. Sensitivities to the way ice clouds are parameterised in RTTOV-10 display a range of up to 2.5 K in window channels but absolute biases still exceed 3 K for all choices. Because of the lack of satellite based FIR observations due to a technological gap in the spectral region, an algorithm is created to 'fill in' the available data. Correlations between selected IASI channels and simulated unobserved wavelengths in the far infrared are used to estimate radiances between 25.25 - 644.75 cm-1 at 0.5 cm-1 intervals. The same method is used in the 2760 - 3000 cm-1 region. The spectrum is validated by comparing the Integrated Nadir Longwave Radiance (INLR) product (spanning the whole 25.25 - 3000 cm-1 range) with the corresponding broadband measurements from the Clouds and the Earth's Radiant Energy System (CERES) instrument on the Terra and Aqua satellites at simultaneous nadir overpasses, revealing mean differences of 0.3 Wm-2sr-1 (0.5% relative difference) lower for IASI relative to CERES and significantly lower biases in nighttime only scenes. Averaged global data over a single month produces mean differences of about 1 Wm-2sr-1 in both the all and the clear-sky (1.2% relative difference). The new high resolution spectrum is presented for global mean clear and total skies where the far infrared is shown to contribute 44% and 47% to the total OLR respectively, which is consistent with previous estimates. In terms of spectral cloud radiative forcing, the FIR contributes 19% and in some subtropical instances appears to be negative, results that would go un-observed with a traditional broadband analysis. The equivalent complete IASI OLR model product is simulated from GCM data using RTTOV-10. The same process of applying predictors to the satellite measurements is applied to the model simulated radiances, with appropriate modifications, to produce a directly comparable model product. Annual mean all-sky radiances are still greatly overestimated at all wavenumbers with a total radiance bias of 4.52 Wm-2 across the whole range. Compensating negative biases outside of the HIRS coverage that were hypothesised are absent, with the far infrared contributing to the overall bias rather than cancelling it. Equivalent clear-sky biases are much lower overall at 0.39 Wm-2, in part due to spectral and spatial cancellation of errors. A flux-to-flux comparison is enabled by estimating the spatial distribution of anisotropic factors, using collated HIRS OLR fluxes and IASI OLR radiances, which yields global mean model fluxes in excess of 12 Wm-2 higher than observations in the all-sky. The difference between this and the fluxes calculated using the climate model's broadband radiation code (Edward-Slingo) are around 10 Wm-2 which is outside the range of uncertainty in the method used to estimate the flux. However, it is discussed that tuning of the climate model's broadband code to known flux values is a required practice to ensure global energy budgets balance but can produce inaccurate parameterised variables. An equivalent analysis adjusting the ice cloud parametrisation to reflect the radiances that have the biggest differences to the original configuration selected showed a bias reduction of 4.5 Wm-2, which is still not enough to completely explain its size, suggesting the existence of residual cloud problems. Finally, it is suggested that the way forward in separating and constraining cloud errors, in both radiative transfer codes, is a rigorous process of testing them with observation cloud properties and reanalysis data as inputs