Data assimilation: making sense of Earth Observation

Lahoz, W. A.; Schneider, Philipp

doi:10.3389/fenvs.2014.00016

Cited by 214 publications

(219 citation statements)

References 219 publications

(267 reference statements)

Supporting

Mentioning

219

Contrasting

Order By: Relevance

“…The errors displayed by reanalysis products arise from three sources: observation error, model error and assimilation error (Thorne and Vose, 2010;Parker, 2016;Lahoz and Schneider, 2014;Dee et al, 2014;Zhou et al, 2017). Specifically, observation error incorporates systematic and random errors in instruments and their replacements, errors in data reprocessing and representation error, which arises due to the spatiotemporal incompleteness of observations (Dee and Uppala, 2009;Desroziers et al, 2005).…”

Section: Introductionmentioning

confidence: 99%

“…Model error refers mainly to the inadequate representation of physical processes in NWP models (Peña and Toth, 2014;Bengtsson et al, 2007), such as the lack of time-varying surface conditions such as vegetation growth (Zhou and Wang, 2016b;Trigo et al, 2015), and incomplete cloud-precipitation-radiation parameterizations (Fujiwara et al, 2017;Dolinar et al, 2016). Assimilation error describes errors that arise in the mapping of the model space to the observation space and errors in the topologies of cost functions (Dee, 2005;Dee and Da Silva, 1998;Lahoz and Schneider, 2014;Parker, 2016).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

On the suitability of current atmospheric reanalyses for regional warming studies over China

Zhou

Wang

2018

Atmos. Chem. Phys.

View full text Add to dashboard Cite

Abstract. Reanalyses are widely used because they add value to routine observations by generating physically or dynamically consistent and spatiotemporally complete atmospheric fields. Existing studies include extensive discussions of the temporal suitability of reanalyses in studies of global change. This study adds to this existing work by investigating the suitability of reanalyses in studies of regional climate change, in which land-atmosphere interactions play a comparatively important role. In this study, surface air temperatures (T a ) from 12 current reanalysis products are investigated; in particular, the spatial patterns of trends in T a are examined using homogenized measurements of T a made at ∼ 2200 meteorological stations in China from 1979 to 2010. The results show that ∼ 80 % of the mean differences in T a between the reanalyses and the in situ observations can be attributed to the differences in elevation between the stations and the model grids. Thus, the T a climatologies display good skill, and these findings rebut previous reports of biases in T a . However, the biases in theT a trends in the reanalyses diverge spatially (standard deviation = 0.15-0.30 • C decade −1 using 1 • × 1 • grid cells). The simulated biases in the trends in T a correlate well with those of precipitation frequency, surface incident solar radiation (R s ) and atmospheric downward longwave radiation (L d ) among the reanalyses (r = −0.83, 0.80 and 0.77; p < 0.1) when the spatial patterns of these variables are considered. The biases in the trends in T a over southern China (on the order of −0.07 • C decade −1 ) are caused by biases in the trends in R s , L d and precipitation frequency on the order of 0.10, −0.08 and −0.06 • C decade −1 , respectively. The biases in the trends in T a over northern China (on the order of −0.12 • C decade −1 ) result jointly from those in L d and precipitation frequency. Therefore, improving the simulation of precipitation frequency and R s helps to maximize the signal component corresponding to regional climate. In addition, the analysis of T a observations helps represent regional warming in ERA-Interim and JRA-55. Incorporating vegetation dynamics in reanalyses and the use of accurate aerosol information, as in the Modern-Era Retrospective Analysis for Research and Applications, version 2 (MERRA-2), would lead to improvements in the modelling of regional warming. The use of the ensemble technique adopted in the twentieth-century atmospheric model ensemble ERA-20CM significantly narrows the uncertainties associated with regional warming in reanalyses (standard deviation = 0.15 • C decade −1 ).

show abstract

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

On the suitability of current atmospheric reanalyses for regional warming studies over China

Zhou

Wang

2018

Atmos. Chem. Phys.

