Analysis of hydro-climatic interactions in SE Asia using data-based modelling

The identification and quantification of hydro-climatic cycles is important for un- derstanding land-atmosphere interactions, and is useful for evaluating the outputs of General Circulation Models (GCMs). This is particularly relevant in Southeast Asia, where tropical convection contributes a large influx of energy and moisture to the upper atmosphere. The analyses presented here cover interactions over a range of temporal scales, from diurnal to inter-annual. They also cover a range of spatial scales, including both observations and GCM outputs at inter-regional scales, and observations at intra-regional scales. Data Based M?delling (DBM) methods are used as an innovative way of iden- tifying climate signals from noisy data, and of estimating the uncertainties in complex environmental systems. Cycles and trends are identified using Dynamic Harmonic Regression, and rainfall and river discharges are investigated using Transfer Functions. To complement established DBM methods, a new approach is presented for analysing and comparing hydrograph peaks from different catchments . . For the inter-regional observational analyses, existing time series of observed net radiation, rainfall, latent heat flux and river discharge are obtained from typical , SE Asian regions. These series are used to identify temporal cycles and trends, and to evaluate inter-regional variations and their influences at different time scales. There are relatively few such studies available for the Tropics, so this investigation helps to fill a gap and to provide a baseline for evaluating future studies and/or GeM Land Surface Schemes (LSSs) are known to provide a POor repreSentation of climatic cycles in the humid tropics. For the inter-regional GeM model analyses, outputs from the UK Met Office HadGAMl model Were obtalned for the relevant SE Asian grid cells. These outputs were used to identify temporal dynamics in a similar way to the analysis of observations. The analysis of model outputs Was used to investigate how well the model simulates climate variability, and to explore the underlying physical processes. The analysis of intra-regional observations presents a comparison of rainfall and catchment discharges within a particular tropical region, namely the Danum Valley, in the Sabah region of Borneo. The analysis focuses on high-resolution variability in different-sized catchments, in an attempt to target the temporal and spatial resolution that characterises the humid tropics but is less well represented by LSSs within climate models.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Design and laboratory testing of a new flow-through directional passive air sampler for ambient particulate matter

A new type of directional passive air sampler (DPAS) is described for collecting particulate matter (PM) in ambient air. The prototype sampler has a non-rotating circular sampling tray that is divided into covered angular channels, whose ends are open to winds from sectors covering the surrounding 360 degrees. Wind-blown PM from different directions enters relevant wind-facing channels, and is retained there in collecting pools containing various sampling media. Information on source direction and type can be obtained by examining the distribution of PM between channels. Wind tunnel tests show that external wind velocities are at least halved over an extended area of the collecting pools, encouraging PM to settle from the air stream. Internal and external wind velocities are well-correlated over an external velocity range of 2.0-10.0 m s(-1), which suggests it may be possible to relate collected amounts of PM simply to ambient concentrations and wind velocities. Measurements of internal wind velocities in different channels show that velocities decrease from the upwind channel round to the downwind channel, so that the sampler effectively resolves wind directions. Computational fluid dynamics (CFD) analyses were performed on a computer-generated model of the sampler for a range of external wind velocities; the results of these analyses were consistent with those from the wind tunnel. Further wind tunnel tests were undertaken using different artificial particulates in order to assess the collection performance of the sampler in practice. These tests confirmed that the sampler can resolve the directions of sources, by collecting particulates preferentially in source-facing channels

Field-testing a new directional passive air sampler for fugitive dust in a complex industrial source environment

Quantifying the sources of fugitive dusts on complex industrial sites is essential for regulation and effective dust management. This study applied two recently-patented Directional Passive Air Sampler (DPAS) to measure the fugitive dust contribution from a Metal Recovery Plant (MRP) located on the periphery of a major steelworks site. The DPAS can collect separate samples for winds from different directions (12 x 30° sectors), and the collected dust may be quantified using several different measurement methods. The DPASs were located up and down-prevailing-wind of the MRP processing area to (i) identify and measure the contribution made by the MRP processing operation; (ii) monitor this contribution during the processing of a particularly dusty material; and (iii) detect any changes to this contribution following new dust-control measures. Sampling took place over a 12-month period and the amount of dust was quantified using photographic, magnetic and mass-loading measurement methods. The DPASs are able to effectively resolve the incoming dust signal from the wider steelworks complex, and also different sources of fugitive dust from the MRP processing area. There was no confirmable increase in the dust contribution from the MRP during the processing of a particularly dusty material, but dust levels significantly reduced following the introduction of new dust-control measures. This research was undertaken in a regulatory context, and the results provide a unique evidence-base for current and future operational or regulatory decisions

