No abstract

No abstract

A new static lighting concentrator with optical coupler

Agro‐climatic classification helps to determine the different features of a region. This climatic classification provides a useful insight for a farmer to grow their crops according to the conditions of their region. This study identifies the shifting of moisture index from average values in different agro‐climatic zones of Pakistan. Unpredictable climate remains dominant over long periods. Observational data of precipitation and evapotranspiration were used to determine the agro‐climatic zone during the period 1951–2010. This study reveals that almost 87% of Pakistan is in extremely arid to semi‐arid zones, a 5% decrease in over the last 30 years (1981–2010). The largest decrease of 8% and increase of 5% were observed in the extremely arid and humid zones, respectively. The semi‐arid zone is more vulnerable to drought, while intensity and severity are greater in the extremely arid region. An agro‐climatic regional analysis identifies 1952, 1969, 2000, 2001 and 2002 as years when the most severe droughts were observed during the study period. The trends of precipitation and temperature were performed at 95% significance level on a monthly, seasonal and annual basis over the entire agro‐climatic zone of Pakistan during 1951–2014. The annual precipitation trends show a significant increase of 0.828 mm year−1 in arid regions, whereas the maximum temperature trends shows a significant increase of 0.014 °C year−1 and 0.018 °C year−1 in extremely arid and humid regions, respectively. The trend of minimum temperature shows an increase over the whole region, which may place pressure on the water demands of crops.

Due to rapid growth of population, massive deforestation and anthropogenic activities, noticeable change in climate conditions is being observed in Pakistan. Increased aridity due to climate change is a growing environmental problem of the agricultural country like Pakistan. It is essential to assess and monitor aridity to combat the probable land degradation and drought desertification. Identification of arid and semi arid regions on climatic basis is the first essential step in any project of land reclamation for agricultural and other purposes.A geographic information system is used in this paper for the assessment of aridity in Pakistan from long term climatic data of fifty years This study will be a good predicator for agricultural scientist, agronomist and hydrologist to plan according the climate of the region.

No abstract

The climatology of precipitation and drought are analyzed by using different indices in the region of south central Asia (SCA). The spatial precipitation pattern is delineated by using principal component analysis (PCA) over the period of 1951–2010, which identifies six subregions in the SCA. The monthly and annual trends of precipitation were analyzed by applying the five statistical tests: Student’s t, Mann–Kendall, and Spearman’s rho tests for linear trend and turning point analysis and Sen’s slope for randomness and slope magnitude, respectively, at the α = 0.05 significance level. The time series analysis shows data similarity between Global Precipitation Climatology Centre (GPCC) and area-weighted precipitation of 52 meteorological stations in Pakistan, which results in a high correlation (R2 = 0.93). Two main drought periods were identified (1971 and 2000–02); also, 2001 was an extremely dry year in the SCA region. The drought in 1952 was the most severe in Pakistan; the longest drought period was 2000–02. Intense droughts were reported in the whole SCA region when the annual percent of precipitation was below 80%. It is noted that the A-5 region (northeast SCA), where 19 droughts were reported, is the most vulnerable. The monthly precipitation analysis shows a significant increasing trend in the months of September and June in the A-3 (northwest SCA) and A-5 regions, respectively, while a decreasing trend is observed in January and August in the A-4 region (east SCA). The decadal analysis shows significant decreasing trend (−21.5 mm decade−1) in region A-4, while the highest increasing trends (17.1 and 7.5 mm decade−1) are observed in Pakistan and the A-5 region respectively.

No abstract