View full text Add to dashboard Cite

show abstract

“…As described in the previous section, DA applications require specific, frequent and high quality measurements, which may not be compatible with the distributed, intermittent and, potentially, lower-quality nature of citizen-based data (Shanley et al, 2013;Buytaert et al, 2014;Lahoz and Schneider, 2014). That is why interpolation and merging techniques are commonly used to integrate citizen observations within mathematical models.…”

Section: Data Assimilationmentioning

confidence: 99%

“…It is worth noting that, as Refsgaard (1997) stated, usually the processes previously described are denoted as Data Assimilation (DA). However, in this Thesis, DA methods are referred to a particular group of model updating methods in which only model states are updated (Lahoz et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

Improving Flood Prediction Assimilating Uncertain Crowdsourced Data into Hydrological and Hydraulic Models

Mazzoleni¹

2017

View full text Add to dashboard Cite

“…transport and chemistry, but we need to ensure that ozone is treated in a consistent manner. Data assimilation is a process 20 by which observations are introduced into a model while constraining these to follow model physics (Lahoz et al, 2010) . We have used an updated version of the DIAMOND model (Rösevall et al, 2007) to treat the Odin observations.…”

mentioning

confidence: 99%

A long term study of polar ozone loss derived from data assimilation of Odin/SMR observations

Sagi

Murtagh

2016

Preprint

View full text Add to dashboard Cite

Abstract. Odin, a Swedish-led satellite project in collaboration with Canada, France and Finland, was launched on 20 February 2001 and continues to produce profiles of chemical species relevant to understanding the middle and upper atmosphere. Longterm observations of stratospheric ozone are useful for trend analysis of chemical ozone loss. This study concerns ozone loss over both poles utilizing 12 years of ozone data from Odin/Sub-Millimetre Radiometer (SMR). We have applied the data assimilation technique described by Rösevall et al. (2007) with a number of improvements to study the inter-annual Two SMR ozone products retrieved from the emission lines centred at 501 GHz and 544 GHz were used. An internal comparison of the two analyses using 501 GHz and 544 GHz ozone has been carried out by inspecting the vortex mean ozone in March and October during 2002and 2003-2012 in the Northern and Southern Hemisphere, respectively. Ozone de-10 rived from data assimilation using the two data sets match within 10% at the levels studied, while below 550 K in the Southern Hemispheremore than 50% of the difference is found. Here, 544 GHz ozone is 0.5 parts per million volume ( ppmv) lower than 501 GHz ozone because of better sensitivity in 544 GHz ozone in the lower stratosphere. Comparisons with other studies have been mainly performed against Sonkaew et al. (2013) since Sonkaew et al. (2013) is one of the few studies having consistent estimations of ozone depletion using a SCanning Imaging Absorption SpectroMeter for Atmospheric CHartographY (SCIA- IntroductionOzone depletion and climate change are indirectly linked. Several studies have predicted that the stratospheric cooling induced 5 by the increasing atmospheric carbon dioxide will enhance ozone depletion (Austin et al., 1992; Shindell et al., 1998). In practice, the Arctic lower stratosphere has been getting colder over the past decades (WMO, 2011). The linear dependence, demonstrated by (Rex et al., 2006), between the ozone depletion and the volume of air having temperature below the threshold for polar stratospheric cloud (PSC) formation implies that the stratospheric O 3 depletion in Northern Hemisphere may become worse if the cooling trend continues. It is therefore important to have continuous observations and trend analyses of the ozone 10 depletion.Ozone loss has been quantified by using a variety of techniques based on different assumptions and instruments (e.g. Eichmann et al., 2002;Grooß and Müller, 2003; Rex et al., 2006; Singleton et al., 2007; Tilmes et al., 2004; Tsvetkova et al., 2007). However, most of the studies were done for individual winters in the last decade. For instance, in the Arctic winter 2010/2011 several groups reported the unprecedented dramatic ozone depletion over the Arctic polar region approaching that 15 of the Antarctic ozone hole (e.g. Arnone et al., 2012; Manney et al., 2011; Sinnhuber et al., 2011). This winter was obviously different from other Arctic winters from 2000 since the polar vortex was strong and isolated the vo...

show abstract

Data assimilation: making sense of Earth Observation

Cited by 214 publications

References 219 publications

On the suitability of current atmospheric reanalyses for regional warming studies over China

On the suitability of current atmospheric reanalyses for regional warming studies over China

Improving Flood Prediction Assimilating Uncertain Crowdsourced Data into Hydrological and Hydraulic Models

A long term study of polar ozone loss derived from data assimilation of Odin/SMR observations

Contact Info

Product

Resources

About