Diagnosis of Tropospheric Moisture over Saudi Arabia and Influences of IOD and ENSO

Abstract

A diagnostic study of atmospheric moisture data over Saudi Arabia derived from a 43-yr National Centers for Environmental Prediction–National Center for Atmospheric Research (NCEP–NCAR) reanalysis revealed that moisture convergence in the lower troposphere and divergence in and above the middle troposphere occurs throughout the year. Although the amount of precipitable water content in the middle troposphere is high, precipitation is less than expected over this semiarid region during a boreal summer monsoon season because of strong moisture divergence. The net tropospheric moisture flux over the arid and semiarid regions of Saudi Arabia shows seasonal and interannual variability. The seasonal variability has a strong semiannual signal with its primary peak February–April and its secondary peak June–August. This pattern is consistent with a similar semiannual signal observed in rainfall climatology. The restricted moisture supply to southwestern Saudi Arabia during summer presumably explains the lack of precipitation in other areas of the country. Winter precipitation, however, is widespread. The increased transport of net atmospheric moisture flux is higher during El Niño and positive Indian Ocean dipole (IOD) phenomena. During these events, influx across the Red Sea (west) side of Saudi Arabia increases. The net flux to the region is reduced by a slight increase of outflux across the Persian Gulf (east) side. Reanalysis data and model-sensitivity experiments show that El Niño or a concurrent positive IOD and El Niño event more strongly amplify net transport than does an independent positive IOD event. The partial-lag correlation analysis with net moisture flux from the Red Sea side shows that the positive IOD mode has a peak correlation coefficient of ∼0.5 with close to a 5-month lead and that El Niño has a peak correlation coefficient of ∼0.6 with close to a 2-month lead.

Assessment of uncertainties in projected temperature and precipitation over the Arabian Peninsula: a comparison between different categories of CMIP3 models

“…The mountain ranges have sharp elevation to the west near the Red Sea and they gradually decrease towards the East. The western sharp edge of the mountain facing the Red Sea plays an important role in the occurrence of heavy rainfall in the peninsula (Chakraborty et al 2006). In general, the climate of the peninsula is characterized by arid and semi-arid (Almazroui et al 2012b).…”

Dynamical downscaling of rainfall and temperature over the Arabian Peninsula using RegCM4

“…In fact, the NAP sub-region is mainly low-elevation terrain, while the SAP incorporates more complex terrain. In addition, the NAP climate is mainly influenced by mid-latitude circulations, while the SAP climate is mainly influenced by south-westerly monsoons (Chakraborty et al 2006), where local topography plays a role in enhancing convective systems (Abdullah & Al-Mazroui 1998). This drives a doublepeaked rainy season over the SAP and a unimodal annual cycle over the NAP (e.g.…”

Seasonal characteristics of the large-scale moisture flux transport over the Arabian Peninsula

“…Because of the close proximity and intimate relationship of the Findlater/Somali Jet with the Indian/Asian summer monsoon, the study of the Arabian Sea wind and moisture circulations has been the subject of several studies, based on the various climatic datasets (see, for instance, Min and Schubert 1997;Chakraborty et al 2006a;JianQi et al 2008, including the pioneering moisture flux analysis over deserts by Starr and Peixoto (1958)). For a description of the surface winds behavior during the active Somali Jet period (May-June), see, for instance, Halpern and Woiceshyn (1999).…”