Directional Analysis of Sub-Antarctic Climate Change on South Georgia 1905-2009

Directional analysis has been used to study changes in the sub-polar climate of the mountainous and glacierised sub-Antarctic island of South Georgia (54-55°S, 36-38°W). Significantly for climate change studies, South Georgia lies in the Scotia Sea between polar and temperate latitudes, and approximately 1000 km northeast and downwind of the Antarctic Peninsula - one of the fastest-warming regions on Earth (Vaughan et al., 2001). South Georgia was chosen for directional analysis because its climate is substantially advected by predominantly westerly circulations, and because it has a long (since 1905) meteorological record from King Edward Point (KEP) on its eastern side. Additional shorter records from Bird Island at the northwest tip of South Georgia allow comparison between windward (Bird Island) and leeward (KEP) climate regimes. The variation of mountain barrier heights with direction from KEP allows climate changes to be studied under different amounts of orographic influence (from ~700 m to ~2200 m). Records of glacier advance and retreat provide further independent evidence of climate change for comparison with the meteorological record. Directional climate analysis is based on a series of monthly-mean pressure fields defining the orientation and strength of synoptic-scale air-mass advection over the Scotia Sea. These fields are used to define directional climatologies for six 30° sectors with bearings from 150-180° to 300-330°; these sectors encompass 99% of recorded months since 1905. The climatologies summarise the frequencies of air masses from each sector, and the accompanying temperatures and precipitation. The 6 sectors can be broadly associated with 4 air-mass types and source regions: (i) sectors 150-210° advect cold polar maritime air that originated over the Antarctic continent before passing over the Weddell Sea, (ii) sectors 210-270° advect warmer, more stable polar maritime air from the Bellingshausen Sea/Antarctic Peninsula region, (iii) sector 270-300° has warmer, drier returning polar maritime circulated from the Bellingshausen Sea and across the Andes, and (iv) sector 300-330° has warm, humid tropical maritime air from the South Atlantic High. Detailed climatologies are compared for 4 distinct time periods covering: glacier advance (1920-1951), glacier retreat (1951-82), the latest decade (2000-2009), and a reference period (1905-1982). The comparisons show how climate changes between periods are composed of alterations in (i) air-mass frequency from different sectors, and (ii) temperature and precipitation within sectors. The ability of directional analysis to explain climate-change processes is confirmed by comparing directional results for the periods of glacier advance and glacier retreat. Specifically, during the ‘advance’ period the air masses came 20% more frequently from the 4 colder, southerly sectors and correspondingly less frequently from the 2 warmer, northerly sectors. Moreover, the temperature of air coming from each sector was 0.1-0.8°C cooler than during the ‘retreat’ period. Further directional analysis will compare records from the latest decade with previous periods to investigate recent sub-polar climate change, and particularly any advected warming from the Antarctic Peninsula. Directional analysis and advection climatologies can be used to test climate model performance and to examine atmospheric processes under changing climates. Previous directional analyses in an upland region of northwest England have detected changes in its mid-latitude temperate climate that were masked by directionally unsorted data (Malby et al., 2007, Ferranti et al., 2009); the South Georgia study now shows how similar methods can give insights into sub-polar climate change

Directional ammonia. Final report.

Directional passive samplers have been developed by EA/LEC (Lin et al, 2010a; Lin et al, 2010b, Lin et al, 2011; Ferranti 2012) and one application they could be potentially used for is ammonia source monitoring. The Whim ammonia release experiment site was used to test the EA/Lancaster directional passive ammonia samplers (DPAS) downwind of a line source of ammonia gas. The aim of the experiments was to assess the performance of the DPAS systems for monitoring the directional distribution of ammonia at this site. Two types of ammonia samplers were tested in the DPAS systems, both of which have been developed by CEH Edinburgh: the CEH Adapted Low-cost Passive High Absorption (ALPHA) sampler (Tang et al., 2001) and the CEH Mini Annular Denuder (MANDE) flux sampler. Testing was carried out over a period of six months with 5 exposure periods. This report summarises the results from these experiments and presents some discussion and interpretation. ALPHA samplers proved not well suited for use in DPAS systems for two reasons: Firstly ALPHAs are designed to monitor concentration, whereas the DPAS system is designed to monitor fluxes. Effectively, ALPHAs use diffusive membranes to control the collection of gaseous species so that collection is by diffusion rather than by interception of fluxes. The second, related drawback was that the continuous diffusional sampling by the ALPHA samplers: ammonia as it disperses throughout the internal DPAS chamber becomes well mixed and hence each DPAS direction sampled slowly but continuously leading to a high “background” contribution to the measured ammonia mass in addition to the ammonia brought in with the specific wind direction. MANDE samplers were much more successfully used in the DPAS. Though they also have a level of ammonia diffusion within the DPAS housing samplers leading to an above background ammonia measurement in all directions, this is an order of magnitude smaller effect than with the ALPHA. The direction in which the ammonia is coming from is clearly identifiable: in this case the line source release directions. Using the frequency of wind direction and the sampling rate of the MANDE as a function of wind speed, a wind run concept developed by EA/LEC has been applied to the data to calculate a “weighted ammonia wind run” which clearly shows a good reflection of the directions from which the ammonia was emitted. Overall the DPAS-MANDE combination shows significant potential for studying the directional variation of ammonia in the environment when deployed in conjunctional with meteorological measurements. One caveat to be highlighted is that further work is required to assess sampling rate – wind-speed variation in order to move from a weighted ammonia wind run measurement to interpretation in terms of atmospheric ammonia concentrations